UNITED STATES GOVERNMENT
MEMORANDUM

To: Public Information (MS 5030)
Plan Coordinator, FO, Plans Section (MS 5231)

Public Information copy of plan

Control # - N-09781

Type - Initial Exploration Plan

Lease(s) - OCS-G32556 Block - 19 Atwater Valley Area OCS-G33863 Block - 18 Atwater Valley Area
Operator - Anadarko Petroleum Corporation

Drill & Complete Wells CC, DD, GG, GV, QQ, EE, KK, KV

Not Found

Attached is a copy of the subject plan.

It has been deemed submitted as of this date and is under review for approval.

Tonya Jez Plan Coordinator

G33863/AT/18
G33863/AT/18
G32556/AT/19
G33863/AT/18
G33863/AT/18
G32556/AT/19
G32556/AT/19
G33863/AT/18 4267 FSL, 6783 FEL 7512 FSL, 3926 FEL 7452 FNL, 6272 FWL 2761 FNL, 2730 FEL 2820 FNL, 1653 FEL 705 FSL, 5349 FWL 1726 FSL, 5336 FWL 2055 FNL, 2638 FEL G33863/AT/18
G33863/AT/18
G32556/AT/19
G33863/AT/18
G33863/AT/18
G32556/AT/19
G32556/AT/19
G33863/AT/18 WELL/CC
WELL/DD
WELL/EE
WELL/GG
WELL/GV
WELL/KK
WELL/KV WELL/QQ Botm Lse/Area/Blk Surface Location Surf Lse/Area/Blk Site Type/Name Description -

Rig Type - Subject: From: April 28, 2014

## INITIAL EXPLORATIO N PLAN (N-9781)

ANADARKO PETROLEUM CORPORATION

ATWATER VALLEY BLOCK 18/19 OCS-G 33863/32556

PUBLIC COPY

RECORD OF CHANGE LOG

Submission Type Date Sent to BOEM Summary of Submission Page Numbers

Initial 2/3/2014 Initial EP submission. All Amendment 3/10/2014 Submit PDF copy of OCD air modeling report (printed copy submitted with Initial EP submittal). N/A

Amendment 4/11/2014 Submit CALPUFF air modeling protocol per BOEM/Fish & Wildlife request. N/A

Final Copy of Plan 4/17/2014 Complete Initial EP submittal with amendments included. All
Add Record of Change Log 4/17/2014 Add record of change log. 1

# PUBLIC

INITIAL EXPLORATION PLAN

ATWATER VALLEY BLOCK 18/19 OCS-G 33863/32556

OFFSHORE, LOUISIANA & MISSISSIPPI

Anadarko Petroleum Corporation
1201 Lake Robbins Drive The Woodlands, Texas 77380 Contact: Bridget O’Farrell Bridget.OFarrell-Villarreal@anadarko.com (832) 636-1694

1 – Hard Copy Confidential
1 – CD Confidential 1 – Hard Copy Public Information
1 – CD Public Information



### January 2014

## INITIAL EXPLORATION PLAN LEASE OCS-G 33863/32556 Atwater Valley Block 18/19

A. Plan Contents

B. General Information

C. Geological, Geophysical

D. Hydrogen Sulfide Information

E. Biological, Physical and Socioeconomic Information

F. Wastes and Discharge Information

G. Air Emissions Information

H. Oil Spill Information

I. Environmental Monitoring Information

J. Lease Stipulations

K. Support Vessels and Aircraft Information

L. Onshore Support Facilities Information

M. Coastal Zone Management Act Information

N. Environmental Impact Analysis

O. Administrative Information

## SECTION A PLAN CONTENTS

(a) Plan Information Form

Under this Initial Exploration Plan (EP), Anad arko Petroleum Corporati on (Anadarko) proposes to drill and complete eight wells total in Atwater Valley 18/19.

 Five well locations will be in Atwater Valley 18: Location CC, DD, GG, GV and QQ.

 Three well locations will be in Atwa ter Valley 19: Location EE, KK and KV.

The wells will be drilled using a dynamically pos itioned (DP) drillship or DP semi-submersible drilling rig. Drilling and completion operations fo r all well locations w ill utilize a subsea BOP
stack. OCS Plan Information Form BOEM-137 is enclosed as Attachment A-1.

(b) Location

Enclosed as Attachment A-2 is a well location plat at a scale of 1 inch = 2,000 feet that depicts the surface locations and water depth of the proposed wells.

(c) Safety and Pollution Prevention Features

Safety features on the drilling rig will include well control, pollution prevention, safe welding procedures, and blowout prevention equipment as described in Title 30 CFR Part 250, Subparts C, D, E, G and O; and as fu rther clarified by BOEM/BSEE Notices to Lessees, and applicable regulations of the Environmenta l Protection Agency and the U.S. Coast Guard. The appropriate life rafts, life jackets, ring buoys, etc., as prescr ibed by the U.S. Coast Guard, will be maintained on the facility at all times.

### (d) Storage Tanks and Production Vessels

The proposed wells will be drilled with a DP dr illship or DP semi-submersible drilling rig.

Type of Facility Type Of Storage
Tank Tank Capacity Number of Tanks Total Capacity Fluid Gravity

(API) Total Capacity of all Tanks for Rig Type

DP Drillship Fuel Oil Storage Tank 5,514 bbls 2 11,028 bbls No. 2 Diesel 12 tanks total= 62,874 bbls

Fuel Oil Storage Tank 12,458 bbls 2 24,916 bbls No. 2 Diesel

Fuel Oil Storage Tank 12,065 bbls 2 24,130 bbls No. 2 Diesel

Fuel Oil Settling
Tanks 640 bbls 2 1,280 bbls No. 2 Diesel

Fuel Oil Service
Tanks 480 bbls 3 1,440 bbls No. 2 Diesel

Fuel Oil Emergency
Generator Tank 80 bbls 1 80 bbls No. 2 Diesel

DP SemiSubmersible Fuel Oil Hull Tanks 4,541 bbl s 2 9,082 bbls No. 2 Diesel 7 tanks total= 16,689 bbls

Fuel Oil Hull Tanks 3,392 bbl s 2 6,784 bbls No. 2 Diesel

Fuel Oil Deck Day
Tank 629 bbls 1 629 bbls No. 2 Diesel

Fuel Oil Deck Settling
Tank 164 bbls 1 164 bbls No. 2 Diesel

Fuel Oil Emergency
Generator 30 bbls 1 30 bbls No. 2 Diesel

### (e) Pollution Prevention Measures

The drilling rig utilized for these operations will comply with all applicable regulations regarding pollution prevention and control. The rig has a Shipboard Oil Pollution Emergency Plan (SOPEP), which is reviewed and approved annually by the American Bureau of Shipping (ABS). The SOPEP is provided to assist employees in d ealing with an unexpected discharge of oil. Its primary purpose is to set in motion the necessary actions to stop or minimi ze the discharge of oil and to mitigate its effects. Effective planning en sures that the necessary actions are taken in a structured, logical and timely manner.

Pollution prevention measures includ e installation of curbs, gutters, drip pans, and drains on deck areas to collect all contaminants and debris. Most deck drains and some of the joints at the edge of the rig floor go overboard or into the moon pool, respectively. To prevent ocean discharge from the drains there is a dedicated drip pan un der the rotary table. The pipe racks, mud pump room, sack store, and drill floor drains go to a holding tank, which is se rved by a dedicated oily water separator. The well test area, engine room , and other major machinery spaces drains all go to slops tanks, which are served by a large general-serv ice, oily water separa tor. The containment devices are temporary. They are not meant for perm anent storage of waste. On the rare occasion that they contain wastes, they are pumped, moppe d, or cleaned within a short period of time. The chances of damage to a containment structur e during such time as it contains wastes are exceedingly small.

(f) Additional Pollution Prevention Measures

No additional measures are proposed under this pla n. The activities proposed in this plan are not
located offshore Florida.

(g) Description of Previously Approved Lease Activities

Anadarko does not have previously approve d well locations in Atwater Valley 18/19.

BHP Billiton Petroleum (GOM) Inc. previously had an Initial Exploration Plan approved for Atwater Valley 18 only. Anadarko will not be re vising or utilizing any of the well locations approved under Plan Control No.: N-7103.

Control # Plan Type/Approval Well Location(s) Status of Well Location

N-7103 Initial EP Approved A
B
C Previously permitted locations. AT 18 #001 was PA’d. Open location Open locationU.S. Department of the Interior   20%&RQWURO1XPEHU %XUHDXRI2FHDQ(QHUJ\0DQDJHPHQW 20%$SSURYDO([ SLUHV 

### OCS PLAN INFORMATION FORM

General Information
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Project and Worst Case Discharge (WCD) Information
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Description of Proposed Activities and Tentative Schedule (Mark all that apply)

Proposed Activity Start Date End Date No. of Days

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Description of Drilling Rig Description of Structure
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Description of Lease Term Pipelines
From (Facility/Area/Block) To (Facility/Area/Block) Diameter (Inches) Length (Feet)

Form BOEM- 0137 'HFHPEHU

- 6XSHUVHGHVDOOSUHYLRXVHGLWLRQVRIWKLVIRUPZKLFKPD\QRWEH XVHG Exploration drilling, completion & installation of subsea wellhead and/or manifold-AT 18, CC

Exploration drilling, completion & installation of subsea wellhead and/or manifold-AT 19, KV 

### A ttachment A-1

X

Anadarko Petroleum Corporation 00981
Bridget O'Farrell

1201 Lake Robbins Dr. 832-636-1694

The Woodlands, TX 77380 Bridget.OFarrell-Villarreal@anadarko.com

$29,384.00 Pay.gov: 25DV21AG, Agency: 74556983633

OCS-G33863/32556 AT 18/19 Stromboli

X X Fourchon (primary); Alt. Galveston, Cameron, Lake Charles, Houma, Pascagoula

GV (AT 18)/KV (AT 19) 63,744 bbls (AT 18) / 250,188 bbls (AT 19) 28.7

71 63,744 bbls (AT 18) / 250,188 bbls (AT 19)

X

X

X

X

6/24/2014 12/31/2014 190

3/1/2015 9/7/2015 190

4/25/2016 11/1/2016 190

11/4/2016 5/13/2017 190

9/6/2017 3/15/2018 190

7/10/2018 1/16/2019 190

1/1/2020 7/9/2020 190

7/1/2020 7/9/2021 190

X

XOCS PLAN INFORMATION FORM ( CONTINUED ) Include one copy of this page for each proposed well/structure Proposed Well/Structure Location

Well or Structure Name/N umber (If renaming well or structure, reference previous name): Previously reviewed under an approved EP or
DOCD? S-7363 Yes No

Is this an existing well
or structure? Yes No If this is an existing we ll or structure, list the Complex ID or API No. Do you plan to use a subsea BOP or a surface BOP on a floa ting facility to conduct your proposed activities? Yes No

WCD info For wells, volume of uncontrolled blowout (Bbls/day): For structures, volume of all storage and pipelines (Bbls): API Gravity of fluid

Surface Location Bottom-Hole Location (For Wells) Completion (For mult iple completions, enter separate lines)

Lease No. OCS OCS OCS
OCS

Area Name

Block No.

Blockline Departures (in feet) N/S Departure: F____ L N/S Departure: F____ L N/S Departure: F____ L N/S Departure: F____ L N/S Departure: F____ L E/W Departure: F____ L E/W Departure: F____ L E/W Departure: F____ L E/W Departure: F____ L E/W Departure: F____ L

Lambert XY
coordinates X: X: X:
X:
X:

Y: Y: Y:
Y:
Y:

Latitude/ Longitude Latitude Latitude Latitude
Latitude
Latitude Longitude Longitude Longitude Longitude Longitude Water Depth (Feet): MD (Feet): TVD (Feet):

Anchor Radius (if applicable) in feet: MD (Feet): MD (Feet): MD (Feet): TVD (Feet): TVD (Feet): TVD (Feet):

Anchor Locations for Drilling Rig or Construction Barge ( If anchor radius supplied above, not necessary)

Anchor Name
or No. Area Block X Coordinate Y Coordinate Length of Anchor Chain on Seafloor

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

Form BOEM- 0137 (December 2011 - Supersedes all previous editions of this form which may not be used.)

# AT 18 “Gnome” 

# Stromboli Prospect

APC SL

‐ AT 18 “DD”

X:978173 Y:10145103

Lat: 27.941 Lon: ‐ 89.052
7512’ FSL, 3926’ FEL

APC SL

‐ AT 18 “CC”

X:975301 Y:10141870

Lat: 27.932 Lon: ‐ 89.060
4267’ FSL, 6783’ FEL APC SL

‐ AT 19 “EE”

X:988360 Y:10145062

Lat: 27.942 Lon: ‐ 89.020
7452’ FSL, 6272’ FWL

APC SL

‐ AT 19 “KV”

X:987423 Y:10139337

Lat: 27.926 Lon: ‐ 89.023
1726’ FSL, 5336’ FWL

APC SL

‐ AT 19 “KK”

X:987439 Y:10138306

Lat: 27.923 Lon: ‐ 89.023
705’ FSL, 5349’ FWL



# SHL PLAT 

# 18 19 APC SL

‐ AT 18 “GV”

X:980582 Y:10150777

Lat: 27.597 Lon: ‐ 89.045
2820’ FNL, 1653’ FEL APC SL

‐ AT 18 “GG”

X:979365 Y:10150705

Lat: 27.957 Lon: ‐ 89.048
2761’ FNL, 2730’ FEL APC SL

‐ AT 18 “QQ”

X:979462 Y:10151381

Lat: 27.597 Lon: ‐ 89.048
2055’ FNL, 2638’ FEL

### SECTION B GENERAL INFORMATION

(a) Applications and Permits

Prior to beginning exploration operations the following application(s) will be submitted for approval:

Application/Permit Issuing Agency Status
Permit to Drill Bureau of Safety and Environmental Enforcement (BSEE) To be submitted

(b) Drilling Fluids

Type of Drilling Fluid Estimated Volume Per Well Water-based (NaCl saturated, seawater, freshwater, barite) for Pump and Dump 19,000 bbls

Synthetic-based (internal olefin, ester) 18,500 bbls
Oil-based N/A

(c) Oils Characteristics

Oil will not be produced under this Initial Explor ation Plan. Therefore th e oils characteristics information is not required per NTL 2008-G04 2(d), extended by NTL 2014-G03.

(d) New or Unusual Technology

Anadarko does not propose to use any new or u nusual technology to drill the wells proposed in this plan.

(e) Bonding Statement

The bond requirements for the activities and facili ties proposed in this EP are satisfied by an
area-wide bond furnished and maintained accord ing to 30 CFR Part 556, subpart I; NTL 2000- G16, “Guidelines for General Lease Sure ty Bonds,” and National NTL 2008-N07, “Supplemental Bond Procedures”.

(f) Oil Spill Financial Responsibility (OSFR)

Anadarko Petroleum Corporation (Company Number 00981) has demonstrated oil spill financial responsibility for the facilities proposed in this EP according to 30 CFR Part 553, and NTL 2008-N05, “Guidelines for Oil Sp ill Financial Responsibility for Covered Facilities”.

### (g) Deepwater Well Control Statement

Anadarko Petroleum Corporation (Company Number 00981) has the financia l capability to drill a relief well and conduct other emergenc y well control operations if required.

(h) Blowout Scenario

Purpose

This overview provides a generic blowout scenario, additional information regarding any potential oil spill, and the measures Anadarko w ill take to prevent a blowout and if necessary promptly respond to manage a blowout scenario if one occurs. Th e following overview is pursuant with 30 CFR 250.213(g), 250.219, 250.250 and NTL No. 2010-N06.

Background

The Atwater Valley 18, Location GG well is current ly the primary drill location and is located 2,735 ' FNL & 2,715 ' FEL (in Atwater Valley 18). This overview has been developed to document the additional information requirement s for Exploration Plans as requested by NTL
No. 2010-N06

Information Requirements:

Blowout Scenario

The Atwater Valley 18, Location GG well is to be drilled utilizing a M ODU rig with a marine riser and sub-sea BOP. A typical casing program will be used including a wellhead system, conductor casing, surface casing, intermediate casi ng, as well as two drilling liners to reach the planned total depth.

The blowout scenario assumes that a hydrocarbon influx occurs followed by a well control event from the objective sands. The sub-sea BOP an d marine riser subsequently fail followed by a
blowout to the seabed. The worst case discharge (WCD) scen ario assumes 8-1/2 " open hole with
a 9-7/8 " drilling liner, an 11-7/8 " drilling liner, and 14 " intermediate casing string set.

The WCD scenario for the Atwater Valley 18, Location GV (location with highest WCD flow rate in AT 18) assumes a 10-5/8" OH with an 11- 7/8" drilling liner and 14" intermediate casing string.

The WCD scenario for the Atwater Valley 19, Location KV (location with highest WCD flow rate in AT 19) assumes a 14" OH with a 14" intermediate casing string.

### Estimated flow rate of the potential blowout for Atwater Valley 18, Location GG (Primary drill location):

Category Initial EP Type of Activity Exploration Drilling Facility Location (area/block) AT 18 Facility Designation Location GG Distance to Nearest Shoreline (miles) 71 Uncontrolled blowout (volume per day) 50,781 bbls Type of Fluid(s) Crude Oil



### Estimated flow rate of the potential bl owout for Atwater Valley 18, Location GV:

Category Initial EP Type of Activity Exploration Drilling Facility Location (area/block) AT 18 Facility Designation Location GV Distance to Nearest Shoreline (miles) 71 Uncontrolled blowout (volume per day) 63,744 bbls Type of Fluid(s) Crude Oil



### Estimated flow rate of the potential bl owout for Atwater Valley 19, Location KV:

Category Initial EP Type of Activity Exploration Drilling Facility Location (area/block) AT 19 Facility Designation Location KV Distance to Nearest Shoreline (miles) 71 Uncontrolled blowout (volume per day) 250,188 bbls Type of Fluid(s) Crude Oil



### a) Potential for the well to bridge over:

Discussions regarding geologic information ar e considered proprietary and have been omitted from this public copy of the EP.

### b) Likelihood and measures taken for surface and/or sub-sea intervention to stop the
blowout:

The likelihood of surface intervention to prev ent, or stop, a blowout is high and is based on the following equipment specific to a capable MODU that will be contracted to do this drilling program:

 ROV Secondary BOP Control System: The BOP will be confirmed to have
an ROV Intervention Panel and circuits that have the following attributes:

 Hot stab capable of closing one set of:

 Blind-Shear Rams

 Pipe Rams

 Unlatch the Lower Marine Riser Package

 Hot stab has been function tested in conjunction with the stump test and was tested at the same rate and pressure as the pump installed on the ROV used by the rig.

The panel can also be operated by an ROV from an independent supply boat in the event of a loss of rig scenario.

 Deadman/Autoshear function: The rig will be equipped with an automated sequence that closes the blind shear rams in the event of any of the following scenarios:

 Inadvertent disconnect of the LMRP

 Loss of both hydraulic pressure an d electrical supply from the surface BOP control system

No human interface is to be required once these systems are armed.

c) Availability of a rig to drill a relief well:

As per the Mutual Aid agreements between E&P Operators in the Gulf of Mexico, Anadarko will select from the best rig option av ailable in the Gulf of Mexico fleet if, and when, it is required for relief well work.

As of January 15, 2014 there were 14 additional rigs in the Gulf of Mexico which would be capable of operating under the conditions asso ciated with drilling a relief well for this prospect. A rig which could be used to drill a relief well is the Discoverer India which is a dynamically positioned drillship capable of operating in the water depths, and drilling to the total well depths, associated with a relief well for this prospect. The rig is currently
under contract to Chevron and is on location in Walker Ridge 143.

There are no nearby platforms from which to drill a relief well. It is not feasible to drill a
relief well from land.

### d) Rig constraints:

A rig with a 15,000 psi BOP stack and capable of drilling in 5,000 ' of water is required for any relief well operations.

e) Time taken to mobilize a rig and drill a relief well:

An estimated 7-21 days is required to suspend operations on a deepwater GOM well,
mobilize to a relief well loca tion, and begin relief well drill ing operations. This estimate includes 0-14 days to suspend current opera tions on an existing well and 7 days to
mobilize to location and be r eady to spud a relief well. The estimated time to drill the relief well and perform kill operations is 180 days for an estimated total of 187-201 days from time of blowout to completion of a relief well.

The time estimate provided for the plan well is inclusive of 'both' drilling 'and' completion operations. As a completion is no t typically part of relief well operations no time has been included for completion operations in the relief well estimate. Therefore
the estimated time for a relief well should be less than for the plan well. In addition, information and learning from the drilling of the original well ma y provide opportunities to optimize drilling performance for relief we ll operations and thus reduce the required drilling time.

f) Assumptions and calculations used in a pproved or proposed Oil Spill Response
Plan:

Regional OSRP–Green Canyon 683, Location G (Approved 9/25/13)

 The Merlin reservoir simula tor and Avalon nodal analysis programs were used to
estimate the WCD. The estimated worst case discharge for Green Canyon 683 #002 (Location G) is 403,608 bbls. (Plan Control No.: S-7623)

 The maximum total volume during a blow out could potentially be 61,752,024 bbls assuming 153 days for the maximum durati on of a blowout, multiplied by the worst case daily uncontrolled bl owout volume of 403,608 bbls.

 The volume denoted in the Regional OSRP is higher than the NTL 2010-N06 (403,608 bopd) calculations submitted under th e Supplemental EP. Anadarko elected to denote a higher volume (410,000 bbls) in the Regional OSRP for planning purposes to demonstrate additional equipm ent response capabilities per previous discussions with Mr. Mike Tolbert, OSRD.

### Initial EP–Atwater Valley 18, Location GG (WCD for Primary Drill Location)

 Nodal analysis was performed to calcu late worst case discharge volumes. The estimated worst case discharge for the well is 50,781 bopd.

 The maximum total volume during a blowout at Atwater Valley 18, Location GG could potentially be 10,206,981 bbls assuming 201 days for the maximum duration of a blowout, multiplied by the worst case daily uncontrolled blowout volume of 50,781 bopd.

Initial EP–Atwater Valley 18, Locat ion GV (Highest WCD for AT 18)

 Nodal analysis was performed to calc ulate worst case discharge volumes. The estimated worst case discharge for the well is 63,744 bopd.

 The maximum total volume during a blowout at Atwater Valley 18, Location GV could potentially be 12,812,544 bbls assuming 201 days for the maximum duration of a blowout, multiplied by the worst case daily uncontrolled blowout volume of 63,744 bopd.

Initial EP–Atwater Valley 19, Locat ion KV (Highest WCD for AT 19)

 Nodal analysis was performed to calcu late worst case discharge volumes. The estimated worst case discharge for the well is 250,188 bopd.

 The maximum total volume during a blowout at Atwater Valley 19, Location KV could potentially be 50,287,788 bbls assuming 201 days for the maximum duration of a blowout, multiplied by the worst case daily uncontrolled blowout volume of 250,188 bopd.

### g) Measures taken to enhance the ability to prevent or reduce the likelihood of a
blowout

 Well design : Anadarko utilizes a systematic we ll design process for the planning and construction of a well operation. This pr ocess utilizes the depth of experience Anadarko possesses in the deepwater aren a and involves a multi-disciplinary team peer review of the well design, shallow h azards, and formation pressure hazards expected during the drilling pha se of the well. This process minimizes the potential for an unplanned well control event that coul d lead to a blowout. This process will also include Professional Engineer review and certification of the final casing design and cementing program.

A detailed pre-drill assessment of form ation pressure provided by Anadarko’s Geologic/Geophysical team, along with th ird party consultants, allows for development of a mud program that provi des an overbalanced mud weight for the safe drilling of the well. For an expl oration well this may also include taking formation pressures to confirm the act ual formation pressure during the well construction process and minimize the risk of an unplanned well control event.

The well construction process also require s a systematic review and management acceptance of the start-up preparation work for the rig and crews along with the third party technical audit work on the rig and the rig’s well control equipment. This review and audit process measures the ri g’s ability to handle an unplanned well control event and provides assurance that the rig can successfully mitigate a loss of well control event and prevent it fr om becoming a blowout scenario.

 Barrier Philosophy: For all well designs, Anadar ko requires and uses a redundant barrier philosophy, that being two independent barriers for both internal and external flow paths in the final wellbore. It is also standard practi ce to conduct pressure testing, in accordance with the applicable regulations, to evaluate integrity on all relevant barriers. In addition, all intermed iate and production casings returned to the
wellhead will be locked down before subse quent wellbore constr uction proceeds.

 BOP and well control equipment: The rig will have an 18-3/4 " 15,000 psi BOP with primary and secondary BOP control systems. The BOP will have been completely recertified compliant to OEM sp ecifications and all applicable federal regulations by a qualified th ird party. Prior to commencement of operations an independent third party verification will be obt ained to verify that the subsea BOP is designed for the specific equipment on th e rig and this specific well design.

###  BOP and well control equipment testing : To ensure effectiveness of the BOP and well control equipment, a testing program will be conducted prior to running the BOP and then during drilling operations as well. This testing program will be in compliance with applicable federal regulati ons for pressure and function testing and will also provide periodic assessment on the performance of both primary and secondary BOP control systems including act ual interface operations with the ROV and the ROV panel.

 Well control training and drills: Anadarko requires that key nominated onshore and offshore positions including rig contract or personnel to hold a WellCAP, or equivalent, well control traini ng certificate, renewable ever y two years for the type of floating drilling operation being conducted. Anadarko also monitors compliance of its personnel with the applicable federal regulations, including those found in 30 CFR
Part 250 Sub-Part O.

A comprehensive program of well control drills will be conducted offshore to ensure readiness to identify and then manage a well control situation and thereby minimize the potential for a well control event to lead to a blowout scenario.

h) Arrangements for drilling a relief well

 Anadarko maintains a master agreement with Wild Well Control for advice, management, engineering, well kick pre and post modeling, and resource support for an unplanned loss of well control event. In the event of any well control event, Wild
Well Control would be cont acted and mobilized if re quired to support Anadarko’s operational team both in the ons hore and offshore locations.

 The conceptual relief well design will be similar to the design of the Atwater Valley 18, Location GG well in that casing weights, grades and setting poi nts are anticipated to be identical or very similar. A finalized relief well design can be prepared within two days of initialization.

 A block wide shallow hazard assessment has been completed for Atwater Valley 18 and 19. Furthermore, the potential for high density chemo-synthetic communities in the study area are negligible. Depending on the nature of the blowout scenario, well geometry, and total depth required to inters ect the blowout, the most suitable surface location will be chosen and submitted for approval as the location for the relief well.

###  Anadarko’s philosophy is to carry an adequate inventory of well construction equipment to drill a complete well(s) from surface to total depth. Back-up long lead equipment equivalent to the original well design will be carried in stock to allow a rapid response. This includes a spare deepwater sub-sea wellhead system and the large OD casing (36 " , 22 " , 18 " , 16 " , and 13-5/8 " ) and connectors required for the first part of the well. Smaller OD casing is considered readily available on the ground in
the GoM and would be resourced out of ex isting inventory or from suppliers as required.

 Existing service agreements will be in pl ace for support services including drilling fluids, casing running, cementing, ROV’s, so lids control, mud logging, directional drilling, LWD/MWD, logging, boats and helicopters.

 Specialist services for range finding to dri ll the relief well in close proximity to the original wellbore at the re servoir depth may potentially be provided through Vector Magnetics LLC. During drilling operations Anadarko maintains in-house directional drilling services personnel, (e.g. Schlumberger and/or Halliburton), to support and supplement Vector Magnetics under our ex isting directional dr illing agreements.

### SECTION C GEOLOGICAL AND GEOPHYSICAL INFORMATION

(a) Geological Description

Discussions regarding geologic information are considered proprietary and have been omitted from this public copy of the EP, along with so me of the associated geologic attachments.

(b) Structure Contour Maps

Current structure maps drawn to the top of each productive hydrocarbon sand showing the entire lease block, the surface locations of each well and locations of geological cross-sections, are
enclosed as Attachment C-1. (Omitted from this public copy of the EP.)

(c) Interpreted 2-D and/or 3-D Seismic Lines

Interpreted seismic lines are enclosed as Attachment C-2. (Omitted from this public copy of the EP.)

(d) Geological Structure Cross-Sections

Interpreted geological structure cross-sections showing the locat ion and depth of each proposed
well are enclosed as Attachment C-3. (Omitted from this public copy of the EP.)

(e) Shallow Hazards Report

A Shallow Hazards Report for Atwater Valley 18/19 is being submitted with this EP. The data was provided within the geohazard report, “3D Geohazard Assessment-Gulf of Mexico-Atwater Valley-Blocks 018 and 019-Stromboli Prospect” (Gardline Report 9172).

### (f) Shallow Hazards Assessment

Site Clearance Letters for th e proposed wellsites are include d with this EP submittal and
enclosed as Attachment C-4.

(g) High-resolution Seismic Lines

High resolution seismic lines are enclosed as Attachment C-5.

(h) Stratigraphic Column

A generalized stratigraphic column depicting the wells from the seafloor to total depth is
included as Attachment C-6. (Omitted from this public copy of the EP.)

(i) Time Vs. Depth Tables

The proposed activities under this EP are not cons idered to be in areas where there is no well control. Therefore, a seismic travel time versus depth table is not required per NTL 2008-G04, extended by NTL 2014-G03.

# ANADARKO PETROLEUM C ORPORATION

3D GEOHAZARD ASSESSM ENT

GULF OF MEXICO

ATWATER VALLEY BLOCK AT018

STROMBOLI PROSPECT

AT018

- CC PROPOSED WEL L LOCATION

WELL CLEARANCE LETTE R

APRIL 201 3

Gardline Project Ref. 95 20 Report Status Final

Issue Date July 15 , 2013

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.comAnadarko Petroleum Corporation Gardline Report 9520
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- CC Well Location



### REPORT AUTHORIZATION AND DISTRIBUTION

Report Status Final

Issue Date July 15 , 2013

Compilation Geophysicist L Fuentes

Authori z ation Geophysics

..................... A R Haigh

Quality Assurance

..................... M DeLeon

Distribution

6 copies

Anadarko Petroleum Corporation

1201 Lake Robbins Drive The Woodlands, TX 77380

For attention of:

Rick Kincaid

iiAnadarko Petroleum Corporation Gardline Report 9520
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### SERVICE WARRANTY

**USE OF THIS REPORT**

This report has been prepared with due care, diligence and with the skill reasonably expected of a reputable contractor experienced in the types of work, carried out under the contract. As such, the findings in this report are based on an interpretation of data which is a matter of opinion on which professionals may differ and, unless clearly stated, is not a recommendation of any course of action.

Gardline Surveys, Inc. has prepared this report for the client identified on the front cover in fulfilment of its contractual obligations under the referenced contract, and the only liabilities Gardline Surveys, Inc. will accept are those contained therein.

Please be aware that further distribution of this report, in whole or part, or the use of the data for a purpose not expressly stated within the contractual work scope is at the client’s sole risk, and Gardline Surveys, Inc recommends that this disclaimer be included in any such distribution.

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.com

iiiStudy Area Atwater Valley Green Canyon Lloyd Ridge Mississippi Canyon Destin Dome

De Soto Canyon Mobile Pensacola

Ship Shoal Area Eugene Island Area Viosca Knoll

Viosca Knoll Main Pass Area

Ewing Bank South Timbalier Area West Delta Area Louisiana Alabama Mississippi
Florida 

# Location Map

Study AreaAnadarko Petroleum Corporation Gardline Report 9520
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### TABLE OF CONTENTS

REPORT AUTHORIZATION AND DISTRIBUTION ii

SERVICE WARRANTY iii

LOCATION MAP iv

TABLE OF CONTENTS v

LIST OF FIGURES vi

LIST OF CHARTS vii

WELL CLEARANCE LETTER
– PROPOSED AT018

- CC WELL LOCATION 1

1. LOCATION COORDINATES 3

1.1 Proposed AT018

- CC Well Location 3

2. VELOCITY DATA 4

2.1 Velocity Dat a 4

3. SEABED CONDITIONS 6

3.1 Bathymetry 6

3.2 Seafloor Morphology and Man Made Features 6

4. SUBSEABED CONDITIONS 7

4.1 Geology and Lithology 7

4.2 Unit A 7

4.3 Unit B 7

4.4 Unit C 7

4.5 Unit D 8

4.6 Shallow Gas Assess ment 9

4.7 Shallow Water Flow Assessment 9

5. CONCLUSIONS AND RECOMMENDATIONS 10

APPENDIX A
– Public Shallow Hazards Statements

APPENDIX B
– Sensitive Sessile Benthic Community Statements

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### LIST OF FIGURES

Proposed A T0 18

- CC Well Location

1 Seabed Depth Extract

2 Seabed Morphology Extract

3 Seabed Amplitude Extract

4 Geohazard Summary Extract

5 Sand Lithology Summary

6 Inline Data Example

7 Crossline Data Example

8 Top Hole Prognosis

9 ROV Plat

10 Power Spectrum

11 Bathymetry Plat

12 Public Information Plat

13 Proprietary Information Plat

14 Vicinity Map

15 10

- Mile Radius Plat

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### LIST OF CHARTS

The following chart at a scale of 1" = 2,000ft is enclosed:

Chart No Title Drawing No

1 Biological, Physical and Socio

- Economic Map 9520

. 01

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### WELL C LEA RANCE LETTER – PROPOSED AT018

- CC WELL LOCATION

Ju ly 15 , 2013 Anadarko Petroleum Corporation

1201 Lake Robbins Drive The Woodlands, TX 77380

Attention: Rick Kincaid

Well Clearance Letter Proposed AT018

- CC Well Location

Block 018 , Atwater Valley Area
OCS - G33863

Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Well Clearance

L etter for the proposed AT018

- CC well location in Block 018

, Atwater Valley Area (OCS

- G 33863 ). This letter addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this well clearance

ass e ssment is Top of Salt or

- 10,279ft below sea surface (6,112ft below seabed). We understand that Anadarko Petroleum Corporation plans to drill the proposed exploration well from a dynamically positioned drilling vessel; therefore, an anchoring assessment is not required. Relevant letter

- size chart extracts, data examples, and a Top Hole Prognosis are presented with this Well Clearance Letter. This geohazard assessment is based on the interpretation of 3D seismic data. This site clearance letter is issued as a supplement to Gardline Report No.9172 en titled: 3D Geohazard

Asse ssment, Atwater Valley Block 018, dated August 2012

.

Archaeological Survey. Anadarko Petroleum Corporation provided for review the complete archaeological survey report acquired by C&C Technologies Survey Services: Archaeological Survey

Blocks 18 (OCS -G- 33863) and 19 (OCS -G- 32556) Atwater Valley Area for the Anadarko Stromboli Prospect.

3D Geophysical Survey. Anadarko Petroleum Corporation provided the 3D dataset to Gardline Surveys Inc. on tape media in SEG

- Y format for loading onto a Seismic Micro

- Technology (SMT) workstation. The 3D data cube contains a survey with 4 millisecond sample rate data to a record length of 6 .0 seconds TWT below sea surface. Inlines are oriented north to south, have a numerical increment of one, and exhibit a line spacing of 65.62ft. Crosslines are oriented west to east, have a numerical increment of one, and exhibit a line spacing of 41.01ft.

• The acquisition parameters are:

o Atwater Valley (I) DW V

Shooting Direction: N/S Configuration: 4 sources, 6

- 10 streamers

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Maximum offset: 8000 m
Channels: 324 per streamer Shotpoint interval: 47.25 m per array Group interval: 25 m CMP line spacing: 40 m
CMP bin dimension: 12.5 m x 40 m Record Length: 9 s below sea bottom

Nominal f old: 43 Vintage: April 1999

• The basic processing parameters are:

o Atwater Valley (I) DW V

480

- m x 500

- m velocity grid Demultiple 3D DMO velocity and stacking technology
One

- pass 3D poststack migration

12.5

- m x 20

- m final bin dimension

The data exhibits a good frequency response across the upper 1 second below seabed, with an
effe ctive frequency range of 5 Hz to 60Hz. The data exhibits a dominant frequency of approximately 53Hz with significant higher usable frequencies. This frequency range resu lts in a mean vertical resolvability of approximately 10m and a layer detectability of 5ft

.

In summary and with reference to NTL No. 2008

- G04 a) The 3D data provides images of sufficient resolution of the shallow section allowing a clear analysis of the shallow conditions b) The data can be loaded to a workstation at 16bit resolution or greater, and is un

- scaled c) There is no trace or sample decimation d) The sample interval and bin size are maintained throughout the assessment area e) The data possess a frequency content of 50Hz or higher across the first second below

seabe d (See Power Spectrum Diagram: Figure 10 ) f) Seabed reflection is free of gaps and defined by a wavelet of stable shape and phase, allowing auto

- tracking of the seabed event with minimum user intervention and guidance g) There are no significant acquisition artefacts throughout the dataset h) There are no merge points in the data i) Processed bin sizes are 65.62ft x 41.01ft j) The sample rate of the data is 4ms k) An accurate velocity model has been utilized in the shallow section allowing optimum structural and stratigraphy resolution with no evidence of under or over migration l) There is no significant multiple energy m) The proposed activities are not in an area of high archaeological potential.

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### 1. LOCATION COORDINATES

**1.1 Proposed AT018** 

**- CC**  **Well Location**

Proposed AT 18 CC Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 55' 56.56” North Easting 975,301 US ft E
Longitude 89° 03’ 37.04 ” West Northing 10,141,870 US ft N
FEL of Atwater Valley 18 6,779 US ft Inline 5242
FSL of Atwater Valley 18 4,270 US ft Crossline 10492
Water Depth:

- 4,167 ft Slope: 1.3° NE

Nearest Shoreline 71 Miles @ 343°
Port of Operation Fourchon 106 Miles @ 320°

Nearest Manned Platform MC941

- (Mirage/Titan) 7 Miles @ 341°

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### 2. VELOCITY DATA

**2.1 Velocity Data** 

Time

- to

- depth conversion for the water column was derived using the Advocate and Hood (1993) polynomial.

Water Depth (ft) =

0.1105 – 5066.9193X + 468.6693X 2

– 554.7107X 3 + 340.7019X 4

– 116.991X 5 + 20.728X 6

– 1.4658X 7

Wh ere X = one way time in seconds to seabed

.

One Way Time To Seabed (s) Seabed Depth (ft) Seabed Depth (m) Vavg (m/s)

0.0 0 0 0

1.0 4910 1496 1496

1.1 5400 1646 1496

1.2 5892 1796 1496

1.3 6384 1946 1497

1.4 6877 2096 1497

1.5 7370 2246 1498

1.6 7865 2397 1498

1.7 8360 2548 1499

1.8 8856 2699 1499

1.9 9353 2851 1500

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Sub

- seabed time to depth conversion was performed using a polynomial function successfully applied in an adjacent project and approved by Anadarko Petroleum Company :

Vavg = = - 45.841X 5 + 190.08X 4

– 183.08 X3 - 14.729X2 + 735.59X +4900

Where A = two way time in seconds below seabed

.

The resultant velocity was then multiplied by the time below seabed to produce depth below
seabed ; t his horizon depth was summed with seabed depth to produce horizon depth below
sea surface.

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### 3. SEABED CONDITIONS

**3.1 Bathymetry** 

Seabed depth at the proposed AT018

- CC well location is

- 4,167 ft below sea surface ( Figure

1 ). The seafloor slopes to the NE at 1 .3 °.

**3.2 Seafloor Morphology and Man Made Features** 

The proposed AT018

- CC well location is in the south of Block AT 0 18

. The seabed a t the proposed well location is smooth and featureless ( Figure 2 ). Soft clays and silts are predicted
at seabed. Sediments appear conducive for jetting of seabed casing with no hard layers predicted.

The p roposed well AT018

- CC is located in a region with a number of seabed fault

intersections with the nearest fault being located approximately 1,279 ft to the southwest ; this fault should not affect the proposed well.

There is an existing well AT0 18

- 1 located 11,253 ft to the northeast. The following are the

coordinates:

Well Installation:

Operator Block Well No. API No. Depth ( ft) TVD Easting Northing Status

BHP Billiton AT 018 001 60 818 40024 00 4,266 28,651 980,051 10,152,077 PA

There are no anomalous seabed amplitudes indicative of hydrocarbon macroseep observed within a 2,000ft radius of the proposed location ( Figure 3 ).

No items of archaeological significance were identified within 2,000ft of the proposed location (archaeological report submitted under a separate cover)

.

No other features are observed within a 2,000ft radius that could affect well emplacement or jettin g of casing.

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### 4. SUBSEABED CONDITIONS

**4.1 Geology and Lithology** 

The sub

- seabed geology has been divided into four units separated by four horizons ( Figures

6 through 8 ). A Geohazard Summary Extract and Sand Lithology Extract complete the well

assessment ( Figures 4 and 5 )

.

**4.2 Unit A** 

The upper most interval within Unit A

, from s eabed to

- 4,428ft below sea surface (261ft below seabed)

, is interpreted as clays and silts with occasional minor coarser interbeds.

The lower interval of Unit A

, from

- 4,428ft to

- 4,802 ft below sea surface (261ft to 635ft below seabed)

, is interpreted to comprise of clays and silts.

No shallow gas or shallow water flow is predicted with in Unit A at the proposed well location.

A vertical borehole will not penetrate any faults wi thin Unit A.

Horizon H10 marks the base of Unit A at

- 4,802ft below sea surface (635ft below seabed).

**4.3 Unit B** 

The upper interval of Unit B

, from

- 4,802t to

- 5,620 ft below sea surface (635ft to 1,453ft below seabed)

, is expected to comprise slightly higher energy clays and silts with the possibility of

several coarser interbeds. Due to the increased potential for some unconsolidated interbeds

in this interval m inor drilling fluid circulation and minor wellbore stability problems may occur

w ithin this interval.

The lower interval of Unit B

, from

- 5,620ft to

- 5,714ft below sea surface (1,453ft to 1,547 ft below seabed)

, is interpreted to consist of clays and silts with occasional coarser interbeds.

No shallow gas or shallow water flow is predicted with in Unit B at the proposed well location.

A vertical borehole will not penetrate any faults within Unit B.

Horizon H20 marks the base of Unit B at

- 5,714 ft below sea surface (1,547ft below seabed).

**4.4 Unit C** 

Lithology within the upper interval of this unit

, from

- 5,714ft to

- 6,313 f t below sea surface (1 ,547ft to 2,146ft below sea surface)

, is interpreted as higher energy clays and silts with

several coarser interbeds that may represent sands

. The proposed well is located on the

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southwest edge of a sand fairway package that extends from the southwest part of the adjacent Block AT019 into the northwest of Block AT018 ( Figure 5 ) . A number of high

amplitude anomalies associated with this sand fairway package are located within 2,000ft

around the propos ed well location and have been assigned a high risk of gas. The vertical borehole will not intersect any of these anomalies ; t he closest being approximately 389 ft to

the southeast of the proposed well. However, given the location of the well on the periphery
of this higher energy sand fairway

, a Slight Risk of Gas is assigned to this interval

. In

addition to higher energy, the likely sandy nature of this interval is a favorable environment for the development of shallow water flow. A previou sly drilled well (AT063

- 2) located 3.8 miles to the southeast of the present well experienced a low shallow water flow event at

- 2,012ft

below seabed which correlates with this interval. Given this drilling provenance and the relatively close association with possible gas anomalies in the sand fairway

, a Moderate
Shallow Water Flow Risk classification is assigned to this interval.

The lithology from

- 6,313 f t to

- 6,575 ft below sea surface (2,146ft to 2,408ft below seabed) is interpreted as clays and silts with several coarser interbeds that may represent sands. Minor drilling fluid circulation and wellbore stability problems may also occur.

The lower interval within Unit C from

- 6,575ft to

- 6,846ft below sea surface (2,408 f t to 2,679 ft below seabed) is interpreted to comprise a further higher

- energy package with indications of clays and silts with several coarser interbeds that may represent sands. The well path is located outside the main cluster of high

- amplitude anomalies, with the closest anomaly considered a significant risk of gas being over 1300ft to the southeast

. However, due to the higher energy interpreted sandy nature of this interval, and the overlying more clay prone
interval , a Slight Shallow Water Flow Risk is assigned. Additionally, minor drilling fluid circulation and wellbore stability problems may also occur.

A vertical borehole will not penetrate any faults within Unit C.

Horizon H30 marks the base of Unit C at

- 6,846ft below sea surface (2,679ft below seabed).

**4.5 Unit D** 

The upper interval of Unit D from

- 6,846 ft to

- 7,520ft below sea surface (2,679ft to 3,353 ft below seabed)

, is interpreted to consist of clays and silts with occasional coarser interbeds.

From

- 7,520ft to

- 8,825 ft below sea surface (3,353 ft to 4,654 ft below seabed) is interpreted as

a higher energy package comprising clays and silts with numerous coarser interbeds. This interval exhibits character of shallow water flow, with potential for rapid deposition

, and inadequate dewatering. As such, a Moderate Shallow Water Flow Risk is assigned to this

interval

. Downdip connectivity of these sandy interbeds is broken by a fault occurring to the southwest of the location, this could potentially limit the severity of any shallow water flow experienced. To the north, south and east, these sandy interbeds exhibit significant character of shallow gas, both up and downdip, and are considered a moderate risk of gas. At the

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proposed location the amplitude is reduced and direct connectivity to the anomalies is broken by faulting. However, given the potential for shallow gas in the general vicinity, it is considered prudent to assign a Slight Risk of Gas to this interval

.

Within the interval from

- 8,825m to

- 10,279m below sea surface (4,658m to 6,112m below seabed) the stratigraphy is interpreted to consist of clays with occasional coarser interbeds that may represent sands. A possible <40 ft thick sand interbed occurs just above the salt at

- 10,068ft below sea surface (5,901ft below seabed)

. It remains possible that this reflectivity could be from the top salt surface, but it appears out of the general context and slightly

anomalous . The reflection exhibits a moderate risk of gas character around 35 ft to the east of the proposed location, but the location is downdip of this anomaly. As such, the close presence of better defined gas indicators results in a Slight Risk of Gas classification assigned at the level of the interbed.

A vertical borehole will penetrate three faults within Unit D. T he upper fault is interpreted at

- 7,056ft below sea surface (2,889ft below seabed) and extends back to seafloor. This fault presents a significant risk for drilling fluid circulation and wellbore stability problems, especially if pressures over hydrostatic are exerted by the drilling fluid column. The deeper two fault s

occur at

- 7,931 ft and 8,825ft below sea surface (3,764 ft and 4,658ft below seabed), and have

limited vertical extent

. M inor drilling fluid circulation and wellbore stability problem s may o ccur at the level of these fault s if pressures over hydrostatic are exerted by the drilling fluid column.

Top of Salt marks the base of Unit D and the base of this interpretation at

- 10,279ft below sea surface (6,112ft below seabed).

**4.6 Shallow Gas**  **Assessment**

Within Unit C , a Slight Risk of Gas is assigned from

- 5,714 ft to

- 6,313ft below sea surface (1,547ft to 2,146ft below seabed).

Within Unit D, a Slight Risk of Gas is assigne d between

- 7,520ft to

- 8,825ft below sea surface (3,353ft to 4,658ft below seabed) and at the level of a <40ft thick sand interbed at

- 10,068ft below sea surface (5,901ft below seabed).

**4.7 Shallow Water Flow Assessment** 

Within Unit C , a Moderate Shallow Water Flow Risk is interpreted from

- 5,714ft to

- 6,313ft below sea surface (1,547ft to 2,146ft below seabed) and a Slight Shallow Water Flow Risk is assigned from

- 6,575ft to

- 6,846ft below sea surface (2,408ft to 2,679ft below seabe d).

Within Unit D, a Moderate Shallow Water Flow Risk is assigned from

- 7,520ft to

- 8,825 ft below sea surface (3,353ft to 4,658ft below seabed).

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### 5. CONCLUSIONS AND RECOMMENDATIONS

• Seabed No significant problems are anticipated at seabed. Shallow soils are expected to be conducive to the jetting of seabed casing with no hardgrounds predicted.

• Unit A
No drilling hazards or problems are predicted.

• Unit B
Minor drilling and minor wellbore stability problems are possible from

- 4,802ft to

- 5,620ft below sea surface (635ft to 1,453ft below seabed).

• Unit C
Within Unit C, a Slight Risk of Gas and a Moderate Shallow Water Flow Risk is ass igned

to the interval from

- 5,714ft to

- 6,313ft below sea surface (1,547ft to 2,146ft below seabed). Drilling Caution is advised and appropriate drilling methodology is recommended to contain a possible water flow event through out this interval. Additionally, minor drilling fluid circulation and wellbore stability problems may also occur within this interval.

A Slight Shallow Water Flow Risk is also interpreted from - 6,575ft to

- 6,846ft belo w sea surface (2,408ft to 2,679ft below seabed). Appropriate drilling methodology is recommended

to contain a shallow water flow event through this interval. Additionally, minor drilling fluid circulation and wellbore stability problems may also occur wi thin this interval.

Minor drilling and minor wellbore stability problems are possible from

- 6,313ft to

- 6,575ft below sea surface (2,146ft to 2,408ft below seabed).

• Unit D
Within Unit D, a Slight Risk of Gas and Moderate Shallow Water Flow Risk is assigned

between

- 7,520ft to

- 8,825ft below sea surface (3,353ft to 4,658ft below seabed)

. Drilling
Caution is advised and appropriate drilling methodology is recommended to contain a possible water flow event throughout this interval. Additionally, minor drilling fluid circulation and wellbore stability problems may also occur within this interval.

A Slight Risk of Gas is assigned at the level of a <40ft thick sand interbed at

- 10,068ft below sea surface (5,901ft below seabed). Drilling Caution i s advised; however

, it is likely that full well control will have been established by this depth.

A vert ical borehole will penetrate three faults within Unit D. The upper fault occurs at

- 7,056ft below sea surface (2,889ft below seabed) ; and extends to seabed. As such

, drilling fluid circulation problems are considered possible at the level of this fault if pressures over

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hydrostatic are exerted by the drilling fluid column. The two less extensive deeper faults

occur at

- 7,931ft below sea surface (3,764 ft below seabed) and at

- 8,825ft below sea surface (4,658ft below seabed). Minor drilling fluid circulation and wellbore stability problems may

occ ur at the level of this fault. It is recommended that casing seats avoid the level of the faults as formation integrity could be compromised.

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Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- CC Well Location

We appreciate the opportunity to work with you on this project, and look forward to continuing as your geohazards consultants. Please contact us if you have any questions or if we can be of
further assistance.

Sincerely, Gardline Surveys Inc.

Andrew Haigh Matilde DeLeon Geophysical Manager Quality Assurance

Copies Submitted: 6 copies to Rick Kincaid at Anadarko Petroleum Corporation

.

Attachments:

Proposed AT018 CC Well Location

Seabed Depth Extract

Seabed Morphology Extract

Seabed Amplitude Extract

Geohazard Summary Extract

Sand Lithology Summary

Inline Data Example

Crossline Data Example

Top Hole Prognosis

ROV Plat

Power Spectrum

Bathymetry Plat

Public Information Plat

Proprietary Information Plat

Vicinity Map

10

- Mile Radius Plat

12

## Top Hole Prognosis for Proposed AT018-CC Well Location 975,301ft E / 10,141,870ft N Inline: 5242 / Crossline: 10492 Horizon Subsea Depth

(ft) BML Depth

(ft) Horizon
TWT (sec) Lithology, Structure & Stratigraphy Potential Drilling Hazards & Constraints Risk
of
Gas SWF
Risk

Seabed -4,167 0 1.703 Seabed is smooth sloping to the northeast at 1.3°. Surficial sediments comprises of soft clays and silts, passing into clays and silts with occasional minor coarser interbeds.



## Figure 8 Interface -6,313 2,146 2.492 Horizon H10 -4,802 635 1.953

Interface -6,575 2,408 2.579 None predicted

Unit A

Unit B

Horizon H20 -5,714 1,547 2.286

Interface -7,520 3,353 2.878 Horizon H30 -6,846 2,679 2.667

Top of Salt -10,279 6,112 3.627 -7,056 2,889 2.734 Fault Interface -5,620 1,453 2.253 Interface -4,428 261 1.808 None predicted Vavg
BML (m/s)

0

5,441 5,081

5,498 5,306

5,707 5,557

6,353 5,603 5,285 4,976 Clays and silts

Unit C

Unit D Fault -7,931 3,764 3.001 5,800

Interface/Fault -8,825 4,658 3.253 6,010

Sand Interbed -10,068 5,901 3.575 6,305 Minor drilling fluid circulation and minor wellbore stability problems possible within this interval Clays and silts with several coarser interbeds

None predicted Clays and silts with occasional coarser interbeds
Slight Risk of Gas and Moderate Shallow Water Flow Risk Clays and silts with several coarser interbeds that may represent sands

Minor drilling fluid circulation and minor wellbore stability problems possible within this interval Clays and silts with several coarser interbeds that my represent sands

Slight Shallow Water Flow Risk. Minor drilling fluid circulation and wellbore stability problems possible Clays and silts with several coarser interbeds that may represent sands

Drilling fluid circulation problems may occur at the level of the fault if pressures over hydrostatic are exerted by the drilling fluid column Clays and silts with occasional coarser interbeds

Clay and silts with numerous coarser interbeds that may represent sands Slight Risk of Gas and Moderate Shallow Water Flow Risk

Drilling fluid circulation problems may occur at the level of the fault if pressures over hydrostatic are exerted by the drilling fluid column

Clays with occasional coarser interbeds that may represent sands Slight Risk of Gas and Moderate Shallow Water Flow Risk

Slight Risk of Gas, Full well control should have been established at these depths <40ft thick sand interbed

Base of interpretation

# ±

6 ®33 3

3 Proposed AT018-CC Well -4180

-4190 -4200 -4210

-4170 -4160 -4220

-4150 -4230 -4240

-4250

-4260 -4270 -4280 -4290

-4140 -4300

-4240 -4220 -4160 -4230 -4270 -4260

-4160

-4150 -4280

-4150 -4140 -4210

-4160

-4240-4260 -4270

-4180 -4200

-4180 -4160 -4200

-4150

-4180 -4250 -4210

-4210

-4150 -4150

-4230 -4170

-4170 -4150 -4160 -423089°3'0"W89°4'0"W89°5'0"W

27°57'0"N

27°56'0"N

27°55'0"N970,000975,000980,000 10,135,000 10,140,000 10,145,000 10,150,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1 = 2,000' 

## Bathymetry Plat Figure 11 2

, 0

0

0

f t R a d

i u s Proposed AT018-CC Easting: 975,301ft E Northing: 10,141,870ft N FEL of AT018-CC: 6,779ft FSL of AT018-CC: 4,270ft

ATWATER VALLEY BLOCK 18(OCS-G33863)

ATWATER VALLEY BLOCK 62(OCS-G32560)

# ±

®33 3

3 Proposed AT018-CC Well89°3'0"W89°4'0"W89°5'0"W

27°57'0"N

27°56'0"N

27°55'0"N970,000975,000980,000 10,135,000 10,140,000 10,145,000 10,150,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1" = 2,000' 

## Well Location Plat - Public Information Figure 12 ATWATER VALLEY BLOCK 18(OCS-G33863)

ATWATER VALLEY BLOCK 62(OCS-G32560) Location Call N/S Call E/W X Coordinate Y Coordinate Latitude Longitude WD AT018-CC SL 4,270ft FSL 6,779ft FEL 975,301 10,141,870 27° 55' 56.56'' N 89° 03' 37.04'' W -4,167 Proposed Location - AT018-CCNearest Shoreline Range: 71mi Bearing: 343° Fourchon Range: 106mi Bearing: 320°

Lund Henderson Lloyd Ridge

Walker Ridge Destin Dome

Atwater Valley Green Canyon De Soto Canyon

The Elbow

Florida Plain Vernon Basin Apalachicola

Garden Banks

Keathley Canyon Florida Middle Ground

Howell Hook Lund South Pensacola

Amery Terrace Mobile

Viosca Knoll

Viosca Knoll

Sigsbee Escarpment New Orleans Baton Rouge Pensacola

Lafayette Pascagoula Gulfport 

# Vicinity Map - Atwater Valley Block 019

Figure 14Anadarko Petroleum Corporation Gardline Report 9520
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- CC



### APPENDIX A – Public Shallow Hazards Statement s

28Anadarko Petroleum Corporation Gardline Report 9520
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- CC

Public S hallow Hazards Statement – AT018

- CC

Ju ly 15 , 2013

US Department of the Interior Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

- 2394

Attention:

Reference: Shallow Hazards Analysis Atwater Valley Block 018
OCS

- (G 33863 )

Ladies/Gentlemen:

Anadarko Petroleum Corpor ation contracted Gardline Surveys, Inc. to prepare a Well Clearan ce Letter for the proposed AT018

- CC well location in Block 018, Atwater Valley Area (OCS

- G 33863 ). This letter addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this geohazard assessm ent is to Top of Salt at

- 10,279ft below sea surface (6,112ft below seabed).

This hazard summary letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block 018, dated August 2012.

**Seabed Hazards.**

The seabed is smooth and featureless. No problems are expected at the proposed AT018

- CC well

location.

There are no indications of seabed fluid seeps within 2,000ft of the well location.

No existing seabed infrastructure is located within 2,00 0 ft of the proposed well.

**Sub**

**- Seabed Hazards.**  Drilling Caution is indicated within Units C and D for a Slight Risk of Gas

.

Moderate Shallow Water Flow Risk is assigned to two intervals within Unit s C and D

. A Slight
Shallow Water Flow Risk is anticipated within an interval in Unit C

.

29Anadarko Petroleum Corporation Gardline Report 9520
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- CC

Proposed AT 18 CC Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 55' 56.56” North Easting 975,301 US ft E
Longitude 89° 03’ 37.04 ” West Northing 10,141,870 US ft N
FEL of Atwater Valley 18 6,779 US ft Inline 5242
FSL of Atwater Valley 18 4,270 US ft Crossline 10492
Water Depth:

- 4,167 ft Slope: 1.3° NE

Nearest Shoreline 71.34 Miles @ 343° 25’ 48’’
Port of Operation Fourchon 106.42Miles @ 320° 36’ 0’’

Nearest Manned Platform MC941

- (Mirage/Titan) 7.38 Miles @ 341° 31’ 18”

**Conclusions and Recommendations.** Drilling techniques will take into consideration the possibility of encountering possible gas within
defined interval s in Unit C and in Unit D. Appropriate drilling methodology should be utilized to contain a potentially non

- persistent Slight Shallow Wate r Flow Risk interpreted in Unit C . Appropriate drilling methodology should be utilized to contain a possible Moderate Shallow Water Flow Risk in the
intervals within Unit C and within Unit D

.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations



## PUBLIC INFORMATION

30Anadarko Petroleum Corporation Gardline Report 9520
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- CC



### APPENDIX B – Sensitive Sessile Benthic Community Statements

31Anadarko Petroleum Corporation Gardline Report 9520
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- CC

Sensitive Sessile Ben thi c Community Statement – AT018

- CC



### Anadarko Petroleum Corporation

Ju ly 15 , 2013

US Department of the Interior

Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

Reference: Sensitive Sessile Benthic Community Summary Atwater Valley, Block 018
OCS

- (G 33863 )

Ladies/Gentlemen: Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Site Clearan ce Letter for the proposed AT018

- CC well locat ion in Atwater Valley, Block 018

, Stromboli Prospect (OCS

- G G 33863 ). This letter addresses location proximity to potential sensitive sessile benthic community sites. Anadarko Petroleum Corporation will be drilling this well from a dynamically positioned drilling module ; therefore

, no anchors will impact seabed.

This s ensitive sessile benthic community summary letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block 018, dated August 2012 . A Biological, Physical and Socio

- Economic Map is included at the end of this appendix illustrating the areas of potential seabed impact.

**Potential Sensitive Sessile Benthic**  **Communities.** Features or areas that could support high density sensitive sessile benthic communities are **not** located within 2,000ft of any proposed mud and cuttings discharge location.

Proposed AT 18 CC Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 55' 56.56” North Easting 975,301 US ft E
Longitude 89° 03’ 37.04 ” West Northing 10,141,870 US ft N
FEL of Atwater Valley 18 6,779 US ft Inline 5242
FSL of Atwater Valley 18 4,270 US ft Crossline 10492
Water Depth:

- 4,167 ft Slope: 1.3° NE

Nearest Shoreline 71.34 Miles @ 343° 25’ 48’’
Port of Operation Fourchon 106.42Miles @ 320° 36’ 0’’

Nearest Manned Platform MC941

- (Mirage/Titan) 7.38 Miles @ 341° 31’ 18”

32Anadarko Petroleum Corporation Gardline Report 9520
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- CC

No potential sensitive sessile benthic community site is located within 2,000ft of the proposed

location

.

**Conclusions and Recommendations:** The proposed AT018

- CC well location will not impact any sites favorable for development of sensitive

sessile benthic communities.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations

33

# ANADARKO PETROLEUM C ORPORATION

3D GEOHAZARD ASSESSM ENT

GULF OF MEXICO

ATWATER VALLEY BLOCK AT018

STROMBOLI PROSPECT

AT018

- DD PROPOSED WEL L LOCATION

WELL CLEARANCE LETTE R

APRIL 201 3

Gardline Project Ref. 95 2 1 Report Status Final

Issue Date July 15 , 2013

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.comAnadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location



### REPORT AUTHORIZATION AND DISTRIBUTION

Report Status Final

Issue Date July 15 , 2013

Compilation Geophysicist L Fuentes

Authori z ation Geophysics

..................... A R Haigh

Quality Assurance

..................... M DeLeon

Distribution

6 copies

Anadarko Petroleum Corporation

1201 Lake Robbins Drive

The Woodlands, TX 77380

For attention of:

Rick Kincaid

iiAnadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location



### SERVICE WARRANTY

**USE OF THIS REPORT**

This report has been prepared with due care, diligence and with the skill reasonably expected of a reputable contractor experienced in the types of work, carried out under the contract. As such, the findings in this report are based on an interpretation of data which is a matter of opinion on which professionals may differ and, unless clearly stated, is not a recommendation of any course of action.

Gardline Surveys, Inc. has prepared this report for the client identified on the front cover in fulfilment of its contractual obligations under the referenced contract, and the only liabilities Gardline Surveys, Inc. will accept are those contained therein.

Please be aware that further distribution of this report, in whole or part, or the use of the data for a purpose not expressly stated within the contractual work scope is at the client’s sole risk, and Gardline Surveys, Inc recommends that this disclaimer be included in any such distribution.

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.com

iiiStudy Area Atwater Valley Green Canyon Lloyd Ridge Mississippi Canyon Destin Dome

De Soto Canyon Mobile Pensacola

Ship Shoal Area Eugene Island Area Viosca Knoll

Viosca Knoll Main Pass Area

Ewing Bank South Timbalier Area West Delta Area Louisiana Alabama Mississippi
Florida 

# Location Map

Study AreaAnadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location



### TABLE OF CONTENTS

REPORT AUTHORIZATION AND DISTRIBUTION ii

SERVICE WARRANTY iii

LOCATION MAP iv

TABLE OF CONTENTS v

LIST OF FIGURES vi

LIST OF CHARTS vii

WELL CLEARANCE LETTER
– PROPOSED AT018

- DD WELL LOCATION 1

1. LOCATION COORDINATES 3

1.1 Propos ed AT018

- DD Well Location 3

2. VELOCITY DATA 4

2.1 Velocity Data 4

3. SEABED CONDITIONS 6

3.1 Bathymetry 6

3.2 Seafloor Morphology and Man Made Features 6

4. SUBSEABED CONDITIONS 7

4.1 Geology and Lithology 7

4.2 Unit A 7

4.3 Unit B 7

4.4 Unit C 7

4.5 Unit D 8

4.6 Shallow Gas Assess ment 9

4.7 Shallow Water Flow Assessment 9

5. CONCLUSIONS AND RECOMMENDATIONS 10

APPENDIX A
– Public Shallow Hazards Statements

APPENDIX B
– Sensitive Sessile Benthic Community Statements

vAnadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location



### LIST OF FIGURES

Proposed A T0 18

- DD Well Location

1 Seabed Depth Extract

2 Seabed Morphology Extract

3 Seabed Amplitude Extract

4 Geohazard Summary Extract

5 Sand Lithology Summary

6 Inline Data Example

7 Crossline Data Example

8 Top Hole Prognosis

9 ROV Plat

10 Power Spectrum

11 Bathymetry Plat

12 Public Information Plat

13 Proprietary Information Plat

14 Vicinity Map

15 10

- Mile Radius Plat

viAnadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location



### LIST OF CHARTS

The following chart at a scale of 1" = 2,000ft is enclosed:

Chart No Title Drawing No

1 Biological, Physical and Socio

- Economic Map 9521

. 01

viiAnadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location



### WELL C LEA RANCE LETTER – PROPOSED AT018

- DD WELL LOCATION

Ju ly 15 , 2013 Anadarko Petroleum Corporation

1201 Lake Robbins Drive The Woodlands, TX 77380

Attention: Rick Kincaid

Well Clearance Letter Proposed AT018

- DD Well Location

Block 018 , Atwater Valley Area
OCS - G33863

Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Well Clearance

L etter for the proposed AT018

- DD well location in Block 018

, Atwater Valley Area (OCS

- G 33863 ). This letter addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this well clearance

ass e ssment is Top of Salt or

- 10,071ft below sea surface (5,881ft below seabed). We understand that Anadarko Petroleum Corporation plans to drill the proposed exploration well from a dynamically positioned drilling vessel; therefore, an anchoring assessment is not required nor provided. Relevant

letter

- size chart extracts, data examples, and a Top Hole Prognosis are presented with this Well Clearance Letter. This geohazard assessment is based on the interpretation of 3D seismic data. This site clearance letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard

Asse ssment, Atwater Valley Block 018, dated August 2012

.

Archaeological Survey. Anadarko Petroleum Corporation provided for review the complete archaeological survey report acquired by C&C Technologies Survey Services : A rchaeological Survey

Blocks 18 (OCS -G- 33863) and 19 (OCS -G- 32556) Atwater Valley Area for the Anadarko Stromboli Prospect.

3D Geophysical Survey. Anadarko Petroleum Corporation provided the 3D dataset to Gardline Surveys Inc. on tape media in SEG

- Y format for loading onto a Seismic Micro

- Technology (SMT) workstation. The 3D data cube contains a survey with 4 millisecond sample rate data to a record length of 6 .0 seconds TWT below sea surface. Inlines are oriented north to south, have a numerical

in crement of one, and exhibit a line spacing of 65.62ft. Crosslines are oriented west to east, have a numerical increment of one, and exhibit a line spacing of 41.01ft.

• The acquisition parameters are:

o Atwater Valley (I) DW V

Shooting Direction: N/S
Con figuration: 4 sources, 6

- 10 streamers

1Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location

Maximum offset: 8000 m
Channels: 324 per streamer Shotpoint interval: 47.25 m per array Group interval: 25 m CMP line spacing: 40 m
CMP bin dimension: 12.5 m x 40 m Record Length: 9 s below sea bottom

Nominal fold: 43 Vintage: April 1999

• The basic processing parameters are:

o Atwater Valley (I) DW V

480

- m x 500

- m velocity grid Demultiple 3D DMO velocity and stacking technology
One

- pass 3D poststack migration

12.5

- m x 20

- m final bin dimension

The data exhibits a good frequency response across the upper one second below seabed, with an
effe ctive frequency range of 5 Hz to 60Hz. The data exhibits a dominant frequency of approximately 53Hz with significant higher usable frequencies. This frequency range results in a mean vertical resolvability of approximately 10ft and a layer detectability of 5ft

.

In summary and with reference to NTL No. 2008

- G04 a) The 3D data provides images of sufficient resolution of the shallow section allowing a clear analysis of the shallow conditions b) The data can be loaded to a workstation at 16bit resolution or greater, and is un

- scaled c) There is no trace or sample decimation d) The sample interval and bin size are maintained throughout the assessment area e) The data possess a frequency content of 50Hz or higher across the first second below

seabe d (See Power Spectrum Diagram: Figure 10 ) f) Seabed reflection is free of gaps and defined by a wavelet of stable shape and phase, allowing auto

- tracking of the seabed event with minimum user intervention and guidance g) There are no significant acquisition artefacts throughout the dataset h) There are no merge points in the data i) Processed bin sizes are 65.62ft x 41.01ft j) The sample rate of the data is 4ms k) An accurate velocity model has been utilized in the shallow section allowing optimum structural and stratigraphy resolution with no evidence of under or over migration l) There is no significant multiple energy m) The proposed activities are not in an area of high archaeological potential.

2Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location



### 1. LOCA TION COORDINATES

**1.1 Proposed AT018** 

**- DD**  **Well Location**

Proposed AT 18

- DD Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 56' 29.05” North Easting 978,173 US ft E
Longitude 89° 03’ 05.63 ” West Northing 10,145,103 US ft N
FEL of Atwater Valley 18 3, 907 US ft Inline 5286
FSL of Atwater Valley 18 7,503 US ft Crossline 10571
Water Depth:

- 4,190 ft Slope: 3.5° SW

Nearest Shoreline 71 Miles @ 343°
Port of Operation Fourchon 106 Miles @ 320°

Nearest Manned Platform MC941

- (Mirage/Titan) 7 Miles @ 356 °

3Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location



### 2. VELOCITY DATA

**2.1 Velocity Data** 

Time

- to

- depth conversion for the water column was derived using the Advocate and Hood (1993) polynomial.

Water Depth (ft) =

0.1105 – 5066.9193X + 468.6693X 2

– 554.7107X 3 + 340.7019X 4

– 116.991X 5 + 20.728X 6

– 1.4658X 7

Wh ere X = one way time in seconds to seabed

.

One Way Time To Seabed (s) Seabed Depth (ft) Seabed Depth (m) Vavg (m/s)

0.0 0 0 0

1.0 4910 1496 1496

1.1 5400 1646 1496

1.2 5892 1796 1496

1.3 6384 1946 1497

1.4 6877 2096 1497

1.5 7370 2246 1498

1.6 7865 2397 1498

1.7 8360 2548 1499

1.8 8856 2699 1499

1.9 9353 2851 1500

4Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location

Sub

- seabed time to depth conversion was performed using a polynomial function successfully applied in an adjacent project and approved by Anadarko Petroleum Corporation :

Vavg = = - 45.841X 5 + 190.08X 4

– 183.08 X3 - 14.729X2 + 735.59X +4900

Where A = two way time in seconds below seabed

.

The resultant velocity was then multi plied by the time below seabed to produce depth below
seabed ; t his horizon depth was summed with seabed depth to produce horizon depth below
sea surface.

5Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location



### 3. SEABED CONDITIONS

**3.1 Bathymetry** 

Seabed depth at the proposed AT018

- DD well location is

- 4,190 ft below sea surface ( Figure

1 ). The seafloor slopes to the SW at 3.5 °.

**3.2 Seafloor Morphology and Man Made Features** 

The proposed AT018

- DD well location is in east

- central Block AT 0 18

. The seabed a t the proposed well location is smooth and featureless ( Figure 2 ). Soft clays and silts are predicted
at seabed. Sediments appear conducive for jetting of seabed casing with no hard layers predicted.

The p roposed AT018

- DD well is located in a n area of num er ous seabed fault intersections

. The seabed rendering illustrates a slight rise due to flexure or draping over an old surface,

but no fault is observed at seabed at this location. Major structural fault s are located 2,199ft to the southwest and 500ft to the east and north. These fault s only affect the well at depth ( Figure 6 )

.

E xisting well AT0 18

- 1 is located 7,130 ft to the northeast. The following are the

coordinates:

Well Installation:

Operator Block Well No. API No. Depth (ft) TVD Easting Northing Status

BHP Billiton At018 001 60 818 40024 00 4,266 28,651 980,051 10,152,077 PA

There are no anomalous seabed amplitudes indicative of hydrocarbon macroseep observed

within 2,000ft radius of the proposed location ( Figure 3 ).

No items of archaeological significance were identified within 2,000ft of the proposed location (archaeological report submitted under a separate cover)

.

No other features are observed within a 2,000ft radius that could affect well emplacement or jetting of casing.

6Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location



### 4. SUBSEABED CONDITIONS

**4.1 Geology and Lithology** 

The sub

- seabed geology has been divided into four units separated by four horizons ( Figures

6 through 8 ). A Geohazard Extract and Sand Lithology Extract complete the well assessment ( Figures 4 and 5 )

.

**4.2 Unit A** 

The upper most interval within Unit A from s eabed to

- 4,456ft below sea surface (266ft below seabed) is interpreted as clays and silts with occasional minor coarser interbeds.

The lower interval of Unit A from

- 4,456ft to

- 4,788ft below sea surface (266ft to 598ft below seabed) is interpreted to comprise of clays and silts.

No shallow gas or shallow water flow is predicted with in Unit A at the proposed well location.

A vertical borehole will not penetrate any faults within Unit A.

Horizon H10 marks the base of Unit A at

- 4,788ft below sea surface (598ft below seabed).

**4.3 Unit B** 

The upper interval of Unit B from

- 4,788 f t to - 5,441ft below sea surface (598ft to 1,252ft below seabed) is interpreted to consist of clays and silts with several coarser interbeds. Due to the potential for possible poorly consolidated sediments in this interval, especially uppermost,

m inor drilling fluid circulation and wellbore stability problems may occur.

A vertical borehole will not penetrate any faults within Unit B.

Horizon H20 marks the base of Unit B at

- 5,441 ft below sea surface (1,252 f t below seabed).

**4.4 Unit C** 

T he upper interval of Unit C from

- 5,441ft to

- 5,668ft below sea surface (1,252ft to 1,478ft below seabed) is interpreted as clays and silts with several coarser interbeds that may represent sands. D ue to the potential for possible poorly consolidated sediments in this interval, m inor drilling fluid circulation and wellbore stability problems may occur.

The l ithology from

- 5,668ft to

- 6,887 f t below sea surface (1,478ft to 2,697ft below sea surface) is interpreted as higher energy clays and silts with numerous coarser interbeds that may represent sands

. The proposed well is located within a sand fairway package that extends from the southwest of the adjacent Block AT019 into the northwest of Block AT 018 ( Figure 5 )

.

7Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location

A number of high

- amplitude anomalies are located within 2,000ft around the proposed well

location and have been assigned a high risk of gas. The vertical borehole will not intersect any of these anomalies , t he closest being approximately 592 ft to the northeast of the proposed location . However, given the location of the well within this higher energy sand fairway

, and the possibility of connectivity a Slight Risk of Gas is assigned to this interval

. In addition the higher energy, and frequently sandy component in this interval creates a favorable environment for the development of shallow water flow. A previously drilled well (AT063

- 2) located 3.8 miles to the southeast of the present well experienced a low shallow
water flow event at - 2,012ft below seabed which correlates with this interval. Given this drilling provenance and the relatively close association with possible gas anomalies in the sand fairway

, a High Shallow Water Flow Risk classification is assigned to this interval.

T he lower interval within Unit C from

- 6,887ft to

- 7,009ft below sea surface (2,697 f t to 2,819 ft below seabed) is interpreted to comprise a further higher

- energy package with indications of several coarser interbeds that may represent sands. M inor drilling fluid circulation and wellbore stability problems may occur.

A vertical borehole will not penetrate any faults within Unit C.

Horizon H30 marks the base of Unit C at

- 7,009ft below sea surface (2,819ft below seabed).

**4.5 Unit D** 

The upper interval of Unit D

, from

- 7,009 ft to

- 7,503ft below sea surface (2,819ft to 3,313 ft below seabed)

, is interpreted as clays and silts with occasional minor coarser interbeds.

From

- 7,503ft to

- 8,686 ft below sea surface (3,313 ft to 4,497 ft below seabed), the lithology is interpreted as a higher energy package comprising clays and silts with numerous coarser
interbeds. This interval, with the potential for rapid deposition and inadequate dewatering, is assigned a Moderate Shallow Water Flow Risk

. Within 2,000ft of the proposed location

, amplitude anomalies occur in this interval that are classed as a Moderate Risk of Gas, the closest approach being 600ft to the northwest. Some of these interpreted sandy interbeds within which the anomalies occur exhibit connectivity to the wellbore and as such a Slight
Risk of Gas is assigned. In addition due to the potential for poorly consolidated material within this interval minor drilling fluid circulation and wellbore stability problems could occur.

F rom - 8,686ft to

- 9,753ft below sea surface (4,497ft to 5,563ft below seabed) is interpreted to
consist of clays with occasional coarser interbeds that may represent sands.

Within the interval

, from

- 9,753 m to

- 10,071m below sea surface (5 ,563m to 5,881 m be low seabed)

, the stratigraphy is interpreted to consist of clays with several coarser interbeds that may represent sands. A slight increase in amplitude is observed in this interval immediately above top of salt and there is considered the possibility that these may contain small volumes
of fluid ; hence a Slight Risk of Gas is assigned.

8Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location

A vertical borehole will penetrate a fault within Unit D. This fault occur s at

- 8,686 ft below sea surface (4,497 ft below seabed), and has a limited vertical extent

. However, immediately north of the proposed well location an antithetic fault occurs that intersects the wellbore at the same level, this fault exhibits connectivity to seabed. It is therefore interpreted that drilling fluid

circulation and wellbore stab ility problems could occur at this level, especially if pressures over hydrostatic are exerted by the wellbore.

Top of Salt marks the base of Unit D and the base of this interpretation at

- 10,071ft below sea surface (5,881ft below seabed).

**4.6 Shallow Gas**  **Assessment**

Within Unit C , a Slight Risk of Gas is assigned from

- 5,668 ft to

- 6,887 ft below sea surface (1,478ft to 2,697ft below seabed).

Within Unit D, a Slight Risk of Gas is assigne d between

- 7,503ft to

- 8,686 ft below sea surface (3,313ft to 4,497ft below seabed) and from - 9,753ft to

- 10,071ft below sea surface (5,563ft to 5,881ft below seabed).

**4.7 Shallow Water Flow Assessment** 

Within Unit C , a High Shallow Water Flow Risk is interpreted from

- 5,668ft to

- 6,887ft below sea surface (1,478ft to 2, 697 ft below seabed)

.

Within Unit D, a Moderate Shallow Water Flow Risk is assigned from

- 7,503ft to

- 8,686 ft below sea surface (3,313ft to 4,497ft below seabed).

9Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location



### 5. CONCLUSIONS AND RECOMMENDATIONS

• Seabed

No significant problems are anticipated at seabed. Shallow soils are expected to be conducive to the jetting of seabed casing with no hardgrounds predicted.

• Unit A
No drilling hazards or problems are predicted.

• Unit B

Minor drilling fluid and wellbore st ability p roblems are possible throughout this unit from

- 4,788 ft to

- 5,441ft below sea surface (598ft to 1,252ft below seabed).

• Unit C

Within Unit C , a Slight Risk of Gas and a High Shallow Water Flow Risk is assigned from

- 5,668ft to

- 6,887ft below sea surface (1,478ft to 2,697ft below seabed). Drilling Caution is advised and appropriate drilling methodology is recommended to contain a possible water flow event through out this interval. Additionally, minor drilling fluid circulation and wellbore stability problems may also occur within this interval. Due to the potential for poorly consolidated material in this interval it is recommended casing seats avoid this section.

Minor drilling fluid and wellbore stability problems are possible from

- 5,44 1ft to

- 5,668ft below sea surface (1,252ft to 1,478ft below seabed) and from

- 6,887ft to

- 7,009ft below sea surface (2,697ft to 2,819ft below seabed).

• Unit D
Within Unit D, a Slight Risk of Gas and Moderate Shallow Water Flow Risk is assigned

between -7 ,503ft to

- 8,686ft below sea surface (3,313ft to 4,497ft below seabed). Drilling
Caution is advised and appropriate drilling methodology is recommended to contain a possible water flow event throughout this interval. Additionally, minor drilling fluid ci rculation and wellbore stability problems may also occur within this interval. Due to the potential for poorly consolidated material in this interval it is recommended casing seats avoid this section.

Within Unit D, a Slight Risk of Gas is assigned withi n

- 9,753ft to

- 10,071ft below sea surface (5,563ft to 5,881ft below seabed

. Drilling Caution is advised; however

, it is likely that full well control will have been established by this depth.

A vert ical borehole will penetrate a fault within Unit D at

- 8,686ft below sea surface (4,497ft below seabed). This fault extends to seafloor and therefore drilling fluid circulation and wellbore stability problems may occur if pressures over hydrostatic are exerted by the drilling
fluid column . It is recomme nded that casing seats avoid the level of the fault as formation

10Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location

integrity could be compromised.

We appreciate the opportunity to work with you on this project, and look forward to continuing as your geohazards consultants. Please contact us if you have any questions or if we can be of
further assistance.

Sincerely, Gardline Surveys Inc.

Andrew Haigh Matilde DeLeon Geophysical Manager Quality Assurance

Copies Submitted: 6 copies to Rick Kincaid at Anadarko Petroleum Corporation

.

Attachments:

Proposed AT018 DD Well Location

Seabed Depth Extract

Seabed Morphology Extract

Seabed Amplitude Extract

Geohazard Summary Extract

Sand Lithology Summary

Inline Data Example

Crossline Data Example

Top Hole Prognosis

ROV Plat

Power Spectrum

Bathymetry Plat

Public Information Plat

Proprietary Information Plat

Vicinity Map

10

- Mile Radius Plat

11

## Top Hole Prognosis for Proposed AT018-DD Well Location 978,173ft E / 10,145,103ft N
Inline: 5286 / Crossline: 10571 Horizon Subsea Depth

(ft) BML Depth

(ft) Horizon
TWT (sec) Lithology, Structure & Stratigraphy Potential Drilling Hazards & Constraints Risk
of
Gas SWF
Risk

Seabed -4,190 0 1.708 Seabed is smooth sloping to the southwest at 3.5°. Surficial sediments comprise of soft clays and silts. Underlying the seabed the lithology comprises of clays and silts with occasional minor coarser interbeds.



## Figure 8 Interface -7,503 3,313 2.871 Horizon H20 -5,441 1,252 2.186

Interface/Fault -8,686 4,497 3.214 None predicted
Unit A

Unit B

Horizon H30 -7,009 2,819 2.717 Interface -6,887 2,697 2.678 -4,456 266 1.815 Interface

Interface -5,668 1,478 2.267 Horizon H10 -4,788 598 1,944 None predicted Vavg
BML (m/s)

0

5,698 5,237

5,947 5,582 5,561 5,071

5,669 5,250 Clays and silts

Unit C

Unit D

Interface -9,753 5,563 3.495 6,225

Top of Salt -10,071 5,881 3.575 6300 None predicted Clays and silts with several coarser interbeds especially uppermost

Minor drilling fluid circulation and minor wellbore stability problems possible within this interval Clays and silts with several coarser interbeds that may represent sands

Slight Risk of Gas and High Shallow Water Flow Risk.Minor drilling fluid circulation and minor wellbore stability problems possible within this interval Clays and silts with numerous coarser interbeds that may represent sands

Minor drilling fluid circulation and minor wellbore stability problems possible within this interval Clays and silts with several coarser interbeds that may represent sands

None predicted Clays and silts with occasional coarser interbeds

Slight Risk of Gas and Moderate Shallow Water Flow Risk Clays and silts with numerous coarser interbeds that may represent sands

Drilling fluid circulation problems may occur at the level of the fault if pressures over hydrostatic are exerted by the drilling fluid column Clays with occasional coarser interbeds that may represent sands

Slight Risk of Gas Clays with several coarser interbeds that may represent sands

Base of interpretation

# ±

®33 3

3 -4180

-4190 -4200 -4210

-4170 -4160 -4220

-4150 -4230 -4240

-4250

-4260 -4270 -4280 -4290

-4140 -4300

-4240 -4220 -4160 -4230 -4270 -4260

-4160

-4150 -4280

-4150 -4140 -4210

-4160

-4240-4260 -4270

-4180 -4200

-4180 -4160 -4200

-4150

-4180 -4250 -4210

-4210

-4150 -4150

-4230 -4170

-4170 -4150 -4160 -423089°3'0"W89°4'0"W89°5'0"W

27°57'0"N

27°56'0"N

27°55'0"N970,000975,000980,000 10,135,000 10,140,000 10,145,000 10,150,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1 = 2,000' 

## Bathymetry Plat Figure 11 2

, 0

0

0

f t R a d

i u s Proposed AT018-DD Easting: 978,173ft E Northing: 10,145,103ft N FEL of AT018-DD: 3,907ft FSL of AT018-DD: 7,503ft

ATWATER VALLEY BLOCK 18(OCS-G33863)

ATWATER VALLEY BLOCK 62(OCS-G32560)

# ±

6

®33 3

3 Proposed AT018-DD Well AT018-00189°3'0"W89°4'0"W89°5'0"W

27°57'0"N

27°56'0"N

27°55'0"N970,000975,000980,000 10,135,000 10,140,000 10,145,000 10,150,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1" = 2,000' 

## Well Location Plat - Public Information Figure 12 ATWATER VALLEY BLOCK 18(OCS-G33863)

ATWATER VALLEY BLOCK 62(OCS-G32560) Location Call N/S Call E/W X Coordinate Y Coordinate Latitude Longitude WD AT018-DD SL 7,503ft FSL 3,907ft FEL 978,173 10,145,103 27° 56' 29.05"N 89° 03' 05.63"W -4,190 Proposed Location - AT018-DDNearest Shoreline Range: 71mi Bearing: 343° Fourchon Range: 106mi Bearing: 320°

Lund Henderson Lloyd Ridge

Walker Ridge Destin Dome

Atwater Valley Green Canyon De Soto Canyon

The Elbow

Florida Plain Vernon Basin Apalachicola

Garden Banks

Keathley Canyon Florida Middle Ground

Howell Hook Lund South Pensacola

Amery Terrace Mobile

Viosca Knoll

Viosca Knoll

Sigsbee Escarpment New Orleans Baton Rouge Pensacola

Lafayette Pascagoula Gulfport 

# Vicinity Map - Atwater Valley Block 019

Figure 14Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location



### APPENDIX A – Public Shallow Hazards Statement s

28Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location

Public S hallow Hazards Statement – AT018

- DD July 15 , 2013

US Department of the Interior Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

- 2394

Attention:

Reference: Shallow Hazards Analysis Atwater Valley Block 018
OCS

- (G 33863 )

Ladies/Gentlemen:

Anadarko Petroleum Corporation contracted Gardline Surveys, Inc. to prepare a Well Clearan ce Letter for the proposed AT018

- DD well location in Block 018, Atwater Valley Area (OCS

- G 33863 ). This letter addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this geohazard assessm ent is to Top of Salt at

- 10,071 ft below sea surface (5,881ft below seabed).

This hazard summary lett er is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block 018, dated August 2012.

**Seabed Hazards.**

The seabed is smooth and featureless. No problems are expected at the proposed AT018

- DD well

location

.

There are no indications of seabed fluid seeps within 2,000ft of the well location.

No existing seabed infrastructure is located within 2,00 0 ft of the proposed well.

**Sub**

**- Seabed Hazards.**  Drilling Caution is indicated within Units C and D for a Slight Risk of Gas

.

High Shallow Water Flow Risk is assigned to an interval within Unit C

. A Moderate Shallow Water

Flow Risk is anticipated within an interval in Unit D

.

29Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location

Proposed AT 18 DD Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 56' 29.05” North Easting 978,173. US ft E
Longitude 89° 03’ 05.63 West Northing 10,145,103 US ft N
FEL of Atwater Valley 18 3,907 US ft Inline 5286
FSL of Atwater Valley 18 7,503 US ft Crossline 10571
Water Depth:

- 4,190 ft Slope: 3.5° SW

Nearest Shoreline 71 Miles @ 343°
Port of Operation Fourchon 106 Miles @ 320°

Nearest Manned Platform MC941

- (Mirage/Titan) 7 Miles @ 355°

**Conclusions and Recommendations.** Drilling techniques will take into consideration the possibility of encountering possible gas within
defined interval s in Unit C and in Unit D

. Appropriate drilling methodology should be utilized to contain a possible Moderate and High Shallow Water Flow Risk in the intervals within Unit C and within Unit

D

.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations



## PUBLIC INFORMATION

30Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location



### APPENDIX B – Sensitive Sessile Benthic Community Statements

31Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location

Sensitive Sessile Ben thi c Community Statement – AT018

- DD



### Anadarko Petroleum Corporation

July 15 , 2013

US Department of the Interior Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

Reference: Sensitive Sessile Benthic Community Summary Atwater Valley, Block 018
OCS

- (G 33863 )

Ladies/Gentlemen: Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Site Clearan ce Letter for the proposed AT018

- DD well locat ion in Atwater Valley, Block 018

, Stromboli Prospect (OCS

- G G 33863 ). This letter addresses location proximity to potential sensitive sessile benthic community sites. Anadarko Petroleum Corporation will be drilling this well from a dynamically positioned drilling module ; therefore

, no anchors will impact seabed.

This sensitive sessile benthic community summary letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block 018, dated August 2012 . A Biological, Physical and Socio

- Econom ic Map is included at the end of this appendix illustrating the areas of potential seabed impact.

**Potential Sensitive Sessile Benthic**  **Communities.** Features or areas that could support high density sensitive sessile benthic communities are **not** located within 2,000ft of any proposed mud and cuttings discharge location.

Proposed AT 18 DD Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 56' 29.05” North Easting 978,173. US ft E
Longitude 89° 03’ 05.63 West Northing 10,145,103 US ft N
FEL of Atwater Valley 18 3,907 US ft Inline 5286
FSL of Atwater Valley 18 7,503 US ft Crossline 10571
Water Depth:

- 4,190 ft Slope: 3.5° SW

Nearest Shoreline 71 Miles @ 343°
Port of Operation Fourchon 106 Miles @ 320°

Nearest Manned Platform MC941

- (Mirage/Titan) 7.00 Miles @ 355°

32Anadarko Petroleum Corporation Gardline Report 9521
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- DD Well Location

No potential sensitive sessile benthic community site is located within 2,000ft of the proposed

location

.

**Conclusions and Recommendations:** The proposed AT018

- DD well location will not impact any sites favorable for development of sensitive

sessile benthic communities.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations

33

# ANADARKO PETROLEUM C ORPORATION

3D GEOHAZARD ASSESSM ENT

GULF OF MEXICO

ATWATER VALLEY BLOCK AT 18

STROMBOLI PROSPECT

AT0 18 -GG PROPOSED WEL L LOCATION

WELL CLEARANCE LETTE R

APRIL 201 3

Gardline Project Ref. 95 15 Report Status Final

Issue Date July 15, 2013

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.comAnadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG



### REPORT AUTHORIZATION AND DISTRIBUTION

Report Status Final

Issue Date July 15 , 2013

Compilation Geophysicist L Fuentes

Authori z ation Geophysics

..................... A R Haigh

Quality Assurance

..................... M DeLeon

Distribution

6 copies

Anadarko Petroleum Corporation

1201 Lake Robbins Drive The Woodlands, TX 77380

For attention of:

Rick Kincaid

iiAnadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG



### SERVICE WARRANTY

**USE OF THIS REPORT**

This report has been prepared with due care, diligence and with the skill reasonably expected of a reputable contractor experienced in the types of work, carried out under the contract. As such, the findings in this report are based on an interpretation of data which is a matter of opinion on which professionals may differ and, unless clearly stated, is not a recommendation of any course of action.

Gardline Surveys, Inc. has prepared this report for the client identified on the front cover in fulfilment of its contractual obligations under the referenced contract, and the only liabilities Gardline Surveys, Inc. will accept are those contained therein.

Please be aware that further distribution of this report, in whole or part, or the use of the data for a purpose not expressly stated within the contractual work scope is at the client’s sole risk, and Gardline Surveys, Inc recommends that this disclaimer be included in any such distribution.

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.com

iiiStudy Area Atwater Valley Green Canyon Lloyd Ridge Mississippi Canyon Destin Dome

De Soto Canyon Mobile Pensacola

Ship Shoal Area Eugene Island Area Viosca Knoll

Viosca Knoll Main Pass Area

Ewing Bank South Timbalier Area West Delta Area Louisiana Alabama Mississippi
Florida 

# Location Map

Study AreaAnadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG



### TABLE OF CONTENTS

REPORT AUTHORIZATION AND DISTRIBUTION ii

SERVICE WARRANTY iii

LOCATION MAP iv

TABLE OF CONTENTS v

LIST OF FIGURES vi

LIST OF CHARTS vii

WELL CLEARANCE LETTER
– PROPOSED AT 18 GG WELL LOCATION 1

1. LOCATION COORDINATES 4

1.1 Proposed AT 18 GG Well Location 4

2. VELOCITY DATA 5

2.1 Velocity Data 5

3. SEABED CONDITIONS 7

3.1 Bathymetry 7

3.2 Seafloor Morphology and Man Made Features 7

4. SUBSEABED CONDITIONS 8

4.1 Geology and Lithology 8

4.2 Unit A 8

4.3 Unit B 8

4.4 Unit C 8

4.5 Unit D 10

4.6 Shallow Gas Assessment 10

4.7 Shallow Water Flow Assessment 10

5. CONCLUSIONS AND RECOMMENDATIONS 11

APPENDIX A
– Public Shallow Hazards Statements 29

APPENDIX B
– Sensitive Sessile Benthic Community Statements 32

vAnadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG



### LIST OF FIGURES

Proposed A T 18 GG Well Location

1 Seabed Depth Extract

2 Seabed Morphology Extract

3 Seabed Amplitude Extract

4 Geohazard Summary Extract

5 Sand Lithology Summary

6 Inline Data Example

7 Crossline Data Example

8 Tie Line to AT018

- 001

9 Top Hole Prognosis

10 ROV Plat

11 Power Spectrum

12 Bathymetry Plat

13 Public Information Plat

14 Proprietary Information Plat

15 Vicinity Map

16 10

- Mile Radius Plat

viAnadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG



### LIST OF CHARTS

The following chart at a scale of 1" = 2,000ft is enclosed:

Chart No Title Drawing No

1 Biological, Physical and Socio

- Economic Map 9515

. 01

viiAnadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG



### WELL C LEARANCE LETTER – PROPOSED AT0 18 GG WELL LOCATION
July 15 , 2013 Anadarko Petroleum Corporation

1201 Lake Robbins Drive The Woodlands, TX 77380

Attention: Rick Kincaid

Well Clearance Letter Proposed AT0 18 GG Well Location

Block 18 , Atwater Valley Area
OCS - G 33863

Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Well Clearance Letter for the proposed AT018 GG well location in Block 18

, Atwater Valley Area (OCS

- G 33863 ). This letter addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this well clearance

ass essment is Top of Salt or

- 10,827ft below sea surface (6,587ft below seabed). We understand that Anadarko Petroleum Corporation plans to drill the proposed exploration well from a dynamically positioned drilling vessel; therefore, an anchoring assessment is not required nor provided. Relevant

letter

- size chart extracts, data examples, and a Top Hole Prognosis are presented with this Well Clearance Letter. This geohazard assessment is based on the interpretation of 3D seismic data. This site clearance letter is issued as a supplement to Gardline Report No.9172 en titled: 3D Geohazard

Asse ssment, Atwater Valley Block 018 and 019, dated August 2012

.

Archaeological Survey. Anadarko Petroleum Corporation provided for review the complete archaeological survey report acquired by C&C Technologies Survey Services: Archaeological Survey

Blocks 18 (OCS -G- 33863) and 19 (OCS -G- 32556) Atwater Valley Area for the Anadarko Stromboli Prospect.

3D Geophysical Survey. Anadarko Petroleum Corporation provided the 3D dataset to Gardline Surveys Inc. on tape media in SEG

- Y format for loading onto a Seismic Micro

- Technology (SMT) workstation. The 3D data cube contains a survey with 4 millisecond sample rate data to a record length of 6 .0 seconds TWT below sea surface. Inlines are oriented north to south, have a numerical increment of one, and exhibit a line spacing of 65.62ft. Crosslines are oriented west to east, have a numerical increment of one, and exhibit a line spacing of 41.01ft.

• The acquisition parameters are:

o Atwater Valley (I) DW V

Shooting Direction: N/S Configuration: 4 sources, 6

- 10 streamers

1Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG

Maximum offset : 8000 m
Channels : 324 per streamer Shotpoint interval : 47.25 m per array Group interval : 25 m CMP line spacing : 40 m
CMP bin dimension : 12.5 m x 40 m Record Length: 9 s below sea bottom

Nominal fold: 43 Vintage: April 1999

• The basic processing parameters are:

o Atwater Valley (I) DW V

480

- m x 500

- m velocity grid Demultiple 3D DMO velocity and stacking technology
One

- pass 3D poststack migration

12.5

- m x 20

- m final bin dimension

. The data exhibits a good frequency response across the upper 1second below seabed, with an effective frequency range of 5 to 65Hz ( Figure 1 1 ) . The data exhibits a dominant frequency of approximately 53Hz with significant higher usable frequencies. This frequency range results in a mean vertical resolvability of approximately 10m and a layer detectability of 5ft

.

In summary and with reference to NTL No. 2008

- G04 : a) The 3D dat a provides images of sufficient resolution of the shallow section allowing a clear analysis of the shallow conditions b) The data can be loaded to a workstation at 16bit resolution or greater, and is un

- scaled c) There is no trace or sample decimation d) The sample interval and bin size are maintained throughout the assessment area e) The data possess a frequency content of 50Hz or higher across the first second below seabed (See Power Spectrum Diagram : ( Figure 1 1 ) f) Seabed reflection is free of gaps and defined by a wavelet of stable shape and phase, allowing auto

- tracking of the seabed event with minimum user intervention and guidance g) There are no significant acquisition artefacts throughout the dataset h) There are no merge points in the data i) Processed bin sizes are 65.62ft x 41.01ft j) The sample rate of the data is 4 ms k) An accurate velocity model has been utilized in the shallow section allowing optimum structural and stratigraphy resolution with no evidence of under or over migration l) There is no significant multiple en ergy

2Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG

m) The proposed activities are not in an area of high archaeological potential.

3Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG



### 1. LOCATION COORDINATES

**1.1 P**  **roposed AT0 18** 

**- GG**  **Well Location**

Proposed AT0 18

- GG Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 57' 24.70 ” North Easting 979,365 US ft E
Longitude 89° 02’ 53.39 ” West Northing 10,150,705 US ft N
FEL of Atwater Valley 18 2,715 US ft Inline 5304
FNL of Atwater Valley 18 2,735 US ft Crossline 10707
Water Depth:

- 4,240 ft Slope: 1.5° NE

Nearest Shoreline 71 Miles @ 343°
Port of Operation Fourchon 106 Miles @ 320°

Nearest Manned Platform MC941

- (Mirage/Titan) 6 Mile s @ 328 °

4Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG



### 2. VELOCITY DATA

**2.1 Velocity Data** 

Time

- to

- depth conversion for the water column was derived using the Advocate and Hood (1993) polynomial.

Water Depth (ft) =

0.1105 – 5066.9193X + 468.6693X 2

– 554.7107X 3 + 340.7019X 4

– 116.991X 5 + 20.728X 6

– 1.4658X 7 Where X = one way time to seabed (in s econds)

One Way Time To Seabed (s) Seabed Depth (ft) Seabed Depth (m) Vavg (m/s)

0.0 0 0 0

1 .0 4910 1496 1496

1.1 5400 1646 1496

1.2 5892 1796 1496

1.3 6384 1946 1497

1.4 6877 2096 1497

1.5 7370 2246 1498

1.6 7865 2397 1498

1.7 8360 2548 1499

1.8 8856 2699 1499

1.9 9353 2851 1500

5Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG

Sub

- seabed time to depth conversion was performed using a polynomial function successfully applied in an adjacent project and approved by Anadarko Petroleum Company :

Vavg = = - 45.841X 5 + 190.08X 4

– 183.08 X3 - 14.729X2 + 735.59X +4900

Where X = two way time in seconds below seabed

.

The resultant velocity was then multiplied by the time below seabed to produce depth below
seabed ; t his was summed with seabed depth to produce horizon depth below sea surface.

6Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG



### 3. SEABED CONDITIONS

**3.1 Bathymetry** 

Seabed depth at the proposed AT018

- GG well location is

- 4,240 ft below sea surface ( Figure

1 ). The seafloor slopes to the northeast at 1 .5 °.

**3.2 Seafloor Morphology and Man Made Features** 

The proposed AT 018

- GG well location is in the northeast of Block AT18

. T he seabed is

smooth and featureless a t the proposed well location ( Figure 2 ). Soft clays and silts are predicted at seabed. Sediments appear conducive for jetting of seabed casing with no hard layers predicted.

An existing well AT 0 18

- 00 1 is located 1,543ft to the northeast. The following are the

coordinates:

Well Installation:

Operator Block Well No. API No. Depth (ft) TVD Easting Northing Status

BHP Billiton A T 018 001 60 818 40024 00 4,266 28,651 980,051 10,152,077 PA

There are no anomalous seabed amplitudes indicative of hydrocarbon macroseep observed within a 2,000ft radius of the proposed location ( Figure 3 ).

No items of archaeological significance were identified within 2,000ft of the proposed location (archaeologi cal report submitted under a separate cover)

.

No other features are observed within a 2,000ft radius that could affect well emplacement or jetting of casing.

7Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG



### 4. SUBSEABED CONDITIONS

**4.1 Geology and Lithology** 

The sub

- seabed geology has been divided into f our units separated by four horizons ( Figures

6 through 9 ). A Geohazard Extract and Sand Lithology Extract complete the well assessment ( Figures 4 and 5 )

.

**4.2 Unit A** 

The upper most interval within Unit A from Seabed to

- 4,479ft below sea surface (238ft below seabed) is interpreted to consist of clays and silts with occasional minor coarser interbeds.

The lower interval of Unit A from

- 4,479ft to

- 4,865ft below sea surface (238ft to 625ft below seabed) is interpreted to comprise of clays and silts.

No shallow gas or shallow water flow is predicted with in Unit A at the proposed well location.

A vertical borehole will not penetrate any faults within Unit A.

Horizon H10 marks the base of Unit A at

- 4,865ft below sea surface (625ft below seabed).

**4.3 Unit B** 

The upper interval of Unit B from

- 4,865ft to

- 5,176ft below sea surface (625ft to 936ft below seabed) is expected to comprise of clays and silts with occasional coarser interbeds.

The lower interval of Unit B from

- 5,176ft to

- 5,425ft below sea surface (936ft to 1,185ft below seabed) is interpreted to consist of clays and silts with several coarser interbed s. The coarser

interbeds in this lower interval of Unit B may cause minor drilling fluid circulation and mino r wellbore stability problems.

No shallow gas or shallow water flow is predicted with in Unit B at the proposed well location.

A vertical borehole will not penetrate any faults within Unit B.

Horizon H20 marks the base of Unit B at

- 5,425ft below sea surface (1,185ft below seabed).

**4.4 Unit C** 

Lithology within the upper interval of Unit C from

- 5,425ft to

- 6,045ft below sea surface (1,185ft to 1,805ft below sea surface) is interpreted to consist of a clay

- prone sequence with

occasional coarser interbeds.

8Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG

From

- 6,045ft to

- 6,282ft below sea surface (1,805ft to 2,042ft below seabed) the stratigraphy is interpreted as clays and silts with several coarser interbeds that possibly represent sands.

T he proposed well is located on the north east edge of a sand fairway that extends from the

southwest of the adjacent block (Block AT0 19 ) into the east

- central part of Block AT0 18 and
continues to cross the center of the block to the northwest ( Figure 5 )

. A cluster of high amplitude anomalies located around 600ft to the east and northeast of the proposed well are interpreted as a high risk of gas. The vertical borehole will not traverse any of these

anomalies , with the nearest risk of gas anomaly being 312ft to the southeast. However, the sands within this package could possibly connect to the borehole, and as such a Slight Risk
of Gas is assigned within this interval. In addition due to the sandy nature of this interval

, potentially rapidly deposited with inadequate dewatering time

, with a possible clay rich impermeable overburden forms a favorable setting for development of shallow water flow, and

a Moderate Shallow Water Flow Risk is assigned to this inter val. This interval did not present any reported drilling problems at the nearby offset well AT018

- 001.

The lithology from

- 6,282ft to

- 6,428ft below sea surface (2,042ft to 2,188ft below seabed) is interpreted to comprise of clays and silts with occasional coarser interbeds.

The interval f rom

- 6,428ft to

- 7,170ft below sea surface (2,188ft to 2,930ft below seabed) is interpreted to consist of clays and silts with several coarser interbeds that may represent sands. The well path is located outside the main cluster of high amplitude anomalies that occur around 2,000ft to the southwest that are interpreted as fluid charged sands

. A previously drilled well located 4.9 miles to the southeast (AT0 63

- 00 2) experienced a low

volume shallow water flow event in sands at 2,012ft below seabed ; correlating with this

interval

. The nearest offset well, AT018

- 001 did encounter some shallow gas shows and some ballooning of the wellbore through this interval. At the proposed location this interval is thicker and exhibits higher energy character than observed at the existing AT018

- 001 well. The proposed location is also more centrally placed within the Unit C sand fairways than the existing AT018

- 001 well ( Figure 5 ). However, the seismic over the existing AT018

- 001 well does present an anomaly that could be the source of the gas shows observed ( Figure 8 ) and

t his anomaly is not present at the proposed well location. Taking into account all these

observations and the acoustic signature of the interval, suggestive of potentially r apidly deposited sandy interbeds that have may have experienced inadequate dewatering a Slight
Risk of Gas and a Moderate Shallow Water Flow Risk is assigned to this interval.

A clay

- rich sequence with occasional coarser

- grained interbeds is interpreted from

- 7,170ft to

- 7,307ft below sea surface (2,930ft to 3,067ft below seabed).

The lower interval within Unit C from

- 7,307ft to

- 7,639ft below sea surface (3,067ft to 3,398ft below seabed) is interpreted to comprise of clays with several coarser interbeds. The coarser interbeds within this package may induce minor drilling fluid circulation and wellbore stability problems. The existing well AT018

- 001 did encounter some minor shallow gas shows in this interval, but there is no clear indication of any anomalies on the seismic data to support any

9Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG

shallow gas occurrence at the proposed well location.

A vertical borehole will not penetrate any faults within Unit C.

Horizon H30 marks the base of Unit C at

- 7,639ft below sea surface (3,398 ft below seabed).

**4.5 Unit D** 

The upper interval of Unit D

, from

- 7,639ft to

- 8,041ft below sea surface (3,398ft to 3,802 ft below seabed)

, is interpreted to consist of clays and silts with occasional coarser interbeds. No drilling hazards or problems are exp ected with in this upper interval.

From

- 8,041ft to

- 8,653ft below sea surface (3,802ft to 4,413 ft below seabed)

, is interpreted

as a slightly higher

- energy deposited package with clays and several coarser interbeds. This interval exhibits character of shallow water flow, with potential for rapid deposition

, and inadequate dewatering. As such, a Slight Shallow Water Flow Risk is assigned to this

interval. Due to the potential for coarser, potentially poorly consolidated sediments with in this interval, minor drilling fluid circulation and wellbore stability problems may also occur. The nearby offset well AT018

- 001 did not report any problems from this interval, which is acoustically similar on the seismic data.

Str atigraphy from

- 8,653ft to

- 10, 82 7ft b elow sea surface (4,413ft to 6,587ft below seabed) is interpreted to consist of clays with occasional coarser interbeds.

No shallow gas is predicted withi n Unit D at the proposed well location. T he risk of gas anomaly is approximately 625ft WSW.

Top of Salt marks the base of Unit D and the Base of this interpretation at

- 10,827ft below sea surface (6,587ft below seabed).

**4.6 Shallow Gas Assessment** 

Within Unit C , a Slight Risk of Gas is assigned to the interval from

- 6,045ft to

- 6,282ft below

sea surface (1,8 05ft to 2,042ft below seabed), and also from

- 6,428ft to

- 7,170ft below sea surface (2,188ft to 2,930ft below seabed).

**4.7 Shallow Water Flow Assessment** 

Within Unit C , a Moderate Shallow Water Flow Risk is interpreted in the interval from

- 6,0 45ft to

- 6,282ft below sea surface (1,805ft to 2,042ft below seabed) and from

- 6,428ft to

- 7,170ft below sea surface (2,188ft to 2,930ft below seabed).

Within Unit D, a Slight Shallow Water Flow Risk is assigned from

- 8,041ft to

- 8,653ft below sea surface (3,802ft to 4,413ft below seabed).

10Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG



### 5. CONCLUSIONS AND RECOMMENDATIONS

• Seabed No significant problems are anticipated at seabed. Shallow soils are expected to be conducive to the jetting of seabed casing with no hardgrounds predicted.

• Unit A
No drilling hazards or problems predicted.

• Unit B
Minor drilling and minor wellbore stability problems are possible from

- 5,176ft to

- 5,425 ft below sea surface ( 936ft to 1,185ft below seabed).

• Unit C
Within Unit C, a Slight Risk of Gas and a Moderate Shallow Water Flow Risk is assigned

to the interval from

- 6,045ft to

- 6,282ft below sea surface (1,805ft to 2,042ft below seabed)

, and from

- 6,428ft to

- 7,170ft below sea surface (2,188ft to 2,930ft below seabed). Drilling
Caution is advised and appropriate drilling methodology is recommended to deal with a

po ssible water flow event through this interval. The existing AT018

- 001 well, did encounter some shallow gas shows and minor drilling problems f rom the lower interval

.

Within Unit C, a Moderate Shallow Water Flow Risk is also interpreted from

- 6,428ft to

- 7,170ft below sea surface (2,188ft to 2,930ft below seabed). Appropriate drilling methodology is recommended to deal with a possible water flow event through this interval. Additionally, minor drilling fluid circulation and wellbore stability problems ma y also occur

within this interval.

Minor drilling fluid circulation and wellbore stability problems may also occur from

- 7,307ft to

- 7,639ft below sea surface (3,067ft to 3,398ft below seabed).

• Unit D

A Slight Shallow Water Flow Risk is interpreted in Unit D

, from

- 8,041ft to

- 8,653 ft below sea surface (3,802ft to 4,413ft below seabed). Appropriate drilling methodology should be utilized to contain a potentially non

- persistent shallow water flow event within this interval. Minor drilling fluid circula tion and wellbore stability problems may also occur with in this

interval.

11Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GG

We appreciate the opportunity to work with you on this project, and look forward to continuing as your geohazards consultants. Please contact us if you have any questions or if we can be of
further assistance.

Sincerely, Gardline Surveys Inc.

Andrew Haigh Matilde DeLeon Geophysical Manager Quality Assurance

Copies Submitted: 6 copies to Rick Kincaid at Anadarko Petroleum Corporation.

Attachments:

Proposed AT018

- GG Well Location

Seabed Depth Extract

Seabed Morphology Extract

Seabed Amplitude Extract

Geohazard Summary Extract

Sand Lithology Summary

Inline Data Example

Crossline Data Example

Arbitrary Line Data Example

Top Hole Prognosis

ROV Plat

Power Spectrum

Bathymetry Plat

Public Information Plat

Proprietary Information Plat

Vicinity Map

10

- Mile Radius Plat

12

## Top Hole Prognosis for Proposed AT18 GG Well Location 979,365ft E / 10,150,705ft N
Inline: 5304 / Crossline: 10707 Horizon Subsea Depth

(ft) BML Depth

(ft) Horizon
TWT (sec) Lithology, Structure & Stratigraphy Potential Drilling Hazards & Constraints Risk
of
Gas SWF
Risk

Seabed -4,240 0 1.725 Seabed is smooth sloping to the northeast at 1.5°. Surficial sediments comprise of soft clays and silts. Underlying the seabed lithology comprises of clays and silts with occasional minor coarser interbeds



## Figure 9 Interface -6,045 1,805 2.398 Horizon H10 -4,865 625 1.971

Interface -6,282 2,042 2.479 Clays and silts

Clays and silts with occasional coarser interbeds None predicted

None predicted

None predicted

Minor drilling fluid circulation and minor wellbore stability problems possible within this interval Unit A

Unit B

Unit D Interface -7,170 2,930 2.769 Horizon H20 -5,425 1,185 2.179

Interface -7,307 3,067 2.812

Horizon H30 -7,639 3,398 2.914

Interface -8,041 3,802 3.034

Top of Salt -10,827 6,587 3.765 Clay-prone sequence with occasional coarser interbeds

Clays and silts with several coarser interbeds that may represent sands

Clay-prone sequence with occasional coarser-grained interbeds

Clays with occasional coarser interbeds None predicted

Unit C

Base of interpretation Clays and silts with occasional coarser interbeds Clays and silts with several coarser interbeds

Slight Risk of Gas. Moderate Shallow Water Flow Risk

None Predicted

Slight Risk of Gas and Moderate Shallow Water Flow Risk. Minor drilling fluid circulation and wellbore stability problems possible

None Predicted -6,428 2,188 2.528 Interface

Interface -8,653 4,413 3.208 Clays and silts with several coarser interbeds that may represent sands Interface -5,176 936 2.088 Interface -4,479 238 1.821

Clays with several coarser interbeds Minor drilling fluid circulation and wellbore stability problems possible

Clays and silts with occasional coarser interbeds None Predicted

Clays with several coarser interbeds that may represent sands Slight Shallow Water Flow Risk. Minor drilling fluid circulation and wellbore stability problems possible

None Predicted Vavg
BML (m/s)

0

5,365 5,078

5,418

5,613 5,220

5,643

5,717

5,809

6,457 5,450

5,952 5,159 4,970

# ±

6

®33 3

3

-4210
-4180

-4200 -4190

-4170 -4220

-4160 -4230 -4240

-4150 -4250 -4260 -4270 -4280 -4290 -4300 -4310

-4140 -4320 -4330

-4150 -4150

-4150

-4240 -4150 -4280 -4260

-4170 -4210

-4270

-4250

-4230 -4140 -4200

-4220 -4240 -4200-4260 -4180 -4270

-4160 -4180 -4210

-4160 -4170 -4210

-4210

-4180 -4160

-4160 -4230

-4230

-4160

-4150 -4150 AT018-00189°3'0"W89°4'0"W89°5'0"W

27°57'0"N

27°56'0"N

27°55'0"N970,000975,000980,000 10,135,000 10,140,000 10,145,000 10,150,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1 = 2,000' 

## Bathymetry Plat Figure 12 AT018-GG Easting: 979,365ft E Northing: 10,150,705ft N FEL of AT018-GG: 2,715ft FNL of AT018-GG: 2,735ft

2 , 0 0 0 f t R

a d i u s

ATWATER VALLEY BLOCK 18(OCS-G33863)

# ±

6

®33 3

3 Proposed AT018-GG Well AT018-00189°3'0"W89°4'0"W89°5'0"W

27°57'0"N

27°56'0"N

27°55'0"N970,000975,000980,000 10,135,000 10,140,000 10,145,000 10,150,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1" = 2,000' 

## Well Location Plat - Public Information Figure 13 ATWATER VALLEY BLOCK 18(OCS-G33863) Location Call N/S Call E/W X Coordinate Y Coordinate Latitude Longitude WD AT018-GG SL 2,735ft FNL 2,715ft FEL 979,365 10,150,705 27° 57' 24.70"N 89° 02' 53.39"W -4,240 Proposed Location - AT018-GGNearest Shoreline Range: 71mi Bearing: 343° Fourchon Range: 106mi Bearing: 320°

Lund Henderson Lloyd Ridge

Walker Ridge Destin Dome

Atwater Valley Green Canyon De Soto Canyon

The Elbow

Florida Plain Vernon Basin Apalachicola

Garden Banks

Keathley Canyon Florida Middle Ground

Howell Hook Lund South Pensacola

Amery Terrace Mobile

Viosca Knoll

Viosca Knoll

Sigsbee Escarpment New Orleans Baton Rouge Pensacola

Lafayette Pascagoula Gulfport 

# Vicinity Map - Atwater Valley Block 018

Figure 15Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 GG



### APPENDIX A – Public Shallow Hazards Statement s

29Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 GG

Public S hallow Hazards Statement – AT018

- GG July 15 , 2013

US Department of the Interior Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

- 2394

Attention:

Reference: Shallow Hazards Analysis Atwater Valley Block 18
OCS

- (G 33863 )

Ladies/Gentlemen:

Anadarko Petroleum Corporation contracted Gardline Surveys, Inc. to prepare a Well Clearance Letter for the proposed AT018

- GG well location in Block 18 , Atwater Valley Area (OCS

- G 33863 ). This letter

addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this geohazard assessment is to Top of
Salt at

- 10,827ft below sea surface (6,587ft below seabed).

This hazards summary lette r is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block 018and 019, dated August 2012.

**Seabed Hazards.**

The seabed is smooth and featureless. No problems are expected at the proposed AT 18 GG well

location.

There are no indications of seabed fluid seeps within 2,000ft of the well location.

No existing seabed infrastructure is located within 2,00 0 ft of the proposed well. There is an existing

well AT0 18

- 00 1 located 1 ,543ft to the northeast. The following are the coordinates:

Well Installation:

Operator Block Well No. API No. Depth (ft) TVD Easting Northing Status

BHP Billiton AT 018 001 60 818 40024 00 4,266 28,651 980,051 10,152,077 PA

Two pipelines are located on the adjacent Block AT019 approximately 6,315ft and 5,335ft to the east and northeast. The following are detailed of the pipelines:

**Pipeline Installations**

Operator Area Block

- Origin/Termination Outside Diameter (in) Product Status

ATP O&G AT063 / MC941 5 in BLKO ACT

ATP O&G MC941 / AT063 4in UBEH ACT

30Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 GG

**Sub**

**- Seabed Hazards.**  Drilling Caution is indicated for a Slight Risk of Gas at the well location within two interval s of Unit C.

Moderate Shallow Water Flow Risk is assigned to two intervals within Unit C

. A Slight Shallow

Water Flow Risk is anticipated within an interval in Unit D.

Proposed AT 18 GG Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 57' 24.70 ” North Easting 979,365 US ft E
Longitude 89° 02’ 53.39 ” West Northing 10,150,705 US ft N
FEL of Atwater Valley 18 2,715 US ft Inline 5304
FNL of Atwater Valley 18 2,735 US ft Crossline 10707
Water Depth:

- 4,240 ft Slope: 1.5° NE

Nearest Shoreline 71 Miles @ 343°
Port of Operation Fourchon 106 Miles @ 320°

Nearest Manned Platform MC941

- (Mirage/Titan) 6 Miles @ 328 °

**Conclusions and Recommendations.** Drilling techniques will take into consideration the possibility of encountering possible gas within two
interval of Unit C . Appropriate drilling methodology should be utilized to contain a potentially non

persistent Slight Shallow Water Flow Risk interpreted in the lower interval of Unit D . Appropriate drilling methodology should be utilized to deal with a possible Moderate Shallow Water Flow Risk in
the intervals within Unit C.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations



## PUBLIC INFORMATION

31Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 GG



### APPENDIX B – Sensitive Sessile Benthic Community Statements

32Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 GG

Sensitive Sessile Ben thic Community Statement – AT018

- GG



### Anadarko Petroleum Corporation

July 15 , 2013

US Department of the Interior Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

Reference: Sensitive Sessile Benthic Community Summary Atwater Valley, Block 18
OCS

- (G 33863 )

Ladies/Gentlemen: Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Site Clearan ce Letter for the proposed AT018

- GG well locat ion in Atwater Valley, Block 18

, Stromboli Prospect (OCS

G G 33863 ). This letter addresses location proximity to potential sensitive sessile benthic community

sites. Anadarko Petroleum Corporation will be drilling this well from a dynamically positioned drilling

module ; therefore

, no anchors will impact seabed.

This sensitive sessile benthic community summary letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block 018, dated August 2012 . A Biological, Physical and Socio

- Econom ic Map is included at the end of this appendix illustrating the areas of potential seabed impact.

**Potential Sensitive Sessile Benthic**  **Communities.** Features or areas that could support high density sensitive sessile benthic communities are **not** located within 2,000ft of any proposed mud and cuttings discharge location.

Proposed AT018

- GG Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 57' 24.70 ” North Easting 979,365 US ft E
Longitude 89° 02’ 53.39 ” West Northing 10,150,705 US ft N
FEL of Atwater Valley 18 2,715 US ft Inline 5304
FNL of Atwater Valley 18 2,735 US ft Crossline 10707
Water Depth:

- 4,240 ft Slope: 1.5° NE

Nearest Shoreline 71 Miles @ 343°
Port of Operation Fourchon 106 Miles @ 320°

Nearest Manned Platform MC941

- (Mirage/Titan) 6 Miles @ 328 °

33Anadarko Petroleum Corporation Gardline Report 9515
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 GG

No potential sensitive sessile benthic community site is located within 2,000ft of the proposed

location

.

**Conclusions and Recommendations:** The proposed AT018

- GG well location will not impact any sites favorable for development of sensitive

sessile benthic communities.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations

34

# ANADARKO PETROLEUM C ORPORATION

3D GEOHAZARD ASSESSM ENT

GULF OF MEXICO

ATWATER VALLEY BLOCK AT0 18

STROMBOLI PROSPECT

AT0 18 -GV PROPOSED WEL L LOCATION

WELL CLEARANCE LETTE R

APRIL 201 3

Gardline Project Ref. 95 1 8 Report Status Final

Issue Date July 15 , 2013

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.comAnadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV



### REPORT AUTHORIZATION AND DISTRIBUTION

Report Status Final

Issue Date Ju ly 15 , 2013

Compilation Geophysicist L Fuentes

Authori z ation Geophysics

..................... A R Haigh

Quality Assurance

..................... M DeLeon

Distribution

6 copies

Anadarko Petroleum Corporation

1201 Lake Robbins Drive

The Woodlands, TX 77380

For attention of:

Rick Kincaid

iiAnadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV



### SERVICE WARRANTY

**USE OF THIS REPORT**

This report has been prepared with due care, diligence and with the skill reasonably expected of a reputable contractor experienced in the types of work, carried out under the contract. As such, the findings in this report are based on an interpretation of data which is a matter of opinion on which professionals may differ and, unless clearly stated, is not a recommendation of any course of action.

Gardline Surveys, Inc. has prepared this report for the client identified on the front cover in fulfilment of its contractual obligations under the referenced contract, and the only liabilities Gardline Surveys, Inc. will accept are those contained therein.

Please be aware that further distribution of this report, in whole or part, or the use of the data for a purpose not expressly stated within the contractual work scope is at the client’s sole risk, and Gardline Surveys, Inc recommends that this disclaimer be included in any such distribution.

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.com

iiiStudy Area Atwater Valley Green Canyon Lloyd Ridge Mississippi Canyon Destin Dome

De Soto Canyon Mobile Pensacola

Ship Shoal Area Eugene Island Area Viosca Knoll

Viosca Knoll Main Pass Area

Ewing Bank South Timbalier Area West Delta Area Louisiana Alabama Mississippi
Florida 

# Location Map

Study AreaAnadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV



### TABLE OF CONTENTS

REPORT AUTHORIZATION AND DISTRIBUTION ii

SERVICE WARRANTY iii

LOCATION MAP iv

TABLE OF CONTENTS v

LIST OF FIGURES vi

LIST OF CHARTS vii

WELL CLEARANCE L ETTER
– PROPOSED AT018 GG WELL LOCATION 1

1. LOCATION COORDINATES 4

1.1 Proposed AT018

- GV Well Location 4

2. VELOCITY DATA 5

2.1 Velocity Data 5

3. SEABED CONDITIONS 7

3.1 Bathymetry 7

3.2 Seafloor Morphology and Man Made Features 7

4. SUBSEABED CONDITIONS 8

4.1 Geology and Lithology 8

4.2 Unit A 8

4.3 Unit B 8

4.4 Unit C 8

4.5 Unit D 10

4.6 Shallow Gas Assessment 10

4.7 Sh allow Water Flow Assessment 11

5. CONCLUSIONS AND RECOMMENDATIONS 12

APPENDIX A
– Public Shallow Hazards Statements 29

APPENDIX B
– Sensitive Sessile Benthic Community Statements 32

vAnadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV



### LIST OF FIGURES

Proposed A T 18 GV Well Location

1 Seabed Depth Extract

2 Seabed Morphology Extract

3 Seabed Amplitude Extract

4 Geohazard Summary Extract

5 Sand Lithology Summary

6 Inline Data Example

7 Crossline Data Example

8 Tie Line to AT018

- 001

9 Top Hole Prognosis

10 ROV Plat

11 Power Spectrum

12 Bathymetry Plat

13 Public Information Plat

14 Proprietary Information Plat

15 Vicinity Map

16 10

- Mile Radius Plat

viAnadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV



### LIST OF CHARTS

The following chart at a scale of 1" = 2,000ft is enclosed:

Chart No Title Drawing No

1 Biological, Physical and Socio

- Economic Map 9518

. 01

viiAnadarko Petroleum Corporation Gardline Report 9520
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT018

- CC Well Location



### WELL C LEA RANCE LETTER – PROPOSED AT018

- CC WELL LOCATION

Ju ly 15 , 2013 Anadarko Petroleum Corporation

1201 Lake Robbins Drive The Woodlands, TX 77380

Attention: Rick Kincaid

Well Clearance Letter Proposed AT018

- CC Well Location

Block 018 , Atwater Valley Area
OCS - G33863

Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Well Clearance

L etter for the proposed AT018

- CC well location in Block 018

, Atwater Valley Area (OCS

- G 33863 ). This letter addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this well clearance

ass e ssment is Top of Salt or

- 10,279ft below sea surface (6,112ft below seabed). We understand that Anadarko Petroleum Corporation plans to drill the proposed exploration well from a dynamically positioned drilling vessel; therefore, an anchoring assessment is not required. Relevant letter

- size chart extracts, data examples, and a Top Hole Prognosis are presented with this Well Clearance Letter. This geohazard assessment is based on the interpretation of 3D seismic data. This site clearance letter is issued as a supplement to Gardline Report No.9172 en titled: 3D Geohazard

Asse ssment, Atwater Valley Block 018, dated August 2012

.

Archaeological Survey. Anadarko Petroleum Corporation provided for review the complete archaeological survey report acquired by C&C Technologies Survey Services: Archaeological Survey

Blocks 18 (OCS -G- 33863) and 19 (OCS -G- 32556) Atwater Valley Area for the Anadarko Stromboli Prospect.

3D Geophysical Survey. Anadarko Petroleum Corporation provided the 3D dataset to Gardline Surveys Inc. on tape media in SEG

- Y format for loading onto a Seismic Micro

- Technology (SMT) workstation. The 3D data cube contains a survey with 4 millisecond sample rate data to a record length of 6 .0 seconds TWT below sea surface. Inlines are oriented north to south, have a numerical increment of one, and exhibit a line spacing of 65.62ft. Crosslines are oriented west to east, have a numerical increment of one, and exhibit a line spacing of 41.01ft.

• The acquisition parameters are:

o Atwater Valley (I) DW V

Shooting Direction: N/S Configuration: 4 sources, 6

- 10 streamers

1Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV

Maximum offset: 8000 m
Channels: 324 per streamer Shotpoint interval: 47.25 m per array Group interval: 25 m CMP line spacing: 40 m
CMP bin dimension: 12.5 m x 40 m Record Length: 9 s below sea bot tom
Nominal fold: 43 Vintage: April 1999

• The basic processing parameters are:

o Atwater Valley (I) DW V

480

- m x 500

- m velocity grid Demultiple 3D DMO velocity and stacking technology
One

- pass 3D poststack migration

12.5

- m x 20

- m final bin dimension

. The data exhibits a good frequency response across the upper 1second below seabed, with an effective frequency range of 5 to 65Hz ( Figure 11 ) . The data exhibits a dominant frequency of approximately 53Hz with significant higher usable frequencies. This frequency range results in a mean vertical resolvability of approximately 10m and a layer detectability of 5ft

.

In summary and with reference to NTL No. 2008

- G04 : a) The 3D data provides images of sufficient resolution of the shallow section allowing a clear analysis of the shallow conditions b) The data can be loaded to a workstation at 16bit resolution or greater, and is un

- scaled c) There is no trace or sample decimation d) The sample interval and bin size are maintained throughout the assessment area e) Th e data possess a frequency content of 50Hz or higher across the first second below seabed (See Power Spectrum Diagram: (Figure 10) f) Seabed reflection is free of gaps and defined by a wavelet of stable shape and phase, allowing auto

- tracking of the seabed event with minimum user intervention and guidance g) There are no significant acquisition artefacts throughout the dataset h) There are no merge points in the data i) Processed bin sizes are 65.62ft x 41.01ft j) The sample rate of the data is 4ms k) An accurate velocity model has been utilized in the shallow section allowing optimum structural and stratigraphy resolution with no evidence of under or over migration l) There is no significant multiple energy

2Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV

m) The proposed activities are not in an area of high archaeological pot ential.

3Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV



### 1. LOCATION COORDINATES

**1.1 P**  **roposed AT0 18** 

**- GV**  **Well Location**

Proposed AT 18 GV Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 57' 25.62” North Easting 980,582 US ft E
Longitude 89° 02’ 39.83” West Northing 10,150,777 US ft N
FEL of Atwater Valley 18 1,498 US ft Inline 5322
FNL of Atwater Valley 18 2,663 US ft Crossline 10709
Water Depth:

- 4,271 ft Slope: 1.5° NE

Nearest Shoreline 71.34 Miles @ 343° 25’ 48’’

Port of Operation Fourchon 106.42Miles @ 320° 36’ 0’’

Nearest Manned Platform MC941

- (Mirage/Titan) 6.25 Miles @ 328° 17’ 24”

4Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV



### 2. VELOCITY DATA

**2.1 Velocity Data** 

Time

- to

- depth conversion for the water column was derived using the Advocate and Hood (1993) polynomial.

Water Depth (ft) =

0.1105 – 5066.9193X + 468.6693X 2

– 554.7107X 3 + 340.7019X 4

– 116.991X 5 + 20.728X 6

– 1.4658X 7 Where X = one way time to seabed (in seconds)

One Way Time To Seabed (s) Seabed Depth (ft) Seabed Depth (m) Vavg (m/s)

0.0 0 0 0

1.0 4910 1496 1496

1.1 5400 1646 1496

1.2 5892 1796 1496

1.3 6384 1946 1497

1.4 6877 2096 1497

1.5 7370 2246 1498

1.6 7865 2397 1498

1.7 8360 2548 1499

1.8 8856 2699 1499

1.9 9353 2851 1500

5Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV

Sub

- seabed time to depth conversion was performed using a polynomial function successfully applied in an adjacent project and approved by Anadarko Petroleum Company :

Vavg = = - 45.841X 5 + 190.08X 4

– 183.08 X3 - 14.729X2 + 735.59X +4900

Where X = two way time in seconds below seabed

.

The resultant velocity was then multiplied by the time below seabed to produce depth below
seabed ; t his was summed with seabed depth to produce horizon depth below sea surface.

6Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV



### 3. SEABED CONDITIONS

**3.1 Bathymetry** 

Seabed depth at the proposed AT018

- GV well location is

- 4,271 ft below sea surface (Figure 1). The seafloor slopes to the northeast at 1 .5 °.

**3.2 Seafloor Morphology and Man Made Features** 

The proposed AT 018

- GV well location is in the northeast of Block AT18

. The seabed is smooth and featureless at the proposed well location (Figure 2). Soft clays and silts are predicted at seabed. Sediments appear conducive for jetting of seabed casing with no hard layers predicted.

An existing well AT 0 18

- 001 is located 1,375ft to the northwest. The following are the

coordinates:

Well Installation:

Operator Block Well No. API No. Depth (ft) TVD Easting Northing Status

BHP Billiton A T 018 001 60 818 40024 00 4,266 28,651 980,051 10,152,077 PA

There are no anomalous seabed amplitudes indicative of hydrocarbon macroseep observed within a 2,000ft radius of the proposed location (Figure 3).

No items of archaeological significance were identified within 2,000ft of the proposed location (archaeologi cal report submitted under a separate cover)

.

No other features are observed within a 2,000ft radius that could affect well emplacement or jetting of casing.

7Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV



### 4. SUBSEABED CONDITIONS

**4.1 Geology and Lithology** 

The sub

- seabed geology has been divided into f our units separated by four horizons (Figures

6 through 9 ). A Geohazard Extract and Sand Lithology Extract complete the well assessment ( Figures 4 and 5 )

.

**4.2 Unit A** 

The upper most interval with in Unit A from Seabed to

- 4,479ft below sea surface (263ft below seabed) is interpreted to consist of clays and silts with occasional minor coarser interbeds.

The lower interval o f Unit A from

- 4,479ft to

- 4,848ft below sea surface (263ft to 577ft below seabed) is interpreted to comprise of clays and silts.

No shallow gas or shallow water flow is predicted with in Unit A at the proposed well location.

A vertical borehole will not penetrate any faults within Unit A.

Horizon H10 marks the base of Uni t A at

- 4,848ft below sea surface (577ft below seabed).

**4.3 Unit B** 

The upper interval of Unit B from

- 4,848ft to

- 5,234ft below sea surface (577ft to 963ft below seabed) is expected to comprise of clays and silts with occasional coarser interbeds.

The lower interval of Unit B from

- 5,234ft to

- 5,407ft below sea surface (963ft to 1,136ft below seabed) is interpreted to consist of clays and silts.

No shallow gas or shallow water flow is predicted with in Unit B at the proposed well location.

A vertical borehole will not penetrate any faults within Unit B.

Horizon H20 marks the base of Unit B at

- 5,407ft below sea surface (1,136ft below seabed).

**4.4 Unit C** 

Lithology within the upper interval of Unit C from

- 5,407ft to

- 5,886ft below sea surface (1,136ft to 1,615ft below sea surface) is i nterpreted to consist of clays, silts, with occasional

coarser interbeds.

From

- 5,886 ft to

- 6,299ft below sea surface (1,615ft to 2,028ft below seabed) is interpreted as higher energy clays and silts with several coarser interbeds that possibly represent sands

.

8Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV

The proposed well is located on the north east edge of a sand fairway that extends from the

southwest of the adjacent block (Block AT0 19 ) into the east

- central part of Block AT0 18 and
continues to cross the center of the block to the northwest (Figure 5). A number of high amplitude anomalies located within 2,000 ft to the west , northwest, south and southeast and

north of the proposed well are interpreted as a high risk of gas. The vertical borehole will not traverse any of these anomalies , with the neare st risk of gas anomaly being 510ft to the west

. However, these higher amplitude anomalies apperar possibly connected (downdip) to the proposed well location, and as such, even though there is not an anomalous response at the location, a Slight Risk of Gas is assigned wi thin this interval. D ue to the sandy nature of this

interval , potentially rapidly deposited with inadequate dewatering time

, with a likely clay rich impermeable overburden forms a favorable setting for development of shallow water flow, and

a Moderate Sha llow Water Flow Risk is assigned to this interval. This interval did not present any reported drilling problems at the nearby offset well AT018

- 001, however, this existing well is a little further away from the higher energy deposits.

The lithology from

- 6,299ft to

- 6,492ft below sea surface (2,028ft to 2,221ft below seabed) is interpreted to comprise of clays and silts with occasional coarser interbeds.

The interval f rom

- 6,492ft to

- 7,175 ft below sea surface (2,221ft to 2,904ft below seabed) is interpreted to consist of clays and silts with several coarser interbeds that may represent sands. The well path is located in the northeast edge of a package of northwest to southeast trending sands

. A previously drilled well located 4.9 3 miles to the southeast (AT0 63

- 002) experienced a low volume shallow water flow event in sands at 2,012ft below seabed ; correlating with this interval

. The nearest offset well, AT018

- 001 did encounter some shallow gas shows and some ballooning of the wellbore through this interval. At the proposed

location this interval is thicker than encountered at AT

- 018

- 001, and exhibits a similar higher energy character. The proposed location is also more centrally placed within the Unit C sand fairways than the existing AT018

- 001 well ( Figure 5 ). However, the seismic over the existing

AT018

- 001 well does present an anomaly that could be the source of the gas shows observed ( Figure 8 ) and although this interbed does extend to the proposed AT018

- GV location the

am plitude character is reduced . Taking into account all these observations and the acoustic signature of the interval, suggestive of potentially r apidly deposited sandy interbeds that have may have experienced inadequate dewatering a Slight Risk of Gas and a Moderate
Shallow Water Flow Risk is assigned to this interval.

A clay

- rich sequence with occasional coarser

- grained interbeds is interpreted from

- 7,175 ft to

- 7,325ft below sea surface (2,904ft to 3,054ft below seabed).

The lower interval within Unit C from

- 7,325ft to

- 7,739ft below sea surface (3,054ft to 3,468 ft below seabed) is interpreted to comprise of clays with several coarser interbeds. The coarser interbeds within this package may induce minor drilling fluid circulation and wellbore st ability problems. The existing well AT018

- 001 did encounter some minor shallow gas shows in this

interval and the character at the proposed well location is similar ( Figure 8 ) , but other than the

9Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV

elevated amplitude character there are no other indicators of shallow gas, and therefore a Slight Risk of Gas is assigned to this interval. The existing AT

- 018

- 001 did not report any shallow water flow from this interval. Given the similarities in between the proposed and existing well locations at this level then no shallow water flow risk is assigned.

A vertical borehole will not penetrate any faults within Unit C.

Horizon H30 marks the base of Unit C at

- 7,739ft below sea surface (3,468ft below seabed).

**4.5 Unit D** 

The upper interval of Unit D

, from

- 7,739ft to

- 7,977f t below sea surface (3,468ft to 3,707 ft below seabed)

, is interpreted to consist of clays and silts with occasional coarser interbeds. No drilling hazards or problems are expected with in this upper interval.

From

- 7,977ft to

- 8,848 ft below sea surface (3,707 ft to 4 ,577 ft below seabed)

, is interpreted

as a slightly higher

- energy deposited package with clays and several coarser interbeds. This interval exhibits character of shallow water flow, with potential for rapid depositio n, and inadequate dewatering. The nearby offset well AT018

- 001 did not report any problems from this interval, which is acoustically similar on the seismic data, with just a slight increase in energy character at the proposed well location

. As such, a Sl ight Shallow Water Flow Risk is assigned to this interval. Due to the potential for coarser, potentially poorly consolidated

sediments with in this interval, minor drilling fluid circulation and wellbore stability problems may also occur.

Str atigraphy from

- 8,848 ft to

- 10, 717ft below sea surface (4,577ft to 6,447ft below seabed) is interpreted to consist of clays with occasional coarser interbeds.

No shallow gas is predicted withi n Unit D at the proposed well location. The risk of gas anomaly is approximately 2,027 ft WSW.

Top of Salt marks the base of Unit D and the Base of this interpretation at

- 10,717 ft below sea

surf ace (6,447ft below seabed).

**4.6 Shallow Gas Assessment** 

Within Unit C , a Slight Risk of Gas is assigned to the interval from

- 5,886 ft to

- 6,299ft below sea surface (1,615ft to 2,028ft below seabed), from

- 6,492ft to

- 7,175ft below sea surface (2,221ft to 2,904ft), and also from

- 7,325ft to

- 7,739ft below sea surface (3,054ft to 3,468 ft below seabed).

Within D, a Slight Risk of Gas -7 ,977ft to

- 8,848ft below surface (3,707ft to 4,577ft below seabed).

10Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV

**4.7 Shallow Water Flow Assessment** 

Within Unit C , a Moderate Shallow Water Flow Risk is interpreted in the interval from

- 5,886ft to

- 6,299ft below sea surface (1,615ft to 2,028ft below seabed), and from

- 6,492ft to

- 7,175ft below sea surface (2,221ft to 2,904ft).

Within Unit D, a Slight Shallow Water Flow Risk is assigned from

- 7,977ft to

- 8,848ft below sea surface (3,707ft to 4,577ft below seabed).

11Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV



### 5. CONCLUSIONS AND RECOMMENDATIONS

• Seabed No significant problems are anticipated at seabed. Shallow soils are expected to be conducive to the jetting of seabed casing with no hardgrounds predicted.

• Unit A

No drillin g hazards or problems predicted.

• Unit B
No drilling hazards or problems predicted.

• Unit C
Within Unit C, a Slight Risk of Gas and a Moderate Shallow Water Flow Risk is assigned

to the interval from

- 5,886 ft to

- 6,299ft below sea surface (1,615ft to 2,028 ft below seabed)

, and from

- 6,492ft to

- 7,175ft below sea surface (2,221ft to 2,904ft below seabed). Drilling
Caution is advised and appropriate drilling methodology is recommended to deal with a possible water flow event through this interval. The existing AT018

- 001 well, did encounter some shallow gas shows and minor drilling problems f rom the lower interval

.

Within Unit C, a Slight Risk of Gas is assigned to the interval from

- 7,325ft to

- 7,739ft below sea surface (3,054ft to 3,468ft below seabed). Drilling Caution is advised. The existing

AT018

- 001 well, did encounter some shallow gas shows f rom this interval.

Minor drilling fluid circulation and wellbore stability problems may also occur from

- 7,307ft to

- 7,639ft below sea surface (3,067ft to 3,398ft below seabed).

• Unit D
Within Unit D, a Slight Shallow Water Flow Risk is assigned from

- 7,977ft to

- 8,848ft below sea surface (3,707ft to 4,577ft below seabed). Appropriate drilling methodology should be utilized to contain a potentially non

- persistent shallow water flow event within this interval. Minor drilling fluid circulation and wellbore stability problems may also occur with in this

interval. The existing AT018

- 001 well did not report any problems from this interval.

12Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- GV

We appreciate the opportunity to work with you on this project, and look forward to continuing as your geohazards consultants. Please contact us if you have any questions or if we can be of
further assistance.

Sincerely, Gardline Surveys Inc.

Andrew Haigh Matilde DeLeon Geophysical Manager Quality Assurance

Copies Submitted: 6 copies to Rick Kincaid at Anadarko Petroleum Corporation.

Attachments:

Proposed AT018

- GV Well Location

Seabed Depth Extract

Seabed Morphology Extract

Seabed Amplitude Extract

Geohazard Summary Extract

Sand Lithology Summary

Inline Data Example

Crossline Data Example

Arbitrary Line Data Example

Top Hole Prognosis

ROV Plat

Power Spectrum

Bathymetry Plat

Public Information Plat

Proprietary Information Plat

Vicinity Map

10

- Mile Radius Plat

13

## Top Hole Prognosis for Proposed AT018-GV Well Location 980,582ft E / 10,150,777ft N Inline: 5322 / Crossline: 10709 Horizon Subsea Depth

(ft) BML Depth

(ft) Horizon
TWT (sec) Lithology, Structure & Stratigraphy Potential Drilling Hazards & Constraints Risk
of
Gas SWF
Risk

Seabed -4,271 0 1.738 Seabed is smooth sloping to the northeast at 1.5°. Surficial sediments comprise of soft clays and silts.Underlying the seabed the lithology comprises of clays and silts with occasional minor coarser interbeds.



## Figure 9 Interface -5,886 1,615 2.345 Horizon H10 -4,848 577 1.966

Interface -6,299 2,028 2.487 None predicted Unit A

Unit B

Horizon H20 -5,407 1,136 2.174

Interface -7,175 2,904 2.774

Horizon H30 -7,739 3,468 2.948

Top of Salt -10,717 6,446 3.744 Base of interpretation -6,492 2,221 2.552 Interface Interface -5,234 963 2.111 Interface -4,534 263 1.844 None predicted Vavg
BML (m/s)

0

5,322 5,065

5,415 5,209

5,607

5,733

6,427 5,457 5,166 4,977 Clays and silts

Unit C

Unit D Interface -7,325 3,054 2.821 5,640

Interface -7,977 3,706 3.019 5,787

Interface -8,848 4,577 3.266 5,991 Clays and silts with occasional coarser interbeds None predicted

Clays and silts

Clay-prone sequence with occasional coarser interbeds

Clays and silts with several coarser interbeds that may represent sands

Clays and silts with occasional coarser interbeds

Clays and silts with several coarser interbeds that may represent sands

Clay-prone sequence with occasional coarser-grained interbeds

Clays with several coarser interbeds

Clays and silts with occasional coarser interbeds

Clays with several coarser interbeds that may represent sands

Clays with occasional coarser interbeds None predicted

None predicted

Slight Risk of Gas and Moderate Shallow Water Flow Risk

None predicted

Slight Risk of Gas and Moderate Shallow Water Flow Risk

None predicted

Slight Risk of Gas.Minor drilling fluid circulation and wellbore stability problems possible

None predicted

Slight Shallow Water Flow Risk. Minor drilling fluid circulation and wellbore stability problems possible

None predicted

# ±

6

®33 3

3

-4210
-4180

-4200 -4190

-4170 -4220

-4160 -4230 -4240

-4150 -4250 -4260 -4270 -4280 -4290 -4300 -4310 -4320

-4140 -4330 -4340

-4280 -4200

-4150

-4230 -4220

-4160 -4200

-4150 -4200

-4240 -4150 -4240

-4180

-4190 -4160 -4210

-4170 -4270

-4250

-4140

-4150 -4230

-4180 -4260 -4270 -4210

-4220 -4220

-4160 -4210

-4210 -4160 -4170 -4230

-4160

-4150 -4150-4260 AT018-00189°3'0"W89°4'0"W89°5'0"W

27°58'0"N

27°57'0"N

27°56'0"N

27°55'0"N970,000975,000980,000 10,140,000 10,145,000 10,150,000 10,155,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1 = 2,000' 

## Bathymetry Plat Figure 12 2

, 0

0

0

f t R a d

i u s Proposed AT018-GV Easting: 980,582ft E Northing: 10,150,777ft N FEL of AT018-GV: 1,498ft FNL of AT018-GV: 2,663ft

ATWATER VALLEY BLOCK 18(OCS-G33863) 2

, 0

0 0 f t R

a d

i u

s MISSISSIPPI CANYON BLOCK 986(OCS-G33770)

ATWATER VALLEY BLOCK 62(OCS-G32560)

# ±

6

®33 3

3 Proposed AT018-GV Well

AT018-00189°3'0"W89°4'0"W89°5'0"W

27°58'0"N

27°57'0"N

27°56'0"N

27°55'0"N970,000975,000980,000 10,140,000 10,145,000 10,150,000 10,155,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1" = 2,000' 

## Well Location Plat - Public Information Figure 13 2

, 0

0

0 f t R

a d i u

s

Location Call N/S Call E/W X Coordinate Y Coordinate Latitude Longitude WD AT018-GV SL 2,663ft FNL 1,498ft FEL 980,582 10,150,777 27° 57' 25.62''N 89° 02' 39.83''W -4,271 Proposed Location - AT018-GV

ATWATER VALLEY BLOCK 18(OCS-G33863)

MISSISSIPPI CANYON BLOCK 986(OCS-G33770)

ATWATER VALLEY BLOCK 62(OCS-G32560)Nearest Shoreline Range: 71mi Bearing: 343° Fourchon Range: 106mi Bearing: 320°

Lund Henderson Lloyd Ridge

Walker Ridge Destin Dome

Atwater Valley Green Canyon De Soto Canyon

The Elbow

Florida Plain Vernon Basin Apalachicola

Garden Banks

Keathley Canyon Florida Middle Ground

Howell Hook Lund South Pensacola

Amery Terrace Mobile

Viosca Knoll

Viosca Knoll

Sigsbee Escarpment New Orleans Baton Rouge Pensacola

Lafayette Pascagoula Gulfport 

# Vicinity Map - Atwater Valley Block 018

Figure 15Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 GV



### APPENDIX A – Public Shallow Hazards Statement s

29Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 GV

Public S hallow Hazards Statement – AT018

- GV July 15 , 2013

US Department of the Interior Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

- 2394

Attention:

Reference: Shallow Hazards Analysis Atwater Valley Block 18
OCS

- (G 33863 )

Ladies/Gentlemen:

Anadarko Petroleum Corporation contracted Gardline Surveys, Inc. to prepare a Well Clearance Letter for the proposed AT018

- GV well location in Block 18 , Atwater Valley Area (OCS

- G 33863 ). This letter addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this geohazard assessment is to Top of
Salt at

- 10,717 ft b elow sea surface (6,447 ft below seabed).

This hazards summary letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block 018 and 019, dated August 2012.

**Seabed Hazards.**

The seabed is smooth and featureless . No pr oblems are expected at the proposed AT 18 GV well

location.

There are no indications of seabed fluid seeps within 2,000ft of the well location.

No existing seabed infrastructure is located within 2,00 0 ft of the proposed well. There is an existing

well A T0 18

- 00 1 located 1,375ft to the northwest. The following are the coordinates :

Well Installation:

Operator Block Well No. API No. Depth (ft) TVD Easting Northing Status

BHP Billiton AT 018 001 60 818 40024 00 4,266 28,651 980,051 10,152,077 PA

Two pipelines are located on the adjacent Block AT019 approximately 5,174ft and 5,353 ft to the east and northeast. The following are detailed of the pipelines:

**Pipeline Installations**

Operator Area Block

- Origin/Termination Outside Diameter (in) Product Status

ATP O&G AT063 / MC941 5 in BLKO ACT

ATP O&G MC941 / AT063 4in UBEH ACT

30Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 GV

**Sub**

**- Seabed Hazards.**  Drilling Caution is indicated for a Slight Risk of Gas at the well location within two interval s of Unit C

and within an interval in Unit D

.

Moderate Shallow Water Flow Risk is assigned to two intervals within Unit C

. A Slight Shallow

Water Flow Risk is anticipated within an interval in Unit D.

Proposed AT 18 GV Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 57' 25.62” North Easting 980,582 US ft E
Longitude 89° 02’ 39.83” West Northing 10,150,777 US ft N
FEL of Atwater Valley 18 1,498 US ft Inline 5322
FNL of Atwater Valley 18 2,663 US ft Crossline 10709

Water Depth:

- 4,271 ft Slope: 1.5° NE

Nearest Shoreline 71.34 Miles @ 343° 25’ 48’’
Port of Operation Fourchon 106.42Miles @ 320° 36’ 0’’

Nearest Manned Platform MC941

- (Mirage/Titan) 6.25 Miles @ 328° 17’ 24”

**Conclusions and Recommendations.** Drilling techniques will take into consideration the possibility of encountering possible gas within two

interval of Unit C and within an interval in Unit D

. Appropriate drilling methodology should be utilized to deal with a possible Moderate Shallow Wate r Flow Risk in the intervals within Unit C.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations



## PUBLIC INFORMATION

31Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 GV



### APPENDIX B – Sensitive Sessile Benthic Community Statements

32Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 GV

Sensitive Sessile Ben thic Community Statement – AT018

- GV



### Anadarko Petroleum Corporation

July 15 , 2013

US Department of the Interior Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

Reference: Sensitive Sessile Benthic Community Summary Atwater Valley, Block 18
OCS

- (G 33863 )

Ladies/Gentlemen: Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Site Clearan ce Letter for the proposed AT018

- GV well locat ion in Atwater Valley, Block 18

, Stromboli Prospect (OCS

G G 33863 ). This letter addresses location proximity to potential sensitive sessile benthic community

sites. Anadarko Petroleum Corporation will be drilling this well from a dynamically positioned drilling

module ; therefore

, no anchors will impact seabed.

This sensitive sessile benthic community summary letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block 018, dated August 2012 . A Biological, Physical and Socio

- Economic Map is included at the end of this appendix illustrating the areas of potential seabed impact.

**Potential Sensitive Sessile Benthic**  **Communities.** Features or areas that could support high density sensitive sessile benthic communities are **not** located within 2,000ft of any proposed mud and cuttings discharge location.

Proposed AT 18 GV Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 57' 25.62” North Easting 980,582 US ft E
Longitude 89° 02’ 39.83” West Northing 10,150,777 US ft N
FEL of Atwater Valley 18 1,498 US ft Inline 5322
FNL of Atwater Valley 18 2,663 US ft Crossline 10709
Water Depth:

- 4,271 ft Slope: 1.5° NE

Nearest Shoreline 71.34 Miles @ 343° 25’ 48’’
Port of Operation Fourchon 106.42Miles @ 320° 36’ 0’’

Nearest Manned Platform MC941

- (Mirage/Titan) 6.25 Miles @ 328° 17’ 24”

33Anadarko Petroleum Corporation Gardline Report 9518
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 GV

No potential sensitive sessile benthic community site is located within 2,000ft of the proposed

location

.

**Conclusions and Recommendations:**

The proposed AT018

- GV well location will not impact any sites favorable for development of sensitive

sessile benthic communities.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations

34

# ANADARKO PETROLEUM C ORPORATION

3D GEOHAZARD ASSESSM ENT

GULF OF MEXICO

ATWATER VALLEY BLOCK AT 0 18

STROMBOLI PROSPECT

AT0 18

- QQ PROPOSED WEL L LOCATION

WELL CLEARANCE LETTE R

Gardline Project Ref. 9648 Report Status Final

Issue Date July 30 , 2013

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.comAnadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

ii 

### REPORT AUTHORIZATION AND DISTRIBUTION

Report Status Final

Issue Date July 30 , 2013

Compilation Geophysicist L Fuentes

Authori z ation Geophysics

..................... A R Haigh

Quality Assurance

..................... M DeLeon

Distribution

6 copies

Anadarko Petroleum Corporation

1201 Lake Robbins Drive

The Woodlands, TX 77380

For attention of:

Rick KincaidAnadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

iii 

### SERVICE WARRANTY

**USE OF THIS REPORT**

This report has been prepared with due care, diligence and with the skill reasonably expected of a reputable contractor experienced in the types of work, carried out under the contract. As such, the findings in this report are based on an interpretation of data which is a matter of opinion on which professionals may differ and, unless clearly stated, is not a recommendation of any course of action.

Gardline Surveys, Inc. has prepared this report for the client identified on the front cover in fulfilment of its contractual obligations under the referenced contract, and the only liabilities Gardline Surveys, Inc. will accept are those contained therein.

Please be aware that further distribution of this report, in whole or part, or the use of the data for a purpose not expressly stated within the contractual work scope is at the client’s sole risk, and Gardline Surveys, Inc recommends that this disclaimer be included in any such distribution.

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.comStudy Area Atwater Valley Green Canyon Lloyd Ridge Mississippi Canyon Destin Dome

De Soto Canyon Mobile Pensacola

Ship Shoal Area Eugene Island Area Viosca Knoll

Viosca Knoll Main Pass Area

Ewing Bank South Timbalier Area West Delta Area Louisiana Alabama Mississippi
Florida 

# Location Map

Study AreaAnadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

v 

### TABLE OF CONTENTS

REPORT AUTHORIZATION AND DISTRIBUTION ii

SERVICE WARRANTY iii

LOCATION MAP iv

TABLE OF CONTENTS v

LIST OF FIGURES vi

LIST OF CHARTS vii

WELL CLEARANCE LETTER
– PROPOSED AT018

- QQ WELL LOCATION 1

1. LOCATION COORDINATES 4

1.1 Proposed AT018

- QQ Well Location 4

2. VELOCITY DATA 5

2.1 Velocity Data 5

3. SEABED CONDITIONS 7

3.1 Bathymet ry 7

3.2 Seafloor Morphology and Man Made Features 7

4. SUBSEABED CONDITIONS 8

4.1 Geology and Lithology 8

4.2 Unit A 8

4.3 Unit B 8

4.4 Unit C 8

4.5 Unit D 10

4.6 Shallow Gas Assess ment 10

4.7 Shallow Water Flow Assessment 11

5. CONCLUSIONS AND RECOMMENDATIONS 12

APPENDIX A
– Public Shallow Hazards Statements

APPENDIX B
– Sensitive Sessile Benthic Community StatementsAnadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

vi 

### LIST OF FIGURES

Proposed A T 018

- QQ Well Location

1 Seabed Depth Extract

2 Seabed Morphology Extract

3 Seabed Amplitude Extract

4 Geohazard Summary Extract

5 Sand Lithology Summary

6 Inline Data Example

7 Crossline Data Example

8 Tie Line to AT018

- 001

9 Top Hole Prognosis

10 ROV Plat

11 Power Spectrum

12 Bathymetry Plat

13 Public Information Plat

14 Proprietary Information Plat

15 Vicinity Map

16 10

- Mile Radius PlatAnadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

vii 

### LIST OF CHARTS

The following chart at a scale of 1" = 2,000ft is enclosed:

Chart No Title Drawing No

1 Biological, Physical and Socio

- Economic Map 9648

. 01Anadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

1 

### WELL C LEARANCE LETTER – PROPOSED AT0 18

- QQ WELL LOCATION
July 30 , 2013 Anadarko Petroleum Corporation

1201 Lake Robbins Drive The Woodlands, TX 77380

Attention: Rick Kincaid

Well Clearance Letter Proposed AT0 18

- QQ Well Location

Block 0 18 , Atwater Valley Area
OCS - G 33863

Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Well Clearance Letter for the proposed AT0 18

- QQ well location in Block 0 18

, Atwater Valley Area (OCS

- G 33863 ). This letter addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this well clearance

ass e ssment is Top of Sal t or

- 10,858ft below sea surface (6,603ft below seabed). We understand that Anadarko Petroleum Corporation plans to drill the proposed exploration well from a dynamically positioned drilling vessel; therefore, an anchoring assessment is not required nor provided. Relevant

letter

- size chart extracts, data examples, and a Top Hole Prognosis are presented with this Well Clearance Letter. This geohazard assessment is based on the interpretation of 3D seismic data. This site clearance letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard

Asse ssment, Atwater Valley Block 018 and 019, dated August 2012

.

Archaeological Survey. Anadarko Petroleum Corporation provided for review the complete archaeological survey report acquired by C&C Technologies Survey Services: Archaeological Survey

Blocks 18 (OCS -G- 33863) and 19 (OCS -G- 32556) Atwater Valley Area for the Anadarko Stromboli Prospect.

3D Geophysical Survey. Anadarko Petroleum Corporation provided the 3D dataset to Gardline Surveys Inc. on tape media in SEG

- Y format for loading onto a Seismic Micro

- Technology (SMT) workstation. The 3D data cube contains a survey with 4 millisecond sample rate data to a record length of 6.0 seconds TWT below sea surface. Inlines are oriented north to south, have a numerical increment of one, and exhibit a line spacing of 65.6ft. Crosslines are oriented west to east, have a numerical increment of one, and exhibit a line spacing of 41.0 ft.

• The acquisition parameters are:

o Atwater Valley (I) DW V

Shooting Direction: N/S Configuration: 4 sources, 6

- 10 streamersAnadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

2 Maximum offset: 8000 m
Channels: 324 per streamer Shotpoint interval: 47.25 m per array Group interval: 25 m CMP line spacing: 40 m
CMP bin dimension: 12.5 m x 40 m Record Length: 9 s below sea bottom
Nominal fold: 43 Vintage: April 1999

• The basic processing parameters are:

o Atwater Valley (I) DW V

480

- m x 500

- m velocity grid Demultiple 3D DMO velocity and stacking technology
One

- pass 3D poststack migration

12.5

- m x 20

- m final bin dimension

. The data exhibits a good frequency response across the upper one second below seabed, with an effective frequency range of 5 to 65Hz ( Figure 1 1 ) . The data exhibits a dominant frequency of approximately 53Hz with significant higher usable frequencies. This frequency range results in a mean vertical resolvability of approximately 10m and a layer detectability of 5ft

.

In summary and with reference to NTL No. 2008

- G04 : a) The 3D data provides images of sufficient resolution of the shallow section allowing a clear analysis of the shallow conditions b) The data can be loaded to a workstation at 16bit resolution or greater, and is un

- scaled c) There is no trace or sample decimation d) The sample interval and bin size are maintained throughout the assessment area e) The data possess a frequency content of 50Hz or higher across the first second below

seabe d (See Power Spectrum Diagram: Figure 1 1 ) f) Seabed reflection is free of gaps and defined by a wavelet of stable shape and phase,

a llowing auto

- tracking of the seabed event with minimum user intervention and guidance g) There are no significant acquisition artefacts throughout the dataset h) There are no merge points in the data i) Processed bin sizes are 65.62ft x 41.01ft j) The sample rate of the data is 4ms k) An accurate velocity model has been utilized in the shallow section allowing optimum structural and stratigraphy resolution with no evidence of under or over migration l) There is no significant multiple energyAnadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

3 m) The proposed activities are not in an area of high archaeological potential.Anadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

4 

### 1. LOCATION COORDINATES

**1.1 P**  **roposed AT0 18** 

**- QQ**  **Well Location**

Proposed AT 0 18

- QQ Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 57' 31.41 ” North Easting 979,462 US ft E
Longitude 89° 02’ 52.44 ” West Northing 10,151,381 US ft N
FEL of Atwater Valley 0 18 2,618 US ft Inline 5 305
FNL of Atwater Valley 0 18 2,059 US ft Crossline 10724
Water Depth:

- 4,255 ft Slope: 2.1° NE

Nearest Shoreline 71 Miles @ 343°
Port of Operation Fourchon 106 Miles @ 320°

Nearest Manned Platform MC941

- (Mirage/Titan) 6 Miles @ 300°Anadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

5 

### 2. VELOCITY DATA

**2.1 Velocity Data** 

Time

- to

- depth conversion for the water column was made using the Advocate and Hood (1993) polynomial.

Seabed Depth (ft) =

0.1105 – 5066.9193X + 468.6693X 2

– 554.7107X 3 + 340.7019X 4

– 116.991X 5 + 20.728X 6

– 1.4658X 7

Wh ere X = one way time to seabed in seconds.

One Way Time To Seabed (s) Seabed Depth (ft) Seabed Depth (m) Vavg (m/s)

0.0 0 0 0

1.0 4910 1496 1496

1.1 5400 1646 1496

1.2 5892 1796 1496

1.3 6384 1946 1497

1.4 6877 2096 1497

1.5 7370 2246 1498

1.6 7865 2397 1498

1.7 8360 2548 1499

1.8 8856 2699 1499

1.9 9353 2851 1500Anadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

6 Sub

- seabed time to depth conversion was performed using a polynomial function successfully applied in an adjacent project and approved by Anadarko Petroleum Company :

Vavg = = - 45.841X 5 + 190.08X 4

– 183.08 X3 - 14.729X2 + 735.59X +4900

Where X = two way time in seconds below seabed

.

The resultant velocity was then multiplied by the time below seabed to produce depth below
seabed ; t his was summed with seabed depth to produce horizon depth below sea surface.Anadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

7 

### 3. SEABED CONDITIONS

**3.1 Bath**  **ymetry**

Seabed depth at the proposed AT018

- QQ well location is

- 4,255 ft below sea surface ( Figure

1 ). The seafloor slopes to the northeast at 2.1 °.

**3.2 Seafloor Morphology and Man Made Features** 

The proposed AT 018

- QQ well location is in the northeast of Block AT 0 18

. The seabed is smooth and featureless at the proposed well location ( Figure 2 ). Soft clays and silts are predicted at seabed. Sediments appear conducive for jetting of seabed casing with no hard layers predicted.

A seabed fault occurs 2,780ft to the southwest of the proposed well. The fault should not impact the proposed well.

An existing well AT 0 18

- 001 is located 949 ft to the northeast. The following are the

coordinates:

Well Installation:

Operator Block Well No. API No. Depth (ft) TVD Easting Northing Status

BHP Billiton AT 018 001 60 818 40024 00 4,266 28,651 980,051 10,152,077 PA

There are no anomalous seabed amplitudes indicative of hydrocarbon macroseep observed within a 2,000ft radius of the proposed location ( Figure 3 ).

No items of archaeological significance were identified within 2,000ft of the proposed location (A rchaeological report submitted under a separate cover)

.

No other features are observed within a 2,000ft radius that could affect well emplacement or jetting of casing.Anadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

8 

### 4. SUBSEABED CONDITIONS

**4.1 Geology and Lithology** 

The sub

- seabed geology has been divided into four units separated by four horizons ( Figures

6 through 9 ). A Geohazard Extract and Sand

- Prone Lithology Extract complete the well

assessment ( Figures 4 and 5 )

.

**4.2 Unit A** 

The upper most interval wit hin Unit A from s eabed to

- 4,466ft below sea surface (211 ft below seabed) is interpreted to consist of clays and silts with occasional minor coarser interbeds.

The lower interval of Unit A from

- 4,4 66ft to

- 4,832ft below sea surface (211ft to 577 ft below seabed) is interpreted to comprise of clays and silts.

No shallow gas or shallow water flow is predicted with in Unit A at the proposed well location.

A vertical borehole will not penetrate any fa ults within Unit A.

Horizon H10 marks the base of Unit A at

- 4,832ft below sea surface (577ft below seabed).

**4.3 Unit B** 

The upper interval of Unit B from

- 4,832ft to

- 5,281ft below sea surface (577ft to 1,026 ft below seabed) is expected to comprise of clays and silts with occasional coarser interbeds.

The lower interval of Unit B from

- 5,281ft to

- 5,465ft below sea surface (1,026ft to 1,210 ft below seabed) is interpreted to consist of clays and silts with several coarser interbed s. T he

coarser interbeds in this lower interval of Unit B may cause minor drilling fluid circulation and

mino r wellbore stability problems.

No shallow gas or shallow water flow is predicted with in Unit B at the proposed well location.

A vertical borehole will not penetrate any faults within Unit B.

Horizon H20 marks the base of Unit B at

- 5,465ft below sea surface (1,210ft below seabed).

**4.4 Unit C** 

Lithology within the upper interval of Unit C from

- 5,465ft to

- 5,548ft below sea surface (1,210ft to 1,293 ft be low sea surface) is interpreted to consist of a cla y- prone sequence with

several coarser interbeds. Due to the potential for some possible poorly consolidated coarser

material within this interval m inor drilling fluid circulation and minor wellbore stabil ity problemsAnadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

9 may occur.

The stratigraphy from

- 5,548ft to

- 5,902ft below sea surface (1,293ft to 1,647ft below seabed) is interpreted to consist of clays and silts with several coarser interbeds that may represent

sands. Due to the potential for some possible poorly consolidated coarser material within this interval minor drilling fluid circulation and minor wellbore stability problems may occur.

.

From

- 5,902 ft to

- 6,494ft below sea surface (1,647ft to 2,239ft below seabed) is interpreted as clays and silts with several coarser interbeds that possibly represent sands. The proposed

well is located on the north east edge of a sand fairway that extends from the southwest of the adjacent block (Block AT0 19 ) into the east

- central part of Block AT0 18 and continues to cross

the center of the block to the northwest ( Figure 5 ) . A cluster of high amplitude anomalies located approximately 250 ft to the east and northeast of the proposed well are interpreted as a high risk of gas. The vertical borehole w ill not intersect any of these anomalies ; h owever, the sands within this package do exhibit a slight amplitude response . A s such a Slight Risk
of Gas is assigned within this interval. In addition

, the combination of the sandy nature of this

interval which was potentially rapidly deposited with inadequate dewatering time , plus a possible clay

- rich impermeable overburden, combine to create a favorable setting for

de velopment of shallow water flow; a Moderate Shallow Water Flow Risk is assigned to this

interval. This interval did not present any reported drilling problems at the nearby offset well

AT018

- 001. However, AT018

- 001 presents a slight reduction in seismic amplitude perhaps indicating a reduced sandy content at that well.

The interval f rom -6 ,494 f t to

- 7,200ft below sea surface (2,239ft to 2,946ft below seabed) is interpreted to consist of clays and silts with several coarser interbeds that may represent sands. The well path is located outside the main cluster of high amplitude anomalies that occur around 2,000ft to the southwest that are interpreted as fluid

- charged sands

. A previously drilled well located 5.1 miles to the southeast (AT0 63

- 00 2) experienced a low

volume shallow water flow event in sands at 2,012ft below seabed ; correlating with this

interval

. The nearest offset well, AT018

- 001 did encounter some shallow gas shows and some ballooning of the wellbore through this interval. At the proposed location this interval is thicker and exhibits higher energy character than observed at the existing AT018

- 001 well. The proposed location is also more centrally placed within the Unit C sand fairways than the existing AT018

- 001 well ( Figure 5 ). However, the seismic profile over the existing AT018

- 001

well does present an anomaly that could be the source of the observed gas shows ( Figure 8 );

t his anomaly is considerably weaker at the proposed well location. Taking into account all

these observations

, plus the acoustic signature of the interv al which is suggestive of potentially r apidly

- dep osited sandy interbeds that may have experienced inadequate dewatering , a Slight Risk of Gas and a High Shallow Water Flow Risk is assigned to this

interval.

A clay

- prone sequence with occasional coarser

- grained interbeds is interpreted from

- 7,200 ft

to

- 7,335 ft bel ow sea surface (2,946ft to 3,080ft below seabed).Anadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

10 The lower interval within Unit C from

- 7,335ft to

- 7,644ft below sea surface (3,080ft to 3,389 ft below seabed) is interpreted to comprise of clays with several coarser interbeds. The coarser interbeds within this package may induce minor drilling fluid circulation and wellbore stability problems. The existing well AT018

- 001 did encounter some minor shallow gas shows in this interval, but there is no clear indication of any anomalies on the seismic data to support any shallow gas occurrence at the proposed well location.

A vertical borehole will not penetrate any faults within Unit C.

Horizon H30 marks the base of Unit C at

- 7,644ft below sea surface (3,389ft below seabed).

**4.5 Unit D** 

The up per interval of Unit D from

- 7,644ft to

- 8,098ft below sea surface (3,389ft to 3,843 ft below seabed) is interpreted as clays and silts with occasional coarser interbeds. No drilling hazards or problems are expected with in this interval.

From

- 8,0 98ft to

- 8,715 ft below sea surface (3,843 ft to 4,460 ft below seabed)

, is interpreted

as a slightly higher

- energy deposited package with clays and several coarser interbeds. This

interval exhibits the characteristics of shallow water flow with the potential for ra pid deposition

, plus inadequate dewatering. As such, a Slight Shallow Water Flow Risk is assigned to this

interval. Due to the potential for coarser and potentially poorly

- consolidated sediments with in this interval, minor drilling fluid circulation and wellbore stability problems may also occur. Additionally, these sand interbeds exhibit an increase in amplitude and these sands exhibit a risk of gas ~818ft to the west. Although we suspect the gas is being trapped by faults, we still

c onsider a Slight Risk of Gas within this interval. The nearby offset well AT018

- 001 did not report any problems from this interval, which is acoustically similar on the seismic data.

Str atigraphy from

- 8,715 ft to

- 10, 8 58ft below sea surface (4,460ft to 6,603ft below seabed) is interpreted to consist of clays with occasional coarser interbeds.

A vertical borehole will penetrate three faults within Unit D at

- 8,994ft,

- 9,972ft, and

- 10,562ft below sea surface (4,739ft, 5,717ft, and 6,307ft below seabed). Minor drilling fluid circulation and wellbore stability problems are possible at the level of these small

- scale faults.

Top of Salt marks the base of Unit D and the base of this interpretation at

- 10,858ft below sea surface (6,603ft below seabed).

**4.6 S**  **hallow Gas Assessment**

Within Unit C , a Slight Risk of Gas is assigned to the interval from

- 5,902 ft to

- 6,494ft below sea surface (1,647ft to 2,239ft below seabed), and also from

- 6,494ft to

- 7,200ft below sea surface (2,239ft to 2,946ft below seabed).Anadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

11 Within Unit D , a Slight Risk of Gas is assigned to the interval from

- 8,098 ft to

- 8,715ft below sea surface (3,843ft to 4,460ft below seabed).

**4.7 Shallow Water Flow Assessment** 

Within Unit C , a High Shallow Water Flow Risk is interpreted in the interval from

- 6,494 ft to

- 7,200ft below sea surface (2,239ft to 2,946ft below seabed) . A Moderate Shallow Water

Flow Risk is interpreted from

- 5,902 ft to

- 6,494ft below sea surface (1,647ft to 2,239 ft below seabed).

Within Unit D, a Slight Shallo w Water Flow Risk is assigned from

- 8,098 f t to

- 8,715ft below sea surface (3,843ft to 4,460ft below seabed).Anadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

12 

### 5. CONCLUSIONS AND RECOMMENDATIONS

• Seabed No significant problems are anticipated at seabed. Shallow soils are expected to be conducive to the jetting of seabed casing with no hardgrounds predicted.

• Unit A
No drilling hazards or problems predicted.

• Unit B
Minor drilling and minor wellbore stab ility p roblems are possible from

- 5,281ft to

- 5,465 ft below sea surface ( 1,026 ft to 1,210 ft below seabed).

• Unit C

Within Unit C, a Slight Risk of Gas and a High Shallow Water Flow Risk is assigned to the

interval from

- 6,494ft to

- 7,200ft below sea surface (2,239ft to 2,946ft below seabed). Drilling Caution is advised and appropriate drilling methodology is recommended to deal with a possible water flow event through this interval. The existing AT018

- 001 well did encounter some shallow gas shows and minor drilling problems f rom this interval

.

Within Unit C, a Slight Risk of Gas and a Moderate Shallow Water Flow Risk is also interpreted from

- 5,902ft to

- 6,494ft below sea surface (1,647ft to 2,239ft below seabed). Appropriate drilling methodology is recommended to deal with a possible water flow event through this interval.

Minor drilling fluid circulation and wellbore stability problems may also occur from

- 5,465 ft to

- 5,548ft below sea surface (1,210ft to 1,293ft below seabed), from

- 5,548ft to

- 5,902ft below sea surface (1,293ft to 1,647ft below seabed) and from

- 7,335ft to

- 7,644ft below sea surface (3,080ft to 3,389ft below seabed).

• Unit D
Within Unit D, a Slight Risk of Gas and a Slight Shallow Water Flow Risk is assigned to

the interval from

- 8,098ft to

- 8,715ft below sea surface (3,843ft to 4,460ft below seabed ). Drilling Caution and appropriate drilling methodology should be utilized to contain a potentially non

- persistent shallow water flow event within this interval. Minor drilling fluid circulation and wellbore stability problems may also occur with in this interval.Anadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT018

- QQ

13 We appreciate the opportunity to work with you on this project, and look forward to continuing as your geohazards consultants. Please contact us if you have any questions or if we can be of

further assistance.

Sincerely, Gardline Surveys Inc.

Andrew Haigh Matilde DeLeon Geophysical Manager Quality Assurance

Copies Submitted: 6 copies to Rick Kincaid at Anadarko Petroleum Corporation.

Attachments:

Proposed AT018

- QQ Well Location

Seabed Depth Extract

Seabed Morphology Extract

Seabed Amplitude Extract

Geohazard Summary Extract

Sand Lithology Summary

Inline Data Example

Crossline Data Example

Arbitrary Line Data Example

Top Hole Prognosis

ROV Plat

Power Spectrum

Bathymetry Plat

Public Information Plat

Proprietary Information Plat

Vicinity Map

10

- Mile Radius Plat

## Top Hole Prognosis for Proposed AT018-QQ Well Location 979,462ft E / 10,151,381ft N
Inline: 5305 / Crossline: 10724 Horizon Subsea Depth

(ft) BML Depth

(ft) Horizon
TWT (sec) Lithology, Structure & Stratigraphy Potential Drilling Hazards & Constraints Risk
of
Gas SWF
Risk

Seabed -4,255 0 1.740 Seabed is smooth sloping to the northeast at 2.1°. Surficial sediments comprise of soft clays and silts. Underlaying the seabed the lithology comprises of clays and silts with occasional minor coarser interbeds



## Figure 9 Interface -5,902 1,647 2.358 Horizon H20 -5,465 1,210 2.203

Interface -6,494 2,239 2.560 None predicted Unit A

Unit B

Horizon H30 -7,644 3,389 2.962 Interface -5,548 1,293 2.233 -4,466 211 1.825 Interface

Interface -5,281 1,026 2.136 Horizon H10 -4,832 577 1.968 None predicted Vavg
BML (m/s)

0

5,329 5,227

5,461

5,714 5,247 4,962

5,182 5,065 Clays and silts

Unit C

Unit D Interface -7,200 2,946 2.789 5,616

Top of Salt -10,858 6,603 3.784 6,461 Interface -7,335 3,080 2.831 5,646

Interface -8,098 3,843 3.061 5,818

Interface -8,715 4,460 3.236 5,963

Fault -9,972 5,717 3.566 6,262

Fault -10,562 6,307 3.712 6,397 Fault -8,994 4,739 3.312 6,029 None predicted Clays and silts with occasional coarser interbeds

Minor drilling fluid circulation and minor wellbore stability problems possible within this interval Clays and silts with occasional coarser interbeds

Minor drilling fluid circulation and minor wellbore stability problems possible within this interval Clays and silts with several coarser interbeds

Clays and silts with several coarser interbeds that may represent sands Minor drilling fluid circulation and minor wellbore stability problems possible within this interval

Slight Risk of Gas and Moderate Shallow Water Flow Risk Clays and silts with several coarser interbeds that may represent sands

Slight Risk of Gas and High Shallow Water Flow Risk Clays and silts with several coarser interbeds that may represent sands

None predicted Clay-prone sequence with occasional coarser-grained interbeds

Minor drilling fluid circulation and wellbore stability problems possible Clays with several coarser interbeds

None predicted Clays and silts with occasional coarser interbeds

Slight Risk of Gas and Slight Shallow Water Flow Risk. Minor drilling fluid circulation and wellbore stability problems possible Clays with several coarser interbeds that may represent sands

Clays with occasional coarser interbeds

Minor drilling fluid circulation and wellbore stability problems possible at
faults

Base of Interpretation

# ±

6

®33 3

3

-4210
-4180

-4200 -4190

-4170 -4220

-4160 -4230 -4240 -4250 -4260

-4150 -4270 -4280 -4290 -4300 -4310 -4320

-4140 -4330 -4340

-4260

-4250

-4160 -4220

-4210

-4140 -4270 -4210

-4280 -4220

-4270

-4160

-4170 -4160 -4230 -4240

-4200

-4160 -4200 -4210

-4230 -4220

-4160 -4150 -4150 AT018-00189°3'0"W89°4'0"W89°5'0"W 27°59'0"N

27°58'0"N

27°57'0"N

27°56'0"N970,000975,000980,000 10,145,000 10,150,000 10,155,000 10,160,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1 = 2,000' 

## Bathymetry Plat Figure 12 2

, 0

0

0

f t R a d

i u s Proposed AT018-QQ Easting: 979,462ft E Northing: 10,151,381ft N FEL of AT018-QQ: 2,618ft FNL of AT018-QQ: 2,059ft ATWATER VALLEY BLOCK 18(OCS-G33863)

MISSISSIPPI CANYON BLOCK 986(OCS-G33770)

# ±

6

®33 3

3 Proposed AT018-QQ Well AT018-00189°3'0"W89°4'0"W89°5'0"W

27°59'0"N

27°58'0"N

27°57'0"N

27°56'0"N970,000975,000980,000 10,145,000 10,150,000 10,155,000 10,160,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1" = 2,000' 

## Well Location Plat - Public Information Figure 13 ATWATER VALLEY BLOCK 18(OCS-G33863)

Location Call N/S Call E/W X Coordinate Y Coordinate Latitude Longitude WD AT018-QQ SL 2,059ft FNL 2,618ft FEL 979,462 10,151,381 27° 57' 31.41'' N 89° 02' 52.44'' N -4,255 Proposed Location - AT018-QQ MISSISSIPPI CANYON BLOCK 986(OCS-G33770)Nearest Shoreline Range: 71mi Bearing: 343° Fourchon Range: 106mi Bearing: 320°

Lund Henderson Lloyd Ridge

Walker Ridge Destin Dome

Atwater Valley Green Canyon De Soto Canyon

The Elbow

Florida Plain Vernon Basin Apalachicola

Garden Banks

Keathley Canyon Florida Middle Ground

Howell Hook Lund South Pensacola

Amery Terrace Mobile

Viosca Knoll

Viosca Knoll

Sigsbee Escarpment New Orleans Baton Rouge Pensacola

Lafayette Pascagoula Gulfport 

# Vicinity Map - Atwater Valley Block 018

Figure 15Anadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 QQ

30 

### APPENDIX A – Public Shallow Hazards Statement sAnadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 QQ

31 Public S hallow Hazards Statement – AT018

- QQ July 30 , 2013

US Department of the Interior Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

- 2394

Attention:

Reference: Shallow Hazards Analysis Atwater Valley Block 18
OCS

- (G 33863 )

Ladies/Gentlemen:

Anadarko Petroleum Corporation contracted Gardline Surveys, Inc. to prepare a Well Clearance Letter for the proposed AT018

- QQ well location in Block 18 , Atwater Valley Area (OCS

- G 33863 ). This letter addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this geohazard assessment is to Top of
Sa lt at

- 10,858ft below sea surface (6,603ft below seabed).

This hazards summary letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block 018and 019, dated August 2012.

**Seabed Hazards.**

The seabed is smooth and featureless. No problems are expected at the propos ed AT 18 QQ well

location.

There are no indications of seabed fluid seeps within 2,000ft of the well location.

No existing seabed infrastructure is located within 2,00 0 ft of the proposed w ell. There is an existing

well AT0 18

- 00 1 located 949 ft to the northeast. The following are the coordinates:

Well Installation:

Operator Block Well No. API No. Depth (ft) TVD Easting Northing Status

BHP Billiton AT 018 001 60 818 40024 00 4,266 28,651 980,051 10,152,077 PA

Two pipelines are located on the adjacent Block AT019 approximately 6,113ft and 6,330 ft to the east and northeast. The following are detailed of the pipelines:

**Pipeline Installations**

Operator Area Block

- Origin/Termination Outside Diameter (in) Product Status

ATP O&G AT063 / MC941 5 in BLKO ACT

ATP O&G MC941 / AT063 4in UBEH ACTAnadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 QQ

32 **Sub**

**- Seabed Hazards.**  Drilling Caution is indicated for a Slight Risk of Gas at the well location within two interval s of Unit C.

High and Moderate Shallow Water Flow Risk is assigned to two intervals within Unit C

. A Slight
Shallow Water Flow Risk is anticipated with in an interval in Unit D.

Proposed AT 18 QQ Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 57' 31.411” North Easting 979,462 US ft E
Longitude 89° 02’ 52.438” West Northing 10,151,381 US ft N
FEL of Atwater Valley 18 2,618 US ft Inline 5305
FNL of Atwater Valley 18 2,059 US ft Crossline 10724

Water Depth:

- 4,255 ft Slope: 2.1° NE

Nearest Shoreline 71.34 Miles @ 343° 25’ 48’’
Port of Operation Fourchon 106.42Miles @ 320° 36’ 0’’

Nearest Manned Platform MC941

- (Mirage/Titan) 6.06 Miles @ 300° 06’ 0”

**Conclusions and Recommendations.** Drilling techniques will take into consideration the possibility of encountering possible gas within two
interval of Unit C . Appropriate drilling methodology should be utilized to contain a potentially non

persistent Slight Shallow Water Flow Risk interpr eted in the lower interval of Unit D . Appropriate drilling methodology should be utilized to deal with a possible High and Moderate Shallow Water

Flow Risk in the intervals within Unit C.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations



## PUBLIC INFORMATIONAnadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 QQ

33 

### APPENDIX B – Sensitive Sessile Benthic Community StatementsAnadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 QQ

34 Sensitive Sessile Benthic Community Statement – AT018

- QQ



### Anadarko Petroleum Corporation

July 30 , 2013

US Department of the Interior Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

Reference: Sensitive Sessile Benthic Community Summary Atwater Valley, Block 18
OCS

- (G 33863 )

Ladies/Gentlemen: Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Site Clearan ce Letter for the proposed AT018

- QQ well locat ion in Atwater Valley, Block 18

, Stromboli Prospect (OCS

G G 33863 ). This letter addresses location proximity to potential sensitive sessile benthic comm unity

sites. Anadarko Petroleum Corporation will be drilling this well from a dynamically positioned drilling

module ; therefore

, no anchors will impact seabed.

This sensitive sessile benthic community summary letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block 018, dated August 2012 . A Biological, Physical and Socio

- Economic Map is included at the end of this appendix illustrating the areas of potential seabed impact.

**Potential Sensitive Sessile Benthic**  **Communities.** Features or areas that could support high density sensitive sessile benthic communities are **not** located within 2,000ft of any proposed mud and cuttings discharge location.

Proposed AT 18 QQ Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 57' 31.411” North Easting 979,462 US ft E
Longitude 89° 02’ 52.438” West Northing 10,151,381 US ft N
FEL of Atwater Valley 18 2,618 US ft Inline 5305

FNL of Atwater Valley 18 2,059 US ft Crossline 10724
Water Depth:

- 4,255 ft Slope: 2.1° NE

Nearest Shoreline 71.34 Miles @ 343° 25’ 48’’
Port of Operation Fourchon 106.42Miles @ 320° 36’ 0’’

Nearest Manned Platform MC941

- (Mirage/Titan) 6.06 Miles @ 300° 06’ 0”Anadarko Petroleum Corporation Gardline Report 9648
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Locations AT018 QQ

35 No potential sensitive sessile benthic community site is located within 2,000ft of the proposed

location

.

**Conclusions and Recommendations:** The proposed AT018

- QQ well location will not impact any sites favorable for development of sensitive

sessile benthic communities.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations

# ANADARKO PETROLEUM C ORPORATION

3D GEOHAZARD ASSESSM ENT

GULF OF MEXICO

ATWATER VALLEY BLOCK AT019

STROMBOLI PROSPECT

AT019

- EE PROPOSED WEL L LOCATION

WELL CLEARANCE LETTE R

APRIL 201 3

Gardline Project Ref. 9522 Report Status Final

Issue Date July 17, 2013

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.comAnadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

ii 

### REPORT AUTHORIZATION AND DISTRIBUTION

Report Status Fin al

Issue Date July 17, 2013

Compilation Geophysicist L Fuentes

Authori z ation Geophysics

..................... A R Haigh

Quality Assurance

..................... M DeLeon

Distribution

6 copies

Anadarko Petroleum Corporation

1201 Lake Robbins Drive

The Woodlands, TX 77380

For attention of:

Rick KincaidAnadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

iii 

### SERVICE WARRANTY

**USE OF THIS REPORT**

This report has been prepared with due care, diligence and with the skill reasonably expected of a reputable contractor experienced in the types of work, carried out under the contract. As such, the findings in this report are based on an interpretation of data which is a matter of opinion on which professionals may differ and, unless clearly stated, is not a recommendation of any course of action.

Gardline Surveys, Inc. has prepared this report for the client identified on the front cover in fulfilment of its contractual obligations under the referenced contract, and the only liabilities Gardline Surveys, Inc. will accept are those contained therein.

Please be aware that further distribution of this report, in whole or part, or the use of the data for a purpose not expressly stated within the contractual work scope is at the client’s sole risk, and Gardline Surveys, Inc recommends that this disclaimer be included in any such distribution.

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.comStudy Area Atwater Valley Green Canyon Lloyd Ridge Mississippi Canyon Destin Dome

De Soto Canyon Mobile Pensacola

Ship Shoal Area Eugene Island Area Viosca Knoll

Viosca Knoll Main Pass Area

Ewing Bank South Timbalier Area West Delta Area Louisiana Alabama Mississippi
Florida 

# Location Map

Study AreaAnadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

v 

### TABLE OF CONTENTS

REPORT AUTHORIZATION AND DISTRIBUTION ii

SERVICE WARRANTY iii

LOCATION MAP iv

TABLE OF CONTENTS v

LIST OF FIGURES vi

LIST OF CHARTS vii

WELL CLEARANCE LETTER
– PROPOSED AT019

- EE WELL LOCATION 1

1. LOCATION COORDINATES 3

1.1 Proposed AT019

- EE Well Location 3

2. VELOCITY DATA 4

2.1 Velocity Data 4

3. SEABED CONDITIONS 6

3.1 Bathymetry 6

3.2 Seafloor Morphology and Man Made Features 6

4. SUBSEABED CONDITIONS 7

4.1 Geology and Lithology 7

4.2 Unit A 7

4.3 Unit B 7

4.4 Unit C 8

4.5 Unit D 9

4.6 Shallow Gas Assess ment 9

4.7 Shallow Water Flow Assessment 9

5. CONCLUSIONS AND RECOMMENDATIONS 10

APPENDIX A
– Public Shallow Hazards Statements 28

APPENDIX B
– Sensitive Sessile Benthic Community Statements 31Anadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

vi 

### LIST OF FIGURES

Proposed A T0 19

- EE Well Location

1 Seabed Depth Extract

2 Seabed Morphology Extract

3 Seabed Amplitude Extract

4 Geohazard Summary Extract

5 Sand Lithology Summary

6 Inline Data Example

7 Crossline Data Example

8 Top Hole Prognosis

9 ROV Plat

10 Power Spectrum

11 Bathymetry Plat

12 Public Information Plat

13 Proprietary Information Plat

14 Vicinity Map

15 10

- Mile Radius PlatAnadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

vii 

### LIST OF CHARTS

The following chart at a scale of 1" = 2,000ft is enclosed:

Chart No Title Drawing No

1 Biological, Physical and Socio

- Economic Map 9522

. 01Anadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

1 

### WELL C LEA RANCE LETTER – PROPOS ED AT019

- EE WELL LOCATION
July 17 , 2013 Anadarko Petroleum Corporation

1201 Lake Robbins Drive The Woodlands, TX 77380

Attention: Rick Kincaid

Well Clearance Letter Proposed AT019

- EE Well Location

Block 019 , Atwater Valley Area
OCS - G 32556

Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Well Clearance

L etter for the proposed AT019

- EE well location in Block 019

, Atwater Valley Area (OCS

- G 32556 ). This letter addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this well clearance

ass e ssment is Top of Salt or

- 9,554ft below sea surface (5,250ft below seabed). We understand that Anadarko Petroleum Corporation plans to drill the proposed exploration well from a dynamically positioned drilling vessel; therefore, an anchoring assessment is not required nor provided. Relevant

letter

- size chart extracts, data examples, and a Top Hole Prognosis a re presented with this Well Clearance Letter. This geohazard assessment is based on the interpretation of 3D seismic data. This site clearance letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard

Asse ssment, Atwater Valley B lock s 018 & 019 , dated August 2012

.

Archaeological Survey. Anadarko Petroleum Corporation provided for review the complete archaeological survey report acquired by C&C Technologies Survey Services: Archaeological Survey

Blocks 18 (OCS -G- 33863) and 19 (OCS -G- 32556) Atwater Valley Area for the Anadarko Stromboli Prospect.

3D Geophysical Survey. Anadarko Petroleum Corporation provided the 3D dataset to Gardline Surveys Inc. on tape media in SEG

- Y format for loading onto a Seism ic Micro

- Technology (SMT) workstation. The 3D data cube contains a survey with 4 millisecond sample rate data to a record length of 6.0 seconds TWT below sea surface. Inlines are oriented north to south, have a numerical increment of one, and exhibit a l ine spacing of 65.6ft. Crosslines are oriented west to east, have a n numerical increment of one, and exhibit a line spacing of 41.0 ft.

• The acquisition parameters are:

o Atwater Valley (I) DW V

Shooting Direction: N/S Configuration: 4 sources, 6

- 10 streamersAnadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

2 Maximum offset: 8000 m
Channels: 324 per streamer Shotpoint interval: 47.25 m per array Group interval: 25 m CMP line spacing: 40 m
CMP bin dimension: 12.5 m x 40 m Record Length: 9 s below sea bottom
Nominal fold: 43 Vintage: April 1999

• The basic processing parameters are:

o Atwater Valley (I) DW V

480

- m x 500

- m velocity grid Demultiple 3D DMO velocity and stacking technology
One

- pass 3D poststack migration

12.5

- m x 20

- m final bin dimension

The data exhibits a good frequ ency response across the upper one second below seabed, with an
effe ctive frequency range of 5 to 60Hz. The data exhibits a dominant frequency of approximately 53Hz with significant higher usable frequencies. This frequency range results in a mean ve rtical resolvability of approximately 10m and a layer detectability of 5ft

.

In summary and with reference to NTL No. 2008

- G04 a) The 3D data provides images of sufficient resolution of the shallow section allowing a clear analysis of the shallow conditions b) T he data can be loaded to a workstation at 16bit resolution or greater, and is un

- scaled c) There is no trace or sample decimation d) The sample interval and bin size are maintained throughout the assessment area e) The data possess a frequency content of 50Hz or higher across the first second below

seabe d (See Power Spectrum Diagram: Figure 10 ) f) Seabed reflection is free of gaps and defined by a wavelet of stable shape and phase, allowing auto

- tracking of the seabed event with minimum user intervention and guidance g) T here are no significant acquisition artefacts throughout the dataset h) There are no merge points in the data i) Processed bin sizes are 65.62ft x 41.01ft j) The sample rate of the data is 4ms k) An accurate velocity model has been utilized in the shallow section allowing optimum structural and stratigraphy resolution with no evidence of under or over migration l) There is no significant multiple energy m) The proposed activities are not in an area of high archaeological potential.Anadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

3 

### 1. LOCATION COORDINATES

**1.1 Proposed AT**  **019**

**- EE**  **Well Location**

Proposed AT 0 19 EE Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 56' 30.32” North Easting 988,360 US ft E
Longitude 89° 01’ 12.07” West Northing 10,145,062 US ft N
FWL of Atwater Valley 19 6,280 US ft Inline 544 1
FSL of Atwater Valley 19 7,462 US ft Crossline 10570
Water Depth:

- 4,304 ft Slope: 1.4° NE

Nearest Shoreline 72 Miles @ 341°
Port of Operation Fourchon 108 Miles @ 319°

Nearest Manned Platform MC941

- (Mirage/Titan) 8 Miles @ 326°Anadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

4 

### 2. VELOCITY DATA

**2.1 Velocity Data** 

Time

- to

- depth conversion for the water column was derived using the Advocate and Hood (1993) polynomial.

Seabed depth (ft) =

0.1105 – 5066.9193X + 468.6693X 2

– 554.7107X 3 + 340.7019X 4

– 116.991X 5 + 20.728X 6

– 1.4658X 7 Where X = one way time in seconds to seabed

One Way Time To Seabed (s) Seabed Depth (ft) Seabed Depth (m) Vavg (m/s)

0.0 0 0 0

1.0 4910 1496 1496

1.1 5400 1646 1496

1.2 5892 1796 1496

1.3 6384 1946 1497

1.4 6877 2096 1497

1.5 7370 2246 1498

1.6 7865 2397 1498

1.7 8360 2548 1499

1.8 8856 2699 1499

1.9 9353 2851 1500Anadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

5 Sub

- seabed time to depth conversion was performed using a polynomial function successfully applied in an adjacent project and approved by Anadarko Petroleum Company :

V avg = - 45.841X 5 + 190.08X 4

– 183.08 X3 - 14.729X2 + 735.59X +4900

Whe re X = two way time in seconds below seabed

.

The resultant velocity was then multiplied by the time below seabed to produce depth below
seabed ; this horizon depth was summed with seabed depth to produce horizon depth below
sea surface.Anadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

6 

### 3. SEABED CONDITIONS

**3 .1**  **Bathymetry**

Seabed depth at the proposed AT019

- EE well location is

- 4,304 ft below sea surface ( Figure

1 ). The seafloor slopes to the northeast at 1 .4 °.

**3.2 Seafloor Morphology and Man Made Features** 

The proposed AT 019

- EE well location is in the center of Block AT 0 19 . At the proposed well location the seabed appears to be smooth and featureless ( Figure 2 ). Soft clays and silts are predicted at seabed. Sediments appear conducive for jetting of seabed casing with no hard layers predicted.

The proposed AT019

- EE well location is on a low

- relief ridge . The ridge i s the result of a slight uplift induced by the near by faults and tectonic movement ; no fluid venting is associated with this faulting . The nearest fault is located 2,938 ft to the south of the proposed location ; this fault should not impact the proposed well.

There is an existing well

, AT063

- SS004

, located appro ximately 19,500ft to the SSW. Additionally, there is an existing well

, AT 018- 00 1, located approximately 10,960 ft to the

northwest . The following are the coordinates:

Well Installation:

Operator Block Well No. API No. Depth (ft) TVD Easting Northing Status
ATP Oil & Gas AT063 SS004 608184004100 4,418 27,802 987,101 10,134,998 COM

BHP Billiton A T 018 001 60 818 40024 00 4,266 28,651 980,051 10,152,077 PA

Two pipelines traverse Block AT019

, located approximately 581ft and 795 ft to the east and

northeast respectively. The following are details of the pipelines:

**Pipeline Installations**

Operator Area Block

- Origin/Termination Outside Diameter (in) Product Status

ATP O&G AT063 / MC941 5 in BLKO ACT

ATP O&G MC941 / AT063 4in UBEH ACT

There are no anomalous seabed amplitudes indicative of hydrocarbon macroseep observed within a 2,000ft radius of the proposed location ( Figure 3 ).

No items of archaeological significance were identified within 2,000ft of the proposed location.

No other features are observed within a 2,000ft radius that could affect well emplacement or jetting of casing.Anadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

7 

### 4. SUBSEABED CONDITIONS

**4.1 Geology and Lithology** 

The sub

- seabed geology has been divided into four units separated by four horizons ( Figures

6 through 8 ). A geohazard extract and sand lithology extract utilized to complete the well

assessment are presented in Figures 4 and 5

.

**4.2 Unit A** 

The upper most interval wit hin Unit A from s eabed to

- 4,502 ft below sea surface (198 ft below seabed) is interpreted to consist of clays and silts with occasional minor coarser interbeds.

The lower interval of Unit A from

- 4,502ft to

- 4,744ft below sea surface (198ft to 440 ft below seabed) is interpreted to comprise of clays and silts.

No shallow gas or shallow water flow is predicted with in Unit A at the proposed well location.

A vertical borehole will not penetrate any faults within Unit A.

Horizon H10 marks the base of Unit A at

- 4,744ft below sea surface (44 0 ft below seabed).

**4.3 Unit B** 

The upper interval of Unit B fro m

- 4,744ft to

- 4,997 ft below sea surface (440ft to 693 ft below seabed) is expected to comprise of clays and silts with occasional coarser interbeds. A < 40ft

thick sand interbed occurs at

- 4,929ft below sea surface (625ft below seabed). Minor drilling fluid circulation and minor wellbore stability problems are possible at the level of the interbed.

The lower interval of Unit B from

- 4,997ft to

- 5,620 ft below sea surface (693 ft to 1,316 ft below seabed) is interpreted to consist of slightly higher energy clays and silts with occasional minor

coarser interbeds that may represent sands

. Due to the slightly elevated energy content

within this interval , m ino r drilling fluid circulation and minor wellbore stability problems are predicted

.

No shallow gas or shallow water flow is predicted with in Unit B at the proposed well location.

A vertical borehole will not penetrate any faults within Unit B.

Horizon H20 marks the base of Unit B at

- 5,620 ft below sea surface (1,316ft below seabed).Anadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

8 **4.4 Unit C** 

The lithology within the upper interval from

- 5,620ft to

- 5,746ft below sea surface (1,316 ft to
1,442 ft below seabed) is interpreted as clays and silts with the possibility of several minor coarser interbeds. Some minor drilling fluid circulation and minor wellbore stability problems are predicted within this interval

.

Lithology within the interval from

- 5,746ft to

- 6,597 ft below sea surface (1,442ft to 2,293 f t below sea surface) is interpreted to consist of higher energy clay s and silts with numerous coarser interbeds that may represent sands

. The proposed well is located at the edge of a
sand fairway package that extends from south of the well to the north we st

, and further to the
north and northeast of the well ( Figure 5 ) . A cluster of high

- amplitude anomalies located generally to the south

, we st, and north we st of the proposed well at these depths have been assigned a high risk of gas. The vertical borehole will not traverse any of these anomalies with the nearest risk of gas anomaly being ~550 ft to the southwe st

. However, due to the close encroachment and general higher energy nature of this interval

, a Slight Risk of Gas is assigned

. This interval exhibits the char acteristics of rapid high energy deposition plus a well

defined clay

- prone overburden (Unit B); this combination present favorable conditions for the

formation of shallow water flow. In a ddition

, a previously drilled well (AT063

- 2) located 2.4 miles to the south experienced a low shallow water flow event at 2,012ft below seabed ; these

sands correlate with this interval. As such , a Moderate Shallow Water Flow Risk is assigned to this interval.

From

- 6,597m to

- 7,769m below sea surface (2,293m to 3,415m below seabed) is interpreted

to consist of further slightly higher energy clays and silts with several coarser interbeds that may represent sands. Due to the presence of several possible minor sand interbeds, suggestion of localized rapid deposition and encapsulation within clays and silts

, this interval

is considered a Slight Shallow Water Flow Risk

.

The lower int erval within Unit C from

- 7,769ft to

- 8,393ft below sea surface (3,415 ft to 4,089 ft below seabed) is interpreted to comprise of clays with numerous sands

. The sand interbeds within this interval exhibit a high risk of gas 435 ft to the southwest . At the proposed well location the amplitude response is diminished, and the location is downdip from the high risk of gas anomalies. However, there ramians a slightly elevated amplitude response at the wellbore, and as such a Slight Risk of Gas is assigned within this interval. T he interpreted higher energy

, sandy nature of this lower interval of Unit C and the more continuous sandy

interbeds extending downdip is a favorable environment for the formation of shallow water
flow

, as such a Moderate Shallow Water Flow Risk is assigned to this interval

. M inor

dril ling fluid circulation and minor wellbore stability problems are also considered possible

within this interval due to the increased potential for poorly consolidated material

.

Horizon H30 marks the base of Unit C occurring at

- 8,393ft below sea surface (4,089 ft below seabed).Anadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

9 **4.5 Unit D** 

Unit D from

- 8,393ft to

- 9,554ft below sea surface (4,089ft to 5,250ft below seabed) is interpreted to consist of clays and silts with several coarser interbeds. Minor drilling fluid circulation and wellbore stability problems may occur.

Top of Salt marks the base of Unit D and the base of this int erpretation

, occurring at

- 9,554ft below sea surface (5,250ft below seabed).

**4.6 Shallow Gas Assessment** 

Within Unit C , a Slight Risk of Gas is assigned to the interval from

- 5,746ft to

- 6,597ft below sea surface (1,442ft to 2,293ft below seabed), and within the interval from

- 7,769ft to

- 8,393ft below sea surface (3,415ft to 4,089ft below seabed).

**4.7 Shallow Water Flow Assessment** 

Within Unit C

, a Moderate Shallow Water Flow Risk is assigned from

- 5,746ft to

- 6,597ft below sea surface (1,442ft to 2,293ft below seabed) and from

- 7,769ft to

- 8,393ft below sea surface (3,415ft to 4,089ft below seabed) . A Slight Shallow Water Flow Risk is assigned
from - 6,597ft to

- 7,769ft below sea surface (2,293ft to 3,415ft below seabed).Anadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

10 

### 5. CONCLUSIONS AND RECOMMENDATIONS

• Seabed No significant problems are anticipated at seabed. Shallow soils are expected to be conducive to the jetting of seabed casing with no hardgrounds predicted. An existing pipeline is located 581ft to the east of the proposed well location

.

• Unit A
No drilling hazards or problems predicted.

• Unit B
Minor drilling and minor wellbore stability problems are possible from

- 4,997ft to

- 5,620ft below sea surface (693ft to 1,316ft below seabed) and at t h e level of a <40ft thick sand

interbed at

- 4,929ft below sea surface (625ft below seabed).

• Unit C
Unit C presents a potentially challenging section to drill, with numerous intervals considered a risk of gas and a shallow water flow risk.

Within Unit C, a Slight Risk of Gas and a Moderate Shallow Water Flow Risk is assigned

to the interval from

- 5,746ft to

- 6,597ft below sea surface (1,442ft to 2,293ft below seabed)
and within the interval from - 7,769ft to

- 8,393ft below sea surface (3,415ft to 4,089ft below seabed). Drilling Caution and appropriate drilling methodology is recommended to deal with a possible water flow event through out these interval s

. Sediments in these intervals are most

pro bably poorly consolidated and as such may induce minor drilling fluid circulation and wellbore stability problems.

Within Unit C, a Slight Shallow Water Flow Risk is assigned from

- 6,597ft to

- 7,769ft below sea surface (2,293ft to 3,415ft below seabed). Appropriate drilling methodology is recommended to deal with a possible less

- persistent water flow event through this interval. Additionally, minor drilling fluid circulation and wellbore stability problems may also occur

within this interval.

Minor drilling and minor wellbore stability problems are possible from

- 5,620ft to

- 5,746ft below sea surface (1,316ft to 1,442ft below seabed).

• Unit D
Minor drilling and minor wellbore stability problems are possible throughout Unit D

.Anadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019

- EE Well Location

11 We appreciate the opportunity to work with you on this project, and look forward to continuing as your geohazards consultants. Please contact us if you have any questions or if we can be of

further assistance.

Sincerely, Gardline Surveys Inc.

Andrew Haigh Matilde DeLeon Geophysical Manager Quality Assurance

Copies Submitted: 6 copies to Rick Kincaid at Anadarko Petroleum Corporation

.

Attachments:

Proposed AT019 EE Well Location

Seabed Depth Extract

Seabed Morphology Extract

Seabed Amplitude Extract

Geohazard Summary Extract

Sand Lithology Summary

Inline Data Example

Crossline Data Example

Top Hole Prognosis

ROV Plat

Power Spectrum

Bathymetry Plat

Public Information Plat

Proprietary Information Plat

Vicinity Map

10

- Mile Radius Plat

## Top Hole Prognosis for Proposed AT019-EE Well Location 988,360ft E / 10,145,062ft N
Inline: 5441 / Crossline: 10570 Horizon Subsea Depth

(ft) BML Depth

(ft) Horizon
TWT (sec) Lithology, Structure & Stratigraphy Potential Drilling Hazards & Constraints Risk
of
Gas SWF
Risk

Seabed -4,304 0 1.756 Seabed is sloping to the northeast at 1.4°. The proposed well is located on the low-relief ridge. Surficial sediments comprise of soft clays and silts with occasional minor coarser intebeds



## Figure 8 Interface -5,746 1,442 2.302 Horizon H10 -4,744 440 1.931

Interface -6,597 2,293 2.594 Existing pipeline occurs 581ft to the east

Unit A

Unit B

Unit D Interface -7,769 3,415 2.991 Horizon H20 -5,620 1,316 2.257

Horizon H30 -8,393 4,089 3.148

Top of Salt -9,554 5,250 3.463 Unit C -4,929 625 2.002 Sand Interbed
Interface -4,997 693 2.028 Interface -4,502 198 1.836 Vavg
BML (m/s)

0

5,282 5,027

5,473

5,721 5,252

5,876

6,152 5,078 5,096 4,959 Clays and silts None predicted

Clays and silts with occasional coarser interbeds

Minor drilling fluid circulation and minor wellbore stability problems possible at the level of the interbed <40ft thick sand interbed

Clays and silts with occasional coarser interbeds that may represent sands Minor drilling fluid circulation and minor wellbore stability problems possible

Clays and silts with several coarser interbeds Minor drilling fluid circulation and minor wellbore stability problems possible within this interval

Clays and silts with numerous coarser interbeds that may represent sands Slight Risk of Gas and Moderate Shallow Water Flow Risk

Clays and silts with several sand interbeds Slight Shallow Water Flow Risk. Minor drilling fluid circulation and minor wellbore stability problems possible within this interval

Clays with numerous coarser interbeds that may represent sands Slight Risk of Gas and Moderate Shallow Water Flow Risk, minor drilling fluid circulation and wellbore stability problems possible

Clays and silts with several coarser interbeds Minor drilling fluid circulation and wellbore stability problems possible

Base of interpretation

# ±

6 ®33 3

3

-4510 -4470 -4460 -4360

-4370 -4380

-4390

-4480
-4400 -4410 -4430

-4420 -4440 -4450

-4500 -4490

-4350 -4340

-4520

-4330 -4320 -4530

-4310

-4300 -4290 -4280 -4270

-4540 -4550

-4560 -4260 -4570 -4250

-4240 -4580 -4590 -4230 -4600

-4220 -4210 -4610

-4200 -4190
-4180

-4520

-4510 -4530 -4540 -4520

-4260 -4480

-4550 -4530

-4370

-456089°0'0"W89°1'0"W89°2'0"W

27°58'0"N

27°57'0"N

27°56'0"N

27°55'0"N985,000990,000995,000 10,140,000 10,145,000 10,150,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1 = 2,000' 

## Bathymetry Plat Figure 11 Proposed AT019-EE Easting: 988,360ft E Northing: 10,145,062ft N FWL of AT019-EE: 6,280ft FSL of AT019-EE: 7,462ft ATP 5'' OIL(16173) ATP 4'' UMBILICAL(16181)

BPE&P 2 1/2''OR 2 7/8''CBLC(17364) ATWATER VALLEY BLOCK 19(OCS-G32556)

ATWATER VALLEY BLOCK 63(OCS-G13198) MISSISSIPPI CANYON BLOCK 987(OCS-G28032)

# ±

6 ®33 3

3 Proposed AT019-EE89°0'0"W89°1'0"W89°2'0"W

27°58'0"N

27°57'0"N

27°56'0"N

27°55'0"N985,000990,000995,000 10,140,000 10,145,000 10,150,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1" = 2,000' 

## Well Location Plat - Public Information Figure 12 ATP 5'' OIL(16173)

BPE&P 2 1/2''OR 2 7/8''CBLC(17364) ATP 4'' UMBILICAL(16181)

Location Call N/S Call E/W X Coordinate Y Coordinate Latitude Longitude WD AT019-EE SL 7,462ft FSL 6,280ft FWL 988,360 10,145,062 27° 56' 30.32"N 89° 01' 12.07"W -4,304 Proposed Location - AT019-EE

ATWATER VALLEY BLOCK 19(OCS-G32556)

ATWATER VALLEY BLOCK 63(OCS-G13198) MISSISSIPPI CANYON BLOCK 987(OCS-G28032)Nearest Shoreline Range: 72mi Bearing: 341° Fourchon Range: 108mi Bearing: 319°

Lund Henderson Lloyd Ridge

Walker Ridge Destin Dome

Atwater Valley Green Canyon De Soto Canyon

The Elbow

Florida Plain Vernon Basin Apalachicola

Garden Banks

Keathley Canyon Florida Middle Ground

Howell Hook Lund South Pensacola

Amery Terrace Mobile

Viosca Knoll

Viosca Knoll

Sigsbee Escarpment New Orleans Baton Rouge Pensacola

Lafayette Pascagoula Gulfport 

# Vicinity Map - Atwater Valley Block 019

Figure 14Anadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019 EE Well Location

28 

### APPENDIX A – Public Shallow Hazards Statement sAnadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019 EE Well Location

29 Public Shallow Hazards Statement – AT019 EE July 17, 2013

US Department of the Interior Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

- 2394

Attention:

Reference: Shallow Hazards Analysis Atwater Valley Block 019
OCS

- (G 32556 )

Ladies/Gentlemen:

Anadarko Petroleum Corporation contracted Gardline Surveys, Inc. to prepare a Well Clearan ce Le tter for the proposed AT019 EE well location in Block 019 , Atwater Valley Area (OCS

- G 32556 ). This letter addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this geohazard assessm ent is Top of
Salt at

- 9,554ft below sea surface (5,250ft below seabed).

This hazards summary letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block s 018 an d 019, dated August 2012.

**Seabed Hazards.**

The seabed is smooth and featureless. No problems are expected at the proposed AT019 EE well

location

. There are no indications of seabed fluid seeps within 2,000ft of the well location.

There is an existing w ell

, AT063

- SS004

, located approximately 19,500ft to the SSW. There is an existing well AT018

- 001 located approximately 10,960ft to the northwest. The following are the

coordinates:

Well Installation:

Operator Block Well No. API No. Depth (ft) TVD Easting Northing Status
ATP Oil & Gas AT063 SS004 608184004100 4,418 27,802 987,101 10,134,998 COM

BHP Billiton AT018 001 60 818 40024 00 4,266 28,651 980,051 10,152,077 PA

Two pipelines are located in Block AT019, located approximately 581ft and 795ft to the east and

northeast respectively. The following are details of the pipelines:

**Pipeline Installations**

Operator Area Block - Origin/Termination Outside Diameter (in) Product Status

ATP O&G AT063 / MC941 5 in BLKO ACT

ATP O&G MC941 / AT063 4in UBEH ACTAnadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019 EE Well Location

30 **Sub**

**- Seabed Hazards.**  Drilling Caution is indicated for a Slight Risk of Gas at the well location within Unit C.

Moderate
, and Slight Shallow Water Flow Risk is assigned to some of the intervals within Unit C

.

Proposed AT 19 EE Location (Surface)

Loc ation Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 56' 30.32” North Easting 988,360 US ft E
Longitude 89° 01’ 12.07” West Northing 10,145,062 US ft N
FWL of Atwater Valley 19 6,280 US ft Inline 544 1

FSL of Atwater Valley 19 7,462 US ft Crossline 10570
Water Depth:

- 4,304 ft Slope: 1.4° NE

Nearest Shoreline 72 Miles @ 341°
Port of Operation Fourchon 108 Miles @ 319°

Nearest Manned Platform MC941

- (Mirage/Titan) 8 Miles @ 326°

**Conclusions and Recommendations.**  Drilling techniques will take into consideration the possibility of encountering possible gas within the prescribed interval s with in Unit C. Appropriate drilling methodology should be utilized to contain a potentially non

- persistent Sli ght Shallow Water Flow Risk interpreted in Unit C. Appropriate drilling methodology should be utilized to deal with a possible Moderate Shallow Water Flow Risk with in the prescribed intervals within Unit C.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations



## PUBLIC INFORMATIONAnadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019 EE Well Location

31 

### APPENDIX B – Sensitive Sessile Benthic Community StatementsAnadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019 EE Well Location

32 Sensitive Sessile Ben thi c Com munity Statement – AT019 EE



### Anadarko Petroleum Corporation

July 17, 2013

US Department of the Interior Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

Reference: Sensitive Sessile Benthic Community Summary Atwater Valley, Block 019
OCS

- (G 32556 )

Ladies/Gentlemen: Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Site Clearan ce
Letter for the proposed AT019 EE well locat ion in Atwater Valley, Block 019

, Stromboli Prospect (OCS

- G G 32556 ). This letter addresses location proximity to potential sensitive sessile benthic community sites. Anadarko Petroleum Corporation will be drilling this well from a dynamically positioned drilling module

, therefore no anchors will impact seabed.

This sensitive sessile benthic community summary letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block s 018 and 019, dated August 2012

. A Biological, Physical and Socio

- Economic Map is included at the end of this appendix illustrating the areas of potential seabed impact.

**Potential Sensitive Sessile Benthic**  **Communities.** Features or areas that could support high density sensitive sessile benthic communities are **not** located within 2,000ft of any proposed mud and cuttings discharge location.

Proposed AT 19 EE Location (Surf ace)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 56' 30.32” North Easting 988,360 US ft E
Longitude 89° 01’ 12.07” West Northing 10,145,062 US ft N
FWL of Atwater Valley 19 6,280 US ft Inline 544 1
FSL of Atwater Valley 19 7,462 US ft Crossline 10570
Water Depth:

- 4,304 ft Slope: 1.4° NE

Nearest Shoreline 72 Miles @ 341°
Port of Operation Fourchon 108 Miles @ 319°

Nearest Manned Platform MC941

- (Mirage/Titan) 8 Miles @ 326°Anadarko Petroleum Corporation Gardline Report 9522
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed AT019 EE Well Location

33 No potential sensitive sessile benthic community site is located within 2,000ft of the proposed

location

.

**Conclusions and Recommendations:** The proposed AT019 EE well location will not impact any sites favorable for development of sensitive

sessile benthic communitie s.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations

# ANADARKO PETROLEUM C ORPORATION

3D GEOHAZARD ASSESSM ENT

GULF OF MEXICO

ATWATER VALLEY BLOCK AT019

STROMBOLI PROSPECT

AT019

- KK PROPOSED WEL L LOCATION

WELL CLEARANCE LETTE R

APRIL 201 3

Gardline Project Ref. 95 1 7 Report Status Final

Issue Date July 15, 2013

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.comAnadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK



### REPORT AUTHORIZATION AND DISTRIBUTION

Report Status Final

Issue Date July 15, 2013

Compilation Geophysicist L Fuentes

Authori z ation Geophysics

..................... A R Haigh

Quality Assurance

..................... M DeLeon

Distribution

6 copies

Anadarko Petroleum Corporation

1201 Lake Robbins Drive

The Woodlands, TX 77380

For attention of:

Rick Kincaid

iiAnadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK



### SERVICE WARRANTY

**USE OF THIS REPORT**

This report has been prepared with due care, diligence and with the skill reasonably expected of a reputable contractor experienced in the types of work, carried out under the contract. As such, the findings in this report are based on an interpretation of data which is a matter of opinion on which professionals may differ and, unless clearly stated, is not a recommendation of any course of action.

Gardline Surveys, Inc. has prepared this report for the client identified on the front cover in fulfilment of its contractual obligations under the referenced contract, and the only liabilities Gardline Surveys, Inc. will accept are those contained therein.

Please be aware that further distribution of this report, in whole or part, or the use of the data for a purpose not expressly stated within the contractual work scope is at the client’s sole risk, and Gardline Surveys, Inc recommends that this disclaimer be included in any such distribution.

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.com

iiiStudy Area Atwater Valley Green Canyon Lloyd Ridge Mississippi Canyon Destin Dome

De Soto Canyon Mobile Pensacola

Ship Shoal Area Eugene Island Area Viosca Knoll

Viosca Knoll Main Pass Area

Ewing Bank South Timbalier Area West Delta Area Louisiana Alabama Mississippi
Florida 

# Location Map

Study AreaAnadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK



### TABLE OF CONTENTS

REPORT AUTHORIZATION AND DISTRIBUTION ii

SERVICE WARRANTY iii

LOCATION MAP iv

TABLE OF CONTENTS v

LIST OF FIGURES vi

LIST OF CHARTS vii

WELL CLEARANCE LETTER
– PROPOSED AT019

- KK WELL LOCATION 1

1. LOCATION COORDINATES 3

1.1 Proposed AT019

- KK Well Location 3

2. VELOCITY DATA 4

2.1 Velocity Data 4

3. SEABED CONDITIONS 6

3.1 Bathymet ry 6

3.2 Seafloor Morphology and Man Made Features 6

4. SUBSEABED CONDITIONS 7

4.1 Geology and Lithology 7

4.2 Unit A 7

4.3 Unit B 7

4.4 Unit C 7

4.5 Unit D 9

4.6 Shallow Gas Assess ment 9

4.7 Shallow Water Flow Assessment 9

5. CONCLUSIONS AND RECOMMENDATIONS 10

APPENDIX A
– Public Shallow Hazards Statements 28

APPENDIX B
– Sensitive Sessile Benthic Community Statements 31

vAnadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK



### LIST OF FIGURES

Proposed A T0 19

- KK Well Location

1 Seabed Depth Extract

2 Seabed Morphology Extract

3 Seabed Amplitude Extract

4 Geohazard Summary Extract

5 Sand Lithology Summary

6 Inline Data Example

7 Crossline Data Example

8 Top Hole Prognosis

9 ROV Plat

10 Power Spectrum

11 Bathymetry Plat

12 Public Information Plat

13 Proprietary Information Plat

14 Vicinity Map

15 10

- Mile Radius Plat

viAnadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK



### LIST OF CHARTS

The following chart at a scale of 1" = 2,000ft is enclosed:

Chart No Title Drawing No

1 Biological, Physical and Socio

- Economic Map 9517

. 01

viiAnadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK



### WELL C LEARANCE LETTER – PROPOS ED AT019

- KK WELL LOCATION
July 15 , 2013 Anadarko Petroleum Corporation

1201 Lake Robbins Drive The Woodlands, TX 77380

Attention: Rick Kincaid

Well Clearance Letter Proposed AT019

- KK Well Location

Block 019 , Atwater Valley Area
OCS - G 32556

Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Well Clearance

L etter for the proposed AT019

- KK well location in Block 019

, Atwater Valley Area (OCS

- G 32556 ). This letter addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this well clearance

ass e ssment is Top of Salt or

- 9,893ft below sea surface (5,460ft below seabed). We understand that

Anadarko Pe troleum Corporation plans to drill the proposed exploration well from a dynamically positioned drilling vessel; therefore, an anchoring assessment is not required nor provided. Relevant

letter

- size chart extracts, data examples, and a Top Hole Prognosis a re presented with this Well Clearance Letter. This geohazard assessment is based on the interpretation of 3D seismic data. This site clearance letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard

Asse ssment, Atwater Valley Block s 018 & 019, dated August 2012

.

Archaeological Survey. Anadarko Petroleum Corporation provided for review the complete archaeological survey report acquired by C&C Technologies Survey Services: Archaeological Survey

Blocks 18 (OCS -G- 33863) and 19 (O CS -G- 32556) Atwater Valley Area for the Anadarko Stromboli Prospect.

3D Geophysical Survey. Anadarko Petroleum Corporation provided the 3D dataset to Gardline Surveys Inc. on tape media in SEG

- Y format for loading onto a Seismic Micro

- Technology (SMT) workstation. The 3D data cube contains a survey with 4 millisecond sample rate data to a record length of 6 .0 seconds TWT below sea surface. Inlines are oriented north to south, have a numerical increment of one, and exhibit a line spacing of 65.6 ft. Cr osslines are oriented west to east, have a numerical increment of one, and exhibit a line spacing of 41.0 ft.

• The acquisition parameters are:

o Atwater Valley (I) DW V

Shooting Direction: N/S Configuration: 4 sources, 6

- 10 streamers

1Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK

Maximum offset: 8000 m
Channels: 324 per streamer Shotpoint interval: 47.25 m per array Group interval: 25 m CMP line spacing: 40 m
CMP bin dimension: 12.5 m x 40 m Record Length: 9 s below sea bottom

Nominal fold: 43 Vintage: April 1999

• The basic processing parameters are:

o Atwater Valley (I) DW V

480

- m x 500

- m velocity grid Demultiple 3D DMO velocity and stacking technology
One

- pass 3D poststack migration

12.5

- m x 20

- m final bin dimension

The data exhibits a good frequency response across the upper one second below seabed, with an
effe ctive frequency range of 5 to 60Hz. The data exhibits a dominant frequency of approximately 53Hz with significant higher usable frequencies. This frequency range results in a mean vertical resolvability of approximately 10m and a layer detectability of 5ft

.

In summary and with reference to NTL No. 2008

- G04 a) The 3D data provides images of sufficient resolution of the shallow section allowing a clear analysis of the shallow conditions b) The data can be loaded to a workstation at 16bit resolution or greater, and is un

- scaled c) There is no trace or sample decimation d) The sample interval and bin size are maintained throughout the assessment area e) The data possess a frequency content of 50Hz or higher across the first second below

seabe d (See Power Spectrum Diagram: Figure 10 ) f) Seabed reflection is free of gaps and defined by a wavelet of stable shape and phase, allowing auto

- tracking of the seabed event with minimum user intervention and guidance g) There are no significant acquisition artefacts throughout the dataset h) There are no merge points in the data i) Processed bin sizes are 65.62ft x 41.01ft j) The sample rate of the data is 4ms k) An accurate velocity model has been utilized in the shallow section allowing optimum

structural and stratigraphy resolution with no evidence of under or over migration l) There is no significant multiple energy m) The proposed activities are not in an area of high archaeological potential.

2Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK



### 1. LOCATION COORDINATES

**1.1 Proposed AT019** 

**- KK**  **Well Location**

Propose d AT019

- KK Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 55' 23.29” North Easting 987,439 US ft E
Longitude 89° 01’ 21.10” West Northing 10,138,306 US ft N
FWL of Atwater Valley 19 5,359 US ft Inline 5427
FSL of Atwater Valley 19 706 US ft Crossline 10 405
Water Depth:

- 4,433 ft Slope: <1.0° SE

Nearest Shoreline 72 Miles @ 341°
Port of Operation Fourchon 108 Miles @ 319°

Nearest Manned Platform MC941

- (Mirage/Titan) 9 Miles @ 328°

3Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK



### 2. VELOCITY DATA

**2.1 Velocity Data** 

Time

- to

- depth conversion for the water column was derived using the Advocate and Hood (1993) polynomial.

Seabed depth (ft) =

0.1105 – 5066.9193X + 468.6693X 2

– 554.7107X 3 + 340.7019X 4

– 116.991X 5 + 20.728X 6

– 1.4658X 7 Where X = one way time in seconds to seabed

One Way Time To Seabed (s) Seabed Depth (ft) Seabed Depth (m) Vavg (m/s)

0.0 0 0 0

1.0 4910 1496 1496

1.1 5400 1646 1496

1.2 5892 1796 1496

1.3 6384 1946 1497

1.4 6877 2096 1497

1.5 7370 2246 1498

1.6 7865 2397 1498

1.7 8360 2548 1499

1.8 8856 2699 1499

1.9 9353 2851 1500

4Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK

Sub

- seabed time to depth conversion was performed using a polynomial function successfully applied in an adjacent project and approved by Anadarko Petroleum Company :

Vavg = = - 45.841X 5 + 190.08X 4

– 183.08 X3 - 14.729X2 + 735.59X +4900

Whe re A = two way time in seconds below seabed

.

The resultant velocity was then multiplied by the time below seafloor to produce depth below
seabed ; this horizon depth was summed with seabed depth to produce horizon depth below
sea surface.

5Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK

6 

### 3. SEABED CONDITIONS

**3.1 Bathymetry** 

Seabed depth at the proposed AT019

- KK well location is

- 4,433 ft below sea surface ( Figure

1 ). The seafloor slopes to the southeast at <1 .0 °.

**3.2 Seafloor Morphology and Man Made Features** 

The proposed AT 019

- KK well location is in the south

- central part of Block AT 0 19 . At the proposed well location the seabed appears to be smooth and featureless ( Figure 2 ). Soft clays and silts are predicted at seabed. Sediments appear conducive for jetting of seabed casing with no hard layers predicted.

The proposed well AT019

- KK is located within a graben with the nearest fault occurring 3,401ft to the north of the proposed well; this fault should not affect the proposed well.

There is an existing well AT 063

- SS004 located approximately 3,325 ft to the SSW

. There is an existing well AT 018- 00 1 located approximately 15,588ft to the northwest. The following are the coordinates:

Well In stallation:

Operator Block Well No. API No. Depth (ft) TVD Easting Northing Status
ATP Oil & Gas AT063 SS004 608184004100 4,418 27,802 987,101 10,134,998 COM

BHP Billiton A T 018 001 60 818 40024 00 4,266 28,651 980,051 10,152,077 PA

Two pipelines are located i n Block AT019

, located approximately 996ft and 1,159 ft to the

east and southeast. The following are detailed of the pipelines:

**Pipeline Installations**

Operator Area Block - Origin/Termination Outside Diameter (in) Product Status

ATP O&G AT063 / MC941 5 in BLKO ACT

ATP O&G MC941 / AT063 4in UBEH ACT

There are no anomalous seabed amplitudes indicative of hydrocarbon macroseep observed within a 2,000ft radius of the proposed location ( Figure 3 ).

No items of archaeological significance were identified within 2,000ft of the proposed location (archaeolo gical report submitted under a separate cover).

No other features are observed within a 2,000ft radius that could affect well emplacement or jetting of casing.Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK



### 4. SUBSEABED CONDITIONS

**4.1 Geology and Lithology** 

The sub

- seabed geology has been divided into four units separated by four horizons ( Figures

6 through 8 ). A geohazard extract and sand lithology extract utilized to complete the well

assessment are presented in Figures 4 and 5

.

**4.2 Unit A** 

The upper most interval within Unit A from s eabed to

- 4,727 ft below sea surface (294ft below seabed) is interpreted to consist of clays and silts with occasional minor coarser interbeds.

The lower interval of Unit A from

- 4,727ft to

- 5,003ft below sea surface (294ft to 570ft below seabed) is interpreted to comprise of clays and silts.

No shallow gas or shallow water flow is predicted with in Unit A at the proposed well location.

A verti cal borehole will not penetrate any faults within Unit A.

Horizon H10 marks the base of Unit A at

- 5,003ft below sea surface (570ft below seabed).

**4.3 Unit B** 

The upper interval of Unit B from

- 5,003ft to

- 5,569 ft below sea surface (570ft to 1,136ft below seabed) is expected to comprise of clays and silts with occasional coarser interbeds.

The lower interval of Unit B from

- 5,569ft to

- 6,143 f t below sea surface (1,136 ft to 1,710ft below seabed) is interpreted to consist of slightly higher energy clays and silts with several

minor coarser interbeds. Due to the slightly elevated energy content of this interval m inor drilling fluid circulation and minor wellbore stability problems are predicted within this interval

.

No shallow gas or shallow water flow is predicted with in Unit B at the proposed well location.

A vertical borehole will not penetrate any faults within Unit B.

Horizon H20 marks the base of Unit B at

- 6,143 ft below sea surface (1,710ft below seabed).

**4.4 U**  **nit C**

Lithology within the upper interval of this unit from

- 6,143ft to

- 6,896ft below sea surface (1 ,710ft to 2,463ft below sea surface) is interpreted to consist of higher energy clay s and silts with numerous coarser interbeds that may represent sands

. The proposed well is located

within a sand fairway package that extends from south of the well to the north we st ( Figure 5 )

.

7Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK

A cluster of high

- amplitude anomalies

, located generally to the west of the proposed well

, have been assigned a high risk of gas. The vertical borehole will not traverse any of these

anomalies with the nearest risk of gas anomaly being approximately 365 ft to the south

. However, due to the close encroachment and general higher energy nature of this interval a Slight Risk of Gas is a ssigned

. This interval exhibits character of rapid higher energy deposition and with a well defined clay prone overburden (Unit B) which are favorable
conditions for the formation of shallow water flow. In addition a previously drilled well (AT063

- 2) located 2.4 miles to the south experienced a low shallow water flow event at 2,012ft below

seabed and these sands correlate with th is interval

. As such a High Shallow Water Flow

Risk is assigned to this interval.

The lithology within the thin interval from

- 6,896ft to

- 7,025ft below sea surface (2,463ft to
2,592 ft below seabed) is interpreted as lower energy clays and silts with possibility of several

minor coarser interbeds. Some m inor drilling fluid circulation and minor wellbore stability problems are predicted within this interval.

From

- 7,025m to

- 7,766m below sea surface (2,592m to 3,333m below seabed) is interpreted to consist of further higher energy clays and silts with several coarser interbeds that may represent sands. A better defined <40ft thick sand interbed occurs at

- 7,071ft below sea surface (2,638ft below seabed). This sand interbed presents a slight increase in amplitude

, and may contain small amounts of fluid ; therefore

, a Slight Risk of Gas is assigne d. Due to the presence of numerous sand interbeds, suggestion of rapid deposition and encapsulation within clays and silts this interval is considered a Slight Shallow Water Flow Risk

.

The lower int erval within Unit C from

- 7,766ft to

- 8,529ft below sea surface (3,333ft to 4,096 ft

below seabed) is interpreted to comprise of clays with numerous sands

. Even in this lower interval of Unit C the proposed well path is on the periphery of the sand fairway. A better
defined <40ft more aerially expansive thick sand interbed is identified at

- 8,015ft below sea surface (3,582ft below seabed). This sand interbed also exhibits slight elevated amplitude and the possibility for small amounts of gas to be present within this interbed is considered possible , tho ugh no other direct hydrocarbon indicators are observed

. As such a Slight Risk

of Gas is assigned at the level of the interbed. D ue to the interpreted sandy nature of this lower interval of Unit C with further higher energy depositional character and the possibility of more continuous sandy interbeds a Moderate Shallow Water Flow Risk is assigned. M inor drilling fluid circulation and minor wellbore stability problems are also considered possible

within this interval.

A vertical borehole will penetrate a fault within Unit C at -7, 766ft below sea surface ( 3,333ft below seabed). This fault extends a significant amount into the shallower section into the overlying Unit B, and as such it is possible that drilling fluid circulation problems may occur at

the level of the fault if pressures over background are exerted by the drilling fluid column.

Horizon H30 marks the base of Unit C occurring at

- 8,529ft below sea surface (4,096ft below

8Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK

seabed).

**4.5 Unit D** 

Unit D from

- 8,529ft to

- 9,893ft below sea surface (4,096ft to 5,460ft below seabed)

, is interpreted to consist of clays and silts with several coarser interbeds. Minor drilling fluid circulation and wellbore stability problems may also occur.

A vertical borehole will penetrate a significant faul t within Unit D at

- 9,120 ft below sea surface (4,687 ft below seabed). This fault extends upwards to sea surface. If this fault is not sealed

then drilling fluid circulation problems are possible if pressures over hydrostatic are exerted by the drilling fluid column.

Top of Salt marks the base of Unit D and the base of this interpretation occurring at

- 9,893ft below sea surface (5,460ft below seabed).

**4.6 Shallow Gas Assessment** 

Within Unit C , a Slight Risk of Gas is assigned to the interval from 6,143ft to 6,896ft below sea surface (1,710ft to 2,463ft below seabed), and at the level of two <40ft thick sand

interbeds at

- 7,071ft and

- 8,015ft below sea surface (2,638ft and 3,582ft below seabed)

.

**4.7 Shallow Water Flow Assessment** 

Within Unit C , a High Shallow Water Flow Risk is interpreted to the interval from

- 6,143ft to

- 6,896 ft b elow sea surface (1,710ft to 2,463ft below seabed ) . A Moderate Shallow Water

Flow Risk is assigned from

- 7,766ft to

- 8,529ft below sea surface (3,333ft to 4,096ft below

seab ed). A Slight Shallow Water Flow Risk is assigned from

- 7,025ft to

- 7,766ft below sea surface (2,592ft to 3,333ft below seabed).

9Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK



### 5. CONCLUSIONS AND RECOMMENDATIONS

• Seabed No significant problems are anticipated at seabed. Shallow soils are expected to be conducive to the jetting of seabed casing with no hardgrounds predicted.

• Unit A
No drilling hazards or problems predicted.

• Unit B
Minor drilling and minor wellbore stability problems are possible from

- 5,569ft to

- 6,143ft below sea surface (1,136ft to 1,710ft below seabed).

• Unit C
Unit C presents a potentially challenging section to drill, with numerous intervals considered a shallow water flow risk and additional complications with faulting.

A Slight Risk of Gas and a High Shallow Water Flow Risk is ass igned to the interval from

- 6,143ft to

- 6,896ft below sea surface (1,710ft to 2,463ft below seabed)

. Drilling Caution and appropriate drilling methodology is recommended to deal with a possible water flow event throughout th is interval. Sediments in this interval are likely poorly consolidated and as such may induce minor drilling fluid circulation and wellbore stability problems.

Minor drilling and minor wellbore stability problems are possible from

- 6,896ft to

- 7,025 ft

be low sea surface (2,463ft to 2,592ft below seabed).

Within Unit C, a Slight Shallow Water Flow Risk is also interpreted from

- 7,025ft to

- 7,766ft below sea surface (2,592ft to 3,333ft below seabed). Appropriate drilling methodology is recommended to deal with a possible less

- persistent water flow event through this interval. Additionally, minor drilling fluid circulation and wellbore stability problems may also occur

within this interval. A Slight Risk of Gas is assigned at the level of a better defined <40ft

thick sand interbed at

- 7,071ft below sea surface (2,638ft below seabed). Drilling Caution is

advised at the level of the interbed.

Within the lower section of Unit C, a Moderate Shallow Water Flow Risk is interpreted from

- 7,766ft to

- 8,529 ft below sea surface (3,333ft to 4,096ft below seabed). Appropriate drilling methodology is recommended to deal with a possible water flow event through this interval

. Additionally, due to the potentially poorly consolidated sediment through this interval, minor drilling fluid circulation and wellbore stability problems may also occur within this interval. A Slight Risk of Gas is assigned at the level of a better defined <40ft thick sand interbed at

- 8,015ft below sea surface (3,582ft below seabed). Drilli ng Caution is advised at the level of

the interbed.

10Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK

A vertical borehole will penetrate a fault within Unit C at

- 7, 766ft below sea surface (3,333ft below seabed). Drilling fluid circulation problems may occur at the level of the fault if

pressures over background are exerted by the drilling fluid column

.

• Unit D
Minor drilling and minor wellbore stability problems are possible throughout Unit D

.

A vertical borehole will penetrate a fault within Unit D at

- 9,120ft below sea surface (4,687 ft below seabed). This fault extends upwards to seabed. Drilling fluid circulation problems are possible at the level of the fault if pressures over hydrostatic are exerted by the drilling fluid

column.

11Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019

- KK

We appreciate the opportunity to work with you on this project, and look forward to continuing as your geohazards consultants. Please contact us if you have any questions or if we can be of
further assistance.

Sincerely, Gardline Surveys Inc.

Andrew Haigh Matilde DeLeon Geophysical Manager Quality Assurance

Copies Submitted: 6 copies to Rick Kincaid at Anadarko Petroleum Corporation

.

Attachments:

Proposed AT019 KK Well Location

Seabed Depth Extract

Seabed Morphology Extract

Seabed Amplitude Extract

Geohazard Summary Extract

Sand Lithology Summary

Inline Data Example

Crossline Data Example

Top Hole Prognosis

ROV Plat

Power Spectrum

Bathymetry Plat

Public Information Plat

Proprietary Information Plat

Vicinity Map

10

- Mile Radius Plat

12

## Top Hole Prognosis for Proposed AT019-KK Well Location 987,439ft E / 10,138,306ft N
Inline: 5427 / Crossline: 10405 Horizon Subsea Depth

(ft) BML Depth

(ft) Horizon
TWT (sec) Lithology, Structure & Stratigraphy Potential Drilling Hazards & Constraints Risk
of
Gas SWF
Risk

Seabed -4,433 0 1.806 Seabed is smooth sloping to the southeast at <1.0°. Surficial sediments comprise of soft clays and silts. Underlying the seabed the lithology comprises of clays and silts with occasional minor coarser interbeds



## Figure 8 Interface -6,896 2,463 2.700 Horizon H10 -5,003 570 2.031

Interface -7,025 2,592 2.742 Clays and silts

Clays and silts with occasional coarser interbeds None predicted

None predicted

None predicted

Minor drilling fluid circulation and wellbore stability problems possible
within this interval Unit A

Unit B

Unit D Interface/Fault -7,766 3,333 2.975 Horizon H20 -6,143 1,710 2.446

Sand Interbed -8,015 3,582 3.050

Horizon H30 -8,529 4,096 3.200

Fault -9,120 4,687 3.364

Top of Salt -9,893 5,460 3.567 Clays and silts with numerous coarser interbeds that may represent sands

Clays and silts with several coarser interbeds

<40ft thick sand interbed Slight Risk of Gas and High Shallow Water Flow Risk. Minor drilling fluid circulation and wellbore stability problems possible

Unit C

Base of interpretation Clays and silts with numerous sands Clays and silts with several coarser interbeds

Minor drilling fluid circulation and minor wellbore stability problems possible within this interval Slight Risk of Gas and Slight Shallow Water Flow Risk in this interval. Minor drilling fluid circulation and wellbore stability problems possible within this interval.

Moderate Shallow Water Flow Risk. Minor drilling fluid circulation and wellbore stability problems possible within this interval and at the level of the fault if pressures over hydrostatic are exerted by the drilling fluid column -7,071 2,638 2.757 Sand Interbed <40ft thick sand interbed Interface -5,569 1,136 2.242 Interface -4,727 294 1.924

Clays and silts with several coarser interbeds Minor drilling fluid circulation and wellbore stability problems possible Clays with numerous coarser interbeds that may represent sands

Slight Risk of Gas at the level of the sand interbed

Drilling fluid circulation problems may occur at the level of the fault if pressures over hydrostatic are exerted by the drilling fluid column Vavg
BML (m/s)

0

5,510 5,063

5,538

5,702 5,344

5,748

5,877

6,017

6,202 5,549 5,209 4,986

# ±

6 ®33 3

3

AT063-SS004 -4510

-4500 -4490

-4480 -4520 -4470

-4460 -4340

-4330 -4350

-4370 -4360 -4380

-4390 -4400

-4410

-4450 -4440 -4430

-4420 -4320 -4310

-4530 -4300 -4290 -4540

-4280 -4270

-4550

-4560 -4260 -4570 -4250

-4240 -4580 -4590 -4230 -4600

-4220 -4210 -4610

-4200 -4190
-4180

-4530

-4510 -4560 -4540 -4550 -4520 -4370
-426089°0'0"W89°1'0"W89°2'0"W

27°57'0"N

27°56'0"N

27°55'0"N985,000990,000995,000 10,135,000 10,140,000 10,145,000 10,150,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1 = 2,000' 

## Bathymetry Plat Figure 11 Proposed AT019-KK Easting: 987,439ft E Northing: 10,138,306ft N FWL of AT019-KK: 5,359ft FSL of AT019-KK: 706ft

2 , 0 0 0 f t R

a d i u s ATP 5'' OIL(16173) ATP 4'' UMBILICAL(16181)

BPE&P 2 1/2''OR 2 7/8''CBLC(17364) ATWATER VALLEY BLOCK 19(OCS-G32556)

ATWATER VALLEY BLOCK 63(OCS-G13198)

# ±

6 ®33 3

3

AT063-SS004 Proposed AT019-KK Well89°0'0"W89°1'0"W89°2'0"W

27°57'0"N

27°56'0"N

27°55'0"N985,000990,000995,000 10,135,000 10,140,000 10,145,000 10,150,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1" = 2,000' 

## Well Location Plat - Public Information Figure 12 ATP 5'' OIL(16173)

BPE&P 2 1/2''OR 2 7/8''CBLC(17364) ATP 4'' UMBILICAL(16181)

Location Call N/S Call E/W X Coordinate Y Coordinate Latitude Longitude WD AT019-KK SL 706ft FSL 5,359ft FWL 987,439 10,138,306 27° 55' 23.29"N 89° 01' 21.10"W -4,433 Proposed Location - AT019-KK

ATWATER VALLEY BLOCK 19(OCS-G32556)

ATWATER VALLEY BLOCK 63(OCS-G13198)Nearest Shoreline Range: 72mi Bearing: 341° Fourchon Range: 108mi Bearing: 319°

Lund Henderson Lloyd Ridge

Walker Ridge Destin Dome

Atwater Valley Green Canyon De Soto Canyon

The Elbow

Florida Plain Vernon Basin Apalachicola

Garden Banks

Keathley Canyon Florida Middle Ground

Howell Hook Lund South Pensacola

Amery Terrace Mobile

Viosca Knoll

Viosca Knoll

Sigsbee Escarpment New Orleans Baton Rouge Pensacola

Lafayette Pascagoula Gulfport 

# Vicinity Map - Atwater Valley Block 019

Figure 14Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019 KK



### APPENDIX A – Public Shallow Hazards Statement s

28Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019 KK

Public S hallow Hazards Statement – AT019 KK

Jul y 15 , 2013

US Department of the Interior Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

- 2394

Attention:

Reference: Shallow Hazards Analysis Atwater Valley Block 019
OCS

- (G 32556 )

Ladies/Gentlemen:

Anadarko Petroleum Corporation contracted Gardline Surveys, Inc. to prepare a Well Clearan ce Letter for the proposed AT019 KK well location in B lock 019 , Atwater Valley Area (OCS

- G 32556 ). This letter addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this geohazard assessment is to Top of
Salt at

- 9,893ft below sea surface (5,460ft below seabed).

This hazards summary letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block s 018 and 019, dated August 2012.

**Seabed Hazards.**

The seabed is smooth and featureless. No problems are expected at the proposed AT019 KK well

location.

There are no indications of seabed fluid seeps within 2,000ft of the well location.

No existing seabed infrastructure is located within 2,00 0 ft of the proposed well. There is an existing

well AT

- 18

- 1 located approximately 15,588ft to the northwest. The following are the coordinates:

Well Installation:

Operator Block Well No. API No. Depth (ft) TVD Easting Northing Status

BHP Billiton At018 001 60 818 40024 00 4,266 28,651 980,051 10,152,077 PA

Two pipelines are located on the adjacent Block AT019 approximately 996ft and 1,159ft to the east and southeast. The following are detailed of the pipelines. **Pipeline Installations**

Operator Area Block

- Origin/Termination Outside Diameter (in) Product Status

ATP O&G AT063 / MC941 5 in BLKO ACT

ATP O&G MC941 / AT063 4in UBEH ACT

29Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019 KK

**Sub**

**- Seabed Hazards.**  Drilling Caution is indicated for a Slight Risk of Gas at the well location within Unit C.

High
, Moderate
, and Slight Shallow Water Flow Risk is assigned to some of the intervals within Unit
C

.

Proposed AT 19 KK Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 55' 23.29” North Easting 987,439 US ft E
Longitude 89° 01’ 21.10” West Northing 10,138,306 US ft N
FWL of Atwater Valley 19 5,359 US ft Inline 5427
FSL of Atwater Valley 19 706 US ft Crossline 10550
Water Depth:

- 4,433 ft Slope: <1.0° SE

Nearest Shoreline 72.25 Miles @ 341° 07’ 48’’
Port of Operation Fourchon 108.35Miles @ 319° 22’ 12’’

Nearest Manned Platform MC941

- (Mirage/Titan) 8.9 Miles @ 328° 48’ 00”

**Conclusions and Recommendations.** Drilling techniques will take into consideration the possibility of encountering possible gas within the
interval in Unit C . Appropriate drilling methodology should be utilized to contain a potentially non

persistent Slight Shallow Water Flow Risk interpreted in Unit C . Appropriate drilling methodology should be utilized to deal with a possible High and Moderate Shallow Water Flow Risk in the
intervals within Unit C.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations



## PUBLIC INFORMATION

30Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019 KK



### APPENDIX B – Sensitive Sessile Benthic Community Statements

31Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019 KK

Sensitive Sessile Ben thi c Com munity Statement – AT019 KK



### Anadarko Petroleum Corporation

Jul y 15 , 2013

US Department of the Interior Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

Reference: Sensitive Sessile Benthic Community Summary Atwater Valley, Block 018
OCS

- (G 32556 )

Ladies/Gentlemen: Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Site Clearan ce Letter for the proposed AT019 KK well locat ion in Atwater Valley, Block 019

, Stromboli Prospect (OCS

- G G 32556 ). This letter addresses location proximity to potential sensitive sessile benthic community si tes. Anadarko Petroleum Corporation will be drilling this well from a dynamically positioned drilling module ; therefore

, no anchors will impact seabed.

This sensitive sessile benthic community summary letter is issued as a supplement to Gardline Report

N o.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block s 018 and 019, dated August 2012

. A Biological, Physical and Socio

- Economic Map is included at the end of this appendix illustrating the areas of potential seabed impact.

**Potential Sensitive S**  **essile Benthic Communities.**  Features or areas that could support high density sensitive sessile benthic communities are **not** located within 2,000ft of any proposed mud and cuttings discharge location.

Proposed AT 19 KK Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 55' 23.29” North Easting 987,439 US ft E
Longitude 89° 01’ 21.10” West Northing 10,138,306 US ft N
FWL of Atwater Valley 19 5,359 US ft Inline 5427

FSL of Atwater Valley 19 706 US ft Crossline 10550
Water Depth:

- 4,433 ft Slope: <1.0° SE

Nearest Shoreline 72.25 Miles @ 341° 07’ 48’’
Port of Operation Fourchon 108.35Miles @ 319° 22’ 12’’

Nearest Manned Platform MC941

- (Mirage/Titan) 8.9 Miles @ 328° 48’ 00”

32Anadarko Petroleum Corporation Gardline Report 9517
Well Clearance Letters – Stromboli Prospect - Atwater Valley – Proposed Well Location AT019 KK

No potential sensitive sessile benthic community site is located within 2,000ft of the proposed

location

.

**Conclusions and Recommendations:** The proposed AT019 KK well location will not impact any sites favorable for development of sensitive

sessile benthic communities.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations

33

# ANADARKO PETROLEUM C ORPORATION

3D GEOHAZARD ASSESSM ENT

GULF OF MEXICO

ATWATER VALLEY BLOCK AT 019

STROMBOLI PROSPECT

PROPOSED AT 019

- KV WEL L LOCATION

WELL CLEARANCE LETTE R

MAY 201 3

Gardline Project Ref. 95 1 9 Report Status Final

Issue Date July 15 , 2013

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.comAnadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV



### REPORT AUTHORIZATION AND DISTRIBUTION

Report Status Final

Issue Date July 15 , 2013

Compilation Geophysicist L Fuentes

Authori z ation Geophysics

..................... A R Haigh

Quality Assurance

..................... M DeLeon

Distribution

6 copies

Anadarko Petroleum Corporation

1201 Lake Robbins Drive

The Woodlands, TX 77380

For attention of:

Rick Kincaid

iiAnadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV



### SERVICE WARRANTY

**USE OF THIS REPORT**

This report has been prepared with due care, diligence and with the skill reasonably expected of a reputable contractor experienced in the types of work, carried out under the contract. As such, the findings in this report are based on an interpretation of data which is a matter of opinion on which professionals may differ and, unless clearly stated, is not a recommendation of any course of action.

Gardline Surveys, Inc. has prepared this report for the client identified on the front cover in fulfilment of its contractual obligations under the referenced contract, and the only liabilities Gardline Surveys, Inc. will accept are those contained therein.

Please be aware that further distribution of this report, in whole or part, or the use of the data for a purpose not expressly stated within the contractual work scope is at the client’s sole risk, and Gardline Surveys, Inc recommends that this disclaimer be included in any such distribution.

Gardline Surveys Inc 1500 Bingle Road, Houston, Texas 77055, USA Telephone 713 481 4630 Fax 713 464 8275 www.gardline.com

iiiStudy Area Atwater Valley Green Canyon Lloyd Ridge Mississippi Canyon Destin Dome

De Soto Canyon Mobile Pensacola

Ship Shoal Area Eugene Island Area Viosca Knoll

Viosca Knoll Main Pass Area

Ewing Bank South Timbalier Area West Delta Area Louisiana Alabama Mississippi
Florida 

# Location Map

Study AreaAnadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV



### TABLE OF CONTENTS

REPORT AUTHORIZATION AND DISTRIBUTION ii

SERVICE WARRANTY iii

LOCATION MAP iv

TABLE OF CONTENTS v

LIST OF FIGURES vi

LIST OF CHARTS vii

WELL CLEARANCE LETTER
– PROPOSED AT019

- KV WELL LOCATION 1

1. LOCATION COORDINATES 3

1.1 Proposed AT019

- KV Well Location 3

2. VELOCITY DATA 4

2.1 Velocity Data 4

3. SEABED CONDITIONS 6

3.1 Bathymet ry 6

3.2 Seafloor Morphology and Man Made Features 6

4. SUBSEABED CONDITIONS 7

4.1 Geology and Lithology 7

4.2 Unit A 7

4.3 Unit B 7

4.4 Unit C 7

4.5 Unit D 9

4.6 Shallow Gas Assess ment 9

4.7 Shallow Water Flow Assessment 9

5. CONCLUSIONS AND RECOMMENDATIONS 10

APPENDIX A
– Public Shallow Hazards Statements 28

APPENDIX B
– Sensitive Sessile Benthic Community Statements 31

vAnadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV



### LIST OF FIGURES

Proposed A T0 19 KK Well Location

1 Seabed Depth Extract

2 Seabed Morphology Extract

3 Seabed Amplitude Extract

4 Geohazard Summary Extract

5 Sand Lithology Summary

6 Inline Data Example

7 Crossline Data Example

8 Top Hole Prognosis

9 ROV Plat

10 Power Spectrum

11 Bathymetry Plat

12 Public Information Plat

13 Proprietary Information Plat

14 Vicinity Map

15 10

- Mile Radius Plat

viAnadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV



### LIST OF CHARTS

The following chart at a scale of 1" = 1 ,000ft is enclosed:

Chart No Title Drawing No

1 Biological, Physical and Socio

- Economic Map 9519

. 01

viiAnadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV



### WELL C LEARANCE LETTER – PROPOSED AT019

- KV WELL LOCATION
July 15 , 2013 Anadarko Petroleum Corporation

1201 Lake Robbins Drive The Woodlands, TX 77380

Attention: Rick Kincaid

Well Clearance Letter Proposed AT 019

- KV Well Location

Block 019 , Atwater Valley Area
OCS - G 32556

Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Well Clearance

L etter for the proposed AT 019

- KV well location in Block 019

, Atwater Valley Area (OCS

- G 32556 ). This letter addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this well clearance

ass e ssment is Top of Salt or

- 9,864 ft below sea surface (5,449 ft below seabed). We understand that

Anadarko Pe troleum Corporation plans to drill the proposed exploration well from a dynamically positioned drilling vessel; therefore, an anchoring assessment is not required nor provided. Relevant

letter

- size chart extracts, data examples, and a Top Hole Prognosis a re presented with this Well Clearance Letter. This geohazard assessment is based on the interpretation of 3D seismic data. This site clearance letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard

Asse ssment, Atwater Valley B lock s 018 & 019, dated August 2012

.

Archaeological Survey. Anadarko Petroleum Corporation provided for review the complete archaeological survey report acquired by C&C Technologies Survey Services: Archaeological Survey

Blocks 18 (OCS -G- 33863) and 19 (OCS -G- 32556) Atwater Valley Area for the Anadarko Stromboli Prospect.

3D Geophysical Survey. Anadarko Petroleum Corporation provided the 3D dataset to Gardline Surveys Inc. on tape media in SEG

- Y format for loading onto a Seism ic Micro

- Technology (SMT) workstation. The 3D data cube contains a survey with 4 millisecond sample rate data to a record length of 6 .0 seconds TWT below sea surface. Inlines are oriented north to south, have a numerical increment of one, and exhibit a line spacing of 65.62ft. Crosslines are oriented west to east, have a numerical increment of one, and exhibit a line spacing of 41.01ft.

• The acquisition parameters are:

o Atwater Valley (I) DW V Shooting Direction: N/S Configuration: 4 sources, 6

- 10 st reamers Maximum offset: 8000 m

1Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV

Channels: 324 per streamer
Shot

- point interval: 47.25 m per array Group interval: 25 m CMP line spacing: 40 m
CMP bin dimension: 12.5 m x 40 m Record Length: 9 s ec. below sea bottom
Nominal fold: 43 Vintage : April 1999

• The basic processing parameters are:

o Atwater Valley (I) DW V

480

- m x 500

- m velocity grid Demultiple 3D DMO velocity and stacking technology
One

- pass 3D poststack migration

12.5

- m x 20

- m final bin dimension

. The data exhibits a good frequency response across the upper one second below seabed, with an
effe ctive frequency range of 5 to 60Hz. The data exhibits a dominant frequency of approximately 53Hz with significant higher usable frequencies. This frequency range results in a mean vertical resolvability of approximately 30ft and a layer detectability of 5ft

.

In summary and with reference to NTL No. 2008

- G04 a) The 3D data provides images of sufficient resolution of the shallow section allowing a clear analysis of the shallow conditions b) The data can be loaded on a workstation at 16bit resolution or greater, and is un

- scaled c) There is no trace or sample decimation d) The sample interval and bin size are maintained throughout the assessment area e) The data possess a frequency content of 50Hz or higher across the first second below

seabed . See Power Spectrum Diagram: Figure 10 f) Seabed reflection is free of gaps and defined by a wavelet of stable shape and phase, allowing auto

- tracking of the seabed event with minimum user intervention and guidance g) There are no significant acquisition artefacts throughout the dataset h) There are no merge points in the dat a i) Processed bin sizes are 65.62ft x 41.01ft j) The sample rate of the data is 4ms k) An accurate velocity model has been utilized in the shallow section allowing optimum structural and stratigraphy resolution with no evidence of under or over migration l) There is no significant multiple energy m) The proposed activities are not in an area of high archaeological potential.

2Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV



### 1. LOCATION COORDINATES

**1.1 Proposed AT019** 

**- KV**  **Well Location**

Proposed AT 0 19

- KV Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 55' 33.49” North Easting 987,423 US ft E
Longitude 89° 01’ 21. 68 ” West Northing 10,139,337 US ft N
FWL of Atwater Valley 19 5,343 US ft Inline 5427
FSL of Atwater Valley 19 1737 US ft Crossline 10430
Water Depth:

- 4,415 ft Slope: 1.3° SE

Nearest Shoreline 72 Miles @ 341°
Port of Operation Fourchon 108 Miles @ 319°

Nearest Manned Platform MC941

- (Mirage/Titan) 9 Miles @ 328°

3Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV



### 2. VELOCITY DATA

**2.1 Velocity Data** 

Time

- to

- depth conversion for the seabed depth was made using the Advocate and Hood (1993) polynomial:

Seabed Depth (ft) =

0.1105 – 5066.9193X + 468.6693X 2

– 554.7107X 3 + 340.7019X 4

– 116.991X 5 + 20.728X 6

– 1.4658X 7

Wh ere X = one way time in seconds to seabed

One Way Time To Seabed (s) Seabed Depth (ft) Seabed Depth (m) Vavg (m/s)

0.0 0 0 0

1.0 4910 1496 1496

1.1 5400 1646 1496

1.2 5892 1796 1496

1.3 6384 1946 1497

1.4 6877 2096 1497

1.5 7370 2246 1498

1.6 7865 2397 1498

1.7 8360 2548 1499

1.8 8856 2699 1499

1.9 9353 2851 1500

4Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV

Sub

- seabed time to depth conversion was performed using a formula successfully applied in an adjacent project and approved by Anadarko Petroleum Company :

Vavg = - 45.841X 5 + 190.08X 4

– 183.08 X3 - 14.729X2 + 735.59X +4900

Where X = t wo way time in seconds below seabed

.

The resultant velocity was then multiplied by the one way time below seabed to produce depth below seabed. This was summed with seabed depth to determine depth below sea
surface.

5Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV

6 

### 3. SEABED CONDITIONS

**3.1 Bathymetry** 

Seabed depth at the proposed AT019

- KV well location is

- 4,415 ft below sea surface ( Figure

1 ). The seafloor slopes to the southeast at 1 .3 °.

**3.2 Seafloor Morphology and Man Made Features** 

The proposed AT019

- KV well location is in the south of Block AT 0 19 . At the proposed well location the seabed is smooth and featureless ( Figure 2 ). Soft clays and silts are predicted at
seabed. Sediments appear conducive for jetting of seabed casing with no hard layers predicted.

The proposed well AT019

- KV is located within a graben structure with the nearest fault

located 2,817 ft to the north east of the proposed well. The fault should not affect the proposed well.

There is an existing well AT 063

- SS004 located approximately 4,300 ft to the south

. There

is an existing well AT 0 18

- 001 located approximately 15,400ft to the northwest. The following are the coordinates:

Well Installation:

Operator Block Well No. API No. Depth (ft) TVD Easting Northing Status
ATP Oil & Gas AT063 SS004 608184004100 4,418 27,802 987,101 10,134,998 COM

BHP Billiton A T 018 001 60 818 40024 00 4,266 28,651 980,051 10,152,077 PA

Two pipelines traverse Block AT019 and are located approximately 1,448ft and 1,627 ft to

the east and southeast of the proposed location. The following are details of the pipelines:

**Pipeline Installations**

Operator Area Block

- Origin/Termination Outside Diameter (in) Product Status

ATP O&G AT063 / MC941 5 in BLKO ACT

ATP O&G MC941 / AT063 4in UBEH ACT

There are no anomalous seabed amplitudes indicative of hydrocarbon macroseep observed within a 2,000ft radius of the proposed location ( Figure 3 ).

No items of archaeological significance were identified within 2,000ft of the proposed location (archaeological report submitted under a separate cover).

No other features are observed within a 2,000ft radius that could affect well emplacement or jetting of casing.Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV



### 4. SUBSEABED CONDITIONS

**4.1 Geology**  **and Lithology**

The sub

- seabed geology has been divided into four units separated by four horizons ( Figures

6 through 8 ). A Geohazards Extract and S and Lithology Extract complete the well

assessment and are presented as Figures 4 and 5

.

**4.2 Unit A** 

The upper most interval within Unit A from s eabed to

- 4,697 ft below sea surface (282ft below seabed) is interpreted to consist of clays and silts with occasional minor coarser interbeds.

The lower interval of Unit A from

- 4,697ft to

- 4,951ft below sea surface (282ft to 536ft below seabed) is interpreted to comprise of clays and silts.

No shallow gas or shallow water flow is predicted with in Unit A at the proposed well location.

A vertical borehole will not penetrate any faults within Unit A.

Horizon H1 0 marks the base of Unit A at

- 4,951ft below sea surface (536ft below seabed).

**4.3 Unit B** 

The upper interval of Unit B from

- 4,951ft to

- 5,545 ft below sea surface (536ft to 1,130ft below seabed) is expected to comprise of clays and silts with occasional coarser interbeds.

The lower interval of Unit B from

- 5,545ft to

- 5,939ft below sea surface (1,130ft to 1,524 ft below seabed) is interpreted as clays and silts with several coarser interbeds. Due to the slightly elevated energy content of this interval m inor drilling fluid circulation and minor wellbore stability problems are predicted within this interval.

No shallow gas or shallow water flow is predicted with in Unit B at the proposed well location.

A vertical borehole will not penetrate any faults within Unit B.

Horizon H20 marks the base of Unit B at

- 5,939 ft below sea surface (1,524ft below seabed).

**4.4 Unit C** 

The upper interval of Unit C from

- 5,939ft to

- 6,267ft below sea surface (1,524ft to 1,852ft below seabed) is interpreted to consist of clays and silts with several coarser interbeds that may represent sands. Minor drilling fluid circulation and minor wellbore stability problems are predicted within this interval.

7Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV

Lithology from - 6,267ft to

- 6,729 ft below sea surface (1,852ft to 2,314 ft below sea surface) is interpreted as higher energy clay s and silts with numerous coarser interbeds that may represent sands

. The proposed well is located within a sand fairway that extends from the

south and southeast of the well to the northeast ( Figure 5 ) . A cluster of high

- amplitude anomalies located generally to the southwest of the proposed well have the potential for a high risk of gas ; however , a vertical borehole will not intersect any of these polygons. T he nearest risk of gas anomalies a re located approximately 643 ft to the northwest and

southwest

. The se gas hazards illustrate possible connectivity to the borehole, and we have assigned a Slight Risk of Gas within this interval. This interval exhibits character of rapid higher energy deposition and with a well defined clay prone overburden (Unit B) which are

favorable conditions for the formation of shallow water flow. In addition a previously drilled well (AT063

- 2) located 2.4 miles to the south experienced a low shallow water flow event at 2,012ft below seabed and these sands correlate with th is interval

. However, the amplitude character of this interval is slightly reduced at the proposed location, and as such a Moderate
Shallow Water Flow Risk is assigned to this interval.

The li thology within the this interval from

- 6,729ft to

- 6,992 ft below sea surface (2,314ft to
2,577 ft below seabed) is interpreted to comprise of lower energy clays and silts with the possibility of several minor coarser interbeds

. Some m inor drilling fluid circulation and minor wellbore stability problems are predicted within this interval.

From

- 6,992m to

- 7,830 m below sea surface (2,577m to 3,415m below seabed) is interpreted to consist of clays and silts with several coarser interb eds that may represent sands. I t is possible that the sand interbeds within this interval may contain small volumes of fluid and a Slight Risk of Gas is assigned. Due to the presence and rapid deposition of the sands within

this interval plus the possibility for fluid to be present within some of these sands

, and possible downdip connectivity to additional probable coarser deposits ( Figure 7 ), that may have pore pressure connectivity to the well location, a Moderate Shallow Water Flow Risk is assigned.

The lower int erval wi thin Unit C from

- 7,830ft to

- 8,400ft below sea surface (3,415ft to 3,985 ft below seabed) is interpreted to comprise of clays with numerous sands. The well path is

located within the main cluster of increased amplitude events indicative of sands. Due to this slightly elevated amplitude character a Slight Risk of Gas is assigned to this interval

. D ue to the sandy nature of this interval, and the possibility of relatively continuous sandy interbeds, that descend eastward, possibly linking the pore pressure regimen to deeper levels, we have assigned a Moderate Shallow Water Flow Risk

.

A vertical borehole will penetrate a fault within Unit C at

- 7,830 ft below sea surface ( 3,415 ft below seabed). This fault extends upwards to seabed, and as such if the fault is not sealed then some drilling fluid circulation problems may occur at the level of the fault if pressures over hydrostatic are exerted by the drilling fluid column. Wellbore stability problems could

also occur.

8Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV

Horizon H30 marks the base of Unit C at

- 8,400ft below sea surface (3,985ft below seabed).

**4.5 Unit D** 

Unit D from

- 8,400ft to

- 9,864ft below sea surface (3,985ft to 5,449ft below seabed) is interpreted to consist of clays and silts with several coarser interbeds. Minor drilling fluid

circula tion and wellbore stability problems may also occur.

A vertical borehole will not penetrate a ny fault s within Unit D.

Top of Salt marks the base of Unit D and the base of this interpretation at

- 9,864 ft below sea surface (5,449ft below seabed).

**4.6 Shallow Gas Assessment** 

Within Unit C , a Slight Risk of Gas is assigned to the interval from

- 6,267ft to

- 6,729ft below sea surface (1,852ft to 2,314ft below seabed)

, from

- 6,992ft to

- 7,830ft below sea surface (2,577ft to 3,415ft below seabed), and from -7 ,830ft to

- 8,400ft below sea surface (3,415ft to 3,985ft below seabed).

**4.7 Shallow Water Flow Assessment** 

Within Unit C, a Moderate Shallow Water Flow Risk is assigned to the interval from

- 6,267ft

to

- 6,729ft below sea surface (1,852ft to 2,314ft below seabed), from

- 6,992ft to

- 7,830ft below sea surface (2,577ft to 3,415ft below seabed), and from

- 7,830ft to

- 8,400ft below sea surface (3,415ft to 3,985ft below seabed).

9Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV



### 5. CONCLUSIONS AND RECOMMENDATIONS

• Seabed No significant problems are anticipated at seabed. Shallow soils are expected to be conducive to the jetting of seabed casing with no hardgrounds predicted.

• Unit A
No drilling hazards or problems predicted.

• Unit B
Minor drilling and minor wellbore stability problems are possible from

- 5,545ft to

- 5,939ft below sea surface (1,130ft to 1,524ft below seabed).

• Unit C
Unit C presents a potentially challenging section to drill, with numerous intervals considered a shallow water flow risk and additional complications with faulting.

Within Unit C, a Slight Risk of Gas and a Moderate Shallow Water Flow Risk is assigned

to the interval from

- 6,267ft to

- 6,729ft below sea surface (1,852ft to 2,314ft below seabed),

from

- 6,992ft to

- 7,830ft below sea surface (2,577ft to 3,415ft below seab ed), and from

- 7,830ft to

- 8,400ft below sea surface (3,415ft to 3,985ft below seabed). Drilling Caution is

adv ised and appropriate drilling methodology is recommended to deal with a possible water flow event through this interval. Sediments in this interval are likely poorly consolidated and as such may induce minor drilling fluid circulation and wellbore stability problems.

M inor drilling fluid circulation and wellbore stability problems may also occur from

- 6,729ft to

- 6,992ft below sea surface (2,314ft to 2,577ft below seabed).

Minor drilling and minor wellbore stability problems are possible from

- 5,939ft to

- 6,267ft below sea surface (1,524ft to 1,852ft below seabed).

A vertical borehole will penetrate a fault within Unit C at

- 7,830ft below sea surface (3,415 ft below seabed). Drilling fluid circulation problems may occur at the level of the fault if pressures over hydrostatic are exerted by the drilling fluid column.

• Unit D
Minor drilling and minor wellbore stability problems are possible within Unit D.

10Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV

We appreciate the opportunity to work with you on this project, and look forward to continuing as your geohazards consultants. Please contact us if you have any questions or if we can be of
further assistance.

Sincerely, Gardline Surveys Inc.

Andrew Haigh Matilde DeLeon Geophysical Manager Quality Assurance

Copies Submitted: 6 copies to Rick Kincaid at Anadarko Petroleum Corporation

.

Attachments:

Proposed AT019

- KV Well Location

Seabed Depth Extract

Seabed Morphology Extract

Seabed Amplitude Extract

Geohazard Summary Extract

Sand Lithology Summary

Inline Data Example

Crossline Data Example

Top Hole Prognosis

ROV Plat

Power Spectrum

Bathymetry Plat

Public Information Plat

Proprietary Information Plat

Vicinity Map

10

- Mile Radius Plat

11

## Top Hole Prognosis for Proposed AT019-KV Well Location 987,423ft E / 10,139,337ft N
Inline: 5427 / Crossline: 10430 Horizon Subsea Depth

(ft) BML Depth

(ft) Horizon
TWT (sec) Lithology, Structure & Stratigraphy Potential Drilling Hazards & Constraints Risk
of
Gas SWF
Risk

Seabed -4,415 0 1.797 Seabed is smooth sloping to the southeast at 1.3°. Surficial sediments comprise of soft clays and silts.Underlying the seabed the lithology comprises of clays and silts with occasional minor coarser interbeds



## Figure 8 Interface -6,267 1,852 2.486 Horizon H10 -4,951 536 2.009

Interface -6,729 2,314 2.642 Clays and silts with occasional coarser interbeds None predicted

None predicted

Minor drilling fluid circulation and minor wellbore stability problems possible within this interval Unit A

Unit B

Horizon H20 -5,939 1,524 2.372

Interface/Fault -7,830 3,415 2.991

Horizon H30 8,400 3,985 3.159

Top of Salt -9,864 5,449 3.555 Clays and silts with several coarser interbeds that represent sands

Clays and silts with minor numerous coarser interbeds that may represent sands

Clays with numerous coarser interbeds that may represent sands Minor drilling fluid circulation and minor wellbore stability problems possible within this interval

Base of interpretation Clays and silts with minor coarser interbeds that may represent sands Clays and silts with several coarser interbeds

Slight Risk of Gas and Moderate Shallow Water Flow Risk

Minor drilling fluid circulation and wellbore stability problems possible

Slight Risk of Gas and Moderate Shallow Water Flow Risk. -6,992 2,577 2.728 Interface Interface -5,545 1,130 2.231 Interface -4,697 282 1.910

Clays and silts with several coarser interbeds Minor drilling fluid circulation and wellbore stability problems possible Clays and silts with several sand interbeds

Slight Risk of Gas and Moderate Shallow Water Flow Risk Drilling fluid circulation problems may occur at the level of the fault if pressures over hydrostatic are exerted by drilling fluid column None predicted Vavg
BML (m/s)

0

5,376 5,054

5,478 5,301

5,721

5,851

6,199 5,535 5,208 4,983 Clays and silts

Unit C

Unit D

# ±

6 ®33 3

3

AT063-SS004 -4510

-4500 -4490

-4480 -4520 -4470

-4460 -4340

-4330 -4350

-4370 -4360 -4380

-4390 -4400

-4410

-4450 -4440 -4430

-4420 -4320 -4310

-4530 -4300 -4290 -4540

-4280 -4270

-4550

-4560 -4260 -4570 -4250

-4240 -4580 -4590 -4230 -4600

-4220 -4210 -4610

-4200 -4190
-4180

-4530

-4510 -4560 -4540 -4550 -4520 -4370
-426089°0'0"W89°1'0"W89°2'0"W

27°57'0"N

27°56'0"N

27°55'0"N985,000990,000995,000 10,135,000 10,140,000 10,145,000 10,150,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1 = 2,000' 

## Bathymetry Plat Figure 11 2

, 0

0

0

f t R a d

i u s ATP 5'' OIL(16173) ATP 4'' UMBILICAL(16181)

BPE&P 2 1/2''OR 2 7/8''CBLC(17364) ATWATER VALLEY BLOCK 19(OCS-G32556)

ATWATER VALLEY BLOCK 63(OCS-G13198) Proposed AT019-KV Easting: 987,423ft E Northing: 10,139,337ft N FWL of AT019-KV: 5,343ft FSL of AT019-KV: 1,737ft

# ±

6 ®33 3

3

AT063-SS004 Proposed AT019-KV Well89°0'0"W89°1'0"W89°2'0"W

27°57'0"N

27°56'0"N

27°55'0"N985,000990,000995,000 10,135,000 10,140,000 10,145,000 10,150,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters Chart scale 1" = 2,000' 

## Well Location Plat - Public Information Figure 12 ATP 5'' OIL(16173)

BPE&P 2 1/2''OR 2 7/8''CBLC(17364) ATP 4'' UMBILICAL(16181)

ATWATER VALLEY BLOCK 19(OCS-G32556)

ATWATER VALLEY BLOCK 63(OCS-G13198) Location Call N/S Call E/W X Coordinate Y Coordinate Latitude Longitude WD AT019-KV SL 1,737ft FSL 5,343ft FWL 987,423 10,139,337 27° 55' 33.49'' N 89° 01' 21.68'' -4,415 Proposed Location - AT019-KVNearest Shoreline Range: 72mi Bearing: 341° Fourchon Range: 108mi Bearing: 319°

Lund Henderson Lloyd Ridge

Walker Ridge Destin Dome

Atwater Valley Green Canyon De Soto Canyon

The Elbow

Florida Plain Vernon Basin Apalachicola

Garden Banks

Keathley Canyon Florida Middle Ground

Howell Hook Lund South Pensacola

Amery Terrace Mobile

Viosca Knoll

Viosca Knoll

Sigsbee Escarpment New Orleans Baton Rouge Pensacola

Lafayette Pascagoula Gulfport 

# Vicinity Map - Atwater Valley Block 019

Figure 14Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV



### APPENDIX A – Public Shallow Hazards Statement s

28Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV

Public S hallow Hazards Statement – AT019

- KV July 15 , 2013

US Department of the Interior Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

- 2394

Attention:

Reference: Shallow Hazards Analysis Atwater Valley Block 019
OCS

- (G 32556 )

Ladies/Gentlemen:

Anadark o Petroleum Corporation contracted Gardline Surveys, Inc. to prepare a Well Clearan ce Letter for the proposed AT019

- KV well location in Block 019, Atwater Valley Area (OCS

- G 32556 ). This letter addresses seafloor and shallow geologic conditions that may impact exploratory drilling operations within 2,000ft of the proposed well location. The depth limit of this geohazard assessm ent
is Top of Salt at

- 9,864ft below sea surface (5,4 49 ft below seabed).

This hazards summary letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block s 018 and 019, dated August 2012.

**Seabed Hazards.**

The seabed is smooth and featureless. No problems ar e e xpected at the proposed AT019

- KV well

location.

There are no indications of seabed fluid seeps within 2,000ft of the well location.

**Sub**

**- Seabed Hazards.** 

Drilling Caution is indicated for a Slight Risk of Gas at the well location within Unit C.

Moderate and Slight Shallow Water Flow Risk is assigned to sand intervals within Unit C

.

29Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV

Proposed AT019

- KV Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 55' 33.49” North Easting 987,423 US ft E
Longitude 89° 01’ 21.68 ” West Northing 10,139,337 US ft N
FWL of Atwater Valley 19 5,343 US ft Inline 5427
FSL of Atwater Valley 19 1737 US ft Crossline 10430
Water Depth:

- 4,415 ft Slope: 1.3° SE

Nearest Shoreline 72 Miles @ 341°
Port of Operation Fourchon 108 Miles @ 319°

Nearest Manned Platform MC941

- (Mirage/Titan) 9 Miles @ 328°

**Conclusions and Recommendations.** Drilling techniques will take into consideration the possibility of encountering possible gas within Unit
C

.

Appropriate drilling methodology will be utilized to contain a potentially non

- persistent Slight Shallow

Water Flow Risk within Unit C . Appropriate drilling methodology will be utilized to deal with a possible
Moderate Shallow Water Flow Risk in the sand intervals within Unit C.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations



## PUBLIC INFORMATION

30Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV



### APPENDIX B – Sensitive Sessile Benthic Community Statements

31Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV

Sensitive Sessile Ben thi c Com munity Statement – AT019

- KV



### Anadarko Petroleum Corporation

July 15 , 2013

US Department of the Interior Bureau of Energy, Management, Regulation and Enforcement

1201 Elmwood Park Blvd. New Orleans, LA 70213

Reference: Sensitive Sessile Benthic Community Summary Atwater Valley, Block 018
OCS

- (G 32556 )

Ladies/Gentlemen: Gardline Surveys Inc was contracted by Anadarko Petroleum Corporation to prepare a Site Clearan ce Letter for the proposed AT019

- KV well locat ion in Atwater Valley, Block 019

, Stromboli P rospect (OCS

- G G 32556 ). This letter addresses location proximity to potential sensitive sessile benthic community sites. Anadarko Petroleum Corporation will be drilling this well from a dynamically positioned drilling module ; therefore

, no anchors will impact seabed.

This sensitive sessile benthic community summary letter is issued as a supplement to Gardline Report No.9172 entitled: 3D Geohazard Assessment, Atwater Valley Block s 018 and 019, dated August 2012

. A Biological, Physical and Socio

- Economic Map is included at the end of this appendix illustrating the areas of potential seabed impact.

**Potential Sensitive Sessile Benthic**  **Communities.** Features or areas that could support high density sensitive sessile benthic communities are **not**
located within 2,000ft of any proposed mud and cuttings discharge location.

Proposed AT 19 KV Location (Surface)

Location Coordinates

NAD 27 Datum

- Clarke 1866 Ellipsoid UTM Zone 16N

- CM 93° West

Latitude 27° 55' 33.49” North Easting 987,423 US ft E
Longitude 89° 01’ 21.68 ” West Northing 10,139,337 US ft N
FWL of Atwater Valley 19 5,343 US ft Inline 5427
FSL of Atwater Valley 19 1737 US ft Crossline 10430
Water Depth:

- 4,415 ft Slope: 1.3° SE

Nearest Shoreline 72 Miles @ 341°
Port of Operation Fourchon 108 Miles @ 319°

Nearest Manned Platform MC941

- (Mirage/Titan) 9 Miles @ 328°

32Anadarko Petroleum Corporation Gardline Report 9519
Well Clearance Letter – Stromboli Prospect - Atwater Valley – Proposed Well Location AT 019 KV

No potential sensitive sessile benthic community site is located within 2,000ft of the proposed

location

.

**Conclusions and Recommendations:** The pr oposed AT019

- KV well location will not impact any sites favorable for development of sensitive

sessile benthic communities.

Sincerely, Anadarko Petroleum Corporation

Rick Kincaid

Leader

- Geologic Operations

33

### SECTION D HYDROGEN SULFIDE INFORMATION

Discussions regarding geologic in formation are consider ed proprietary and ha ve been omitted from this public copy of the EP.

Anadarko requests the area be classifi ed as a “zone where the absence of H 2 

### S has been confirmed.”

### SECTION E BIOLOGICAL, PHYSICAL, AND SO CIOECONOMIC INFORMATION

(a) Chemosynthetic Communities Report

The seafloor disturbing activit ies proposed in this plan are in approximately 4,167'-4,433' of water. The wells will be drilled with a DP drillship or DP semi-submersible.

Maps

A map prepared using 3-D seismic data to depi ct bathymetry, seafloor and shallow geological features, and surface locations of the proposed wells is included in Section A.

Analysis

Features or areas that could support high-dens ity chemosynthetic communities are not located within 2,000' of each proposed muds and cuttings discharge location.

Features or areas that could support high-dens ity chemosynthetic communities are not located within 250' of any seafloor disturbances.

(b) Topographic Features Map

The proposed activitie s are not within 1,000 ' of a no-activity zone or within the 3-mile radius zone of an identified topographic feature. Th erefore, no map is required per NTL 2008-G04, extended by NTL 2014-G03.

(c) Topographic Features Statement (Shunting)

Anadarko does not plan to drill more than two wells from the same surface location within the
Protective Zone of an identifie d topographic feature. Theref ore, the topographic features statement required by NTL 2008-G04, extended by NTL 2014-G03, is not applicable.

(d) Live Bottoms (Pinnacle Trend) Map

The activities proposed in this plan are not within 200' of any pinnacle trend feature with vertical relief equal to or greater than 8'. Therefore, no map is required per NTL 2008-G04, extended by
NTL 2014-G03.

(e) Live Bottoms (Low Relief) Map

The activities proposed in this plan are not with in 100' of any live bottom low relief features. Therefore, no map is required pe r NTL 2008-G04, extended by NTL 2014-G03.

### (f) Potentially Sensitive Biological Features

The activities proposed in this pl an are not within 200' of any potentially sensitive biological features. Therefore, no map is requi red per NTL 2008-G04, extended by NTL 2014-G03.

(g) Remotely Operated Vehicle (ROV) Monitoring Survey Plan

Atwater Valley 18/19 is located w ithin Deepwater Grid Area 13. This grid is considered to have “adequate ROV survey coverage”, and, theref ore, under the guidance set out in NTL 2008-G06, a Remotely Operated Vehicle Monito ring Survey Plan is not required.

Pursuant to NTL 2008-G06, operators may be re quired to conduct remotely operated vehicle (ROV) surveys during the propo sed operations for the purpose of biological and physical
observations.

Anadarko is familiar with the ROV survey and reporting provisions of NTL 2008-G06; and if required, will conduct a survey.

Anadarko will utilize ROV equipped with video imaging capabilities. The survey pattern will
consist of six transects centered on the well lo cation with tracks extending approximately 100 meters away from the well on bearings of 30 degrees, 90 degrees, 150 degrees, 210 degrees, 270 degrees and 330 degrees. The seafloor will be videotaped continuously along each track.

Anadarko will make biological and physical observa tions as described in the subject NTL and Form BOEM-141 prior to comm encing operations and prior to moving off location. The observations will be documented using Form BOEM-141, or a facsimile and submitted along with videotapes, and any other imagery obtain ed, to the BOEM/BSEE within 60 days after completion of the final ROV survey.

(h) Threatened and Endangered Species Information

Under Section 7 of the Endangered Species Act (ESA) all federal ag encies must ensure that any actions they authorize, fund, or carry out are not li kely to jeopardize the continued existence of a listed species, or destroy or adversely modify its designated critical habitat.

In accordance with the 30 CFR 550, Subpart B, effective May 14, 2007, and further outlined in Notice to Lessees (NTL) 2008-G04 (extended by NTL 2014-G03), lessees/operators are required to address site-specific information on the presen ce of federally listed threatened or endangered species and critical habitat designated under th e ESA and marine mammals protected under the Marine Mammal Protection Act (M MPA) in the area of proposes activities under this plan.

### Currently there are no designated critical habitats for the listed species in the Gulf of Mexico Outer Continental Shelf; however, it is possible th at one or more of thes e species could be seen in the area of our operations. The following table reflects the Federally-listed endangered and threatened species in the lease ar ea and along the northern Gulf coast:

Species Scientific Name Status Potential Presence Critical Habitat Designated in Gulf of Mexico Lease Area Coastal

Marine Mammals S p erm whale Ph y seter macroce p halus E X -- None

Florida manatee Trichechus manatus latirostris E -- X Florida ( Peninsular ) Blue whale B alaenoptera musculus E X a

-- None Fin whale B alaeno p tera p h y salus E X a

-- None Hum p back whale M e g a p tera novaean g liae E X a

-- None North Atlantic right whale Eubalaena glacialis E X a

-- None Sei whale B alaeno p tera borealis E X a

-- None Sea Turtles
Lo gg erhead turtle Caretta caretta T X X None Green turtle Chelonia m y das T, E b X X None Leatherback turtle Dermochel y s coriacea E X X None Hawksbill turtle Eretmochel y s imbricata E X X None Kemp’s ridley turtle L epidochelys kempii E X X None Birds

Piping Plover Charadrius melodus T -- X Coastal Texas, Louisiana, Mississippi, Alabama, and Florida (Panhandle)

Whooping Crane Grus americana E -- X Coastal Texas (Aransas National Wildlife Refu g e ) Fishes

Gulf sturgeon Acipenser oxyrinchus desotoi T -- X Coastal Louisiana, Mississippi, Alabama, and Florida ( Panhandle ) Terrestrial Mammals Beach mice (Alabama, Choctawhatchee, Perdido Ke y , St. Andrew ) Peromyscus polionotus E -- X Alabama and Florida (Panhandle) beaches

Abbreviations: E = Endangered; T = Threatened.

a The blue, fin, humpback, North Atlantic right, and sei whales are rare or extralimital in the Gulf of Mexico and are unlikely to be present in the lease area. b The green sea turtle is threatened, except for the Florida breeding population, which is listed as endangered.



### The Environmental Impact Analysis in Section N of this plan further discusses potential impacts and mitigation measures related to threatened and endangered species.

(i) Archaeological Report

Atwater Valley 18/19 is not in an area designated as an area of high archaeological potential and, as such, as such, an Archaeological Repor t is not required per NTL 2008-G04, extended by extended by NTL 2014-G03. However an “Archaeological Assessment Report” prepared by C & C Technologies Survey Services (Project #120015) is being submitted with this EP for
reference.

### (j) Air and Water Qu ality Information

This EP does not propose activities for which the State of Florida is an affect ed State. Therefore, the discussion required per NTL 2008-G04, extended by NTL 2014-G03, is not ap plicable to this
EP.

(k) Socioeconomic Information

The activities proposed in this plan are not loca ted offshore Florida. Therefore, socioeconomic information required per NTL 2008-G04, extended by NTL 2014-G03, is not applicable to this
EP.

### SECTION F WASTE AND DISCH ARGE INFORMATION

The following estimates were prepared utilizing Anad arko’s experience with si milar drilling operations. Estimated maximum discharge rates are reflected below.

(a) Projected Generated Wastes

Type of Waste Composition Projected Amount Treatment/Storage/Disposal Synthetic-based drilling
fluids Synthetic-based drilling muds 18,500 bbls/well Re-use and/or transport to shore in DOT approved containers to Fourchon, Louisiana and on to base/transfer station. If recycled, returned to vendor (Baroid or MI.) Cuttings wetted with synthetic-based muds Cuttings coated with synthetic drilling muds/fluids, including drilled out

cement. 6,500 bbls/well Treated and discharged overboard. *Note, an estimated 5-10% of cuttings may be transported to shore in tanks and/or cutting boxes and on
to the base/transfer station if oil still
remains. Water-based drilling
fluids Water-based drilling muds (NaCl saturated, seawater, freshwater, barite) 43,000 bbls/well Discharge overboard or at seafloor.

Cuttings wetted with
water-based fluids Cuttings coated with water-based drilling
muds/fluids 2,400 bbls/well Discharge overboard or at seafloor.

Chemical product waste (well treatment fluids) Ethylene glycol
Methanol 100 bbls/month
25 bbls/month Transport to shore in DOT approved containers to Fourchon, Louisiana for pick up. Completion Fluids Brine, spent acid, prop sand, debris 3,000 bbls/well Transport to shore in DOT approved containers to Fourchon, Louisiana and on to Newpark Base. Non-pollutant completion fluids Low density
uninhibited completion brines 5,000 bbls/well Discharge overboard.

Workover fluids Brine, spent acid, prop sand, debris 3,000 bbls/well Transport to shore in DOT approved containers to Fourchon, Louisiana and on to Newpark Base. Trash and debris Refuse generated during operations 2,850 bbls total Transport to shore in disposal bags by vessel to shorebase for pickup by municipal operations. *Sanitary Wastes Treated human body

waste 7,600,000 gals total Chlorinate and discharge overboard.

*Domestic Waste Gray water 7,600,000 gals total Chlorinate and discharge overboard. Deck drainage Platform washings
and rainwater 5,320,000 bbls total Treat for oil and grease and discharge overboard.
Produced water N/A N/A N/A
Desalinization Unit Seawater 532,000 bbls total Discharge overboard.
Wash water Drill water (fresh) 85,500 bbls total Discharge overboard. Blowout preventer fluid Blend (3% Stack Magic & Filtered Fresh Water) 200,857 gals total Discharge at seafloor.

Ballast water Seawater 47,650 m3/year Discharge overboard.Cont. Type of Waste Composition Projected Amount Treatment/Storage/Disposal Bilge water Seawater 542,070 bbls total Discharge overboard through 15 ppm equipment
Excess cement at the
seafloor Nitrified cement slurry 524 bbls/well Discharge at seafloor

Fire water Seawater 137,142 bb ls/day/well Discharge overboard Cooling water Seawater 137,142 bbls/day/well Discharge overboard
Produced Sand N/A N/A N/A
Used oil Excess oil from engines 6,128 bbls total Transport in DOT approved containers to shore for recycling

(b) Projected Ocean Discharges

Type of Waste Total Amount to be Discharged Disch6arge Rate Discharge Method

*Sanitary Wastes 7,600,000 gals 25 gals per person daily Chlorinate and discharge
overboard *Domestic waste 7,00,000 gals 25 gals per person daily Chlorinate and discharge
overboard Deck drainage 5,320,000 bbls 3,500 bbls/day Treat for oil and grease and discharge Blowout preventer fluid 200,857 gals 925 gals/week/well Vents on weekly basis Discharge at seafloor

Desalinization Unit 532,000 bbls 350 bbls/day Discharge overboard
Wash water 85,500 bbls 50 bbls/day Discharge overboard

Ballast water As needed Not continuous Discharge overboard Bilge water 542,070 bbls 317 bbls/day Discharge overboard through 15 ppm equipment
Excess cement at the
seafloor 4,192 bbls 20 bbls/min Discharge at seafloor

Fire water 234,512,820 bbls 137,142 bbls/day Discharge overboard Cooling water 234,512,820 bbls 137,142 bbls/day Discharge overboard Cuttings wetted with
water-based fluids 19,200 bbls 1,000 bbls/hr max Discharge overboard or at seafloor

Water-based drilling
fluids 344,000 bbls** 1,000 bbls/hr max Discharge overboard or at seafloor

Cuttings wetted with synthetic-based fluids 52,000 bbls 1,000 bbls/hr max*** Treated and discharge overboard *Note, an estimated 5-10% of cuttings may be transported to shore in tanks and/or cutting boxes and on to the base/transfer station if oil still remains

. Non-pollutant completion fluids 40,000 bbls 100 bbls/hour Discharge overboard

*The rig is designed for maximum personnel capacity of 200 people. The discharge rates are based off of maximum personnel capa city but will generally not have this many personnel onboard during drilling and/or completion operations. **The volume ordered out will be an estimated 19,000 bbls/well of mud. Once on location this volume will be cut back and mixed with seawater to different desired mud weights which will increase the volume that is discharged at the seafloor. The estimated volume that wil l be discharged at the seafloor will be approximately 43,000 bbls/well. (43,000 bbls x 8 wells=344,000 bbls) ***The rate for cuttings wetted with synthetic-based fluids varies depending on the hole section and the stage of the actual dr illing process. 

### (c) Modeling Report

The proposed activities under this plan do not meet the U.S. Environmental Protection Agency requirements for an individual NPDES permit. Therefore, modeling report requirements per NTL 2008-G04, extended by NTL 2014-G03, is not applicable to this EP.

### SECTION G AIR EMISSIONS INFORMATION

(a) Screening Questions

Screening Questions for EP’s Yes No Is any calculated Complex Total (CT) Emission amount (in tons) associated with your proposed exploration activities more than 90% of the amounts calculated using the following formulas: CT = 3400D 2/3 for CO, and CT = 33.3D for the other air pollutants (where D = distance to shore in miles)? Yes

Do your emission calculations include any emission reduction measures or modified
emission factors? Yes

Are your proposed exploration activities located east of 87.5 W longitude? No Do you expect to encounter H 2 S at concentrations greater than 20 parts per million (ppm)? No Do you propose to flare or vent natural gas for more than 48 continuous hours from any proposed well? No

Do you propose to burn produced hydrocarbon liquids? No



### (b) Emissions Worksheets

Air emission worksheets have been prepared ut ilizing the maximum horsepower rating from an Anadarko contracted DP drillship, the Noble Bob Douglas . The Noble Bob Douglas has six main engines. The average number of engines on-line at once will be four engines. Rigs typically do not operate at maximum horsepower capacity or engine load, therefore Anadarko has opted to calculate the plan emission am ounts based on the total horse power rating and 50% average engine load. A different rig may be utilized (DP drillship or DP semi-submersible); but the horsepower rating, average engine load, and air em issions will be equal to, or less than, the calculated plan emission amounts shown on the fo llowing pages. Air emission worksheets are
enclosed as Attachment G-1.

Based on the attached Air Quality Review (AQR) spreadsheet, projected potential emissions of nitrogen oxides (NO
x 

### ) are above the corresponding exemption threshold estimated for 2016/2017/2018, therefore, Trinity C onsultants performed an air quality modeling analysis for NOx. Submitted along with this EP are two copies of Trinity Consultants’ “Offshore and Coastal Dispersion Mode ling Analysis Report” for Atwater Valley 18/19 (Project No. 131901.0103). Potential emissions of all other po llutants included in the AQR are below the corresponding exemption threshol ds; therefore modeling has not been performed for any other pollutant(s).

### (c) Summary Information

If drilled with a DP Drillship

Air Pollutant Plan Emission Amounts 1 (tons) Calculated Exemption Amounts 2 (tons) Calculated Complex Total Emission Amounts 3 (tons)

Particulate matter (PM) 72.23 2,364.30 72.23 Sulphur dioxide (SO 2 ) 331.34 2,364.30 331.34 Nitrogen oxides (NO
x ) 2,482.82 2,364.30 2,482.82 Volatile organic compounds (VOC) 74.48 2,364.30 74.48 Carbon monoxide (CO) 541.71 58,297.66 541.71

If drilled with a DP Semi-submersible

Air Pollutant Plan Emission Amounts 1 (tons) Calculated Exemption Amounts 2 (tons) Calculated Complex Total Emission Amounts 3 (tons)

Particulate matter (PM) 68.90 2,364.30 68.90 Sulphur dioxide (SO 2 ) 316.09 2,364.30 316.09 Nitrogen oxides (NO
x ) 2,368.54 2,364.30 2,368.54 Volatile organic compounds (VOC) 71.06 2,364.30 71.06 Carbon monoxide (CO) 516.77 58,297.66 516.77 *Plan emissions amounts (tons) are based on 248 days. **Calculated complex total emission amounts (tons) are based on 248 days.



### The air emission calculations were calculated by:

Bridget O’Farrell Regulatory Analyst (832) 636-1694 Bridget.OFarrell-Vi llarreal@anadarko.comCOMPANYAnadarko Petroleum CorporationAREAATBLOCK18/19LEASEOCS-G 33863, G-32556PLATFORMWELLAT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KVCOMPANY CONTACTBridget O'FarrellTELEPHONE NO.832-636-1694REMARKSDrill and complete8wellsDrillshipFORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page 1 of11EXPLORATION PLAN (EP)AIR QUALITY SCREENING CHECKLISTOMB Control No. 1010-0151OMB Approval Expires: 12/31/2014EMISSIONS FACTORSFuel Usage Conversion FactorsNatural Gas Turbines Natural Gas Engines Diesel Recip. Engine REF. DATESCF/hp-hr 9.524 SCF/hp-hr 7.143 GAL/hp-hr 0.0483AP42 3.2-1 4/76 & 8/84Equipment/Emission Factorsunits PM SOx NOx VOC CO REF. DATENG Turbines gms/hp-hr 0.00247 1.3 0.01 0.83AP42 3.2-1& 3.1-1 10/96NG 2-cycle leangms/hp-hr0.00185 10.9 0.43 1.5AP42 3.2-1 10/96NG 4-cycle leangms/hp-hr0.00185 11.8 0.72 1.6AP42 3.2-1 10/96NG 4-cycle richgms/hp-hr0.00185 10 0.14 8.6AP42 3.2-1 10/96Diesel Recip. < 600 hp. gms/hp-hr 1 1.468 14 1.12 3.03AP42 3.3-1 10/96Diesel Recip. > 600 hp.gms/hp-hr 0.32 1.468 11 0.33 2.4AP42 3.4-1 10/96Diesel Boilerlbs/bbl 0.084 2.42 0.84 0.008 0.21AP42 1.3-12,14 9/98NG Heaters/Boilers/Burnerslbs/mmscf 7.6 0.593 100 5.5 84P42 1.4-1, 14-2, & 147/98NG Flareslbs/mmscf0.593 71.4 60.3 388.5AP42 11.5-1 9/91Liquid Flaringlbs/bbl 0.42 6.83 2 0.01 0.21AP42 1.3-1 & 1.3-3 9/98Tank Vaporslbs/bbl0.03E&P Forum 1/93Fugitiveslbs/hr/comp.0.0005API Study 12/93Glycol Dehydrator Ventlbs/mmscf6.6La. DEQ1991Gas Ventinglbs/scf0.0034Sulfur Content SourceValue UnitsFuel Gas3.33 ppmDiesel Fuel0.4 % weightProduced Gas( Flares)3.33 ppmProduced Oil (Liquid Flaring)1 % weightFORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page2of11COMPANYAREABLOCK LEASEPLATFORM WELLCONTACT PHONE REMARKSAnadarko Petroleum Corporation AT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KV Bridget O'Farrell832-636-1694 0OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HRSCF/DBurnersMMBTU/HR SCF/HRSCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLINGPRIME MOVER>600hp diesel64,370 3109.071 50% 37308.85 24 190 45.37 208.14 1559.63 46.79 340.28 51.72 237.28 1777.97 53.34 387.92PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel00 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/weekVESSELS>600hp diesel(crew)14805 715.081517161.96 6 81 10.44 47.87 358.71 10.76 78.26 2.55 11.69 87.63 2.63 19.122 trips/weekVESSELS>600hp diesel(supply)9266 447.547810741.15 6 54 6.53 29.96 224.51 6.74 48.98 1.06 4.88 36.56 1.10 7.98VESSELS>600hp diesel(tugs)000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITYDERRICK BARGE diesel000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATIONMATERIAL TUG diesel000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew)000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply)000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HRCOUNTTANK-00 00.000.00Flowback AfterOIL BURN00 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00CompletionGAS FLARE00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002014 YEAR TOTAL62.34 285.97 2142.84 64.29 467.53 55.34 253.85 1902.16 57.06 415.02EXEMPTIONCALCULATIONDISTANCE FROM LAND IN MILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngineLoad %FORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page3of11EMISSIONS CALCULATIONS 1ST YEAREMISSIONS CALCULATIONS2NDYEARCOMPANYAREABLOCK LEASEPLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum Corpo AT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KV Bridget O'Farrell832-636-16940OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HRSCF/DBurnersMMBTU/HR SCF/HRSCF/DHR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLINGPRIME MOVER>600hp diesel 64,370 3109.071 50% 37308.85 24 190 45.37 208.14 1559.63 46.79 340.28 51.72 237.28 1777.97 53.34 387.92DrillshipPRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.081517161.96 6 81 10.44 47.87 358.71 10.76 78.26 2.55 11.69 87.63 2.63 19.122 trips/week VESSELS>600hp diesel(supply) 9266 447.547810741.15 6 54 6.53 29.96 224.51 6.74 48.98 1.06 4.88 36.56 1.10 7.98VESSELS>600hp diesel(tugs) 000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITYDERRICK BARGE diesel000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HRCOUNTTANK-00 00.000.00Flowback After OIL BURN00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002015 YEAR TOTAL62.34 285.97 2142.84 64.29 467.53 55.34 253.85 1902.16 57.06 415.02EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngineLoad %FORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page4of11COMPANYAREABLOCK LEASEPLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum Corporation AT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KV Bridget O'Farrell832-636-1694 0OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HRSCF/DBurnersMMBTU/HR SCF/HRSCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLINGPRIME MOVER>600hp diesel 64,370 3109.071 50% 37308.85 24 248 45.37 208.14 1559.63 46.79 340.28 67.51 309.71 2320.72 69.62 506.34DrillshipPRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/weekVESSELS>600hp diesel(crew) 14805 715.081517161.96 6 106 10.44 47.87 358.71 10.76 78.26 3.33 15.26 114.38 3.43 24.962 trips/weekVESSELS>600hp diesel(supply) 9266 447.547810741.15 671 6.53 29.96 224.51 6.74 48.98 1.39 6.37 47.72 1.43 10.41VESSELS>600hp diesel(tugs)000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITYDERRICK BARGE diesel000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATIONMATERIAL TUG diesel000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HRCOUNTTANK-0000.000.00Flowback AfterOIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00CompletionGAS FLARE00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002016 YEAR TOTAL62.34 285.97 2142.84 64.29 467.53 72.23 331.34 2482.82 74.48 541.71EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngineLoad %FORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page5of11EMISSIONS CALCULATIONS3RDYEARCOMPANYAREABLOCK LEASEPLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum CorpAT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KV Bridget O'Farrell832-636-1694 0OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas Engines HP SCF/HR SCF/DBurners MMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLING PRIME MOVER>600hp diesel 64,370 3109.071 50% 37308.85 24 248 45.37 208.14 1559.63 46.79 340.28 67.51 309.71 2320.72 69.62 506.34Drillship PRIME MOVER>600hp diesel 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6 106 10.44 47.87 358.71 10.76 78.26 3.33 15.26 114.38 3.43 24.962 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6 71 6.53 29.96 224.51 6.74 48.98 1.39 6.37 47.72 1.43 10.41VESSELS>600hp diesel(tugs) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC. BPD SCF/HR COUNTTANK- 0 0 0 0.00 0.00Flowback After OIL BURN 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002017 YEAR TOTAL62.34 285.97 2142.8464.29 467.53 72.23 331.34 2482.82 74.48 541.71EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngineLoad %EMISSIONS CALCULATIONS4THYEARFORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page6of11COMPANYAREABLOCK LEASEPLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum CorpAT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KV Bridget O'Farrell832-636-1694 0OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HRSCF/DBurnersMMBTU/HR SCF/HRSCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLING PRIME MOVER>600hp diesel 64,370 3109.071 50% 37308.85 24 248 45.37 208.14 1559.63 46.79 340.28 67.51 309.71 2320.72 69.62 506.34DrillshipPRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.081517161.96 6 106 10.44 47.87 358.71 10.76 78.26 3.33 15.26 114.38 3.43 24.962 trips/week VESSELS>600hp diesel(supply) 9266 447.547810741.15 671 6.53 29.96 224.51 6.74 48.98 1.39 6.37 47.72 1.43 10.41VESSELS>600hp diesel(tugs) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HRCOUNTTANK-0000.000.00Flowback After OIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002018 YEAR TOTAL62.34 285.97 2142.84 64.29 467.53 72.23 331.34 2482.82 74.48 541.71EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngineLoad %EMISSIONS CALCULATIONSTH YEARFORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page7of11COMPANYAREABLOCK LEASEPLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum CorpAT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KV Bridget O'Farrell832-636-1694 0OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HRSCF/DBurnersMMBTU/HR SCF/HRSCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLING PRIME MOVER>600hp diesel 64,370 3109.071 50% 37308.85 24 16 45.37 208.14 1559.63 46.79 340.28 4.36 19.98 149.72 4.49 32.67DrillshipPRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.081517161.96 67 10.44 47.87 358.71 10.76 78.26 0.21 0.98 7.38 0.22 1.612 trips/week VESSELS>600hp diesel(supply) 9266 447.547810741.15 65 6.53 29.96 224.51 6.74 48.98 0.09 0.41 3.08 0.09 0.67VESSELS>600hp diesel(tugs) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HRCOUNTTANK-0000.000.00Flowback After OIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002019 YEAR TOTAL62.34 285.97 2142.84 64.29 467.53 4.66 21.38 160.18 4.81 34.95EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngineLoad %EMISSIONS CALCULATIONS6TH YEARFORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page8of11COMPANYAREABLOCKLEASEPLATFORM WELLCONTACT PHONE REMARKSAnadarko Petroleum Corporation AT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KV Bridget O'Farrell832-636-1694 0OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HRSCF/DBurnersMMBTU/HR SCF/HRSCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOxVOCCODRILLINGPRIME MOVER>600hp diesel64,370 3109.071 50% 37308.85 24 190 45.37 208.14 1559.63 46.79 340.28 51.72 237.28 1777.97 53.34 387.92DrillshipPRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel00 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/weekVESSELS>600hp diesel(crew)14805 715.081517161.96 6 81 10.44 47.87 358.71 10.76 78.26 2.55 11.69 87.63 2.63 19.122 trips/weekVESSELS>600hp diesel(supply)9266 447.547810741.15 6 54 6.53 29.96 224.51 6.74 48.98 1.06 4.88 36.56 1.10 7.98VESSELS>600hp diesel(tugs)000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITYDERRICK BARGE diesel000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATIONMATERIAL TUG diesel000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew)000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply)000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HRCOUNTTANK-00 00.000.00Flowback AfterOIL BURN00 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00CompletionGAS FLARE00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002020YEAR TOTAL62.34 285.97 2142.84 64.29 467.53 55.34 253.85 1902.16 57.06 415.02EXEMPTIONCALCULATIONDISTANCE FROM LAND IN MILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngine Load%FORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page9of 11EMISSIONS CALCULATIONS9TH YEARCOMPANYAREABLOCKLEASEPLATFORM WELLCONTACT PHONE REMARKSAnadarko Petroleum Corporation AT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK Bridget O'Farrell832-636-16940OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HRSCF/DBurnersMMBTU/HR SCF/HRSCF/D HR/D DAYS PM SOx NOxVOC COPM SOx NOx VOC CODRILLINGPRIME MOVER>600hp diesel 64,370 3109.071 50% 37308.85 24 190 45.37 208.14 1559.63 46.79 340.28 51.72 237.28 1777.97 53.34 387.92DrillshipPRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diese 000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.000.00 0.00 0.003 trips/weekVESSELS>600hp diesel(crew) 14805 715.081517161.96 6 81 10.44 47.87 358.71 10.76 78.26 2.55 11.69 87.63 2.63 19.122 trips/weekVESSELS>600hp diesel(supply) 9266 447.547810741.15 6 54 6.53 29.96 224.51 6.74 48.98 1.06 4.88 36.56 1.10 7.98VESSELS>600hp diesel(tugs) 000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITYDERRICK BARGE diesel000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATIONMATERIAL TUG diesel000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HRCOUNTTANK-00 00.000.00Flowback AfterOIL BURN00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00CompletionGAS FLARE00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002021 YEAR TOTAL62.34 285.97 2142.84 64.29 467.53 55.34 253.85 1902.16 57.06 415.02EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngineLoad %EMISSIONS CALCULATIONS10TH YEARFORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page10of11SUMMARYCOMPANYAREABLOCKLEASEPLATFORM WELLAnadarko Petroleum Corporation AT18/19G33863/G32556AT 18:CC, DD, GG,GV, QQ/AT 19:EE,KK, KVEmittedSubstanceYearPMSOxNOxVOCCO201455.34253.85 1902.16 57.06415.02201555.34253.85 1902.16 57.06415.02201672.23331.34 2482.82 74.48541.71201772.23331.34 2482.82 74.48541.71201872.23331.34 2482.82 74.48541.7120194.6621.38160.184.8134.95202055.34253.85 1902.16 57.06415.02202155.34253.85 1902.16 57.06415.02Allowable2364.30 2364.30 2364.30 2364.30 58297.66FORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page 11of 11ACOMPANYAnadarko Petroleum CorporationAREAATBLOCK18/19LEASEOCS-G 33863, G-32556PLATFORMWELLAT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KVCOMPANY CONTACTBridget O'FarrellTELEPHONE NO.832-636-1694REMARKSDrill and complete 9 wellsDP Semi-SubmersibleFORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page 1 of11EXPLORATION PLAN (EP)AIR QUALITY SCREENING CHECKLISTOMB Control No. 1010-0151OMB Approval Expires: 12/31/2014EMISSIONS FACTORSFuel Usage Conversion FactorsNatural Gas Turbines Natural Gas Engines Diesel Recip. Engine REF. DATESCF/hp-hr 9.524 SCF/hp-hr 7.143 GAL/hp-hr 0.0483AP42 3.2-1 4/76 & 8/84Equipment/Emission Factorsunits PM SOx NOx VOC CO REF. DATENG Turbines gms/hp-hr 0.00247 1.3 0.01 0.83AP42 3.2-1& 3.1-1 10/96NG 2-cycle leangms/hp-hr0.00185 10.9 0.43 1.5AP42 3.2-1 10/96NG 4-cycle leangms/hp-hr0.00185 11.8 0.72 1.6AP42 3.2-1 10/96NG 4-cycle richgms/hp-hr0.00185 10 0.14 8.6AP42 3.2-1 10/96Diesel Recip. < 600 hp. gms/hp-hr 1 1.468 14 1.12 3.03AP42 3.3-1 10/96Diesel Recip. > 600 hp.gms/hp-hr 0.32 1.468 11 0.33 2.4AP42 3.4-1 10/96Diesel Boilerlbs/bbl 0.084 2.42 0.84 0.008 0.21AP42 1.3-12,14 9/98NG Heaters/Boilers/Burnerslbs/mmscf 7.6 0.593 100 5.5 84P42 1.4-1, 14-2, & 147/98NG Flareslbs/mmscf0.593 71.4 60.3 388.5AP42 11.5-1 9/91Liquid Flaringlbs/bbl 0.42 6.83 2 0.01 0.21AP42 1.3-1 & 1.3-3 9/98Tank Vaporslbs/bbl0.03E&P Forum 1/93Fugitiveslbs/hr/comp.0.0005API Study 12/93Glycol Dehydrator Ventlbs/mmscf6.6La. DEQ1991Gas Ventinglbs/scf0.0034Sulfur Content SourceValue UnitsFuel Gas3.33 ppmDiesel Fuel0.4 % weightProduced Gas( Flares)3.33 ppmProduced Oil (Liquid Flaring)1 % weightFORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page2of11COMPANYAREABLOCK LEASEPLATFORM WELLCONTACT PHONE REMARKSAnadarko Petroleum Corporation AT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KV Bridget O'Farrell832-636-1694 0OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HRSCF/DBurnersMMBTU/HR SCF/HRSCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLINGPRIME MOVER>600hp diesel61,200 2955.96 50% 35471.52 24 190 43.14 197.89 1482.82 44.48 323.52 49.18 225.59 1690.41 50.71 368.82DP Semi-Submersible PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel00 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/weekVESSELS>600hp diesel(crew)14805 715.081517161.96 6 81 10.44 47.87 358.71 10.76 78.26 2.55 11.69 87.63 2.63 19.122 trips/weekVESSELS>600hp diesel(supply)9266 447.547810741.15 6 54 6.53 29.96 224.51 6.74 48.98 1.06 4.88 36.56 1.10 7.98VESSELS>600hp diesel(tugs)000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITYDERRICK BARGE diesel000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATIONMATERIAL TUG diesel000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew)000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply)000.00 0 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HRCOUNTTANK-00 00.000.00Flowback AfterOIL BURN00 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00CompletionGAS FLARE00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002014 YEAR TOTAL60.10 275.72 2066.04 61.98 450.77 52.79 242.17 1814.60 54.44 395.91EXEMPTIONCALCULATIONDISTANCE FROM LAND IN MILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngineLoad %FORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page3of11EMISSIONS CALCULATIONS 1ST YEAREMISSIONS CALCULATIONS 2ND YEARCOMPANYAREABLOCK LEASEPLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum Corporation AT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KV Bridget O'Farrell832-636-1694 0OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUELRUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HRSCF/DBurnersMMBTU/HR SCF/HRSCF/D HR/D DAYS PM SOx NOxVOC CO PM SOx NOxVOC CODRILLING PRIME MOVER>600hp diesel 61,200 2955.96 50% 35471.52 24 190 43.14 197.89 1482.82 44.48 323.52 49.18 225.59 1690.41 50.71 368.82DP Semi-Submersible PRIME MOVER>600hp diesel 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6 81 10.44 47.87 358.71 10.76 78.26 2.55 11.69 87.63 2.63 19.122 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6 54 6.53 29.96 224.51 6.74 48.98 1.06 4.88 36.56 1.10 7.98VESSELS>600hp diesel(tugs) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC. BPD SCF/HR COUNTTANK- 0 0 0 0.00 0.00Flowback After OIL BURN 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002015 YEAR TOTAL60.10 275.72 2066.04 61.98 450.77 52.79 242.17 1814.60 54.44 395.91EXEMPTIONCALCULATIONDISTANCE FROM LAND IN MILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngineLoad %FORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page4of11COMPANYAREABLOCK LEASEPLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum Corporation AT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KV Bridget O'Farrell832-636-1694 0OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HRSCF/DBurnersMMBTU/HR SCF/HRSCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLINGPRIME MOVER>600hp diesel 61,200 2955.96 50% 35471.52 24 248 43.14 197.89 1482.82 44.48 323.52 64.19 294.46 2206.44 66.19 481.40DP Semi-Submersible PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/weekVESSELS>600hp diesel(crew) 14805 715.081517161.96 6 106 10.44 47.87 358.71 10.76 78.26 3.33 15.26 114.38 3.43 24.962 trips/weekVESSELS>600hp diesel(supply) 9266 447.547810741.15 671 6.53 29.96 224.51 6.74 48.98 1.39 6.37 47.72 1.43 10.41VESSELS>600hp diesel(tugs)000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITYDERRICK BARGE diesel000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATIONMATERIAL TUG diesel000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew)000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HRCOUNTTANK-0000.000.00Flowback AfterOIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00CompletionGAS FLARE00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002016 YEAR TOTAL60.10 275.72 2066.04 61.98 450.77 68.90 316.09 2368.54 71.06 516.77EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngineLoad %FORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page5of11EMISSIONS CALCULATIONS3RDYEARCOMPANYAREABLOCK LEASEPLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum Corporation AT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KV Bridget O'Farrell832-636-1694 0OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HRSCF/DBurnersMMBTU/HR SCF/HRSCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLINGPRIME MOVER>600hp diesel 61,200 2955.96 50% 35471.52 24 248 43.14 197.89 1482.82 44.48 323.52 64.19 294.46 2206.44 66.19 481.40DP Semi-Submersible PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/weekVESSELS>600hp diesel(crew) 14805 715.081517161.96 6 106 10.44 47.87 358.71 10.76 78.26 3.33 15.26 114.38 3.43 24.962 trips/weekVESSELS>600hp diesel(supply) 9266 447.547810741.15 671 6.53 29.96 224.51 6.74 48.98 1.39 6.37 47.72 1.43 10.41VESSELS>600hp diesel(tugs)000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITYDERRICK BARGE diesel000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATIONMATERIAL TUG diesel000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew)000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HRCOUNTTANK-0000.000.00Flowback AfterOIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00CompletionGAS FLARE00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002017 YEAR TOTAL60.10 275.72 2066.04 61.98 450.77 68.90 316.09 2368.54 71.06 516.77EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngineLoad %EMISSIONS CALCULATIONS4THYEARFORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page6of11COMPANYAREABLOCK LEASEPLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum Corporation AT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KV Bridget O'Farrell832-636-1694 0OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HRSCF/DBurnersMMBTU/HR SCF/HRSCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLINGPRIME MOVER>600hp diesel 61,200 2955.96 50% 35471.52 24 248 43.14 197.89 1482.82 44.48 323.52 64.19 294.46 2206.44 66.19 481.40DP Semi-Submersible PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/weekVESSELS>600hp diesel(crew) 14805 715.081517161.96 6 106 10.44 47.87 358.71 10.76 78.26 3.33 15.26 114.38 3.43 24.962 trips/weekVESSELS>600hp diesel(supply) 9266 447.547810741.15 671 6.53 29.96 224.51 6.74 48.98 1.39 6.37 47.72 1.43 10.41VESSELS>600hp diesel(tugs) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITYDERRICK BARGE diesel000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATIONMATERIAL TUG diesel000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HRCOUNTTANK-0000.000.00Flowback AfterOIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00CompletionGAS FLARE00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002018 YEAR TOTAL60.10 275.72 2066.04 61.98 450.77 68.90 316.09 2368.54 71.06 516.77EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngineLoad %EMISSIONS CALCULATIONSTH YEARFORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page7of11COMPANYAREABLOCK LEASEPLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum Corporation AT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KV Bridget O'Farrell832-636-1694 0OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HRSCF/DBurnersMMBTU/HR SCF/HRSCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLINGPRIME MOVER>600hp diesel 61,200 2955.96 50% 35471.52 24 16 43.14 197.89 1482.82 44.48 323.52 4.14 19.00 142.35 4.27 31.06DP Semi-Submersible PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/weekVESSELS>600hp diesel(crew) 14805 715.081517161.96 67 10.44 47.87 358.71 10.76 78.26 0.21 0.98 7.38 0.22 1.612 trips/weekVESSELS>600hp diesel(supply) 9266 447.547810741.15 65 6.53 29.96 224.51 6.74 48.98 0.09 0.41 3.08 0.09 0.67VESSELS>600hp diesel(tugs) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITYDERRICK BARGE diesel000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATIONMATERIAL TUG diesel000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 000.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HRCOUNTTANK-0000.000.00Flowback AfterOIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00CompletionGAS FLARE00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002019 YEAR TOTAL60.10 275.72 2066.04 61.98 450.77 4.45 20.39 152.81 4.58 33.34EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngineLoad %EMISSIONS CALCULATIONS6TH YEARFORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page8of11COMPANYAREABLOCKLEASEPLATFORM WELLCONTACT PHONE REMARKSAnadarko Petroleum Corporation AT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KK, KV Bridget O'Farrell832-636-1694 0OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUELRUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas Engines HP SCF/HR SCF/DBurners MMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLING PRIME MOVER>600hp diesel 61,200 2955.96 50% 35471.52 24 190 43.14 197.89 1482.82 44.48 323.52 49.18 225.59 1690.41 50.71 368.82DP Semi-Submersible PRIME MOVER>600hp diesel 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6 81 10.44 47.87 358.71 10.76 78.26 2.55 11.69 87.63 2.63 19.122 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6 54 6.53 29.96 224.51 6.74 48.98 1.06 4.88 36.56 1.10 7.98VESSELS>600hp diesel(tugs) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC. BPD SCF/HR COUNTTANK- 0 0 0 0.00 0.00Flowback After OIL BURN 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002020YEAR TOTAL60.10 275.72 2066.04 61.98 450.77 52.79 242.17 1814.60 54.44 395.91EXEMPTIONCALCULATIONDISTANCE FROM LAND IN MILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngine Load%FORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page9of 11EMISSIONS CALCULATIONS9TH YEARCOMPANYAREABLOCKLEASEPLATFORM WELLCONTACT PHONE REMARKSAnadarko Petroleum Corporation AT18/19 G33863/G32556AT 18:CC, DD, GG, GV, QQ/AT 19:EE, KKBridget O'Farrell832-636-1694 0OPERATIONSEQUIPMENTRATING MAX. FUELACT. FUELRUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HRSCF/DBurnersMMBTU/HR SCF/HRSCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLINGPRIME MOVER>600hp diesel 61,200 2955.96 50% 35471.52 24 190 43.14 197.89 1482.82 44.48 323.52 49.18 225.59 1690.41 50.71 368.82DP Semi-Submersible PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diese000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6 81 10.44 47.87 358.71 10.76 78.26 2.55 11.69 87.63 2.63 19.122 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6 54 6.53 29.96 224.51 6.74 48.98 1.06 4.88 36.56 1.10 7.98VESSELS>600hp diesel(tugs) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC. BPD SCF/HR COUNTTANK- 0 0 0 0.00 0.00Flowback After OIL BURN 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002021 YEAR TOTAL60.10 275.72 2066.04 61.98 450.77 52.79 242.17 1814.60 54.44 395.91EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES2364.30 2364.30 2364.30 2364.30 58297.6671.0AverageEngineLoad %EMISSIONS CALCULATIONS10TH YEARFORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page10of11SUMMARYCOMPANYAREABLOCKLEASEPLATFORM WELLAnadarko Petroleum Corporation AT18/19G33863/G32556AT 18:CC, DD, GG,GV, QQ/AT 19:EE,KK, KVEmittedSubstanceYearPMSOxNOxVOCCO201452.79242.17 1814.60 54.44395.91201552.79242.17 1814.60 54.44395.91201668.90316.09 2368.54 71.06516.77201768.90316.09 2368.54 71.06516.77201868.90316.09 2368.54 71.06516.7720194.4520.39152.814.5833.34202052.79242.17 1814.60 54.44395.91202152.79242.17 1814.60 54.44395.91Allowable2364.30 2364.30 2364.30 2364.30 58297.66FORM BOEM-0138(December 2011 - Supersedes all previous versions of this form which may not be used).Page 11of 11

### SECTION H OIL SPILL INFORMATION

(a) Oil Spill Response Planning

(i) OSRP Information

All the proposed activities and facilities in this EP are covered by the Regional Oil Spill Response Plan (OSRP) last approved on September 25, 2013 for Anadarko Petroleum Corporation and its subsidiaries, Anadarko US Offshore Corporation and Anadarko E&P Company L.P. (Company Numbers 00981, 02219 and 00148, respectively) in accordance with
30 CFR Part 254.

(ii) Spill Response Sites

Primary Response Equipment Location(s) Preplanned Staging Location(s) 

### Galveston, Texas Harvey, Louisiana Houma, Louisiana Lake Charles, Louisiana Leeville, Louisiana Venice, Louisiana Galveston, Texas Harvey, Louisiana Fourchon, Louisiana Cameron, Louisiana Leeville, Louisiana Venice, Louisiana

(iii) OSRO Information

Anadarko maintains a contract w ith Clean Gulf Associates (CGA) for spill response equipment. Various equipment locations are staged throughout the Gulf of Mexico. CGA equipment can be referenced on their website: http://www.cleangul fassoc.com/. Personnel would be obtained from the Marine Spill Response Corporation’s (MSRC) STARS network, including a supervisor to operate the equipment.

In addition Anadarko has a contract with the Marine Spill Response Co rporation (MSRC) for spill response equipment. MSRC stages equipm ent throughout the Gulf of Mexico and has recently completed a large expansion of its resources, with particular focus on deepwater. The expansion is known as “Deep Blue”. 

### MSRC capabilities and a complete equipment listing are available online at: http:// www.msrc.org/.

Anadarko is a member of the Marine Well Containment Company (MWCC), which provides access to containment response capabilities and incl udes subsea dispersant injection equipment.

### (iv) Worst-Case Scenario Determination

Category Regional OSRP EP EP
Type of Activity Explorat ory Exploratory Exploratory
Facility Location (area/block) GC 683 AT 18 AT 19
Facility Designation* Location G Location GV Location KV

Distance to Neares t Shoreline 120 Miles 71 miles 71 miles
Storage Tanks (t otal) N/A N/A N/A

Flowlines (on f acility) N/A N/A N/A
Pipelines N/A N/A N/A
Uncontrolled Blowout 410,000 bopd* 63,744 bopd 250,188 bopd
Type of Oil(s) Crude Oil Crude Oil Crude Oil
API Gravity 28.9 o 21.9 o 28.7 o

* The volume recently denoted in the Regional OSRP (410,000 bo pd) is higher than the NTL 2010- N06 (403,608 bopd) calculations associated with the GC 683, Location G and GG Supplemental EP. (P lan Control No: S-7623). Anadarko elected to denote a higher v olume in the Regional OSRP for planning purposes to demonstrate equipment response capabilities per previous discussions with
Mr. Mike Tolbert.



### Anadarko has determined that the worst-case scenario from the ac tivities proposed in this Initial EP does not supersede the worst- case scenario for Gr een Canyon 683 as previ ously filed in the Regional OSRP.

Since Anadarko has the cap ability to respond to the worst-case spill s cenario included in our Regional OSRP, and since the worst-case scenario s determined for our EP does not replace the
worst-case scenario in our Regional OSRP last approved on September 25, 2013, I hereby certify that Anadarko has the capability to respond, to th e maximum extent practicable, to a worst-case discharge, or a substantial threat of such a discha rge, resulting from the ac tivities proposed in our
EP.

(b) Worst-Case Discharge Volume Assumptions

Worst-case discharge (WCD) calculations and assump tions within this section utilized guidelines and requirements pursuant with NTL 2010-N06. Di scussions regarding geologic information are considered proprietary and have been omitted from this public copy of the EP.

(c) Oil Spill Response Discussion

For the purpose of NEPA analys is, the largest spill volume or iginating from the proposed activity in Atwater Valley 19 w ould be an uncontrolled blowout during drilling operations at 250,188 barrels of crude oil with an API gravity of 28.7 o 

### . A discussion of the blowout scenario from this proposed activity is included within this Initial EP in accordance with NTL 2010-N06.

### Land Segment and Resource Identification Modeling

Trajectory of a spill and the probability of its impacting a land segment have been projected utilizing information in the Oil Spill Risk An alysis Model (OSRAM) for the Central Gulf of Mexico. Additional information may be referenced in the “Oil-Spill Risk Analysis: Contingency Planning Statistics for Gulf of Mexico OC S Activities” (OCS Report MMS 2004-026), using the average conditional probability for 3, 10, and 30 day impacts.

Atwater Valley 19 is located w ithin Launch Area 60. A ccording to the OSRA M, the trajectory indicates a 4% probability of potential impact to the shoreline in Plaquemines Parish, Louisiana.
The results are shown in Table H-2. Plaquemines Parish is identified as the most probable potential impacted parish or county within the Gulf of Mexico for this operation.

Response

Anadarko will make every effort to respond to the worst-case discharge as effectively as possible. Response equipment available to respond to the worst-case discharge and the estimated time of a spill response from oil spill detecti on to equipment deployment on-site is included in Table H-3. The table estimates individual times needed for procurement, load out, travel time to the site and deployment. In the event of an actual incident equipment and times can vary.

For the purpose of response scenario discussion , an uncontrolled blowout would be considered the largest potential spill volume at 250,188 barrel s of crude oil. An ADIOS weathering model was run based on a similar type of oil expected to be produced fr om this well. Based on this information, approximately 12% (30,023 bbl s) of the initial volume would be evaporated/dispersed within 24 hours.

If approved and appropriate, 4 sorties (8,000 ga llons) from the Basler ai rcraft and 8 sorties (9,600 gallons) from two DC-3 aircrafts could disperse approximately 7,540 barrels of oil.

If the conditions are appropriate, and the necessary approvals and permits have been obtained, in-situ burning may be utilized. Based on in -situ burn operations du ring Deepwater Horizon, approximately 5% (11,008 bbls) of the wo rst case discharge volume after natural evaporation/dispersion after 24 hour s could potentially be burned.

Although unlikely in a spill lastin g 30 days, potential shoreline im pact in Plaquemines Parish, Louisiana could occur depending on environmenta l conditions (w ind, currents and temperature) at the time of an incident. Nearshore response may include the use of shoreline boom on beach areas, or protection/sorbent boom on vegetated ar eas. Surveillance and real time trajectories would aide in determining the most appropr iate strategies to respond to a spill.

Table H.3 provides an example of offshore and n earshore equipment, response times, and personnel to respond to a spill of 220,165 bbls, which is the estima ted amount that would remain considering natural evaporation/ dispersion at 24 hours. This amount could be further reduced through the application of aerial and subsea dispersants, provi ded such applications were approved.

### Anadarko’s contingency plan for de aling with this worst-case di scharge would be to activate its Spill Management Team and equipment resour ces as described in it s Gulf of Mexico Regional Oil Spill Response Plan (OSRP) and provi de continuous support for the duration of the event. Response resources are activated and s upplemented according to need. These resources would remain engaged in the response until the inci dent is deemed complete or until released by
Unified Command.

Anadarko is a member of the Marine Well Containment Company (MWCC), which provides access to containment response capabilities and incl udes subsea dispersant injection equipment.

In the event of a blowout, Anadarko may:

1. Evacuate personnel, if necessary. Deploy emer gency responders in an effort to preserve human life, if necessary.

2. Assess the damage and attempt to stop the flow at the source, if safe to do so, to reduce the amount of oil discharged.

3. Notify agencies.

4. Assess the amount of oil that has been sp illed and calculate add itional potential of oil flow. A continuous aerial surveillance program would be used to assess the growth of the
slick and the volume of oil on the water. Ob servations of the si ze of the slick on the water, combined with observations at the s ource, would be used to provide a constant update. Additional potential to release fuel from the remaining tanks onboard the appropriate DP drillship or DP semi-submer sible drilling rig would be determined by marine surveyors. Operations and Unifie d Command would continue to assess the adequacy of response equipment capacities based on this continually updated mass
balance.

5. Convene the Spill Management Team (SMT). Organize Unified Command and establish objectives and priorities.

6. Monitor the oil spill with aerial surveillance and obtain tr ajectories. If oil is seaward bound, going away from land, discuss additiona l strategies with Unified Command.

7. If oil is moving in the direction of a shoreline and weather co nditions are favorable, request approval to u tilize dispersants.

a. Prior to commencing application operati ons, conduct an on-site survey in consultation with natural resource specialists to determ ine if any threatened or endangered species are present in the projected application ar ea or otherwise at risk from dispersant application.

### b. Upon approval, mobilize one Basler aircra ft and two DC-3 aircrafts from Houma if needed, with surveillance aircraft and spo tter. Rotate aircraft, spraying the leading edge of the spill and working back to the source. Monitor/sample for effectiveness (USCG SMART Team). Truck additional disp ersants from CGA or MSRC stockpile, if necessary.

c. Dispersants are most effective when app lied as soon after discha rge as possible, since weathering of the oil decreas es dispersant effectiveness. The estimated window of opportunity for most effectiv e use of dispersants is w ithin 48-72 hours post-release. The oil may still be dispersible after 72 hours on the water surface, but the effectiveness of dispersant use would likely be diminished after th e oil has been on the water for more than three days. Ultimat ely, the USCG SMART monitoring protocol will be used to determine whether or not dispersant operations are effective.

d. Once the CGA HOSS barge is on locati on and in the skimming mode, dispersants would only be used if required and approved.

8. Deploy offshore mechanical oil containment and recovery equipment. Attempt to recover
as much oil at sea as possible, utilizing:

a. The CGA HOSS barge, will be positioned in a stationary mode, will be situated downwind and down-current from location fo r long-duration, high-volume skimming. Based on average travel times, the HO SS barge could be on location within approximately 51 hours of the release. The de-rated skimming capacity of the HOSS barge is 43,000 bbls per day. However, only the oil encountered by a skimmer can be
recovered. In order to maximize oil encount er rate, boom will be deployed in a V-configuration in front of the HOSS barge to funnel oil to the skimmers. If necessary, temporary barges can be ac tivated to support continuous skimming operations. (These barges arrive on-site at approximately the same time as the HOSS barge.) For an on-going release, multiple barges are deployed to provide for continuous off-loading of skimmer storage vess els and shuttling of recovered oil to an onshore waste handling facility. Sufficient barges are available to provide enough temporary storage for continuous recovery operations.

b. CGA’s Fast Response Units (FRU) coul d arrive on-scene between approximately
13.75-28.5 hours of the initial release. Thes e skimmers operate downstream of the HOSS barge and are used to recover pockets and streamers of oil that may move past the large stationary skimme r. FRUs have approximat ely 200 barrels of on-board storage. Approval will be requested to decan t water after gravity separation, through a hose forward of the skimmer, to optimize temporary storage capacity. Auto boom will
be utilized to concentrate oil so th at it is thick enough to be skimmed.

### 9. Dispersants, Fast Response Units (FRU), Oil Spill Response Vessels (OSRV or R/V) would typically work daylight hours onl y. The HOSS barge can operate continuously, including night operations. Available technology will be considered such as remote sensing devices that will enable 24 hour surveillance, trajecto ries, and planning. All response vessels are designed to be able to remain offshore continuously throughout the response. Even if sea conditions prohibit effective skimming, these resources would remain offshore until skimming operations could be commenced again. Safety would remain the first priority.

10. Prepare site-specific Waste Management Plan, Site Safety Plan, Decontamination Plans,
Communications and Medical Plans.

11. If oil becomes a threat to any shoreline, da ta from the aerial survei llance, weather reports, and trajectories would be used to direct onshore teams to deploy protection/containment boom with reference to Area Contingency Pl ans and in coordination with State and
Federal On-Scene Coordinators.

a. Implement pre-designated strategies.

b. Identify resources at risk in spill vicinity.

c. Develop/implement appropriate protection tactics.

12. Establish site-specific Wildlife Rescue and Rehabilitation Plan.

The following types of additional support may be required for a blowout lasting 120 days.

 Additional Oil Spill Remova l Organization (OSRO) personnel to relieve equipment operators

 Vessels for supporting offshore operations

 Field safety personnel

 Continued surveillance and m onitoring of oil movement

 Helicopter, video cameras

 Infra red (night time spill track ing) capabilities, X-band radar

 Barge to transport recovered oil from offshore skimming system, and temporary storage barges to onshore disposal sites th at are identified in Area Contingency Plans (ACP)

 Logistics needed to support equipment:

- Staging areas

- Parts, trailers, and mechanics to maintain skimmers and boom

- Fueling facilities

- Decontamination stations

- Dispersant stockpile tran sported from Houston to Houma or other potential command post locations

- Communications equipm ent and technicians

###  Logistics needed to s upport responder personnel

- Medical aid stations

- 

### Safety personnel

- Food

- Berthing

- Additional clothing/safety supplies

- Decontamination stations

Anadarko has the capability to respond and cont ain, to the maximum extent practicable as defined in 30 CFR 254.6 and 30 CFR 250.26(d)(1), to the estimated wors t case discharge (WCD) associated with the proposed activity within 30 days. Deployment time for surface containment equipment is subject to availability and loca tion, weather conditions, potential security zones around the spill site, and site/well specific assessment data. Personnel safety is always first and
foremost. Refer to further detail s on equipment and timing provided in Section H–Oil Spill Information and Table H-3 of the EP.

The potential WCD will be further evaluated du ring the Application for Permit to Drill (APD) process, including the Well Containment Screen ing Tool (WCST) and associated subsea containment plan for enhanced planning purposes.

There will be no new or unusual technology deployed that has not been previously deployed for Gulf of Mexico oil spill prev ention, control, and/or cleanup.Table H-1

Worst Case Discharge Calculation (Based on an Uncontrolled Blowout)

Calculations for an Uncontrolled Blowout: Block 19

i. Type of Oil (crude, condensate, diesel) Crude Oil

ii. API Gravity 28.7  ̊

iii. EP Location Used for NTL 2010-N06 WCD for AT 19 Location KV

iv. Largest Anticipated WCD Rate during blowout 250,188 bbls

v. WCD Total for Drilling Operations for AT 19 (> 10 miles from shore): 250,188 bblsTable H-2

Trajectory by Land Segment

Following are the average conditional probabilities (expresse d as percent chance) that an oil spill starting at a particular launch area will contact a la nd segment as included in the Oil Spill Risk Analysis Model (OSRAM) for the Central Gulf of Mexico. This information can be found on the BOEM website using 3/10/30 day potential impact, as applicable. The results are listed below.

Area/Block/

Location OCS-G Launch
Area Land Segment and/or Resource Conditional Probability (%)

3 days 10 days 30 days

Atwater Valley 19,
Location KV

Drilling

(71 miles from shore) G 32556 Launch
Area 60

Central Planning

Area Galveston County, TX Jefferson County, TX Cameron Parish, LA Vermilion Parish, LA Terrebonne Parish, LA Lafourche Parish, LA Plaquemines Parish, LA --

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4Table H-3WCD Scenario Drilling Activities – Based on anuncontrolled blowout (71 miles from shore)Atwater Valley 19, Location KV250,188 bbls of crude (initial volume)220,165 bbls (after evaporation/dispersion)API Gravity 28.7oOffshore Equipment from Spill Detectionto Equipment Deployment ResponseTime: Atwater Valley 19, Location KVOffshore EquipmentOwner/Location Initial StagingHours toStagingAreaTime toProcure(1)TimetoLoad Out(2)TravelTime(Staging/Spill)(3)TimetoDeploy(4)TotalEstimatedResponseTimeTypeDeratedCapacity(bbls)Storage(bbls)No. ofUnits/PersonsBasler Spray AircraftDC 3 Spray AircraftAero Commander--------122ASI/Houma Houma001111.503.5HOSS BargeOperatorsTugs43,000 4,000 183CGA/HarveySTARSVOOHarvey1244046151Texas ResponderTransrec 350 + OSRV4,620'44"Sea Sentry Boom3,300'67"LAMOR10,567 4,000 1114 crewMSRC/Galveston Galveston0222209.25112.25Gulf Coast ResponderTransrec 350 + OSRV5,280'44"Sea Sentry Boom2,640'67"LAMOR10,567 4,000 1114 crewMSRC/Lake Charles Lake Charles02222014.25117.25Deep Blue ResponderLFF 100 Brush + OSRV6,600'44"Sea Sentry Boom660'67"LAMOR18,086 4,000 1114 crewMSRC/Fourchon Fourchon02222019.2122.2FRUOperatorsUtility Boat4,251 200 161CGA/InglesideSTARSVOOIngleside0221212.75116.75FRUOperatorsUtility Boat4,251 200 161CGA/GalvestonSTARSVOOGalveston022129.75113.75FRUOperatorsUtility Boat4,251 200 161CGA/Lake CharlesSTARSVOOCameron.5221215.75119.75FRUOperatorsUtility Boat4,251 200 161CGA/Morgan CitySTARSVOOMorgan City.5221217121FRUOperatorsUtility Boat8,502 400 2122CGA/LeevilleSTARSVOOLeeville0221220124FRUOperatorsUtility Boat8,502 400 2122CGA/VeniceSTARSVOOVenice.5221224.5128.5Spill Team Area Responders (STARS) called out byMarine Spill Response Corporation (MSRC)Vessel of Opportunity=VOOEMS=Enterprise Marine ServicesOffshore Equipment, cont.Owner/Location Initial StagingHours toStagingAreaTime toProcure(1)TimetoLoad Out(2)TravelTime(Staging/Spill)(3)TimetoDeploy(4)TotalEstimatedResponseTimeTypeDeratedCapacity(bbls)Storage(bbls)No. ofUnits/PersonsFRUOperatorsUtility Boat4,251 100 161CGA/HarveySTARSVOOHarvey.5221222126Koseq Skimming Arms,1 setVessel w/ storage/hull17,83010,00021CGA/GalvestonVOOGalveston021129.75123.75MSRC 570 Offshore BargeTugs2 Crucial Disk 88/302,640'44"Sea Sentry II Boom22,244 56,900 1316 crewMSRC/GalvestonVOOGalveston 02222017.25120.25CTCo2603OperatorsTug-- 25,000 161EMS/AmeliaSTARSVOOAmelia0244037142CTCo2604OperatorsTug-- 20,000 161EMS/AmeliaSTARSVOOAmelia0244037142CTCo2605OperatorsTug-- 20,000 161EMS/AmeliaSTARSVOOAmelia0244037142CTCo 5001OperatorsTug-- 45,000 161EMS/AmeliaSTARSVOOAmelia024403714210,000' 42" Auto BoomVOO-- -- 2010 crewCGA/HarveySTARSHarvey.5212221265,000' 42" Auto BoomVOO-- -- 2010 crewCGA/Lake CharlesSTARSCameron.521215.75119.755,000' 42" Auto BoomVOO-- -- 2010 crewCGA/GalvestonSTARSGalveston02129.75113.752,500' 42" Auto BoomVOO-- -- 126 crewCGA/InglesideSTARSIngleside021212.75116.752,500' 42" Auto BoomVOO-- -- 126 crewCGA/PascagoulaSTARSPascagoula021227.75131.7522,400' 42" BoomVOO-- -- 8025 crewAMPOL/New Iberia New Iberia021216.5120.54,800' 42" BoomVOO-- -- 189 crewAMPOL/Harvey Harvey021222126Spotter HeloSurveillance HeloHand Held Radios------------1130PHI/GalvestonPHI/GalvestonSTARSSpill SiteSpill SiteGalveston111.5111.5------1.51.53------2.52.54.5Total 160,553 194,600Nearshore Equipment from Spill Detection to Equipment Deployment Response Time: Atwater Valley 19, Location KVNearshore Equipment*Owner/Location Initial StagingHours toStagingAreaTime toProcure(1)TimetoLoad Out(2)TravelTime(Staging/Spill)(3)TimetoDeploy(4)TotalEstimatedResponseTimeTypeDeratedCapacity(bbls)Storage(bbls)No. ofUnits/PersonsBasler Spray AircraftDC 3 Spray AircraftAero Commander----122ASI/Houma Houma001111.503.5Trinity SWSOperators21,500 249 14CGA/GalvestonSTARSGalveston02129.25113.25SWS EgmopolOperators3,000 100 13CGA/GalvestonSTARSGalveston02124.507.5SWS EgmopolOperators3,000 100 13CGA/Morgan CitySTARSMorgan City.52128011SWS MarcoOperators3,588 34 13CGA/VeniceSTARSVenice.52129.5012.5SWS MarcoOperators3,588 34 13CGA/LeevilleSTARSLeeville.52128.5011.5SWS MarcoOperators3,588 20 13CGA/Lake CharlesSTARSCameron.5212609R/V Grand BayOperators5,000 65 13CGA/VeniceSTARSVenice.522.54.7507.25R/V RW ArmstrongOperators5,000 65 13CGA/LeevilleSTARSLeeville.522.512.75015.25R/V Bastian BayOperators5,000 65 13CGA/Lake CharlesSTARSCameron.522.510.25012.75R/V Timbalier BayOperators5,000 65 13CGA/GalvestonSTARSGalveston022.5608.5CTCo 2606OperatorsTugs-- 20,000 161EMS/Amelia Amelia0244020125CTCo 2607OperatorsTugs-- 23,000 161EMS/Amelia Amelia0244020125CTCo 2608OperatorsTugs-- 23,000 161EMS/Amelia Amelia0244020125CTCo 2609OperatorsTugs-- 23,000 161EMS/Amelia Amelia02440201252,000' Beach Boom-- -- 6 CGA/Galveston Galveston0 121.5 26.51,000' Beach Boom-- -- 4 CGA/InglesideIngleside0 123282,000' Beach Boom-- -- 6 CGA/Pascagoula Pascagoula 0 12 4 2 9Nearshore Equipment, cont.Owner/Location Initial StagingHours toStagingAreaTime toProcure(1)TimetoLoad Out(2)TravelTime(Staging/Spill)(3)TimetoDeploy(4)TotalEstimatedResponseTimeTypeDeratedCapacity(bbls)Storage(bbls)No. ofUnits/Persons10,000' 18" BoomVOO-- -- 104 crewOil Mop/New Iberia New Iberia0211731210,000' 18" BoomVOO-- -- 104 crewOil Mop/Houston Houston12112.531310,000' 18" BoomVOO-- -- 104 crewOil Mop/Port Arthur Port Arthur02112.537.510,000' 18" BoomVOO-- -- 104 crewOil Mop/Houma Fourchon.5211631110,000' 18" BoomVOO-- -- 104 crewOil Mop/Port Allen Port Allen02116.25311.2520,000' 18" BoomVOO-- -- 208 crewOil Mop/Belle Chasse Venice.5211761515,000' 18" BoomVOO-- -- 146 crewOil Mop/Gretna Gretna02118414Wildlife Support Trailer-- -- 1/ 2 crew CGA/HarveyHarvey.5 12 1.5 3 7.5Bird Scare Cannons-- -- 2 CGA/VeniceVenice.5 122 27Bird Scare Cannons-- -- 1CGA/Galveston Galveston 0 1 2 1 2 6Bird Scare Cannons-- -- 1CGA/Ingleside Ingleside 0 1 2 2.5 2 7.5Bird Scare Cannons-- -- 2CGA/Harvey Harvey .5 1 2 1.5 2 6.5Bird Scare Cannons-- -- 2CGA/Lake Charles Cameron.5 12 3.5 2 8.5Bird Scare Cannons-- -- 2CGA/Pascagoula Pascagoula 0 1 2 4.5 2 9.5Spotter HeloSurveillance HeloHand Held Radios------------1130PHI/GalvestonPHI/GalvestonSTARSSpill SiteSpill SiteGalveston111.5111.5------1.51.53------2.52.54.5Total 58,264 89,797*Some equipment may be used offshoreup to approximately 25 miles from shoreH-3 (continued)

Operational Limitations of Response Equipment

 HOSS Barge–8 foot seas

 Fast Response Unit (FRU)–8 foot seas

 Oil Spill Response Vessel (OSRV and R/V)–4 foot seas

 Boom–3 foot seas, 20 knot winds

 Dispersants–winds more than 25 knots, visibility less than 3 nautical miles or ceiling less than 1,000 feet

### SECTION I Environmental Monitoring and Environmental Mitigation Measures

(a) Monitoring

If required, Anadarko will monito r loop currents per NTL 2009-G02.

Anadarko subscribes to Wilkins Weather Service which provides real-time weather conditions such as tropical depressions, storms and/or hurricanes entering the Gulf of
Mexico.

Additional measures to avoid, minimize, and mitigate environmental impacts is included
in Section N–Environmental Impact Analysis.

(b) Incidental Takes

Although marine mammals may be seen in th e area, Anadarko does not believe that its operations proposed under this EP will result in the harassment, capture, collection or killing of any mammals covered by th e Marine Mammal Protection Act.

Anadarko will operate in accordance with appl icable regulations in order to avoid or
minimize incidental takes of marine mammals and other species, including:

 Joint NTL 2012-G02 “Implementation of Seismic Survey Mitigation Measures and Protected Species Observer Program”

 BSEE NTL 2012-G01 “Marine Trash and De bris Awareness and Elimination”,
and

 Joint NTL 2012-G01 “Vessel Strike Avoi dance and Injured/Dead Protected Species Reporting”

### SECTION J LEASE STIPULATIONS INFORMATION

Stipulation No.8–Protected Species (Lease Sale 213-AT 18, Lease Sale 206-AT 19)

This stipulation is meant to reduce the potentia l taking of federally pr otected species. The stipulation requires seismic surveys employ m itigation measures including the use of a
500 meter “exclusion zone”.

Anadarko will operate in accordance with Joint NTL 2012-G01 to minimize the risk of vessel strikes to protected species and will report observations of injured or dead protected species. Anadarko wi ll operate in accordance with BSEE NTL 2012-G01 to prevent intentional and/ or accidental introduction of debris into the marine environment.

### SECTION K Support Vessels and Aircraft Information

(a) General

Type Max. Total Fuel Tank Storage Capacity Max. No. in Area at any Time Trip Frequency or Duration

Supply Vessel 336,227 gallons 1 2 trips/week Helicopter 735.3 gallons 1 10 trips/week
Crew Vessel 50,000 gallons 1 3 trips/week Tug Boats 218,300 gallons 1-2 Duration of operation Anchor Handling Vessel 450,698 gallons 1-2 Duration of operation

(b) Diesel Oil Supply Vessels

Fuel for the rig will be transpor ted via a supply vessel as follows:

a. Size of fuel supply vessel: 230 feet

b. Carrying capacity of fu el supply vessel: 336,227 gallons
c. Frequency that fuel supply vessel will visit the
facilities: once per week

d. Routes the fuel supply vessel will use to travel between the onshore support base and proposed facility: 6 miles from Port Fourchon to the mouth of Bayou Lafourche, then approximately 71 miles to AT 18/19.



### (c) Drilling Fluids Transportation

The following estimates were prepared utilizin g Anadarko’s experience with similar drilling operations. Estimated quantities are reflected in the table below.



### Type of Material Quantity Being Transported Transportation Method Water-based drilling fluid (NaCl saturated, seawater, freshwater, barite) for Pump and Dump 13 gallon tote tanks (liquids) 40-63 sacks on pallet (sack chemicals)* Supply boat

Synthetic-based drilling fluid (internal olefin, ester) 13 gallon tote tanks (liquids) 40-63 sacks on pallet (sack chemicals)** Supply boat

Oil-based drilling fluid N/A N/A

* Estimate 19,000 bbls/well ** Estimate 18,500 bbls/well

Note: The estimated amount of tote tanks and size of sacks may vary during drilling operations.

### (d) Solid and Liquid Wastes Transportation

Type of
Waste Composition Total Projected
Amount Rate Transport
Method Name/Location of Facility Disposal
Method

Syntheticbased drilling
fluid or muds Synthetic-based drilling muds 148,000 bbls
total 18,500 bbls/well Re-use and/or transport to shore in
DOT approved
containers. Waste - Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station. If recycled, returned to vendor (Bariod or MI). Re-used and/or recycled; if can’t
be reused and/or recycled the waste is disposed of at Newpark (injection disposal facility)
or USLL (landfarm).

Cuttings
wetted withsyntheticbased muds Cuttings coated with synthetic drilling muds, including
drilled out

cement 800-1,600
bbls total 100-200
bbls/well*

*An estimated 5-10% of cuttings may be transported to
shore Re-use and/or transport to shore in
DOT approved
containers. Waste - Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station. If recycled, returned to vendor (Bariod or MI). Re-used and/or recycled; if can’t
be reused and/or recycled the waste is disposed of at Newpark (injection disposal facility)
or USLL (landfarm).

Chemical product waste (well

treatment fluids) Ethylene glycol

Methanol 5,700 bbls
total

1,425 bbls
total 100 bbls/month/well

25
bbls/month/well Transport to shore in
DOT approved
containers for pick up Chemwaste in Sulphur,
LA and Veolia Port Arthur, TX or to Newpark,
Port Arthur as nonhazardous waste. Can be returned
to vendor and/or
used at another facility; MEG is
solidified and disposed of in a
landfill.
Methanol is
incinerated or
used for fuels blending. Completion
fluids Brine, spent acid, prop sand,
debris 24,000 bbls
total 3,000 bbls/well Transport to shore in
DOT approved
containers
and/or vessel
tanks for pick up. Sent to Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station Unused brine can
be returned to
vendor and/or
stored for use on another job.
Used brine and spent acid is
transferred to Newpark's Processing & Transfer facility for injection.
Workover
fluids Brine, spent acid, prop sand,
debris 24,000 bbls
total 3,000 bbls/well Transport to shore in
DOT approved containers,
and/or vessel
tanks for pick up. Sent to Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station Unused brine can
be returned to
vendor and/or
stored for use on another job.
Used brine and spent acid is
transferred to Newpark's Processing & Transfer facility for injection.Trash and
debris Refuse generated during operations 2,850 bbls
total 50
bbls/month/well Transport to shore in disposal bags by
vessel to
shorebase for pickup by municipal operations. Recycled Material in ARC, New Iberia, LA. Trash disposed of at
SWDI landfill. Recycled and/or disposed in
landfill.

Used oil Excess oil from engines 6,128 bbls
total 430 bbls/120 days/well Transport in
DOT approved
containers to
shore for pick up. American Recovery Fourchon, LA Recycled

*Total projected amount assumes 8 wells at 190 days/well **Rate per day is an estimated max.average and may vary during drilling operational phases. The total amount is rounded to nearest whole number.



### (e) Vicinity Map

A vicinity map is included in this section as Attachment K-1.A twater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Figure 1

. Location of Atwater Valley Blocks 18 and 19

.

### SECTION L ONSHORE SUPPORT FACILITIES INFORMATION

(a) General

Per NTL 2008-G04, extended by NTL 2014-G03, th e following tables reflect the onshore
facilities Anadarko will utiliz e to provide supplies and se rvice support for the activities proposed in this Exploration Plan.

Name Primary Location Existing/New/Modified Anadarko Service Base Fourchon, LA Existing

Name *Alternate Locations Existing/New/Modified Anadarko Service Base Galveston, TX Existing Anadarko Service Base Cameron, LA Existing Anadarko Service Base Lake Charles, LA Existing Anadarko Service Base Houma, LA Existing Anadarko Service Base Pascagoula, MS Existing

*In the unlikely event Anadarko’s primary service base cannot be utilized Anadarko will exercise the use of an alternate service base during drilling and/or completion operations.



### (b) Support Base Construction or Expansion

No onshore support base constr uction or expansion is pla nned for these activities. Therefore dredging or filling activities associated with construction or expansion of facilities will not be applicable.

(c) Support Base Construction or Expansion Timetable

Since no onshore support base construction or e xpansion is planned for these activities, a timetable for land acquisition and construc tion or expansion is not applicable.

(d) Waste Disposal

Disposed wastes describe those wastes generated by the proposed activity that are disposed of by means other than by release into the water of the GOM at the site where they are generated. These wastes can be di sposed of by offsite release, injection, encapsulation, or placement at either onshore or offshore permitted locations for the purposes of returning them back to the environment.Type of
Waste Composition Total Projected Amount Rate Transport
Method Name/Location of Facility Disposal
Method

Syntheticbased drilling
fluid or muds Synthetic-based drilling muds 148,000 bbls
total 18,500
bbls/well Re-use and/or transport to shore in
DOT approved
containers. Waste - Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station. If recycled, returned to vendor (Bariod or MI). Re-used and/or recycled; if can’t
be reused and/or recycled the waste is disposed of at Newpark (injection disposal facility)
or USLL (landfarm).

Cuttings
wetted withsyntheticbased muds Cuttings coated with synthetic drilling muds, including drilled

out cement 800-1,600
bbls total 100-200 bbls/well*

*An estimated 5-10% of cuttings may be transported to
shore Re-use and/or transport to shore in
DOT approved
containers. Waste - Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station. If recycled, returned to vendor (Bariod or MI). Re-used and/or recycled; if can’t
be reused and/or recycled the waste is disposed of at Newpark (injection disposal facility)
or USLL (landfarm).

Chemical product waste (well

treatment fluids) Ethylene glycol

Methanol 5,700 bbls
total

1,425 bbls
total 100
bbls/month/well

25
bbls/month/well Transport to shore in
DOT approved
containers for pick up. Chemwaste in Sulphur, LA and Veolia Port Arthur, TX or to Newpark, Port
Arthur as non-hazardous

waste. Can be returned
to vendor and/or
used at another facility; MEG is
solidified and disposed of in a
landfill.
Methanol is
incinerated or
used for fuels blending. Completion
fluids Brine, spent acid, prop sand,
debris 24,000 bbls
total 3,000 bbls/well Transport to shore in
DOT approved
containers
and/or vessel
tanks for pick up. Sent to Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station. Unused brine can
be returned to
vendor and/or
stored for use on another job. Used brine and spent
acid is
transferred to Newpark's Processing & Transfer facility for injection.
Workover
fluids Brine, spent acid, prop sand,
debris 24,000 bbls
total 3,000 bbls/well Transport to shore in
DOT approved
containers
and/or vessel
tanks for pick up. Sent to Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station. Unused brine can
be returned to
vendor and/or
stored for use on another job. Used brine and spent
acid is
transferred to Newpark's Processing & Transfer facility for injection.Trash and
debris Refuse generated during operations 2,850 bbls
total 50
bbls/month/well Transport to shore in disposal bags by
vessel to
shorebase for pickup by municipal operations. Recycled Material in ARC, New Iberia, LA. Trash disposed of at SWDI
landfill. Recycled and/or disposed in
landfill.

Used oil Excess oil from engines 6,128 bbls
total 430 bbls/120 days/well Transport in
DOT approved
containers to
shore for pick up. American Recovery Fourchon, LA Recycled

*Total projected amount assumes 8 wells at 190 days/well **Rate per day is an estimated max.average and may vary during drilling operational phases. The total amount is rounded to nearest whole number.

### SECTION M COASTAL ZONE MANAGEM ENT ACT INFORMATION

Alabama and Florida are not affected states.

### Texas

The following is an evaluation that includes findings relating the coastal effects of the proposed activities and associated facilities to the relevant enforceable policies of the Texas’ Coastal Management Program (TCMP), Title 31, Part 16, Chapter 501, Subchapter B :

(Category 2) Construction, Operation & Maintenance of Oil & Gas Exploration & Production Facilities

No operations are proposed in or near any critical area s. The proposed activities are explorative in nature, so no facility construction is propose d. The proposed activities are located approximately 350 miles from the Te xas shoreline; therefore we expect no adverse impacts to CNRAs or beach access a nd use rights of the public. All activities
shall be conducted in a manner that minimi zes significant impacts to coastal resources.
No adverse effects to Texas’ coastal area are expected in association with the proposed
activities.

(Category 3) Discharges of Wastewater and Disposal of Waste from Oil and Gas Exploration and Production Activities

No discharge of wastewater or disposal of waste from the proposed activities will occur in the Texas’ coastal zone; therefore no imp act to Texas’ coastal waters is expected.

(Category 4) Construction and Operation of Solid Waste Treatment, Storage, and Disposal Facilities

No construction of solid waste facilities or expansion of existing facilities in the coastal zone are proposed in the attached plan, ther efore, no adverse effects on any features of Texas’ coastal cone are expected.

(Category 5) Prevention, Response, and Remediation of Oil Spills

The proposed activities will be covered under the Regional O il Spill Response Plan. The plan is in place, practiced, and updated as ne cessary. The best prac tical techniques shall be utilized to prevent the release of pollutant s or toxic substances into the environment. All involved vessels and facilities are design ed to be capable of prompt response and adequate removal of accidental discharges of oil. In addi tion, the proposed activities are 350 miles from shore; therefore no damages to natural resources are expected as the
result of an unauthorized discha rge of oil into coastal waters.

### (Category 6) Discharge of Municipal and Industr ial Waste Water to Coastal Waters

No discharges from the proposed activities will occur in coastal waters. The proposed activities are 350 miles from shore; therefore there will be no effect on coastal waters.

(Category 8) Development in Critical Areas

None of the proposed activities w ill occur in a criti cal area; therefore no effects to Texas’ coastal zone are expected. The activity will not jeopardize the c ontinued existence of species listed as endangered or threaten ed, and will not result in likelihood of the
destruction or adverse modifica tion of a habitat determined to be a critical habitat under the Endangered Species Act. The activity will no t cause or contribute to violation of any applicable surface water quality standards. Th e activity will not violate any requirement imposed to protect a marine sanctuary.

(Category 9) Construction of Waterfront Facilities and Other Structures on Submerged lands

No waterfront facilities or other structures are proposed on submerged lands in the Texas coastal zone, therefore the pr oposed activities are not exp ected to have any adverse impacts on submerged lands.

(Category 10) Dredging and Dredged Material Disposal and Placement

No dredging or disposal/placement of dredge d material is proposed; therefore no adverse effects to coastal waters, submerged lands, cr itical areas, coastal s hore areas, or Gulf beaches are expected.

(Category 11) Construction in the Beach / Dune System

The proposed activities do not include any cons truction projects in cr itical dune areas or areas adjacent to or on Gulf beaches, ther efore, no impact to Texas’ beach or dune systems are expected.

(Category 15) Alteration of Coastal Historic Areas

The proposed activities do not include any altera tion or disturbance of a coastal historic area; therefore, no impacts are expected to adversely affect any historical, architectural, or archaeological site in Texas’ coastal zone.

### (Category 16) Transportation

The proposed activities do not include any tran sportation construction projects within the coastal zone; therefore, no impacts to Texas’ coastal zone are expected.

(Category 17) Emission of Air Pollutants

The proposed activities shall be carried out in conformance with a pplicable air quality laws, standards, and regulations. Emissions fr om the proposed activiti es are not expected to have significant impacts on onshore air quality because of the prevailing atmospheric conditions, emission heights, emission rates, an d the distance of these emissions from the coastline. The proposed activities will occur approximately 350 miles from shore and will be within the exemption limits set by BOEM, therefore, no impacts to Texas’ coastal zone is expected.

(Category 18) Appropriations of Water

The proposed activities do not include the im poundment or diversion of state water, therefore, no impacts to Texas’ coastal zone is expected.

(Category 20) Marine Fishery Management

The proposed activities are lo cated approximately 350 miles from shore and are not expected to have any effect on marine fish ery management or fishery migratory patterns
within waters in the coastal zone of Texas.

(Category 22) Administrative Policies

The necessary information for applicable agencies to make an informed decision on the proposed activities has been provided In conclusion, all activities shall be consistent with Texas’ coastal management program and shall comply with all relevant rules and regulations. No activities are planned within any critical areas. Activities will be carried out avoiding unnecessary conflicts w ith other uses of the vicinity.

### LOUISIANA

Issues identified in the Louisiana Coas tal Zone Management Program include the following: general coastal use guidelines, levees , linear facilities (pipelines); dredged soil deposition; shoreline modifications, surf ace alterations, hydrologic and sediment transport modifications, waste disposal; uses that result in the alteration of waters draining into coastal waters; oil, gas, or other mineral activitie s; and air and water quality.

Relevant enforceable policies were considered in certifying consistency for Louisiana.

### MISSISSIPPI
As authorized by the Federal Coastal Zone Management Act (CZMA), The State of Mississippi developed a Coastal Management Pr ogram (CMP) to allow for the review of proposed Federal license and perm it activities affecting any coasta l use or resources, in or
outside of the Missi ssippi Coastal Zone.

The OCS related oil and gas exploratory and development activities having potential impact on the Mississippi Coastal Zone are based on the location of the proposed facilities, access to those sites, best prac tical techniques for drilling locations, drilling equipment guidelines for the prevention of adverse environmental effects, effective environmental protection, emergenc y plans and contingency plans.

Below are goals identified by the State of Mississippi and our comments and/or corresponding cross references:

Goal 1: To provide for reasonable industrial expansion in the coastal area and to ensure the efficient utilization of waterfront industrial sites so that suitable sites are conserved for water dependent industry.

The activities proposed in this plan are based out of Fourchon, Louisiana. The activities will not provide any industrial expansion on the coastal area of Mississippi. Therefore Mississippi coastal areas will be cons erved for water dependent industry.

Goal 2: To favor the pres ervation of the coastal wetlands and ecosystems, except where a specific alteration of specific coas tal wetlands would serve a higher public interest in compliance with the public pur poses of the public trust in which the
coastal wetlands are held.

Goal 2 is addressed in Section N–Environmental Impact Analysis. The nearest proposed activities will be 110 mile s from the Mississippi coast.

Goal 3: To protect, propagate and conserve the state’s seafood and aquatic life in connection with the revitalization of the se afood industry of the State of Mississippi.

Goal 3 is addressed in Section N–Environmental Impact Analysis. Little impact to the seafood industry can be expected due to th e activities occurring 110 miles from the Mississippi coast.

Goal 4: To conserve the air and waters of the state, and to protect, maintain and improve the quality thereof for public use, for the propagation of wildlife, fish and aquatic life, and for domestic, agricultu ral, industrial, recreational and other legitimate beneficial uses.

Goal 4 is addressed in Section B–General Information, Section G–Air Emissions Information, and Section N–Environmental Impact Analysis.

### Goal 5: To put to beneficial use to the fu llest extent of which they are capable the water resources of the state, and to prevent the waste, unreasonable use, or unreasonable method of use of water.

The activities proposed in this plan are based in Fourchon, Louisiana. As such, Mississippi’s water resources should not be impacted by the proposed activities. Activities occurring at the sites in the OC S will be conducted in accordance with our Regional Oil Spill Response Plan referenced in Section H of this plan.

Goal 6: To preserve the state’s historical and archaeological resources, to prevent their destruction, and to enhance these resources wherever possible.

Goal 6 is addressed in Sec tion B–General Information, and Section N–Environmental Impact Analysis.

Goal 7: To encourage the preservation of na tural scenic qualities in the coastal area.

Goal 7 is addressed in Section F–Wastes and Discharge Information, Section H–Oil Spill Information, Section G–Air Emissions Information, and Section N–Environmental Impact Analysis.

Goal 8: To assist local govern ments in the provision of public facilities services in a manner consistent with the coastal program.

As the proposed activities ar e located 110 miles from the Mi ssissippi coast and are based out of a shorebase in Fourchon, Louisiana, local governments should not be affected.

### SECTION N ENVIRONMENTAL IMPACT ANALYSIS

# Environmental Impact Analysis

INITIAL EXPLORATION PLAN

for Atwater Valley Block 18 (OCS

- G 33863) Atwater Valley Block 19 (OCS

- G 32556)

Offshore Louisiana and Mississippi

December 2013

Prepared for:

Bridget O’Farrell Regulatory Analyst Anadarko Petroleum Corporation
1201 Lake Robbins Drive The Woodlands, Texas 77380

Telephone: (832) 636

- 1554

Prepared by:

CSA Ocean Sciences Inc.

8502 SW Kansas Avenue

Stuart, Florida 34997 Telephone: (772) 219

- 3000Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page ii 

## Contents

Page



### Introduction

................................................................................................................ 1

A. Impact

- Producing Factors

....................................................................................... 5

A.1 Drilling Rig Presence (including noise and lights)

........................................................................... 5

A.2 Physical Disturbance to the Seafloor

.............................................................................................. 5

A.3 Air Pollutant Emissions

................................................................................................................... 8

A.4 Effluent Discharges

......................................................................................................................... 8

A.5 Water Intake

................................................................................................ ................................... 8

A.6 Onshore Waste Disposal

................................................................................................................. 9

A.7 Marine Debris

................................................................................................ ................................ . 9

A.8 Support Vessel and Helicopter Traffic

............................................................................................ 9

A.9 Accidents

................................................................................................ ...................................... 10

A.9.1 Types of Accidents Evaluated

........................................................................................... 10

A.9.2 Small Fuel Spill

.................................................................................................................. 10

A.9.3 Crude Oil Spill (Worst Case Discharge)

............................................................................. 11

A.9.4 Other Accidents Not Analyzed in Detail

............................................................................ 16



### B. Affected Environment

........................................................................................... 17

C. Impact Analysis

..................................................................................................... 17

C.1 Physical/Chemical Environment

................................................................................................... 17

C.1.1 Air Quality

......................................................................................................................... 17

C.1.2 Water Quality

.................................................................................................................... 20

C.2 Seafloor Habitats and Biota

.......................................................................................................... 22

C.2.1 Soft Bottom Benthic Communities

................................................................................... 23

C.2.2 High

- Density Deepwater Benthic Communities

............................................................... 25

C.2.3 Designated Topographic Features

.................................................................................... 27

C.2.4 Pinnacle Trend Area Live Bo t to ms

.................................................................................... 28

C.2.5 Eastern Gulf Live Bottoms

................................................................................................ . 28

C.3 Threatened, Endangered, and Protected Species and Critical Habitat

........................................ 28

C.3.1 Sperm Whale (Enda ngered)

.............................................................................................. 30

C.3.2 West Indian Manatee (Endangered)

................................................................................. 34

C.3.3 Endangered Mysticete Whales

......................................................................................... 35

C.3.4 Non

- Endangered Marine Mammals (Protected)

.............................................................. 35

C.3.5 Sea Turtles (Endangered/Threatened)

............................................................................. 39

C.3.6 Piping Plover ( Threatened)

............................................................................................... 42

C.3.7 Whooping Crane (Endangered)

........................................................................................ 44
C.3.8 Gulf Sturge on (Threatened)

.............................................................................................. 45

C.3.9 Smalltooth Sawfish (Endangered)

..................................................................................... 45

C.3.10 Beach Mice (Endangered)

................................................................................................ . 46

C.3.11 Elkhorn Coral (Endangered)

.............................................................................................. 47

## Contents
(C ontinued)

Page

Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page iii C.4 Coastal and Marine Birds

.............................................................................................................. 47

C.4.1 Marine Birds

...................................................................................................................... 47

C.4.2 Shorebirds and Coastal Nesting Birds

............................................................................... 49

C.5 Fisheries Resources

...................................................................................................................... 51

C.5.1 Pelagic Communities and Ichthyoplankton

...................................................................... 51

C.5.2 Essential Fish Habitat

........................................................................................................ 53

C.6 Archaeological Resources

............................................................................................................. 56

C.6.1 Shipwreck Sites

................................................................................................................. 56

C.6.2 Prehistoric Archaeological Sites

........................................................................................ 57

C.7 Coastal Habitats and Protected Areas

.......................................................................................... 58

C.8 Socioeconomic and Other Resources

........................................................................................... 63

C.8.1 Recreational and Commercial Fishing

.............................................................................. 63

C.8.2 Public Health and Safety

................................................................................................... 64

C.8.3 Employment and Infrastructure

....................................................................................... 65

C.8.4 Recreation and Tourism

.................................................................................................... 66

C.8.5 Land Use

............................................................................................................................ 67

C.8.6 Other Marine Uses

............................................................................................................ 68



### D. Environmental Hazards

......................................................................................... 68

D.1 Geologic Hazards

.......................................................................................................................... 68

D.2 Severe Weather

............................................................................................................................ 69

D.3 Currents and Waves

..................................................................................................................... 69



### E. Alternatives

.......................................................................................................... 69

F. Mitigation Measures

............................................................................................. 69

G. Consultation

......................................................................................................... 70

H. Preparers

.............................................................................................................. 70

I. References

............................................................................................................. 70Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page iv 

## List of Tables

Table Page

1 Notices to Lessees and Operators (NTLs) applicable to this Envi ronmental Impact Analysis (EIA)

........................................................................................................................... 3

2 Matrix of impact

- producing factors and affected environmental resources

......................... 6

3 Conditional probabilities expressed as percent chance that an oil spill starting at Launch Point 3 will contact a certain parish, county, or coastline within 120 days (Modified from: BOEM, 2012b, Appendix C)

........................................................................ 13

4 Benthic community data from stations near the lease area and in similar water depths sampled during the Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology Study (Adapted from: Wei, 2006; Rowe and Kennicutt, 2009)

........... 23

5 Federally listed endangered and threatened species potentially occurring in the lease area and along the northern Gulf Coast

...................................................................... 29

6 W ildlife refuges, wilderness areas, and State and National parks within the geographic range of the potential shoreline contacts after 120 days (From: BOEM, 2012b)

................................................................................................ ................................... 59



## List of Figures

Figure Page

1. Location of Atwater Valley Blocks 18 and 19

......................................................................... 2

2. Bathymetric map of the lease area showing the surface hole locations of the proposed wellsites.

............................................................................................................... 18

3. Location of selected environmental features in relation to the lease area.

........................ 43Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page v 

## Acronyms and Abbreviations

ac acre Anadarko Anadarko Petroleum Corporation

ADIOS 2 Automated Data Inquiry for Oil Spills 2

AT Atwater Valley
bbl barrel

BML below mud line

BOEM Bureau of Ocean Energy Management

BOEMRE Bureau of Ocean Energy Managem ent, Regulation and Enforcement

BOP blowout preventer

B.P. Before Present

BSEE Bureau of Safety and Environmental
Enforcement

CFR Code of Federal Regulations

CH 4 methane

CO carbon monoxide

CO 2 carbon dioxide

CGA Clean Gulf Associates

DP dynamic position ing

EEZ Exclusive Economic Zone

EFH Essential Fish Habitat

EIA Environmental Impact Analysis

EIS Environmental Impact Statement

EP Exploration Plan

ESA Endangered Species Act

FAD fish

- attracting device

FR Federal Register
Gardline Gardline Surveys

, Inc.

GMFMC Gulf of Mexico Fishery Management
Council

GPS global positioning system

H 2 S hydrogen sulfide
ha hectare

HAPC Habitat Area of Pa rticular Concern

HOSS high

- volume open sea skimmer

IPF impact

- producing factor

MC Mississippi Canyon MARPOL International Convention for the Prevention of Pollution from Ships

MMC Marine Mammal Commission

MMPA Marine Mammal Protection Act

MMS Minerals Mana gement Service

MSRC Marine Spill Response Corporation
NAAQS National Ambient Air Quality
Standards

NMFS National Marine Fisheries Service

NOAA National Oceanic and Atmospheric
Administration

NO 2 nitrogen dioxide

NO x nitrogen oxides

NPD ES National Pollutant Discharge Elimination System

NPS National Park Service

NRDA Natural Resource Damage Assessment

NTL Notice to Lessee s and Operators

NWR National Wildlife Refuge

OBM oil

- based mud

OCS Outer Continental Shelf

OSAT Operational Scientific Adv isory Team

OSRA Oil Spill Risk Analysis

OSRP Oil Spill Response Plan

PAH polycyclic aromatic hydrocarbon

PM particulate matter

PSD Prevention of Significant Deterioration

SBM synthetic

- based mud

SHL surface hole location

SO x sulfur oxides

SWSS Sp er m Whale Seismic Study

USCG U.S. Coast Guard

USEPA U.S. Environmental Protection Agency

USFWS U.S. Fish and Wildlife Service

VOC volatile organic compound

WCD worst case dischargeA twater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 1 

## Introduction

Anadarko Petroleum Corporation ( Anadarko ) is submitting a n Initial Exploration Plan (EP) for Atwater Valley (AT) B locks 18 (AT 18) and 19 (AT 19)

. The EP includes eight exploratory well
locations: AT 18

- CC, AT 18

- DD, AT 18

- GG, AT 18

- GV, AT 18

- QQ, AT 19

- EE, AT 19

- KK, and

AT 19

- KV. All surface hole locations (SHLs) and bottom hole locations (BHLs) will be in the same
block. This Environmental Impact Analysis (EIA) provides information on the exploratory wells
based on the SHLs.

The lease area is 71 miles (114 m) from the nearest shoreline, 10 8 miles (172 km) from the onshore support base at Port Fourchon, Louisiana, and 15 2 miles (243 km) from the helicopter support base at Houma, Louisiana ( Figure 1 ). Water depth s at the wellsites range from 1,270 to 1,351 m (4,167 to 4,433 ft). The drilling rig is yet to be determined, but will be either a dynamic positioning (DP) drillship or a DP semisubmersible rig. The expected timeframe to conduct the operations proposed in this EP has not yet been determined. Each of the eight proposed wells
will take approximately 1 90 days to drill and complete, for a t otal of 1, 520 days on site.

This E IA was prepared for submittal to the Bureau of Ocean Energy Management (BOEM) in accordance with applicable regulations, including 30 Code of Federal Regulations (CFR) 550.212(o) and 550.227

. The EIA is a project - and site

- specific analysis of Anadarko ’s planned activities under this EP. This EIA complies with guidance provided in existing Notices to Lessees and Operators (NTLs) issued by the former Minerals Management Service (MMS) and Bureau of Ocean Energy Management, Regulation and Enforcement ( BOEMRE ) , including NTL 2008

- G04
and NTL 2013

- G02

. Potential impacts have been analyzed at a broader level in the Programmatic Environmental Impact Statement (EIS) for the Outer Continental Shelf (OCS) Oil and Gas Leasing Program (MMS, 2007a; BOEM

, 2012a) and in multi

- lease

- sale EISs for the Western and Central Gulf of Mexico Planning Areas (MMS, 2007b; BOEM, 2012b). The analyses
from these documents are incorporated here by reference.

Statistics from offshore drilling in the U.S. Gulf of Mexico provide a reasonable basis for evaluating oil spill risk during exploratory drilling. According to Holand (1997), the average frequency of a loss of well control incident or " blowout " during exploratory drilling in the

U.S. Gulf of Mexico is 0.00593 blowouts per well drilled, or one blowout per 169 exploration wells drilled. Similarly, the MMS Safety and Environmental Management Program blowout incident rate for 1996 to 1999 was approximately five blowouts per 1,000 well starts, or one blowout per 200 well starts (MMS, 2000). More recently, in its Final Supplemental EIS for the Central Gulf of Mexico Planning Area, BOEM confirmed that " significant changes to the spill
rates for the en tire OCS are not anticipated " (BOEM, 201 2b ).

Historically, most blowouts have not resulted in oil spills. Of 151 well blowouts in the Gulf of Mexico from 1971 to 1995, only 18 (12%) resulted in oil spills, with a total combined volume of 1,000 barrels (bbl) of crude oil and condensate released (MMS, 2000). Between 1964 and 1999, almost all offshore spills (94%) from drilling and production

- related operations on the OCS were less than or equal to 1 bbl in size (Anderson and LaBelle, 2000). According to the Bureau of Safety and Environmental Enforcem ent’s ( BSEE’s ) Final Drilling Safety Rule (75 Federal Register [ FR ] 63365) issued following the Macondo incident, the baseline risk of a catastrophic blowout is estimated to be about once every 26 years.A twater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 2 Figure 1

. Location of Atwater Valley Blocks 18 and 19

.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 3 All the proposed activities and facilities discussed in this EP are covered by the Regional Oil Spill Response Plan (OSRP) approved on 25 September 2013 for Anadarko and its subsidiaries,
Anadarko U .S. Offshore Corporation and Anadarko E&P Company L.P. (Company Numbers 00981, 02219

, and 00148, respectively)

, in accorda nce with 30 Code of Federal Regulations ( CFR ) Part 254.

The OSRP details Anadarko’s plan for response to rapidly and effectively manage oil spills that may result from drilling and production operations. Anadarko has designed its response program based o n a regional capability of respon se to spill s ranging from small operational spills

to a worst case discharge (WCD) from a well blowout. Anadarko’s spill response program meets the response planning requirements of the relevant coastal states and applicable F ederal oil spill planning regulations and also includes information regarding Anadarko’s regional oil spill organization and dedicated response assets, potential spill risks, and local environmental
sensitivities. The OSRP descri bes personnel and equi pment mobilization, the incident management team organization, and an overview of actions and notifications to be taken in the event of a spill.

Th is EIA is organized into Sections A through I corresponding to the information required by

NTL 200 8- G04. The main impact

- related discussions are in Section A (Impact

- Producing Factors)
and Section C (Impact Analysis). Table 1 lists and summarizes the NTLs applicable to this EIA.

Table 1. Notices to Lessees and Operators (NTLs) applicable to this Environmental Impact Analysis ( EIA ).

NTL Title Summary

2013- G02 Extension of Prior Notices to

Lessees Extends the effective date of NTL 2008- G04 (and two other NTLs) until the end of the 2013 calendar year

.

2012- N06 Guidance to Owners and Operators
of Offshore Facilities Seaward of the Coast Line Concerning Regional Oil Spill Response Plans Provides clarification, guidance, and information for preparation of regional Oil Spill Response Plans. Recommends description o f response strategy for worst case discharge (WCD) scenarios to ensure capability to respond to oil discharges is both efficient and effective.

2012- BSEE

- G01 Marine Trash and Debris
Awareness and Elimination Instructs operators to exercise caution in the handling and disposal of small items and packaging materials; requires the posting of placards at prominent locations on offshore vessels and structures; and mandates a yearly marine trash and debris awareness training and certification process.

2012- JOINT

- G01 Vessel Strike Avoidance and Injured/Dead Protected Species Reporting Recommends protected species identification guides be carried on all Gulf of Mexico petroleum vessels and that vessel operators and crews maintain a vigilant watch for

mari ne mammals . Vessels are to slow down or stop to avoid striking protected species, and operators are required to report sightings of any injured or dead protected species.

2011- JOINT

- G01 Revisions to the List of OCS Blocks Requiring Arch a eological Resourc e Surveys and Reports Provides new information of which Outer Continental Shelf (OCS) blocks require arch a eological surveys and reports and required survey line s pacing in each block. This

NTL augments NTL 2005 -G07.Table 1. (Continued).

Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 4 NTL Title Summary

2010- N10 Statement of Compliance with Applicable Regulations and
Evaluation of Information Demonstrating Adequate Spill Response and Well Containment

Resources Informs operators using subsea blowout preventers (BOPs) or surface BOPs on floating facilities that applications for well permits mus t include a statement signed by an authorized company official stating that the operator will conduct all activities in compliance with all applicable regulations, including the increased safety measures regulations (75 FR 63346). Informs operators that B OEM will be evaluating whether each operator has submitted adequate information demonstrating that it has access to and can deploy containment resources to promptly respond
to a blowout or other loss of well control.

2010- N06 Information Requirements for Exploration Plans, Development and Production Plans, and Development Operations
Coordination Documents on the

OCS Rescinds the limitations set forth in NTL 2008- G04 regarding a blowout scenario and worst case discharge scenario, and provides guidance regarding the information required in blowout scenario and worst case discharge scenario descriptions.

2009- G40 Deepwater Benthic Communities Provides g uidance for avoiding and protecting high

- density deepwater benthic communities (including chemosynthetic and deepwater coral communities) from damage caused by

OCS oil and gas activities in water depths greater than 300 m (984 ft). Prescribes separation distances of 610 m (2,000 ft) from each mud and cuttings discharge location and 76 m (250 ft) from all other seafloor disturbances.

2009- G39 Biologically Sensitive Underwater
Features and Areas Provides g uidance for avoiding and protecting biologically

sen sitive features and areas (i.e., topographic features, pinnacles, low relief live bottom areas, and other potentially sensitive biological features) when conducting OCS operations in water depths less than 300 m (984 ft) in the
Gulf of Mexico.

2009- G06 Mi litary Warning and Water Test

Areas Provides contact links to individual command headquarters for the military warning and water test areas in the Gulf of Mexico. Lease stipulations require lessees or designated
operators to enter into an agreement with t he appropriate individual military command headquarters concerning the control of electromagnetic emissions and use of boats and aircraft in the applicable warning area or water test area before commencing such traffic.

2008- G04 Information Requirements for Exploration Plans and Development Operations Coordination

Documents Provides g uidance on the information requirements for OCS plans, including EIA requirements and information regarding compliance with the provisions of the Endangered Species
Act and M arine Mammal Protection Act.

2005- G07 Archaeological Resource Surveys and Reports Provides guidance on regulations regarding archaeological discoveries, specifies requirements for archaeological resource surveys and reports, and outlines options for
prote cting archaeological resources.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 5 

## A. Impact

- Producing Factors

Table 2 is a matrix of impact

- producing factors (IPFs) and potentially affected environmental resources adapted from Form BOEM -0 142. An "X" indicates that an IPF could reasonably be expected to affect a certain resource, and a dash (

-- ) indicates no impact or negligible impact.
Where there may be an effect, an analysis is provided in Section C

. Potential IPFs for the proposed activity are listed below and briefly discussed in the following sections.

• Drilling rig presence (including noise and lights)

• Physical disturbance to the seaflo or

• Air pollutant emissions

• Effluent discharges

• Water intake

• Onshore waste disposal

• Marine debris

• Support vessel and helicopter traffic

• Accidents



## A.1 Drilling Rig Presence (including noise and lights)

The wells proposed in this EP will be drilled using either a DP drillship or a DP semisubmersible rig. DP drillships and DP semisubmersible rig s use a global positioning system (GPS), specific computer software, and sensors in conjunction with and their own propellers and thrusters to maintain position. Essentially, through satellite navigation, the location of the vessel is precisely monitored, and thrusters positioned at various locations about the vessel’s hull are activated to provide any requi red station

- keeping adjustment. This allows operations a t sea where mooring or anchoring is not feasible.

The drilling rig for the well s proposed in this EP will be on site for an estimated 1, 520 days (1 90 days per well)

. The physical presence of the drilling rig in the ocean can attract pelagic
fish es and oth er marine life

, as discussed in Section C.5.1

.
Drilling operations produce noise that includes strong tonal components at low frequencies, and

in some cases infrasonic frequencies (MMS, 2000). Drilling noise from DP drillships and DP
semisubmersibles is not particularly intense and is strongest at low frequencies, averaging

10 to 500 Hz (Richardson et al., 1995). From a drilling rig , sound and vibration paths to the water flow either through the air or through the risers (MMS, 2000). Drilling rigs also maintain exterior lighting for navigational and aviation safety in accordance with applicable Federal safety regulations.



## A.2 Physic al Disturbance to the Seafloor

In water depths of 600 m (1,969 ft) or greater, DP drilling vessels disturb only a very small area of the seafloor around the wellbore (SHL) where the bottom template and blowout preventer (BOP) are located. Depending on the specific well configuration, this area is generally about
0.25 h ect a re ([ha ]; 0.62 ac re [ac] (MMS, 2007a).A twater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 6 Table 2. Matrix of impact

- producing factors and affected environmental resources. X = potential impact; dash (

-- ) = no impact or negligible impact.

Environmental Resources Impact

- producing Factors Drilling Rig Presence (incl. noise & lights) Physical Disturbance to Seafloor Air Pollutant Emissions Effluent Discharges Water Intake On shore Waste Disposal Marine Debris Support Vessel/Helo

Traffic Accidents
S mall Fuel Spill Oil Spill (WCD) Physical/Chemical Environment Air quality and greenhouse gases

-- -- -- X ( 9 )

-- -- -- -- -- X (6) X (6) Water quality

-- -- -- X

-- -- -- -- X (6) X (6) Seafloor Habitats and Biota Soft bottom benthic communities

-- X

- - X

-- -- -- -- -- X (6) High

- density deepwater benthic communities

-- -- (4)

-- -- (4)

-- -- -- -- -- X (6) Designated topographic features

-- -- (1)

-- -- ( 1)

-- -- -- -- -- -- Pinnacle trend area live bottoms

-- -- (2)

-- -- (2)

-- -- -- -- -- -- Eastern Gulf live bottoms

-- -- (3)

-- -- (3)

-- -- -- -- -- -- Threatened, Endangered, and Protected Species and Critical Habitat Sperm whale (endangered) X (8 )

-- -- -- -- -- -- X (8) X (6,8) X (6,8) West Indian manatee (endangered)

-- -- -- -- -- -- -- X (8)

-- X (6,8) Endangered mysticete whale s

-- -- -- -- -- -- -- -- -- -- Non

- endangered marine mammals (protected) X

-- -- -- -- -- -- X X (6) X (6) Sea turtles (endangered/threatened) X (8)

-- -- -- -- -- -- X (8) X (6,8) X (6,8) Piping Plover (threatened)

-- -- -- -- -- -- -- -- -- X (6) Whooping Crane (endangered)

-- -- -- -- -- -- -- -- -- X (6) Gulf sturgeon (threatened)

-- -- -- -- -- -- -- -- -- X (6) Smalltooth sawfish (endangered)

-- -- -- -- -- -- -- -- -- X (6) Beach mice (endangered)

-- -- -- -- -- -- -- - - -- X (6) Elkhorn coral (endangered)

-- -- -- -- -- -- -- -- -- X (6) Coastal and Marine Birds

Marine birds X

-- -- -- -- -- -- X X (6) X (6) Shorebird s and coastal nesting birds

-- -- -- -- -- -- -- X

-- X (6) Fisheries Resources Pelagic communities and ichthyoplankton X

-- -- X X

-- -- -- X (6) X (6) Essential Fish Habitat X

-- -- X X

-- -- -- X (6) X (6) Archaeological Resources Shipwreck sites

-- -- (7)

-- -- -- -- -- -- -- X (6) Prehistoric archaeological sites

-- -- (7)

-- -- -- -- -- -- -- X (6) Coastal Habitats and Protected Areas

Beaches

-- -- -- -- -- -- -- -- -- X (6) Wetlands and seagrass beds

-- -- -- -- -- -- -- -- -- X (6) Coastal wildlife refuges and wilderness areas

-- -- -- -- -- -- -- -- -- X (6) Socioeconomic and Other Resources

Recreational and commercial fishing X

-- -- -- -- -- -- -- X (6) X (6) Public health and safety

-- -- -- -- -- -- -- -- -- X (6) Employment and infrastructure

-- -- -- -- -- -- -- -- -- X (6) Recreation and tourism

-- -- -- -- -- -- -- -- -- X (6) Land use

-- -- -- -- -- -- -- -- -- X (6) Other marine uses

-- -- -- -- -- -- -- -- -- X (6)

WCD = worst case discharge.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 7 Table 2 Footnotes and Applicability: (1) Activities that may affect a marine sanctuary or topographic feature. Specifically, if the well, rig site, or any anchors will be on the seafloor within the following: (a) 4- mi le zone of the Flower Garden Banks, or the 3

- mi le zone of Stetson Bank; (b) 1,000

- m, 1

- mi le , or 3

- mi le zone of any topographic feature (submarine bank) protected by the Topographic Features Stipulation attached to an Outer Continental Shelf (OCS) lease; (c) Essential Fish Habitat (EFH) criteria of 500 ft from any no

- activity zone; or (d) Proximity of any submarine bank (500

- ft buffer zone) with relief greater than 2 m that is not protected by the Topographic Features Stipulation attached to an OCS lease.

• Not applicable. The lease is not within or near any marine sanctuary, topographic feature, or

no

- activity zone. There are no submarine banks in the blocks.

(2) Activities with any bottom disturbance within an OCS lease block protected through the Live Bottom (Pinnacle Trend) Stipulation attached to an OCS lease.

• The Live Bottom (Pinnacle Trend) Stipulation is not applicable to the lease area.

(3) Activities within any Eastern Gulf OCS block where seafloor habitats are protected by the Live Bottom (Low

- Relief) Stipulation attached to an OCS lease.

• The Live Bottom (Low

- Relief) Stipulation is not applicable to the lease area.

(4) Activities on blocks designated by the BOEM as being in water depths 4 00 m or greater.

• No impacts on high

- density deepwater benthic communities are anticipated. There are no features indicative of high

- density chemosynthetic communities or coral communities within 610 m (2,000 ft) of any drilling mud/cuttings discharge location.

(5) Exploration or production activities where H 2 S concentrations greater than 500 ppm might be encountered.

• Based on 30 CFR 250.490(c), Anadarko is proposing that BOEM classify the lease area as a zone where
the absence of H 2 S has been confirmed.

(6) All activities that could result in an accidental spill of produced liquid hydrocarbons or diesel fuel that you determine would impact these environmental resources. If the proposed action is located a sufficient distance from a resource that no impact would occur, the EIA can note that in a sentence or two.

• Accidental hydrocarbon spills could affect the resources marked (X) in the matrix, and impacts are analyzed in Section C

. (7) All activities that involve seafloor disturbances, including anchor emplacements, in any OCS block designated by the BOEM as having high

- probability for the occurrence of s hipwrecks or prehistoric sites, including such blocks that will be affected that are adjacent to the lease block in which your planned activity will occur. If the proposed activities are located a sufficient distance from a shipwreck or prehistoric site that no impact would occur, the EIA can note that in a sentence or two.

• No impacts on archaeological resources are expected. The lease area is not on the list of archaeology survey blocks (BOEM, 2012c) and is well beyond the 60

- m depth contour used by the BOEM as the seaward extent for prehistoric archaeological site potential in the Gulf of Mexico. T he geohazards and archaeological assessments indicate multiple sonar contacts in the lease area, but none are interpreted to be historic shipwrecks. A dynamic positioning (DP) drilling vessel will be used; therefore, seafloor disturbances due to anchoring will not occur.

(8) All activities that you determine might have an adverse effect on endangered or threatened marine mammals
or sea turtles or their critical ha bitats.

• IPFs that may affect marine mammals, sea turtles, or their critical habitats include drilling rig presence,
support vessel and helicopter traffic, and accidents. See Section C

. (9) Production activities that involve transportation of produced fluids to shore using shuttle tankers or barges.

• Not applicable.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 8 

## A.3 Air Pollutant Emissions

Air pollutant emissions are calculated in EP Section G and are estimated to be insignificant. Offshore air pollutant emissions will result from drilling rig operations, as well as service vessels and helicopters. These emissions occur mainly from combustion of diesel fuel. The combustion
of fuels occurs on diesel

- powered generators, pumps, or motors and from lighter fuel motors. Primary air pollutants typically associated with OCS activities are suspended particulate matter (PM), sulfur oxides (SO
x ), nitrogen oxides (NO
x ), volatile organic compounds (VOCs), and carbon monoxide (CO).

The Air Quality Emissions Report prepared in accordance with BOEM requi rements demonstrates that the projected emissions are below exemption levels set by the applicable regulations in 30 CFR 250.303. Based on this and the distance to shore, it can be concluded that the emissions will not significantly affect the air quality of the onshore area for any of the criteria pollutants. No further analysis or control measures are required.



## A.4 Effluent Discharges

Effluent discharges are summarized in EP Section F . All offshore discharges will be in
accordance with requirements of the National Pollutant Discharge Elimination System (NPDES)
General Permit No. GMG290000 issued by the U.S. Environmental Protection Agency (USEPA). Any discharges will be in compliance with the permit terms and monitored as required by the permit.

Water

- based drilling muds and cuttings will be released at the seafloor during the initial well
intervals before the marine riser that allows their return to the surface is set. Excess cement slurry will also be released at the seafloor during casing installati on for the riserless portion of the drilling operations. Synthetic

- based drilling muds (SBMs) will be collected on the rig and either reused by the vendor, or transported to Port Fourchon , Louisiana

, for recycling and/or disposal at an approved facility. Cuttings wetted with SBMs will be discharged to the seafloor in accordance with the NPDES permit.

Other effluent discharges in accordance with the NPDES permit will include excess cement,

n on

- contact cooling water, treated sanitary and domestic wastes, deck drainage, desalination unit brine, uncontaminated freshwater and seawater, and ballast water.



## A.5 Water Intake

Seawater will be drawn from the ocean for once

- through, non

- contact cooling of machinery on the drilling rig. Section 316(b) of the Clean Water Act requires NPDES permits to ensure that the location, design, construction, and capacity of cooling water intake structures reflect the best technology available to minimize adverse environmental impact from impingement and entrainment of aquatic orga nisms. The current NPDES General P ermit No. GMG 290000 does not specify requirements for existing facilities (those that started construction before

16 July 2006)

. The drilling vessel ultimately selected for this project will be in compliance with
all coo ling water intake structure requirements.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 9 

## A.6 Onshore Waste Disposal

Wastes generated during drilling are tabulated in EP Section F

. A total of a pproximately 2,333 bbl of trash will be generated over the life of this project. The trash will be transported in disposal bags to shore where it will be picked up by municipal operators for final disposal in accordance with applicable regulations.



## A.7 Marine Debris

Anadarko will comply with all regulations relating to solid wastes handling and disposal

, including the International Convention for the Prevention of Pollution from Ships (MARPOL 73/78) Annex V requirements and USEPA and U.S. Coast Guard ( USCG ) regulations, as
well as those of the BOEM

. For example, BOEM regulations at 30 CFR 250.300(a) and (b)(6) prohibit operators from deliberately discharging containers and other similar materials (i.e., trash and debris) into the marine environment, and 30 CFR 250.300(c) requires durable identification markings on equipment, tools

, and containers (especially drums), and other
material. USEPA and USCG regulations require operators to become proactive in avoiding accidental loss of solid waste items by developing waste management plans, posting informational placards, manifesting trash sent to shore, and using special precautions such as covering outside trash bins to prevent accidental loss of solid waste. In addition to the regulations in 30 CFR 250

, BSEE issued NTL 2012

- BSEE -G01, which instructs operators to exercise caution in the handling and disposal of small items and packaging materials, requires the posting of placards at prominent locations on offshore vessels and structures, and mandates a yearly marine trash and debris awareness training and certification process.



## A.8 Support Vessel and Helicopt er Traffic

Anadarko will use existing shorebase facilities at Port Fourchon, Louisiana

, for onshore support for vessel activities. Air transportation (helicopters) will be based at facilities in Houma,
Louisiana. No terminal expansion or construction is planned at either location

.
The project will be supported by one crew boat and one supply vessel

. The crew boat will make
three round

- trips per week, and the supply vessel s will make two round

- trips per week. The boats typically will move to the project area via the most direct route from the shorebase. Up to two tugboats and anchor handling vessels may be in the project area at any time for the duration of the operation.

A helicopter will make an estimated 10 round

- trips per week between the drilling rig and the heliport. The helicopter will be used to transport personnel and small supplies and will normally
take the most direct route of travel between the shorebase and the lease area when air traffic and weather conditions permit. Heli copters typically maintain a minimum altitude of 213 m (700 ft) while in transit offshore, 305 m (1,000 ft) over unpopulated areas or across coastlines,
and 610 m (2,000 ft) over populated areas and sensitive habitats such as wildlife refuges and park prop erties. Additional guidelines and regulations specify that helicopters maintain an
altitude of 305 m ( 1,000 ft) within 91 m ( 300 ft) of marine mammals (BOEM, 2012 d ).Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 10 

## A.9 Accidents

A.9.1 Types of Accidents Evaluated

The analysis in this EIA focuses on two potential accidents:

• a small fuel spill, which is the most likely type of spill during OCS exploration activities; and

• t he WCD for this EP, which is an oil spill resulting from an uncontrolled blowout.

The following subsections summarize assumptions about the size s and fate s of these spills, as
well as Anadarko’ s spill response plans. Impacts are analyzed in Section C

.

MMS ( 2007b) and BOEM (2012 b ) analyze d three other types of accidents: chemical spills, vessel collisions, and loss of well control. These types of accidents are discussed briefly in

Section A.9.4

.



### A.9.2 Small Fuel Spill

Spill Size . According to the analyses in MMS (2007b) and BOEM (201 2a ), the most likely type of small spill (<1,000 bbl) as a result of OCS activities is a minor diesel fuel spill. Historically, most diesel spills have been <1 bbl, and this size is predicted to be the most common in ongoing and
future OCS activities in the Western and Central Gulf of Mexico Planning Areas. As the spill size increases, the incident rate declines dramatically (MMS, 2007b; BOEMRE, 2011a; BOEM, 201 2b ).
The median size for spills <1 bbl is 0.0 24 bbl, and the median size for spills of 1 to 10 bbl is 3 bbl ( BOEM, 2012a ). For this analysis, a small diesel fuel spill of 3 bbl is assumed. Operationa l experience suggests that the most likely cause of such a spill would be a hose rupture resulting in the loss of the contents of a fuel transfer hose, which is less than 3 bbl.

Spill Fate

The water

- soluble fractions of diesel are dominated by two - and three

- ringed polycyclic aromatic hydrocarbons (PAHs), which are moderately volatile (National Research Council,

2003 a ). The constituents of these oils are light to intermediate in molecular weight and can be readily degraded by aerobic microbial oxidation. Due to its light density, diesel will not sink to
the seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this generally occurs only in coastal areas with high suspended solids loads (National Research Council, 2003 a ) and would not be expected to occur to any appreciable degree in offshore
waters of the Gulf of Mexico. Diesel oil is readily and completely degraded by naturally occurring microbes (National Oceanic and Atmospheric Administration [NOAA], 2006). . The fate of a small fuel spill in the lease area would depend on meteorological and oceanographic conditions at the time, as well as the effectiveness of spill response activities. However, g iven the open ocean location of the lease area and response actions, it is expected that impacts from a small spill would be minimal ( BOEMRE, 2011a; BOEM, 201 2b ).

For purposes of this EIA, the fate of a small diesel fuel spill was estimated using NOA A’s Automated Data Inquiry for Oil Spill s 2 (ADIOS2) model. This model uses the physical properties of oils in its database to predict the rate of evaporation and dispersion over time, as well as changes in the density, viscosity, and water content of the product spilled. It is estimated that over 90% of a small diesel spill would be evaporated or dispersed within 24 hours. The sea
surface area with diesel fuel on it during this 24

- hour period would range from 0.5 to 5 ha (1.2 to 12 ac) depending on sea state and weather conditions.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 11 The ADIOS2 results, coupled with spill trajectory information discussed below for a large spill,
indicate that a small fuel spill would not have any impacts on coastal or shoreline resources.
The lease area is 71 miles (114 km) from the nearest shoreline. Modeling results discussed below indicate that a spill in the lease area w ould have a 4% or less probability of reaching the
coastal areas of Louisiana within 10 days after a spill

. By that time, essentially 100% of a small fuel spill would have been dispersed or evaporated by natural processes, without taking into
account Anadarko ’s response measures. Slicks from spills are expected to persist for relatively short periods of time ranging from minutes (<1 bbl) to hours (<10 bbl) to a few days (10 to 1,000 bbl) an d rapidly spread out, evaporate and disperse into the water column (BOEM, 2012b). Because of the distance of these potential spills on the OCS and the ir lack of persistence, it is unlikely that a spill would make landfall prior to dissipation (BOEM, 2012b).

Spill Response



### A.9.3 Crude Oil Spill (Worst Case Discharge) . In the unlikely event the shipboard prevention procedures fail to prevent a fuel spill, response equipment and trained personnel would be activated so that any spill effects
would be localized and would result only in short

- term environmental consequences.

EP Section 9b provides a detailed discussion of Anadarko’ s response to a spill.

Spill Size

An estimated 7

- 21 days is required to suspend operations on a deepwater Gulf of Mexico well, mobilize to a relief well location, and begin re lief well drilling operations. This estimate includes

0 to 14 days to suspend current operations on an existing well and 7 days to mobilize to location
and be ready to spud a relief well. The estimated time to drill the relief well and perfo rm kill operations is 180 days for an estimated total of 187 to 201 days from time of blowout to completion of a relief well. The detailed analysis of this calculation can be found in

EP Section H

. . AT 19

- KV has the highest WCD for the entir e Initial Exploration Plan at 250,199 bbl per day. AT 18

- GV has the highest WCD for AT 18 with a potential maximum discharge of 63,744 bbl per day. The maximum total volume during a blowout at AT 19

- KV could potentially be 50,287,788 bbl assuming 201 day s for the maximum duration of a blowout, multiplied by the worst case daily uncontrolled blowout volume of 250,188 bbl per day.

Historically, blowouts are rare events and most do not result in oil spills. Holand (1997) estimated a probability of 0.0021 for a deep drilling blowout during exploration drilling based on U.S. Gulf of Mexico data. An updated analysis using the SINTEF database estimates a blowout frequency of 0.0017 per exploratory well for non

- North Sea locations (International Association of Oil & Gas Producers, 2010). As noted by MMS (2007b), from 1992 to 2005, half of blowouts lasted less than half a day, and fewer than 10% of blowouts resulted in spilled oil. BOEM is in the process of updating these spill frequency estimates to include the Macondo event; however, significant changes to the spill rates for the entire OCS are not anticipated ( BOEMRE, 2011 a ; BOEM, 2012 d ). As noted in the Introduction , the baseline risk of a catastrophic blowout is estimated to be once every 26 years ( BSEE Final Drilling Safety Rule, 75 FR 63365).

Included in EP Section H are Anadarko’s calculations and information as required by

NTL 2010

- N06, including descriptions of measures to preve nt a blowout, reduce the likelihood of a blowout, and conduct effective and early intervention in the event of a blowout. Anadarko will also comply with NTL 2010 -N 10 and the Final Drilling Safety Rule, which specif ies additional safety measures for OCS ac tivities.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 12 Spill Trajectory

To address this criticism

, a special OSRA run was conducted for the recent BOEM Western and
Central Gulf of Mexico Planning Area Supplemental EI Ss ( BOEMRE

, 2011 a ; BOEM, 2012 b ) in order to estimate the impacts of a possible future catastrophic long

- duration oil spill. In this OSRA model run a hypothetical high volume, long

- duration oil spill was assumed to have occurred, and the analysis emphasize d modeling a spill that continued for 90 consecutive days, with each traject ory tracked for up to 120 days. . The fate of a large oil spill in the lease area would depend on meteorological and oceanographic conditions at the time. The Oil Spill Risk Analysis (OSRA) model is a computer simulation of oil spill transport that uses realistic data for winds and curren ts to predict spill fate. Although this model has received some criticism recently (Earthjustice, 2011), it is still the most widely scientifically accepted model for estimating the fate of small fuel spills.
The primary criticism of the OSRA model resul ts as provided in Ji et al. (2004) was that the
model did not evaluate the fate of a spill over time periods longer than 30 days, nor d id it predict the fate of a release that continues over a period of weeks or months, as in the Macondo
incident. Also as noted by Ji et al. (2004), the OSRA model does not take into account the chemical composition or biological weathering of oil spills, the spreading and splitting of oil spills, or spill response activities. The model does not assume a particular spill si ze but has generally been used by the BOEM to evaluate contact probabilities for spills greater than 1,000 bbl.

The OSRA model run for this revised analysis was conducted for five hypothetical launch points
in the Central a nd Western Gulf o f Mexico Planning Ar eas

. These launch point s were deliberately located in area s identified as having a high possibility of containing large oil

reserves.

The five launch point areas were as follows:

1. Central Gulf of Mexico shelf are a west of the Mississip pi River (28.98660° N latitude,
92.17851 ° W longitude);

2. Central Gulf of Mexico shelf area east of the Mississippi River ( 29.91388 ° N latitude,
88.15338 ° W longitude);

3. Central Gulf of Mexico slope area ( 27.31998 ° N latitude, 90.22203 ° W longitude);

4. Western Gulf of Mexico shelf area ( 27.55423 ° N latitude, 96.76627 ° W longitude); and

5. We stern Gulf of Mexico slope area ( 27.51367 ° N latitude, 94.51836 ° W longitude).

The results for Launch Point 3 , the launch point nearest to the project area, are presented in
Table 3

.
OSRA is a preliminary risk assessment model. In the event of an actual oil spill, real

- time monitoring and trajectory modeling would be conducted using current and wind data available from the rigs and permanent production structures in the area

. Satellite and aer ial monitoring of the plume and real

- time trajectory modeling using wind and current data would continue on a daily basis to help position equipment and human resources throughout the duration of any major spill or uncontrolled release

.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 13 Table 3. Conditio nal probabilities expressed as percent chance that an oil spill starting at Launch Point 3 will contact a certain parish, county, or coastline within 120 d ays (Modified from: BOEM, 2012b, Appendix C).

Season Winter Spring Summer Fall

Day 3 10 30 120 3 10 30 120 3 10 30 120 3 10 30 120 County or Parish , State Percent Chance
Cameron, TX

-- -- -- 2

-- -- -- -- -- -- -- 2

-- -- -- 2 Willacy, TX

-- -- -- 3

-- -- -- -- -- -- -- 2

-- -- -- 3 Kenedy, TX

-- -- -- 8

-- -- -- 1

-- -- -- 9

-- -- -- 5 Kleberg, TX

-- -- 1 6

-- -- -- -- -- -- -- 4

-- -- 1 6
Nueces, TX

-- -- 1 6

-- -- -- -- -- -- -- 2

-- -- 1 2
Aransas, TX

-- -- -- 5

-- -- -- 1

-- -- -- 3

-- -- -- 2 Calhoun, TX

-- -- 1 6

-- -- -- -- -- -- -- 6

-- -- 1 4 Matagorda, TX

-- -- 2 17

-- -- 3 4

-- -- -- 11

-- -- 1 6
Brazoria, TX

-- -- 3 12

-- -- 1 3

-- -- 2 8

-- -- 1 5 Galveston, TX

-- -- 3 10

-- -- 3 6

-- -- 2 5

-- -- 1 4 Jefferson, TX

-- -- 1 4

-- -- 7 9

-- -- 1 1

-- -- -- 2
Cameron, TX

-- -- 1 4

-- -- 11 12

-- 1 1 4

-- -- -- 4 Vermilion, LA

-- -- 1 2

-- -- 5 6

-- 1 1 2

-- -- -- -- Iberia, LA

-- -- -- 1

-- -- 4 4

-- -- -- -- -- -- -- -- Terrebonne, LA

-- 1 2 3

-- 4 12 14

-- -- -- 2

-- -- -- -- Lafourche, LA

-- -- 1 1

-- 2 8 10

-- -- 1 2

-- -- -- -- Jefferson, LA

-- -- -- 1

-- -- 2 2

-- -- 1 1

-- -- -- -- Plaquemines, LA

-- -- -- 1

-- 2 10 12

-- -- 1 2

-- -- -- -- Jackson, MS

-- -- -- -- -- -- 1 1

-- -- -- -- -- -- -- -- Baldwin, AL

-- -- -- -- -- -- 1 1

-- -- -- -- -- -- -- -- Bay, FL

-- -- -- -- -- -- -- 1

-- -- -- -- -- -- -- -- Franklin, FL

-- -- -- 1

-- -- -- -- -- -- -- -- -- -- -- -- Monroe, FL

-- -- -- -- -- -- -- -- -- -- -- 1

-- -- -- 1

Miami

- Dade, FL

-- -- -- -- -- -- -- -- -- -- -- 1

-- -- -- --

"— " = V alues < 1.0% . A reas where there is <0.5% chance of contact within 120 days are not shown.

Weathering

Weathering decreases the concentration of oil and produces changes in its chemical composition, physical properties, and toxicity. The more toxic, light aromatic and aliphatic hydrocarbons are lost rapidly by evaporation and dissolution from a slick on the water surface. Evaporated hydrocarbons are degraded rapidly by sunlight. Biodegradation of oil on the water surface and in the water column by marine bacteria removes first the n

- alkanes and then the light aromatics from the oil. Other petroleum components are biodegraded more slowly.
Photo

- oxidation attacks mainly the medium and high molecular weight PAHs i n the oil on the
water surface. . Following an oil spill, several physical, chemical, and biological processes, collectively called weathering, interact to change the physical and chemical properties of the oil, influencing potential effects to marine organisms and ecos ystems. The most important weathering processes include spreading, evaporation, dissolution, dispersion into the water column, formation of water

- in

- oil emulsions, photochemical oxidation, microbial degradation, adsorption to suspended particulate matter, and stranding on shore or sedimentation to the seafloor (National Research Council, 2003 a ).Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 14 Spill Response

. BOEM has issued re c ent NTLs following the Macondo spill that clarify additional
oil

- spill prevention and response planning requirements. These NTL s are summarized in Table 1

, and additional BOEM (2012 b) guidance is provided below.

NTL 2012

- N06 – Guidance to Owners and Operators of Offshore Facilities Seaward of the Coast Line Concerning Regional Oil Spill Response Plans : This NTL, effective 10 August 2012, provides clarification, guidance, and information on the preparation and submittal of regi onal OSRPs for owners and operators of oil handling, storage, or transportation facilities, inclusive of pipelines, located seaward of the coastline. It states that lessees, designated operators, and pipeline right

- of

- way holders are responsible for prepa ration and submission of these plans. Some of the clarifications and recommended practices in the NTL are based on lessons learned from the Macondo oil spill response.

NTL 2010

- N10 – Statement of Compliance with Applicable Regulations and Evaluation of

In

formation Demonstrating Adequate Spill Response and Well Containment Resources : This NTL, effective 8 November 2010, applies only to operators conducting operations using subsea or surface BOPs on floating facilities. It requires that lessees and operators must submit a statement signed by an authorized company official with each well permit application indicating that they will conduct all of their authorized activities in compliance with all applicable regulations, including the Increased Safety Measures Regulations at

75 FR 63346. The NTL also informs lessees that BOEMRE will evaluat e whether the operator has submitted adequate information demonstrating that it has access to and can deploy surface and subsea containment resources that would be adequate to promptly respond to a blowout or other loss of well control. The NTL notifies the operator that BOEMRE intends to evaluate the adequacy of each operator to comply in the operator’s current OSRP; therefore, there is an incentive for voluntary compliance.

NTL 2010

- N06

– Information Requirements for Exploration Plans, Development and Production Plans, and Development Operations Coordination Documents on the OCS

Anadarko ’s Regional OSRP was last approved on 25 September 2013. The OSRP provides a detailed plan for Anadarko to respond to rapidly and effectively manage oil spills that may result from drilling and production operations. The OSRP contains detailed information on "Quick Response" procedures

, including: : This NTL, effective 18 June 2010, explains the procedures for the les see or operator to submit supplemental information for new or previously submitted EPs, Development and
Production Plans , or D evelopment O perations C oordination D ocument s. The required supplemental information includes the following: ( 1) a description of the blowout scenario as required by 30 CFR 254(b) and 254(h) ; ( 2) a description of their assumptions and calculations used in determining the volume of the WCD required by 30 CFR 254.26 ; and ( 3) a description of the measures proposed that would enhance the ability to prevent a blowout, to reduce the likelihood of a blowout, and to conduct effective and early intervention in the event of a blowout, including the arrangements for drilling relief wells and any other measures proposed. The early intervention m ethods of the third requirement could actually include the surface and subsea containment resourc es that
BOEM announced in NTL 2010

- N10, which states that BOEM will review to ensure that the measures are adequate to promptly respond to a blowout or other l oss of well control.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 15 • responsibilities of all Anadarko and contract personnel to report any observed discharge from known or unknown sources;

• procedures to locate and determi ne the size of a discharge; an d

• contact information for alerting the spill management team complete with names, phone numbers, and locations.

In the event of a WCD, Anadarko has access to surface and subsea response/containment capabilities that could be implemented through various org anizations under contract.
Anadarko’s primary spill response equipment provider is Clean Gulf Associates (CGA).

CGA has four skimming vessels capable of operating in shallow waters and offshore/nearshore

areas. These vessels have o leophilic brush pack sk imming systems operating in troug hs built
into the hulls

, below

- deck storage

, and marine electronics packages including marine, aircraft and company

- frequency radios ; radar ; moving map plotters ; GPS; satellite phone s; and depth
finders. CGA also offers ni ne Fast Response Systems staged throughout the Gulf of Mex ico
available for offshore use.

The CGA high

- volume open sea skimmer ( HOSS ) barge consists of a skimming system built into an oil recovery barge. There are four 1,000

- bbl recovered oil storage tanks built into the hull where oil can be separated and offloaded. Skimming operations are conducted from the control room overlooking the skimmer deck. The estimated daily recovery capacity for the HOS S barge is approximately 43, 000 bbl

.
CGA is currently adding to its equipment stockpile and has acquired 11 sets of Koseq skimming arms and two Aqua Guard skimmers. In addition, an x

- band radar/infrared tracking system is installed on the HOSS barge. Additional CGA equipment can be referenced on the ir website at http://www.cleangulfassoc.com/equipment

.

Anadarko also has a contract with the Marine Spill Response Corporation (MSRC) for additional spill response equipment. MSRC has a dedicated fleet for the Atlantic/ Gulf of Mexico region and additional available equipment staged throughout the U

. S. MSRC equipment staged throughout
the Gulf of Mexico includes seven oil spill response vessels, two fast response vessels, five oil spill response barges, five platform supply vessels, and 15 shallow water barges. Various equipment is outfitted with x

- band and infrared technology.

MSRC recently completed a large expansion of its resources and capability in the Gulf of Mexico,
with particular focus on deepwater. The expansion is known as " Deep Blue. " Additional MSRC capabilities and a complete equipment listing are available on

- line at http://www.msrc.org/services/oil -s pill -response

.
Anadarko also is a member of the Marine Well Containment Company (MWCC). In the event of an incident, MWCC can provide a 15,000

- psi single ram capping stack and dispersant injection capability. MWCC can also install and operate the interim containment system, including subsea flowlines, manifold, and risers. The interim system is engineered to be used in depths up to 3,048 m (10,000 ft) and has the capacity to contain 60,000 barrels of liquid per day (BLPD) (and 120 million standard cubic feet per day [MMSCFD] of gas) with potential for expansion.

See EP Section H f or a detailed description of Anadarko ’s site

- specific response to the WCD for this plan.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 16 

### A.9.4 Other Accidents Not Analyzed in Detail

BOEM (2012b) discusses three other types of accidents: chemical spills, vessel collisions, and
loss of well control. The information from the EIS on these topics remains valid and is incorporated by reference into this document. These accidents are discussed briefly below along with a hydrogen sul fide ( H 2 S) release . T here are no other site

- specific issues for the drilling of the well s proposed in this EP.

Chemical Spills

. Chemicals are stored and used to condition drill muds and during production and in well completions, stimulation, and workover procedures. The relative quantity of their use is reflected in the largest volumes spilled. Completion fluids are the largest q uantity used
and comprise the largest releases. Between 5 and 15 chemical spills are anticipated each year, with the majority being <50 bbl in size. The most common chemicals spilled are methanol, ethylene glycol, and zinc bromide. Additional production chemicals are needed in deepwater operations where gas hydrates tend to form. Spill volumes are anticipated to remain about the same, but spill frequency can be expected to decrease because of advances in subsea processing ( BOEMRE, 2011 a ; BOEM, 2012 b).

R iser Disconnect SBM Spills

. In deepwater drilling, SBMs a re preferred over petroleum oil

- based muds (OBMs) due to the superior environmental properties of SBMs

. The synthetic base fluid s used in SBMs are less toxic to the marine environment and have the potential to biodegrade.
SBMs have been used in the Gulf of Mexico since the mid

- 1990 s , and between 5 and 20 SBM releases are anticipated each year as a result of offshore drilling programs. The majority of these releases are <50 bbl in size, but acciden tal riser disconnects may result in the release of medium (238 to 2,380 bbl) to large (>2,38 0 bbl) quantities of dril ling fluids. Riser disconnect accidents are of particular concern when SBM s are in use ( BOEMRE , 201 1b ).

Vessel Collisions

. BOEM data show that from 1996 to 2009 there were 226 OCS

- related
collisions. Most collision mishaps are the result of service vessels colliding with platforms or vessel collisions with pipeline risers. Approximately 10 % of vessel collisions with platform s in
the OCS resulted in diesel spills , and in several collision incidents , f ires resulted from hydrocarbon releases. To date, the largest diesel spill associated with a collision occurred in
1979 when an anchor

- handling boat collided with a drilling platform in the Main Pass leas e area, spilling 1,500 bbl. Diesel fuel is the product most frequently spilled

, but oil, natural gas, corrosion inhibitor, hydraulic fluid, and lube oil have also been released as the result of vessel
collision s

. Human error acc ount ed for approximately half of all reported vessel collisions from

2006 to 2009. As summarized in MMS (2007b ) and BOEM (201 2b ), vessel collisions occasionally occur during routine operations. Some of these collisions have caused spills of diesel fuel o r chemicals. Anadarko will comply with all USCG and BOEM mandated safety requirements to minimize the potential for vessel collisions.

Loss of Well Control . A loss of well control is the uncontrolled flow of a reservoir fluid that may
result in the relea se of gas, condensate, oil, drilling fluids, sand, or water. Loss of well control is a broad term that includes very minor up to the most serious well control incidents, while blowouts are considered to be a subset of more serious incidents with greater r isk of oil spill or human injury (MMS, 2007b). Loss of well control may result in the release of synthetic drilling
fluid or loss of oil. Anadarko has a robust system in place to prevent loss of well control.

M easures to prevent a blowout

, reduce the likelihood of a blowout, and conduct effective and early intervention in the event of a blowout are described in the NTL 2010

- 06 packageAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 17 submitted with the exploration plan, as required

. The potential for a loss

- of

- well

- control event will be minimized by adhering to the requirements of applicable regulations such as the Final Drilling Safety Rule and NTL 2010

- N10 , which specify additional safe ty measures for

OCS activities.

H 2 S Release

. Pursuant to 30 CFR 250.490(c), Anadarko is proposing that the lease area be
classified as a zone where the absence of H 2 S has been confirmed.



## B. Affected Environment

Based on the site clearance survey conducted by Gardline Surveys, Inc (Gardline, 2013), w ater depth s at the wellsites are anticipated to range from 1,270 to 1,351 m (4,167 to 4,433 ft). ( Figure 2 ). The seafloor at all of the proposed wellsites appear s to be smooth and featureless.

No anomalous seabed amplitudes indicative of hydrocarbon macroseeps, items of archaeological significance, or other features that could affect the well emplacements, jettings, or casings were identified within 610 m (2,000 ft) of the proposed wellsites (Gardline, 2013).

A detailed description of the regional affected environment, including meteorology,

oceanograp hy, geology, air and water quality, benthic communities, threatened and endangered species, biologically sensitive resources, archaeological resources, socioeconomic conditions, and other marine uses i s provided in MMS ( 2007b ) and BOEM ( 2012b ). These regi onal descriptions remain valid and are incorporated by reference. General background information is presented below, and brief descriptions of each potentially affected resource, including site

- specific and/or new information if available

, are presented i n Section C

.



## C. Impact Analysis

This section analy z es the potential direct and indirect impacts of routine activities and accidents. Impacts have been analyzed extensively in multi

- lease

- sale EISs for the Western and Central Gulf of Mexico Planning Area s (MMS, 2007b ; BOEM, 2012b )

. The information in these documents is incorporated by reference. Potential s ite

- specific issues are addressed in this section.



## C.1 Physical/Chemical Environment

C.1.1 Air Quality

There are no site

- specific air quality data fo r the project area due to the distance from shore

. Because of the distance from shore

- based pollution sources and the lack of sources offshore

, air quality at the wellsites is expected to be good. The attainment status of Federal OCS waters is
unclassifi ed because there is no provision in the Clean Air Act for classification of areas outside

State waters (MMS, 2007b)

.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 18 Figure 2. Bathymetric map of the lease area showing the surface hole location s of the proposed wellsites.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 19 As noted earlier, based on calculations made pursuant to applicable regulations, emissions from drilling activities are not expected to be significant as they are below exemption levels. Therefore, the only potential effects to air quality would be from routine air pollutant emissions,

a small fuel spill , and a large oil spill (WCD).

BOEM has reexamined the analysis for air quality presented in MMS (2007b, 2008) based on
additional information and in consideration of the Macondo oil spill event

. No substa ntial new
information was found that would alter the potential impact s on air quality presented in BOEMRE (2011a) and BOEM (2012b).



### Impacts of Air Pollutant Emissions

Air pollutant emissions are the only routine IPF likely to affect air quality. Offshore air pollutant emissions will result from the drilling rig operations and helicopters and service vessels. These emissions occur mainly from combustion or burning of diesel fuel. The combustion of fuels occurs primarily on diesel

- powered generators, pump s, or motors and from lighter fuel motors. Primary air pollutants typically associated with OCS activities are suspended PM, SO
x , NO
x , VOCs,
and CO. Emissions of pollutants into the atmosphere from these activities are not projected to have significant effects on onshore air quality because of the prevailing atmospheric conditions, emission rates and heights, and resulting pollutant concentrations. T he incremental
contribution to cumulative impacts from activities similar to Anadarko’s proposed activitie s is not significant and will not cause or contribute to a violation of any N ational A mbient A ir Q uality

S tandard (NAAQS) (MMS, 2007b

, 2008). Since the BOEM completed the lease sale EISs, the USEPA has adopted a new short

- term NAAQS for nitrogen dioxide (NO 2 ) . The standard has not yet been implemented in the Gulf Coast states, but given the levels of expected emissions and the distance of the project from shore, emissions from the activities described in Anadarko’ s

propose d EP are not likely to contribu te to violations of any NAAQS onshore.

Carbon dioxide (CO 2 ) and methane ( CH 4 ) emissions from the project would constitute a small incremental contribution to greenhouse gas emissions from all OCS activities. According to the Programmatic EIS (MMS, 2007a), estimated CO 2 emissions from all OCS activities in the

2007

- 2012 leasing program are about 0.08% to 0.016% of the global CO 2 emissions from fossil fuel combustion. Greenhouse gas emissions may contribute to climate change, with important impacts on tempe rature, rainfall, frequency of severe weather, ocean acidification, and sea level rise (Intergovernmental Panel on Climate Change, 2007). Greenhouse gas emissions from this proposed project represent a negligible contribution to the total greenhouse gas e missions from reasonably foreseeable activities in the Gulf of Mexico area and would not significantly alter any of the climate change impacts evaluated in MMS ( 2007 a, b)

. Because of the distance from shore, routine operations in the project area are not ex pected to have any impact on air quality conditions along the coast, including nonattainment areas. As noted in MMS ( 2007b) , emissions of air pollutants from routine activities in the Central and Western Gulf of Mexico Planning Area are projected to have minimal impacts to onshore air quality because of the prevailing atmospheric conditions, emission heights, emission rates, and the distance of these emissions
from the coastline

. The Air Quality Emissions Report ( see EP Section G ) p repared in accordance
with BOEM requirements shows that the projected emissions are below exemption levels; therefore, according to 30 CFR 250.303

, the emissions will not significantly affect the air quality of the onshore area for any of the criteria poll utants. No further analysis or control measures are required

.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 20 The Breton Wilderness Area, which is part of the Breton National Wildlife Refuge (NWR), is designated under the Clean Air Act as a Prevention of Significant Deterioration (PSD) Class I air qual ity area. The BOEM is required to notify the National Park Service (NPS) and U.S. Fish and Wildlife Service ( USFWS ) if emissions from proposed projects may affect the Breton Class I area. Additional review and mitigation measures may be required for sour ces within 186 miles (300 km) of the Breton Class I area that exceed emission limits agreed upon by the administering agencies (NPS, 2010). The lease area is approximately 105 miles (169 km) from the Breton
Wilderness Area

, and no air quality impacts on the Wilderness Area are expected. Anadarko will comply with all BOEM r equirements regarding air emissions.



### Impacts of a Small Fuel Spill

Potential impacts o f a small spill on air quality are expected to be consistent with th os e analyzed
and discussed in M MS ( 2007b ) and BOEM ( 2012 b ,d ). The probability of a small spill would be minimized by Anadarko’ s preventative mea sures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Anadarko’ s OSRP could reduce the potential impacts

. EP Section H includes a detailed discussion of the spill response measures that would be employed

. Given the open ocean location of the lease area, the extent and duration of air quality impacts from a small spill would not be significant.

A small fuel spill would affect air quality near the spill site by introducing VOCs through evaporation. The ADIOS2 model ( see Section A.9.2 ) indicates that over 90% of a small diesel spill would be evaporated or dispersed within 24 hours. T he sea surface area with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac) depending on sea state and weather conditions.

A small fuel spill would not affect coastal air quality because the spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

Potential impacts of a large oil spill on air quality are expected to be consistent with th os e analyzed and discussed in MMS ( 2007b ) and BOEM ( 2012 b ,d).

A large oil spill (WCD) could potentially affect air quality by introducing VOCs through evaporation from the slick. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response

measures. Real

- time wind and current data from the project area would be available at the time of a spill and would be used to assess the fate and effects of VOCs released. Additional air quality impacts could occur if response measures i ncluded in situ burning of the floating oil. Burning would generate a plume of black smoke and result in emissions of NO x , SO
x , CO, and PM, as well as greenhouse gases. However, in situ burning would occur only after authorization
from the USEPA.

Due to the lease area’s distance from the nearest shoreline, most air quality impacts would
occur in offshore waters with minimal chance s to affect onshore air quality.



### C.1.2 Water Quality

There are no site

- specific water quality data for the lease area. Due to the lease location in deep, offshore waters, water quality is expected to be good, with low levels of contaminants.

As noted in MMS ( 2007b), deepwater areas in the northern Gulf of Mexico are relativelyAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 21 homogeneous with respect to temperature, salinity, and oxygen. Kennicutt (2000) noted that the deepwater region has little evidence of contaminants in the dissolved or particulate phases of the water column. However, there are localized occurrences of natural seepage of oil, gas,
and brines in near

- surfac e sediments and up through the water column.

The lease area is located approximately 68 miles (109 km) fr om the Macondo spill site . Based on the general circulation pattern seen in the Gulf of Mexico and satellite imagery, the surface
slick from that discharge did extend over the lease area during the spill

, and there is the possibility that water quality in the lease area was briefly affected.

IPFs potentially affecting water quality are effluent discharges and two types of accidents –

a small fuel spill and a large oil spill (WCD).



### Impacts of Effluent Discharges

In general, turbid water can be expected to extend between a few hundred meters and several kilometers down current from the discharge point for water

- based drilling muds and cuttings. SBMs will be collected on the rig and either reused by the vendor, or transported to

Port Fourchon , Louisiana for recycling and/or disposal in an approved facility. Cuttings wetted with SBMs will be discharged to the seafloor in accordance with the NPDES permit. All NPDES permit limitations and requirements will be met. There will be no persistent impacts on water quality in the lease area ( National Research Council , 1983; Neff, 1987 ; Neff et al., 2000 ).

Treated sanitary and domestic wastes , including those from support vessels, may have a slight transient effect on water quality in the immediate vicinity of these discharges. All NPDES permit limitations and requirements and USCG regulations (as applicable) will be met , therefore, l ittle or no impact on water quality is anticipated.

Deck drainage includes all effluents resulting from rain, deck washings, and runoff from curbs, gutters, and drains, including drip pans in work areas. Rainwater that falls on uncontaminated areas of the drilling rig will flow overboard without treatment. However, rainwater that falls on the drilling rig deck and other areas such as chemical storage areas and places where equipment is exposed will be collected and oil and water separated to meet NPDES permit requirements.

Ba sed on adherence to permit limits and applicable regulations, little or no impact on water quality is anticipated.

Other discharges in accordance with the NPDES permit, such as desalination unit brine and uncontaminated cooling water, fire water, and ballast water are expected to be diluted rapidly

, resulting in little or no impact on water quality.



### Impacts of a Small Fuel Spill

Potential impacts of a small spill on wate r quality are expected to be consistent with th os e analyzed and discussed in MMS ( 2007b ) and BOEM ( 2012 a, b ). The probability of a small spill would be minimized by Anadarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Anadarko’s OSRP could potentially help mitigate and reduce the impacts. EP Section H provides detail on spill response

measures in addition to the summary information provided in this EIA

. Given the open ocean location of the lease area, the extent and duration of water quality impacts from a small spill would not be significant.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 22 A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. However, it is estimated that over 90% of a small diesel spill would be evaporated or dispersed within 24 hours (see Section A.9.2 ).
Th e sea surface area with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac) depending
on sea state and weather conditions.

The water

- soluble fractions of diesel are dominated by two - and three

- ringed PAH s , which are moderately volatile (National Research Council, 2003 a ). The constituents of these oils are light to intermediate in molecular weight and can be readily degraded by aerobic microbial oxidation. Because the density of diesel is less than the density of seawater, diesel will not sink an d pool on the seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this generally occurs only in coastal areas with high suspended solid loads (National Research Council, 2003 a ) and would not be expected to occur to any appreciable degree in offshore waters of the Gulf of Mexico. Diesel oil is readily and completely degraded by naturally occurring microbes (NOAA, 2006).

A small fuel spill would not affect coastal water quality because the spill would not be expected

to m ake landfall or reach coastal waters due to both response efforts that would be undertaken
as well as natural attenuation (see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

Potential impacts of a large oil spill on wate r quality are expected to be consistent with th os e analyzed and discussed in MMS ( 2007b ) and BOEM ( 2012b,d ). A large spill w ould affect water quality by producing a slick on the water surface and increasing the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Most of the oil would be expected to form a slick at the surface, although new information from the Macondo spill indicates that plumes of submerged oil droplets can be produced when subsea dispersants are applied at the wellhead (Camilli et al., 2010; Hazen et al., 2010; Joint Analysis Group, 2010a,b,c). However, dispersants would be applied only after approval from the USEPA. Small droplets in the water may adhere to suspended sediment s and be removed from the water column (Operational Scientific Advisory

Team [ OSAT ], 2010).

Because of the lease area ’s distance to the nearest shoreline , it i s expected that most water quality impacts would occur in offshore waters, especially in the event of a spill lasting less than 30 days ( Table 3 ).



## C.2 Seafloor Habitats and Biota

W ater depth s at the proposed project area range from 1,270 to 1,351 m (4,167 to 4,433 ft)

. The seafloor at the proposed wellsites is smooth and featureless. No anomalous seabed amplitudes indicative of hydrocarbon macroseeps were seen within 610 m (2,000 ft) of any of the wellsites ( Gardline, 2013).

Based on the absence of hard bottom areas detected by side

- scan sonar during the site
clearance s urvey, the seafloor within 610 m (2,000 ft) of the wellsites is expected to consistAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 23 mainly of soft bottom communities. The site clearance survey did not identify any features that could support high

- density deepwater benthic communities within 610 m (2,000 ft) of the
wellsites

, and the presence of chemosynthetic communities is considered negligible ( Gardline, 2013).



### C.2. 1 Soft Bottom Benthic Communities

There are no site

- specific benthic community data from the lease area. However, data from the Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology Study (Wei, 2006;

Rowe and Kennicutt, 2009) can be used to describe typical benthic communities in the area.
Table 4 summarizes data collected at stations in water depths similar to the proposed drilling

area.

Table 4. Benthic community data from stations near the lease area and in similar water depths sampled during the Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology Study (Adapted f rom: Wei, 2006; Rowe and Kennicutt, 2009).

Station Water Depth (m) Abundance

Meiofauna (individuals/m 2 ) Macroinfauna (individuals/m 2 ) Megafauna (individuals/ha)

MT4 1,401 246,058 3,262 1,548

C4 1,463 273,585 3,045 743

Meiofaunal and megafaunal abundances from Rowe and Kennicutt (2009); macroinfaunal abundance from

Wei (2006).

Densities of meiofauna (animals passing through a 0.5

- mm sieve but retained on a 0.062

- mm sieve) in water depths representative of the lease area ( 1,270 to 1,351 m [ 4,167 to 4,433 ft ]) typically range from approximately 185,000 to 285,000 individuals/m 2 (Rowe and Kennicutt, 2009). Nematodes, nauplii, and harpacticoid copepods were the three dominant meiofaunal groups, accounting for about 90% of total abundance.

The benthic macroinfauna is characterized by small mean individual sizes and low densities, both of which reflect the meager primary production in Gulf of Mexi co surface waters (Wei, 2006). Densities decrease exponentially with water depth. Based on an equation presented by Wei (2006), macroinfaunal densities in the water depths of the lease area are expected to be about 2,652 individuals/m 2

.
Polychaetes are t ypically the most abundant macroinfaunal group on the northern Gulf of

Mexico continental slope, followed by amphipods, tanaids, bivalves, and isopods. Wei (2006) recognized four depth

- dependent faunal zones (1 through 4), two of which are divided
ho r izon tally. The lease area is in Zone 2E, which includes parts of the mid Texas

- Louisiana slope, the west flank of the Mississippi Fan, the mid Mississippi Canyon, the head of De Soto Canyon, and the mid West Florida Terrace, with stations ranging in depth fro m 625 to 1, 828 m (2,051 to 5,997 ft )

. The most abundant species in Zone 2E were the polychaetes Litocorsa antennata

, Aricidea suecica

, Tharyx marioni

, Paralacydonia paradoxa , and the bivalve Heterodonta sp . D (Wei, 2006).Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 24 Megafaunal densities from nearby s tations ranged from 625 to 1,548 individuals/ha. Common megafauna included motile groups such as decapods, ophiuroids, holothurians, and demersal fishes as well as sessile groups such as sponges and anemones.

Bacteria also are an important component in t erms of biomass and cycling of organic carbon (Cruz

- Kaegi, 1998). Bacterial biomass at the depth range of the lease area typically is about

1 to 2 g C/m 2 in the top 15 cm (6 in.) of sediments (Rowe and Kennicutt, 2009).

IPFs potentially affecting benthic communities are physical disturbance to the seafloor, effluent discharges (drilling muds and cuttings), and a large oil spill (WCD) resulting from a well blowout
at the seafloor. A small fuel spill would not affect benthic communities because the diesel fuel would float and dissipate on the sea surface.



### Physical Disturbance to the Seafloor

In water depths such as those encountered in the lease area, the areal extent of seafloor impacts will be small compared to the lease area itself .T hese type s of s oft bottom communities are ubiquitous along the northern Gulf of Mexico continental slope (Gallaway, 1988; Gallaway et al., 2003; Rowe and Kennicutt, 2009 ) and i mpacts from the physical disturbance of the seafloor during this pr oject will have no significant impact on soft bottom benthic communities in the region.



### Impacts of Effluent Discharges

Drilling muds and cuttings are the only effluents that are likely to affect benthic communities. During initial well interval(s) before the marine riser is set, cuttings and seawater

- based " spud
mud " will be released at the seafloor. Excess cement slurry will also be released at the seafloor during casing installation for the riserless portion of the drilling operations. Cement slurry

co mponents typically include cement mix and some of the same chemicals used in water

- based drilling muds (Boehm et al., 2001). The main impacts will be burial and smothering of benthic organisms within several meters to tens of meters around the wellbore. Soft bottom sediments disturbed by cuttings, drilling muds, and cement slurry will eventually be recolonized through larval settlement and migration from adjacent areas. Because some deep

- sea biota grow and reproduce slowly, recovery may require several y ears.

Discharges of washed SBM cuttings from the rig may affect benthic communities, primarily within several hundred meters of the wellsite. The fate and effects of SBM cuttings have been reviewed by Neff et al. (2000), and monitoring studies have been c onducted in the Gulf of Mexico by Continental Shelf Associates, Inc. (2004, 2006). In general, washed cuttings with adhering SBMs tend to clump together and form thick cuttings piles close to the drillsite. Areas of SBM cuttings deposition may develop elevated organic carbon concentrations and anoxic conditions (Continental Shelf Associates, Inc., 2006). Where SBM cuttings accumulate in concentrations of approximately 1,000 mg/kg or higher, benthic infaunal communities may be adversely affected due to bo th the toxicity of the base fluid and organic enrichment (with resulting anoxia) (Neff et al., 2000). Infaunal numbers may increase and diversity may decrease as opportunistic species that tolerate low oxygen and high H 2 S predominate (Continental Shelf

As sociates, Inc., 2006). As the base synthetic fluid is decomposed by microbes, the area will gradually return to pre

- drilling conditions. Disturbed sediments will be recolonized through larval settlement and migration from adjacent areas.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 25 T he areal extent of impacts from drilling discharges will be small. Assuming a typical effect
radius of 500 m (1,640 ft), the affected area around the wellsite would represent about 3% of the seafloor within a lease block. Soft bottom communities are ubiquitous along th e northern Gulf of Mexico continental slope (Gallaway, 1988; Gallaway et al., 2003; Rowe and Kennicutt, 2009). Impacts from drilling discharges during this project will have no significant impact on soft bottom benthic communities in the region.



### Impacts o f a Large Oil Spill (WCD)

The most likely effects of a subsea blowout on benthic communities would be within a few
hundred meters of the wellsite. The MMS (2007b) estimat ed that a severe subsurface blowout could resuspend and disperse sediments within a 300

- m (984

- ft) radius. While coarse sediments (sands) would probably settle at a rapid rate within 400 m (1,312 ft) from the blowout site, fine sediments (silts and clays) c ould be resuspended for more than 30 days and dispersed over a much wider area. Based on previous studies, surface sediments at the project area are assumed to largely be silt and clay ( Rowe and Kennicutt, 2009 ).

Discussions in MMS ( 2007a, 2008) in dicat ed that oil spills would be unlikely to affect benthic communities beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, du ring the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 22 miles ( 35 km ) from the wellsite and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resul ted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could contact the seafloor and affect benthic communities beyond the 300

- m (984

- ft) r adius estimated by MMS (2007a, 2008)

, depending on its extent, trajectory, and persistence. This contact could result in smothering and/or toxicity to benthic organisms. The affected area would be recolonized by benthic organisms over a period of months to years (National Research Council, 2003 a ).



### C.2.2 High

- Density Deepwater Benthic Communities

As defined by NTL 2009

- G40, high

- density deepwater benthic communities are f eatures or areas that could support high

- density chemosynthetic communities, or featur es or areas that could support high

- density deepwater corals and other associated high

- density hard bottom

communities. Chemosynthetic communities were discovered in the central Gulf of Mexico in 1984 and have been studied extensively (MacDonald, 2002). Deepwater coral communities are also known from numerous locations in the Gulf of Mexico (Brooke and Schroeder, 2007;

CSA International, Inc., 2007). These communities occur almost exclusively on authigenic carbonates created by chemosynthetic communities

.
The nearest known chemosynthetic community site is approximately 51 miles (82 km) west of
the lease area in Mississippi Canyon (MC) Block 969 . The nearest identified deepwater coral

communities are in MC 943, 8 miles (13 km) north

- northeast of the lease area

.

The geohazards assessment of the lease area did not identify any features that could support high

- density deepwater benthic communities within 610 m (2,000 ft) of the proposed drilling
mud /cuttings discharge locations ( Gardline, 2013)

.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 26 IPFs potentially affecting high

- density deepwater benthic communities include physical disturbance of the seafloor, effluent discharges (drilling muds and cuttings), and a large oil spill (WCD) from a well blowout at the seafloor. A small fuel spill would not affect benthic communities because the diesel fuel would float and dissipate on the sea surface.



### Physical Disturbance to the Seafloor

In water depths such as are encountered in the lease area, DP semisubmersibles disturb the seafloor only around the wellbo re (SHL) where the bottom template and BOP are located. Depending upon the specific well configuration, this area is gene rally about 0.25 ha (0.62 ac).

T he areal extent of these impacts from the DP rig will be small , and NTL 2009

- G40 requires that high

- de nsity deepwater benthic communities and f eatures or areas that could support high

- density chemosynthetic communities, or deepwater corals communities be avoided

. Based
on the Gardline (2013) report, there will be no impacts on chemosynthetic or deepwater coral communities from this project.



### Impacts of Effluent Discharges

The site clearance survey ( Gardline, 2013) did not identify any features that could support high

- density deepwater benthic communities within 610 m (2,000 ft) of the proposed drilling locations, and the presence of chemosynthetic communities in the lease area is considered negligible

. Mo nitoring programs on the Gulf of Mexico continental slope have shown that benthic impacts from drilling discharges typically are concentrated within about 500 m (1,640 ft )
of the wellsite , although detectable deposits may extend beyond this distance (Continental Shelf Associates, Inc., 2004, 2006; Neff et al., 2005). Because of the water depth of the lease area, drilling discharges would be expected to result in thinner, more diffuse accumulations on the seafloor than those documented in the literature. Although small amounts of cuttings particles may reach areas inhabited by high

- density deep water benthic communities, the discharges are not expected to result in significant impacts to these communities.



### Impacts of a Large Oil Spill (WCD)

Previous analyses (MMS, 2007a, 2008) concluded that oil spills would be unlikely to affect benthic communities beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 22 miles ( 35 km ) from the wellsite and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could have the potential to contact hig h- density deepwater benthic communities beyond the 300

- m (984

- ft) radius estimated by MMS (2007a, 2008)

, depending on its extent, trajectory, and persistence. Oil plumes that contact sensitive benthic communities before degrading could potentially impact the resource (BOEM, 2012b). Potential impacts on sensitive resources would be an integral part of the decision and approval process for the use of dispersants , and such approval would be obtained from the USEPA prior to the use of dispersants

.
The biologi cal effects and expected fate of the oil remaining in the Gulf of Mexico from the blowout are still unknown due to the depth and the magnitude of this event. Hazen et al. (2010)Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 27 reported changes in plume hydrocarbon composition with distance from the source . I ncubation experiments with environmental isolates demonstrated faster than expected hydrocarbon biodegradation rates at 5°C. Based on these results, Hazen et al. (2010) suggested the potential exists for intrinsic bioremediation of the oil plume in the deep water column without substantial oxygen drawdown.

Potential impacts of oil on high

- density deepwater benthic communities are discussed in

MMS (2007b). Although chemosynthetic communities live among hydrocarbon seeps, natural seepage is very c onstant and occurs at low rates compared to the potential rates of oil release from a blowout. In addition, seep organisms also require unrestricted access to oxygenated water at the same time as exposure to hydrocarbon energy sources (MacDonald, 2002). Oil droplets or oiled sediment particles could come into contact with chemosynthetic organisms or deepwater corals. As discussed by MMS (2007b), impacts could include loss of habitat, biodiversity, and live coral coverage; destruction of hard substrate; c hange in sediment characteristics; and reduction or loss of one or more commercial and recreational fishery habitats. Sublethal effects could be long

- lasting and affect the resilience of coral colonies to natural disturbances (e.g., elevated water tempera ture and diseases) (BOEM

, 2012d)

.
The potential for a spill to affect deepwater corals is indicated by preliminary findings from a recent (October 2010) survey of deepwater coral habitats near the Macondo spill site (BOEMRE, 2010). Government and academic researchers were working at a site 1,400 m (4,600 ft) deep and approximately 7 miles (11 km) southwest of the Macondo wellhead when they observed dead and dying corals with sloughing tissue and discoloration. Much of the soft
coral observed in an area me asuring about 15 by 40 m (50 by 130 ft) was covered by what appeared to be a brown flocculent substance (floc). Out of 40 large corals, 90% were heavily affected and showed dead and dying parts and discoloration. Another site 400 m (1,312 ft) farther away had a colony of stony corals similarly affected and partially covered with a similar brown substance. Based on hopanoid petroleum biomarkers from the floc, researchers concluded that it contained oil from the Macondo spill. The injured and dead corals were in an area where a subsea plume of oil had been documented during the spill in June, 2010; corals elsewhere in the Gulf of Mexico outside the area affected by the plume did not appear to be experiencing higher mortality. The research team concluded t hat the observed coral injuries likely resulted from exposure to the subsurface oil plume (White et al., 2012).



### C.2.3 Designated Topographic Features

The lease block s are not within or near a designated topographic feature or a no

- activity zone as
identifi ed in NTL 2009

- G39 . The nearest designated topographic feature is Sackett Bank, located in West Delta Block 147, 55 miles (89 km) north

- northwest of the lease area.

There are no IPFs associated with either routine operations or accidents that could cause impacts to designated topographic features due to the distance from the lease area. A small fuel spill would float and dissipate on the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and the difference in water depth

. Near

- bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume

up onto the continental shelf edge

.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 28 

### C.2.4 Pinnacle Trend Area Live Bottoms

The lease area is not covered by the Live Botto m (Pinnacle Trend) Stipulation. As defined by

NTL 2009

- G39, the nearest pinnacle trend is Main Pass Block 290, 97 miles (156 km)
north

- northeast of the lease area.

There are no IPFs associated with either routine operations or accidents that could cause impacts to pinnacle trend area live bottoms due to the distance from the l ease area. A small fuel spill would float on the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impact s on these features would be unlikely due to the distance and the difference in water depth

. Near

- bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume

up onto the continental sh elf edge

.



### C.2.5 Eastern Gulf Live Bottoms

The lease area is not covered by the Live Bottom (Low

- Relief) Stipulation, which pertains to seagrass communities and low

- relief hard

- bottom reef within the Eastern Gulf of Mexico Planning Area blocks in water dept hs of 100 m (328 ft) or less and portions of Pensacola and

Destin Dome Area b locks in the Central Gulf of Mexico Planning Area . The nearest block covered by the live bottom stipulation, as defined by NTL 2009

- G39, is Destin Dome Block 573, approximately 1 28 miles (206 km) of the lease area

.
There are no IPFs associated with either routine operations or accidents that could cause impacts to eastern Gulf live bottom areas due to the distance from the lease area. A small fuel spill would float and dissipate on the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these features would be unlikely due

t o the distance and the difference in water depth

. Near

- bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume

up onto the continental shelf

.



## C.3 Threatened, Endangered, and Protected Species and Critical Habitat

This section discusses species listed as endangered or threatened under the Endangered Species Act ( ESA ) . In addition, it includes all marine mammal species in the region, which are protected
under the Marine Mammal Protection Act ( MMPA ).

Endangered or threatened species that may occur in the project area and/or along the northern
Gulf C oast are listed in Table 5 . The table also indicates the location of critical habitat (if designated in the Gulf of Mexico). Critic al habitat is defined as (1) specific areas within the geographical area occupied by the species at the time of listing, if they contain physical or biological features essential to conservation, and those features may require special management considerations or protection; and (2) specific areas outside the geographical area occupied by the species if the agency determines that the area itself is essential for

conservation. The National Marine Fisheries Service ( NMFS ) has jurisdiction for ESA

- listedAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 29 ceta ceans, sea turtles, and fishes in the Gulf of Mexico. The USFWS has jurisdiction for

ESA

- listed birds and the West Indian m anatee.

Table 5. Federally listed endangered and threatened species potentially occurring in the lease area and along the northern G ulf C oast.

Species Scientific Name Status Potential Presence Critical Habitat Designated
in Gulf of Mexico Lease
Area Coastal

Marine Mammals

Sei whale Balaenoptera borealis E X a

-- None

Blue whale Balaenoptera musculus E X a

-- None

Fin whale Balaenoptera physalus E X a

-- None North Atlantic right whale Eubalaena glacialis E X a

-- None Humpback whale Megaptera novaeangliae E X a

-- None Sperm whale Physeter macrocephalus E X

-- None

West Indian manatee Trichechus manatus latirostris E

-- X Florida (Peninsular)

Sea Turtles

Loggerhead turtle Caretta caretta T X X None

Green turtle Chelonia mydas T, E b X X None

Leatherback turtle Dermochelys coriacea E X X None

Hawksbill turtle Eretmochelys imbricata E X X None Kemp ’ s ridley turtle Lepidochelys kempii E X X None

Birds

Piping Plover Charadrius melodus T

-- X Coastal Texas, Louisiana, Mississippi, Alabama, and Florida (Panhandle)

Whooping Crane Grus americana E

-- X Coastal Texas (Aransas National Wildlife Refuge )
Fishes

Gulf sturgeon Acipenser oxyrinchus desotoi T

-- X Coastal Louisiana, Mississippi, Alabama, and Florida (Panhandle)

Smalltooth sawfish Pristis pectinata E

-- X Southwest Florida and the Florida Keys
Invertebrates

Elkhorn coral Acropora palmata E

-- X Flower Garden Banks

Terrestrial Mammals

Beach mice (A labama, Choctawhatchee, Perdido Key,
St. Andrew) Peromyscus polionotus E

-- X Alabama and Florida (Panhandle) beaches

Abbreviations: E = e ndangered; T = t hreatened.

a The blue, fin, humpback, North Atlantic right, and sei whales are rare or extralimital in the Gulf of Mexico and are unlikely to be present in the lease area.

b The green sea turtle is threatened, except for the Florida breeding population, which is listed as endangered.

As mandated by the ESA, MMS consulted NMFS and the USFWS on possible and potential impacts from the proposed leasing in the Gulf of Mexico on endangered/threatened species and their designated critical habitat (MMS

, 2007a

, b)

. A B iological A ssessment was prepared for each consultation. The formal ESA consultation with NMFS was concluded with receipt of the Biological Opinion on 3 July 2007 (NMFS, 2007). The Biological Opinion concludes that the proposed lease sales and associated activities in the Five

- Year Leasing Plan for Western and Central Planning Areas 2007

- 2012 are not likely to jeopardize the continued existence ofAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 30 threatened and endangered species under NMFS jurisdiction or destroy or adversely modify designated critical habitat. The informal ESA consultation with USFWS was concluded with a
letter dated 14 September 2007. The USFWS concurred with MMS’s determination that proposed actions of the Five

- Year Leasing Plan were not likely to adversely affect threatened/endangered species or designated critical habitat under USFWS jurisdiction. Following the Macondo spill

, BOEMRE requested to reinitiat e an ESA consultation with both
NMFS and USFWS on 30 July 2010. The NMFS responded with a letter to BOEMRE on

24 September 2010 , and t he U SFWS responded with a letter to BOEMRE on 27 September 2010. At present, the NMFS and US FWS have placed th e consultation process on hold because they
feel the environmental baseline information needs to be updated for the post

- Macondo spill
environment ba sed on the results of the Natural Resource Damage Assessment ( NRDA ) process. The NRDA data have yet to be released , and the existing consultation remain s in effect (BOEM, 201 2b). The existing consultation recognizes that BOEM

- required mitigations and other reasonable and prudent measures should reduce the likelihood of impacts from all

BOEM

- authorized activities in the Gulf of Mexico.

Coastal endangered or threatened species that may occur along the northern Gulf Coast include
the West Indian manatee, Piping Plover, Whooping Crane, Gulf sturgeon, and four subspecies of
beach m ouse . Critical habitat has been designated for all of these species as indicated in Table 5
and discussed in individual sections.

Two other coastal species (Bald Eagle and Brown P elican) discussed in MMS (2007b) and BOEM (2012b) are no longer federally listed as endangered or threatened . T hese are discussed in
Section C.4.2

.
There are five sea turtle and six marine mammal species that are currently listed as endangered and threatened by the ESA and known to occur within OCS and slope waters of the Gulf of
Mexico. The listed sea turtles include the l eatherback turtle , Kemp's ridley turtle , hawksbill turtle, loggerhead turtle, and green turtle. Listed marine mammal species include one odontocete (toothed) whale ( sperm whale ) and five mysticete (baleen) whales ( blue whale, fin whale, humpback whale, North Atlantic right whale, and sei whale)( Pritchard, 1997; Würsig et al., 2000 ). No critical habitat has been designated for these species in the Gulf of Mexico.

The sperm whale and five species of sea turtles are the only endangered or threatened species likely to occur at or near the lease area. No critical habitat has been designated for these species in the Gulf of Mexico.

Five endangered mysticete whales (blue whale, fin whale, humpback whale, North Atlantic right whale, and sei whale) also have been reported from the Gulf of Mexico but are considered rare or extralimital there (Würsig et al., 2000). No critical habitat ha s been designated for these species in the Gulf of Mexico.



### C.3.1 Sperm Whale (Endangered)

The only endangered marine mammal likely to be present at or near the project area is the sperm whale ( Physeter macrocephalus )

. Resident populations of s perm whales occur within the
Gulf of Mexico ; a species description is presented in MMS ( 2007b). Gulf of Mexico sperm whales are classified as an endangered species and a " strategic stock " (defined as a stock that may have unsustainable human

- caused impacts) by NOAA F isheries (Waring et al., 2012 ). No
critical habitat for the sperm whale has been designated in the Gulf of Mexico.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 31 The distribution of sperm whales in the Gulf of Mexico is correlated with mesoscale physical
features such as eddies associated with the Loo p Current (Jochens et al., 2008). Sperm whale populations in the north

- central Gulf of Mexico are present there throughout the year (Davis et al., 2000). Results of a multi

- year tracking study show female sperm whales typically concentrated along the upper continental slope between the 200 - and 1,000

- m (656 - and 3,280

- ft) depth contours ( Jochens et al., 2008 ). Male sperm whales were more variable in their movements and were documented in water depths greater than 3,000 m (9,843 ft). Generally,

groups of sperm whales sighted in the Gulf of Mexico during the MMS

- funded Sperm Whale Seismic Study (SWSS) consisted of mixed

- sex groups comprising adult females and immatures, and groups of bachelor males. Typical group size for mixed gro ups was 10 individual s (Jochens et al., 2008). SWSS results show that sperm whales transit through the vicinity of the
lease area. Movements of satellite

- tracked individuals suggest that this area of the Gulf continental slope is within the home range of the Gulf of Me xico p opulation (within the

95% utilization distribution) (Jochens et al., 2008).

IPFs potentially affecting sperm whales include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents – a small fuel spill and a large oil spill (WCD). Effluent discharges are likely to have negligible impacts on sperm whales due to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility of these marine mammals. Compliance with NTL 2012

- BSEE

- G01 will minimize the potential for marine debris

- related impacts on sperm whales

.

C urrent threats to sperm whale populations worldwide are discussed in a final recovery plan for the sperm whale r ecently published by NOAA (NMFS, 2010 a ). Threats are defined as " any factor that could represent an impediment to recovery ," and include fisheries interactions, anthropogenic noise, vessel interactions, contaminants and pollutants, disease, injury from marine debris, research, predation and natural mortality, direct harvest, competition for resources, loss of prey base due to climate change and ecosystem change, and cable laying.

In the Gulf of Mexico , the impacts from many of these threats are identified as either low or
unknown ( BOEMRE, 2011 a ; BOEM, 2012 b).



### Impacts of Drilling Rig Presence, Noise, and Lights

Noise generated from the drilling rig and from routine drilling activities may be audible to sperm
whales and so has the potential to disturb individuals near the lease area

. The drilling rig used during the proposed activity will be located within a deepwater, open ocean environment and will remain stationary during drilling operations. Sounds generated by the rig and by drilling operations will be generally continuous (with some variability in sound level, considering thruster activity)

. This analysis assumes that the continuous nature of sounds produced by the drilling rig will provide individual whales with cues relative to the direction and relative distance (sound inten sity) of the sound source, and the fixed position of the drilling rig will provide multiple options for active avoidance of potential physical impacts. NMFS analyzed the potential for impacts of drilling

- related noise on sperm whales in its Biological Opin ion for the Gulf of
Mexico Oil and Gas Activities: Five

- Year Leasing Plan for Western and Central Planning Areas

2007

- 2012 (NMFS, 2007)

. The analysis noted that semisubmersible drilling rigs emit low sound source levels and concluded that drilling is not expected to produce amplitudes sufficient to cause hearing or behavioral effects in sperm whales; therefore, these effects are insignificant (NMFS, 2007 ).Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 32 In addition, there are other OCS facilities and activities near the lease area, and the region as a whole has a large number of similar noise sources. Drilling

- related noise associated with this project will contribute to increases in the ambient noise environment of the Gulf of Mexico, but it is not expected in amplitudes sufficient to cause either hea ring or behavioral effects to sperm
whales.

Drilling rig lighting and rig presence are not identified as IPFs for sperm whales (MMS, 2007b ; BOEM, 2012a, b ,d ; NMFS, 2007 )



### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sperm whales

, and there is also a risk of vessel strikes, which are identified as a threat in the recovery plan for this species (NMFS, 2010a ). Data concerning the frequency of vessel strikes are presented in MMS ( 2007b). To reduce t he potential for vessel strikes, the BSEE and BOEM issued NTL 2012

- JOINT

- G0 1 , which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. When whales are sighted, vessel operators and crews are required to attempt to maintain a
distance of 91 m (300 ft) or greater whenever possible. Vessel operators are required to reduce vessel speed to 10 knots or less

, when safety permits

, when mother/calf pairs, pods, or large assemblages of cetaceans are observed near an underway vessel. Compliance with this NTL will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing sperm
whales.

NMFS (2007) analyzed the potential for vessel strikes and harassment of sperm whales . With implementation of the mitigation measures in NTL 2012

- JOINT

- G01 , NMFS concluded that the likelihood of collisions between vessels and sperm whales would be reduced to insignificant levels. NMFS concluded that the observed avoidance of passing vessels by sperm whales is an advantageous response to avoid a potential threat and is not ex pected to result in any significant effect on migration, breathing, nursing, breeding, feeding, or sheltering to individuals, or have any consequences at the population level

. With implementation of the vessel strike avoidance measures requirement to main tain a distance of 9 1 m ( 300 ft) from sperm whales, the NMFS concluded that the potential for harassment of sperm whales would be reduced to
discountable levels.

Helicopter traffic also has the potential to disturb sperm whales. Smultea et al. (2008)
docu mented responses of sperm whales offshore Hawaii to fixed wing aircraft flying at an
altitude of 245 m (800 ft). A reaction to the initial pass of the aircraft was observed during

3 (12%) of 24 sightings. All three reactions consisted of a hasty dive and occurred at less than

360 m (1,180 ft) lateral distance from the aircraft. Additional reactions were seen when aircraft
circled certain whales to make further observations. Based on other studies of cetacean responses to sound, the authors concluded tha t the observed reactions to brief overflights by
the aircraft were short

- term and probably of no long

- term biological significance.

W hile flying offshore in the Gulf of Mexico , helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. In the event that a whale is seen during transit, the helicopter will not approach or circle the animal. Although responses are possible (SmulteaAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 33 et al., 2008), the NMFS (2007) and BOEM (2012 d ) concluded that t his altitude would minimize the potential for disturbing sperm whales. Therefore, no significant impacts are expected

.


### Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals including sperm whales are discussed in MMS ( 2007b ), BOEM ( 2012 a, b ,d ), and NMFS (2 007) . Oil impacts on marine mammals are discussed by Geraci and St. Aubin (1990). For this EP , there are no unique site

- specific issues with respect to spill impacts on these animals that were not analyzed in the previous documents

.
The probability of a fuel spill will be minimized by Anadarko’ s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko’ s OSRP could mitigate and lessen the potential for impacts on sperm whales. G iven the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The sea surface area with diesel fuel on it would range from 0.5 to 5 ha (1.2 to

12 ac)

, depending on sea state and weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (Marine Mammal Commission [ MMC ] , 2011 ). However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, as well as the mobility of sperm whal es, no significant impacts would be expected.



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine mammals including sperm whales are discussed in MMS ( 2007b ), BOEM ( 2012 a,b, d), and NMFS (2007)

. For this EP , there are no unique site

- specific issues with respect to spill impacts on these animals.

Impacts of oil spills on sperm whales can include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, no ise, and dispe rsants) (MMC, 2011 ). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contam inated prey; and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime
habitat

, disruption of social structure

, changing prey availability and foraging distribution and/or
patterns

, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC , 2011 ). Ackleh et al. (2012) hypothesized that sperm whales may have temporarily relocated away from areas near the Macondo spill in 2010.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 34 In the event of a large spill, the level of vessel and aircraft activity associated with spill response
could distu rb sperm whales and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate in accordance with NTL 2012

- JOINT

- G01 to reduce the potential for striking or disturbing these animals.



### C.3.2 West Indian Man atee (Endangered)

M ost of the Gulf of Mexico manatee population is located in peninsular Florida (USFWS, 2001). Manatee sightings in Louisiana have increased as the species extends its presence farther west of Florida in the warmer months (Wilson, 2003). A species description is presented in a MMS ( 2007b) and in the recovery plan for this species (USFWS, 2001).

IPFs potentially affecting manatees include support vessel and helicopter traffic and a large oil spill (WCD). A small fuel spill in the lease area would be unlikely to affect manatees due to the
distance to the nearest shoreline. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up

. Compliance with

NTL 2012

- BSEE -G 01 will minimize the potential for marine debris

- related impacts on manatees.



### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb manatees

, and there is also a risk of vessel strikes, which are identified as a threat in the recovery plan for this species (USFWS, 2001).

To reduce the potential for vessel strikes, BSEE and BOEM issued NTL 20 12

- JOINT -G01 , which recommends protected species identification training and that vessel operators and crews

maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid striking protected species

, and requires operators to report sightings of any injured or dead protected species. Compliance with this NTL will minimize the likelihood of vessel strikes, and no significant impacts on manatees are expected.

Helicopter traffic also has the potential to disturb manatees. Rathbun (1988) reported that manatees were disturbed more by helicopters than by fixed

- wing aircraft; however, the helicopter was flown at relatively low altitude s of 20 to 160 m (66 to 525 ft). Helicopters used in support operations maintain a minimum altitude of 213 m (700 ft) while in transit offshore,

305 m (1,000 ft) over unpopulated areas or across coastlines, and 610 m (2,000 ft) over populated areas and sensitive habitats such as wildlife refuges and park properties. In addition, guidelines and regulations specify that helicopters maintain an altitude of 305 m ( 1,000 ft)
within 91 m ( 300 ft) of marine mammals (BOEM, 2012a, d)

. This mitigation measure will minimize the potential for disturbing manatees, and no significant impacts are expected.



### Impacts of a Large Oil Spill (WCD)

In the event that manatees were exposed to oil, effects could include direct impacts from oil

exposu re, as well as indirect impacts due to response activities and materials (e.g., vessel traffic,

no ise, and dispersants) (MMC, 2011). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey (or contaminated vegetation, in the case of manatees); and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat

, disruption ofAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 35 social structur e, changing prey availability and foraging distribution and/or patterns

, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 201 1 ).

In the event that a large spill reached coastal waters where manatees were presen t , the level of vessel and aircraft activity associated with spill response could disturb manatees and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate
in accordance with NTL 2012

- JOINT

- G01 to r educe the potential for striking or disturbing these
animals , and therefore no significant impacts are expected

.



### C.3.3 Endangered Mysticete Whales

Five endangered mysticete whales (blue whale, fin whale, humpback whale, North Atlantic right whale, and sei whale) also have been reported from the Gulf of Mexico but are considered rare or extralimital there (Würsig et al., 2000). No critical habitat has been designated for these species in the Gulf of Mexico.

Because of the rare occurrence of these whales in the Gulf of Mexico and the limited sco pe and duration of the project, it is highly unlikely that any endangered mysticete would come into contact with any project activities, either routine operations or accidents

. NMFS did not include any of these mysticete whales as affected species in its Biological Opinion (NMFS, 2007)

. Potential impacts are analyzed in MMS ( 2007b ) and BOEM ( 2012a,b, d), and those analyses are incorporated by reference. If any of these whales were present in the area, potential impacts
would be the same as those discussed below in Section C.3.4

.



### C.3.4 Non

- Endangered Marine Mammals (Protected)

Excluding the seven endangered species that have been cited previously, there are 22 additional species o f marine mammals that may be found in the Gulf of Mexico

, includ ing 2 species of mysticete whales, dwarf and pygmy sperm whales, 4 species of beaked whales, and 1 4 species
of delphinids . All marine mammals are protected species under the MMPA. The most c ommon

non

- endangered cetaceans in the deepwater environment are odontocetes such as the pantropical spotted dolphin, spinner dolphin, and Clymene dolphin. A brief summary is presented below, and a dditional information on these groups is presented in MMS ( 2007b).

Mysticete whale s . Two species of non

- endangered mysticete whales are known from the Gulf
of Mexico. The Bryde’s whale ( Balaenoptera edeni ) has been sighted most frequently along the

100

- m (328

- ft) isobath (Davis and Fargion, 1996; Davis et al., 2000). Most sightings have been made in the DeSoto Canyon region and off western Florida, although there have been some in
the west

- central portion of the northeastern Gulf. The minke whale ( Balaenoptera

acutorostrata ) is considered rare in the Gulf of M exico, with the only confirmed records coming from strandings (Würsig et al., 2000). Based on the available data, it is possible that Bryde’s
whales could occur in the lease area.

Dwarf and pygmy sperm whales

. At sea, it is difficult to differentiate dwa rf sperm whales ( Kogia sima ) from pygmy sperm whales ( Kogia breviceps ), and sightings are often grouped together as Kogia spp. Both species have a worldwide distribution in temperate to tropical waters. In the Gulf of Mexico, both species occur primarily along the continental shelf edge and in deeper waters off the continental shelf (Mullin et al., 1991). Either species could occur in the
lease area.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 36 Beaked whales . Four species of beaked whales are known from the Gulf of Mexico. They are Blainville’s beaked whale ( Mesoplodon densirostris ), Cuvier’s beaked whale ( Ziphius cavirostris ), Sowerby’s beaked whale ( Mesoplodon bidens ), and Gervais’ beaked whale ( Mesoplodon

europaeus ). Stranding records in the Gulf of Mexico suggest that Gervais’ beaked whale is the most common and Sowerby’s is extralimital. Due to the difficulties of at

- sea identification,
beaked whales in the Gulf of Mexico are identified either as Cuvier’s beaked whales or are grouped into an undifferentiated complex ( Mesoplodon spp. and Ziph ius spp.). In the northern Gulf of Mexico, they are broadly distributed in water depths greater than 1,000 m (3,281 ft) over lower slope and abyssal landscapes (Davis et al., 2000). Any of these species could occur in the
lease area.

D elphinids

. Fourteen species of delphinids are known from the Gulf of Mexico, including Atlantic spotted dolphin ( Stenella frontalis ), bottlenose dolphin ( Tursiops truncatus ), Clymene dolphin ( Stenella clymene ), f alse killer whale ( Pseudorca crassidens )

, Fraser’s do lphin ( Lagenodelphis hosei ) , k iller whale ( Orcinus orca ) , m elon

- headed whale ( Peponocephala electra )

, p antropical spotted dolphin ( Stenella attenuata )

, p ygmy killer whale ( Feresa attenuata )

, short

- finned pilot whale ( Globicephala macrorhynchus ) , R isso’s do lphin ( Grampus griseus )

,
r ough

- toothed dolphin ( Steno bredanensis ) , s pinner dolphin ( Stenella longirostris ) , and s triped dolphin ( Stenella coeruleoalba ). Any of these species could occur in the lease area. The most

common non

- endangered cetaceans in the deepwater environment are the pantropical spotted dolphin, spinner dolphin, and Clymene dolphin.

Bottlenose dolphins

• for which the level of direct human

- caused mortality exceeds the potential biological removal level; . The bottlenose dolphin ( Tursiops truncatus ) is a common inhabitant of the northern Gulf of Mexico, particular ly within continental shelf waters. There are two ecotypes of bottlenose dolphins, a coastal form and an offshore form, which are genetically isolated from each other ( Waring et al., 2012 ). The offshore form of the bottlenose dolphin may occur within
the lease area. Inshore populations of coastal b ottlenose dolphins in the northern Gulf of

Mexico are separated into 37 geographically distinct population units, or stocks, for management purposes by the NMFS (Waring et al.

, 201 2) . NMFS (2013) has proposed t o classify the Gulf of Mexico Northern Coastal Stock, Western Coastal Stock, and all 32 of the Bay, Sound, and Estuarine Stocks as strategic stocks. A “strategic ” stock is defined by the MMPA as a marine
mammal stock

• which, based on the best available scientific information, is declining and is likely to be listed as a threatened species under the ESA within the foreseeable future; or

• which is liste d as a threatened or endangered species under the ESA, or is designated as depleted under the MMPA.

The strategic stock designation in this case was based primarily on the occurrence of an “unusual mortality event” of unprecedented size and duration that h as affected these stock areas. This unusual mortality event began in February 2010 and is ongoing. Carmichael et al. (2012) hypothesized that the unusual number of bottlenose dolphin strandings in the northern Gulf of Mexico during this time may have bee n associated with environmental perturbations including sustained cold weather and the Macondo spill in 2010 as well as large volumes of cold freshwater discharge in the early months of 2011.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 37 IPFs potentially affecting non

- endangered marine mammals include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents – a small fuel spill and a large oil spill (WCD). Effluent discharges are likely to have negligible impacts due to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility of these marine mammals. Compliance with NTL 2012

- BSEE

- G01 will minimize the potential for marine debris

- related impacts.



### Impacts of Drilling Rig Presence, Noise, and Lights

Noise from routine drilling activities has the potential to disturb marine mammals. Most odontocetes (toothed whales and dolphins) use higher frequency sounds than those produced by OCS drilling activities (Richardson et al., 1995). Noise generated durin g drilling operations is generally continuous and fixed in location. Noise intensity associated with these operations is relatively weak . Stronger noise levels will occur during thruster use in dynamic positioning. Thruster noise impacts would be expected at greater distances than vessel noi se alone (LGL Ecological Research Associates, Ltd.

, 2006) but are dependent on variables relating to thruster type and usage. It is expected that marine mammals within or near the lease area
would be able to detect t he presence of the drilling rig and avoid exposure to higher energy sounds, particularly within an open ocean environment. Some odontocetes have shown increased feeding activity around lighted platforms at night (Todd et al

. , 2009). Even temporary
drill rigs present an attraction to pelagic food sources that may attract both cetaceans and sea turtles. Therefore, prey congregation could pose an attraction to protected species that exposes them to higher levels or longer durations of noise that might other wise be avoided.
There are other OCS facilities and activities near the lease area

, and the region as a whole has a large number of similar sources. Species in the northern Gulf of Mexico have been exposed to noise from anthropogenic sources for a long period of time and over large geographic areas and likely do not represent a naïve population with regard to sound (National Research Council, 2003b). Due to the limited duration of drilling activities , this project would represent a temporary contribution to the overall noise regime within the lease area, and potential impacts are expected to be biologically in significant to marine mammal populations.

Drilling rig lighting and rig presence are not identified as IPF s for marine mammals (MMS, 2007b, 2008; BOEMRE, 2011a; BOEM, 2012a,b ).



### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb marine mammals

, and there is also a risk of
vessel strikes. Data concerning the frequency of vessel strikes are presented in MMS ( 2007b). To reduce the potential for vessel strikes, BSEE and BOEM issued NTL 20 12

- JOINT -G01 , which recommends protected species identification t raining and that vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. Vessel op erators and crews are required to attempt to maintain a distance of

91 m (300 ft) or greater when whales are sighted and 45 m (150 ft) when small cetaceans are sighted. When cetaceans are sighted while a vessel is underway, vessels must attempt to

remain parallel to the animal’s course and avoid excessive speed or abrupt changes in direction until the cetacean has left the area. Vessel operators are required to reduce vessel speed to

10 knots or less when mother/calf pairs, pods, or large assemblages of c etaceans are observed near an underway vessel

, when safety permits. Compliance with NTL 2012

- JOINT

- G01 willAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 38 minimize the likelihood of vessel strikes as well as reduce the chance for disturbing marine
mammals , and therefore no significant impacts are expe cted

.

Aircraft traffic also has the potential to disturb marine mammals (W ü rsig et al., 1998). However, while flying offshore, helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. In addition, guidelines and regulations specify that helicopters maintain
an altitude of 305 m ( 1,000 ft) within 91 m ( 300 ft) of marine mammals (BOEM, 2012a, d ). Maintaining this altitude will minimize the potential for disturbing marine mammals , and no

s ignificant impacts are expected ( BOEM, 2012a, d ).



### Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals are discussed in MMS ( 2007b ) and BOEM ( 2012a,b ); oil impacts on marine mammals in general are discussed by Geraci and St. Aubin (1990) . For this

EP , there are no unique site

- specific issues with respect to spill impacts on these animals.

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures including fuel transfer. In the unlikely event of a spill, imple mentation of Anadarko ’s OSRP is expected to
lessen the potential for impacts on marine mammals. EP Section H provides detail on spill

response measures , along with a summary of those measures in this EIA

. Given the open ocean location of the lease area, the limited duration of a small spill and response efforts, it is expected that any impacts would be brief and minimal

.
A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanog raphic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The sea surface area wit h diesel fuel on it would range from 0.5 to 5 ha (1.2 to

12 ac)

, depending on sea state and weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (MMC, 2011 ). However, due to the limited areal extent
and short dur ation of water quality impacts from a small fuel spill, as well as the mobility of marine mammals, no significant impacts would be expected.



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine mammals are discussed in MMS ( 2007b ) and BOEM ( 2012a,b )

. For this EP , there are no unique site

- specific issues

. Impacts of oil spills on marine mammals can include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic , noise, and dispersants) (MMC, 201 1 ). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey (or contaminated vegetation, in the case of manatees); and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals fromAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 39 prime habitat

, disruption of social structure

, changing prey availability and foraging distribution and/or patterns

, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 201 1 ).

In the event of a large spill, the level of vessel and aircraft activity associated with spill response could disturb marine mammals and potentially result in vessel strikes, entanglement , or other injury or stress. Response vessels would operate in accordance with NTL 2012

- JOINT -G01 to reduce the potential for striking or disturbing these animals , and therefore no significant impacts are expected

.



### C.3. 5 Sea Turtles (Endangered/Threatened )

F ive species of endangered or threatened sea turtles may be found near the lease area.
L eatherback turtle ( Dermochelys coriacea ), Kemp's ridley turtle ( Lepidochelys kempii ), and
hawksbill turtle ( Eretmochelys imbricata ) turtles are endangered . The loggerhead turtle ( Caretta caretta ) is currently a threatened species ; however, in March 20 10 , NMFS and USFWS proposed to list the Northwest Atlantic Ocean population of loggerhead turtles as endangered (75 FR 12598) . The green turtle ( Chelonia mydas ) is listed as threatened, except for the Florida
and Pacific c oast of Mexico breeding population s , which are listed as endangered. Species descriptions are presented in MMS ( 2007b).

Leatherback and loggerhead turtle s are the most likely species to be present near the lease area as adults. Green, hawksbill, and Kemp’s ridley turtles are typically inner shelf and near shore species, unlikely to occur near the lease area as adults. Hatchlings or juveniles of any of the sea
turtle species may be present in deepwa ter areas, including the lease area, where they may be
associated with Sargassum and other flotsam.

Sea turtle nesting on the northern Gulf of Mexico coast can be summarized by species as follows:

• Loggerhead turtles – Loggerheads nest in significant number s along the Florida Panhandle and, to a lesser extent, from Texas through Alabama (MMS, 2007b). The nearest significant nesting area of loggerhead turtles is found in Louisiana, on beaches within the Breton NWR;

• Green and leatherback turtles – Green and l eatherback turtles infrequently nest on Florida Panhandle beaches (Florida Fish and Wildlife Conservation Commission, 201 2 );

• Kemp’s ridley turtles – The main Kemp’s ridley nesting site is Rancho Nuevo beach,

Tamau lipas, Mexico (NMFS et al., 2011 ). Kemp’s ridley turtles typically do not nest anywhere near the project area, although there have been occasional reports of Kemp’s ridleys nesting in Alabama (Share the Beach, 2010); and

• Hawksbill turtles – Hawksbills typically do not nest anywhere near the project area.

IPFs potentially affecting sea turtles include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents – a small fuel spill and a large oil spill ( WCD ) . Effluent discharges are likely to have negligible impacts on sea turtles due to rapid dispersion, the small area of ocean affected, and the intermittent nature of the discharges. Compliance with NTL 2012

- BSEE

- G01 will minimize the potential for marine debris

- related impacts on sea turtles.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 40 

### Imp acts of Drilling Rig Presence, Noise, and Lights

Offshore drilling activities produce a broad array of sounds at frequencies and intensities that may be detected by sea turtles (Geraci and St. Aubin, 1987). Potential impacts may include behavioral disrupt ion and temporary or permanent displacement from the area near the sound source. Certain sea turtles, especially loggerheads, may be attracted to offshore structures (Lohoefener et al., 1990) and, thus, may be more susceptible to impacts from sounds produ ced during routine operations. The most likely impacts would be short

- term behavioral changes such as diving and evasive swimming, disruption of activities, or departure from the area. Due to the limited scope and short duration of drilling activities , t hese short

- term impacts are not expected to be biologically significant to sea turtle populations.

Artificial lighting can disrupt the nocturnal orientation of sea turtle hatchlings (Witherington, 1997; Tuxbury and Salmon, 2005). However, hatchlings may r ely less on light cues when they are offshore than when they are emerging on the beach (Salmon and Wyneken, 1990). The NMFS (2007) concluded that the effects of lighting from offshore structures on sea turtles are insignificant.



### Impacts of Support Vessel and Helicopter Traffic

Noise generated from support vessel traffic has the potential to disturb sea turtles

, and there is
also a risk of vessel strikes. Data show that vessel strike is one cause of sea turtle mortality in
the Gulf of Me xico (Lutcavage et al., 1997). While adult sea turtles are visible at the surface during the day and in clear weather, they can be difficult to spot from a moving vessel when resting below the water surface, during nighttime, or during periods of inclemen t weather. To reduce the potential for vessel strikes, BSEE and BOEM issued NTL 20 12

- JOINT -G01 , which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for sea turtles and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. When sea turtles are sighted, vessel operators and crews are required to attempt to
maintain a distance of 45 m (150 ft) or greater whenever possible. Compliance with this NTL will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing sea turtles (NMFS, 2007).

Noise generated from support helicopter traffic also has the potential to disturb sea turtles. However, while flying offshore, helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. This altitude will minimize the potential for disturbing sea turtles, and no significant impacts are expected.



### I mpacts of a Small Fuel Spill

Potential spill impacts on sea turtles are discussed in MMS ( 2007b ), BOEM ( 2012a,b ), and the

NMFS Biological Opinion (NMFS, 2007)

. For this EP , there are no unique site

- specific issues with respect to spill impacts on these animals.

The probability of a fuel spill will be minimized by Anadarko’ s preventative measures including fuel transfer. In the unlikely event of a spill, implementation of Anadarko’ s OSRP is expected to

minimize potential impacts on sea turtles. EP Secti on H provides detail on spill response

measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 41 A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The sea surface area with diesel fuel on it would range from 0.5 to 5 ha (1.2 to

12 ac)

, depe nding on sea state and weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingesti on of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (MMS, 2007b; NMFS, 2010b; BOEM, 2012b ,d ) . However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, no significant impacts would be expected.

A small fuel spill in the lease area would be unlikely to affect sea turtle nesting beaches due to
the distance to nearest shoreline. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up

.


### Impacts of a Large Oil Spill (WCD)

Impacts of oil spills on sea turtles can include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes and smoke (e.g., from in situ burning of oil) ; ingestion of oil (and dispersants) directly or via contaminated food; and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat

, disruption of social structure

, changing food availability and foraging distribution and/or patterns

, changing reproductive behavior/productivity, and changing movement patterns or migration. In the unlikely event of a spill, implementation of Anadarko’ s OSRP is expected to minimize the potential for these types
of impacts on sea turtles. EP Section H provide s detail on spill response measures.

Studies of oil effects on loggerheads in a controlled setting (Lutcavage et al., 1995) suggest that sea turtles show no avoidance behavior when they encounter an oil slick

, and any sea turtle in

an affected area would be expected to be exposed. Sea turtles’ diving behaviors also put them at risk. Sea turtles rapidly inhale a large volume of air before diving and continually resurface

over time , which may result in repeated exposure to volatile vapors and oiling (NMFS, 2007).

Spilled oil reaching sea turtle nesting beaches could have e ffects on nesting sea turtles and egg development (NMFS, 2007). An oiled beach could affect nest site selection or result in no nesting at all (e.g., false crawls). Upon hatching and successfully reaching the water, hatchlings are subject to the same types of oil spill exposure hazards as adults. Hatchlings that contact oil residues while crossing a beach can exhibit a range of effects, from acute toxicity to impaire d movement and normal bodily functions (NMFS, 2007).Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 42 In the event of a large spill, the level of vessel and aircraft activity associated with spill response could disturb sea turtles and potentially result in vessel strikes, entanglement, or other injury o r stress. Response vessels would operate in accordance with NTL 2012

- JOINT

- G01 to reduce the potential for striking or disturbing these animals, and therefore no significant impacts are expected

.
The extent and scope of the Macondo spill represents new information not assessed in the existing ESA Section 7 consultation under the current Five

- Year Program. As a result of this new information, BOEMRE reinitiated ESA Section 7 consultation on the existing Gulf of Mexico lease
sale EIS with NMFS and the US FWS on 30 July 2010. The NMFS responded with a letter to

BOEMRE on 24 September 2010 , and the US FWS responded with a letter to BOEMRE on

27 September 2010. However, NMFS and the US FWS have placed the consultation process on hold pending the results of the NRDA post

- Macondo spill data review, which has yet to be
released. The existing consultation currently remain s in effect (BOEM, 2012b)

.
BOEMRE (2011a) and BOEM (2012b) reexamined the impacts analys es presented in MMS (2007b, 2008) for the five sea turtle species that inhabit the Gulf of Mexico based on additional information and in consideration of the Macondo spill. No new information was found that
would alter the potential impact s on sea turtles described in previous EISs . In most foreseeable cases, exposure to hydrocarbons persisting in the sea following the dispersal of an oil slick will result in sublethal impacts (e.g., decreased health, reproductive fitness, and longevity; and increased vulnerability to disease) to sea turtles.



### C.3. 6 Pipin g Plover (Threatened)

The Piping Plover ( Charadrius melodus ) is a migratory shorebird that overwinters along the southeastern U.S. and Gulf of Mexico coasts. This threatened species is in decline as a result of hunting, habitat loss and modification, pred ation, and disease (USFWS, 2003). Critical overwintering habitat has been designated, including beaches in Texas, Louisiana, Mississippi, Alabama, and Florida ( Figure 3 ) . Piping Plovers inhabit coastal sandy beaches and mudflats, feeding by probing for i nvertebrates at or just below the surface. They use beaches adjacent to foraging areas for roosting and preening (USFWS, 2010a). A species description is presented in

MMS ( 2007b).

A large oil spill (WCD) is the only IPF potentially affecting Piping Plove rs. There are no IPFs associated with routine project activities that could affect these birds. A small fuel spill in the lease area would be unlikely to affect Piping Plovers because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see explanation in

Section A.9.2 ).Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 43 Figure 3. Location of selected environmental features in relation to the lease area.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 44 

### Impacts of a Large Oil Spill (WCD)

Th e lease area is 73 miles (117 km) from the nearest shoreline s inhabited by Piping Plovers ( Figure 3 ). The revised OSRA results (BOEMRE, 2011a; BOEM, 2012b) summarized in
Section A.9.3 ( Table 3 ) predict that during the spring there is a 4 % probability that an oil spill from the lease area would reach a shoreline designated as critical habitat for the Piping Plover
within 10 days. Plovers could ph ysically oil themselves while foraging on oiled shores or secondarily contaminate themselves through ingestion of oiled intertidal sediments and prey (MMS, 2007b). Plovers congregate and feed along tidally exposed banks and shorelines, following the tide out and foraging at the water’s edge. It is possible that some deaths of Piping Plovers could occur, especially if spills occur during winter months when plovers are most common along the coastal Gulf or if spills contacted critical habitat. Impacts could also occur from vehicular traffic on beaches and other activities associated with spill cleanup. Anadarko has extensive resources available to protect and rehabilitate wildlife in the event of a spill reaching the shoreline, as detailed in the OSRP.



### C.3.7 Whooping Crane (Endangered)

The Whooping Crane ( Grus americana ) is an omnivorous wading bird and an endangered species. There are three wild popul ations in North America (Whooping Crane Eastern Partnership, 2010). One population winters along the Texas coast at Aransas NWR and
summers at Wood Buffalo National Park in Canada ; t his population represents the majority of the world’s population of free

- ranging Whooping Cranes and reached a record population of
270 at Aransas NWR in December 2008 (Whooping Crane Eastern Partnership, 2010).

A non migrating population has been reintroduced in central Florida, and another reintroduced population summers in Wisconsin and migrates to the southeastern U.S. for the winter. Whooping Cranes breed, migrate, winter, and forage in a variety of habitats, including coastal marshes and estuaries, inland marshes, lakes, ponds, wet meadows and rivers, and agricultural
fi elds (USFWS, 2007). About 9,000 ha (22,240 ac) of salt flats on Aransas NWR and adjacent islands comprise the principal wintering grounds of the Whooping Crane. Aransas NWR is designated as critical habitat for the species

. A species description is presented in MMS ( 2007b )
and BOEM ( 2012a ). A large oil spill (WCD) is the only IPF potentially affecting Whooping Cranes. A small fuel spill in the lease area would be unlikely to affect Whooping Cranes, due to the
distance from Aransas NWR. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up

.


### Impacts of a Large Oil Spill (WCD)

A large oil spill is unlikely to affect Whooping Cranes as the lease area is approximately

451 miles (726 km ) from its critical habitat designated in the Aransas NWR . T he revised

OSRA modeling (BOEM, 2012b) predicts that there is a 0.5 % or less probability that an oil spill originating in the lease area would reach the Aransas NWR within 30 days and a 5% probability of oil reaching that area in 120 days.

In the event of oil exposure, Whooping Cranes could physically oil themselves while foraging in oiled areas or secondarily contaminate themselves through ingestion of contaminated shellfish, frogs, and f ishes . It is possible that some Whooping Crane deaths could occur. In the event of a spill, Anadarko would work with the applicable State and Federal agencies to prevent impacts from a spill

.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 45 

### C.3. 8 Gulf Sturgeon (Threatened)

The Gulf sturgeon ( Acipenser oxyrinchus desotoi ) is a threatened fish species that inhabits major rivers and inner shelf waters from the Mississippi River to the Suwannee River, Florida (Barkuloo, 1988; Wakeford, 2001). An anadromous fish that migrates from the sea upstream into coastal rivers to spawn in freshwater, it historically ranged from the Mississippi River to Charlotte Harbor, Florida (Wakeford, 2001). Today, this range has contracted to encompass major rivers and inner shelf waters from the Mississippi River to the Suwannee River, Florida. Populations have been depleted or even extirpated throughout this range by fishing, shoreline development, dam construction, water quality changes, and other factors (Barkuloo, 1988; Wakeford, 2001). These declines prompted the listing of the Gulf sturgeon as a threatened species in 1991. The best known populations occur in the Apalachicola and Suwannee Rivers in Florida (Carr, 1996; Sulak and Clugston, 1998), the Choctawhatchee River in Alabama (Fox et al., 2000), and the Pearl River in Mississippi/Louisiana (Morrow et al., 1998). Critical habitat in the Gulf extends from Lake Borgne, Louisiana (St. Bernard Parish) t o Suwannee Sound, Florida (Levy County) (NMFS, 2010 b) ( Figure 3 )

. A species description is presented MMS ( 2007b) and in the recovery plan for this species (USFWS and Gulf States Marine Fisheries Commission, 1995)

.
A large oil spill (WCD) is the only IPF potentially affecting Gulf sturgeon. There are no IPFs associated with routine project activities that could affect these fish. A small fuel spill in the lease area would be unlikely to affect Gulf sturgeon because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see explanation in

Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on Gulf sturgeon are discussed in MMS ( 2007b ) and BOEM ( 2012 a, b ) and by NMFS (2007)

. For this EP , there are no unique site

- specific issues with respect to this species.

The lease area is approximately 137 miles (220 km ) from the nearest Gulf sturgeon critical
habitat. The revised OSRA modeling (BOEM, 2012b) predicts tha t a spill in the lease area has

1% or less probability of contacting any coastal areas inhabited by Gulf sturgeon within

30 or 120 days.

In the event of oil reaching Gulf sturgeon habitat, the fish could be affected by direct ingestion, ingestion of oiled prey, or the absorption of dissolved petroleum products through the gills. Based on the life history of this species, sub

- adult and adul t Gulf sturgeon would be most vulnerable to an estuarine or marine oil spill, and would be vulnerable only from

1 September through 30 April when this species is foraging in estuarine and shallow marine habitats (NMFS, 2007).



### C.3.9 S malltooth S awfish (Enda ngered)

Smalltooth sawfish ( Pristis pectinata ) are found in the tropical and subtropical Atlantic Ocean.
In the W estern Atlantic they have historically ranged from New York to Brazil, including the Gulf of Mexico and Caribbean Sea. This sawfish primarily occurs in estuarine and coastal habitats such as bays, lagoons, and rivers. The smalltooth sawfish was listed as endangered under the

ESA on 1 April 2003. Its critical habitat consists of two units: the Charlotte Harbor Estuary Unit, which comprises app roximately 89,621 ha (221,459 ac ) of coastal habitat; and the Ten Thousand Islands/Everglades Unit, which comprises approximately 250,506 ha ( 619,013 ac ) of coastalAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 46 habitat. The two units are located along the southwestern coast of Florida between Charlot te Harbor and Florida Bay.

A large oil spill (WCD) is the only IPF potentially affecting smalltooth sawfish

. There are no IPFs associated with routine project activities that could affect these fish. A small fuel spill in the lease area would be unlikely to affect smalltooth sawfish because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

Poten tial spill impacts on smalltooth sawfish are similar to those discussed for other coastal and estuarine species in MMS ( 2007b ), BOEM ( 2012a )

, and by the NMFS (2007) in its Biological Opinion. For this EP , there are no unique site

- specific issues with res pect to smalltooth sawfish

.
In the event of oil reaching smalltooth sawfish habitat, the fish could be affected by direct ingestion, ingestion of oiled prey, or the absorption of dissolved petrole um products through the gills.



### C.3. 10 Beach Mice (Endangered)

Four subspecies of endangered beach m ouse ( Peromyscus polionotus ) occur on the barrier islands of Alabama and the Florida Panhandle. They are the Alabama, Choctaw h atchee,
Perdido Key, and St. Andrew beach mice. Critical habitat has been designated for all four subspecies ; Figure 3 shows the critical habitat combined for all four subspecies . Species descriptions are provided in MMS ( 2007b).

A large oil spill (WCD) is the only IPF potentially affecting beach mice. There are no IPFs associated with routine project activities that could affect these animals due to the distance from shore and the lack of any onshore support activities near their habitat. A small fuel spill in
the lease area would not affect beach mice because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on beach mice are discussed in MMS ( 2007b, 2008 ), BOEMRE ( 2011a ),
and BOEM ( 2012a ). For this EP , there are no unique site

- specific issues with respect to these species that were not analyzed in these documents

.

The beach mouse habitat is 169 mi les (272 km) from the lease area. The revised OSRA modeling
summarized in Section A.9.3 predicts that a spill in the lease area has a 1 % or less probability of reaching either the Alabama or Florida shorelines inhabited by beach mice within 120 days.

In the event of oil contacting these beaches, beach mice could experience several types of direct and indirect impacts. Contact with spilled oil could cause skin and eye irritation and subsequent infection; matting of fur; irritation of sweat glands, ear tis sues, and throat tissues; disruption of sight and hearing; asphyxiation from inhalation of fumes; and toxicity from ingestion of oil and contaminated food. Indirect impacts could include reduction of food supply, destruction of habitat, and fouling of nes ts. Impacts could also occur from vehicular traffic and other activities associated with spill cleanup. However, any such impacts are unlikely due to the distance from shore and response actions that would occur in the event of a spill.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 47 

### C.3.11 Elkhorn Co ral (Endangered)

Elkhorn coral ( Acropora palmata ) is found primarily in shallow waters with temperatures ranging
between 26°C and 30°C (79 °F and 86°F) and significant water movement. Elkhorn coral was

once one of the most abundant coral species in waters ranging from 1 to 5 m (3.3 to 16 ft) deep in tropical and subtropical waters. In the northern Gulf of Mexico , e lkhorn coral has been found within the coral cap region of the Flower Garden Banks National Marine Sanctuary ( Flower
Garden Banks National Marine Sanctuary , 2011).

There are no IPFs associated with routine project activities that could affect this species in the
northern Gulf of Mexico

. A small fuel spill would not affect elkhorn coral colonies because the oil would float and dissipate on the sea surface. A WCD would be unlikely to affect the coral cap region of the Flower Garden Banks because of the water depth of the area. A lthough subsurface plumes were reported following the Macondo spill, these plumes resulted from the
use of subsea d ispersant s at the seafloor.



## C.4 Coastal and Marine Birds

C.4.1 Marine Birds

Marine birds include seabirds and other species that may occur in the pelagic environment of the project area (Clapp et al., 1982a,b, 1983; Peake, 1996; Hess and Ribic, 2000). Sea birds spend much of their lives offshore over the open ocean, except during breeding season when they nest along the coast. In addition, other birds such as waterfowl, marsh birds, and shorebird s may occasionally be present over open ocean areas. No endangered or threatened bird species are likely to occur at the project area due to the distance from shore. For a discussion of shorebird s and coastal nesting birds, see Section C.4.2

.
Seabirds of the northern Gulf of Mexico were surveyed from ships during the GulfCet II program. Hess and Ribic (2000) reported that terns, storm

- petrels, shearwaters, and jaegers were the most frequently sighted seabirds in the deepwater area. From these surveys, f our ecological categories of seabirds were documented in the deepwater areas of the Gulf: summer migrants (shearwaters, storm petrels, boobies); summer residents that breed in the Gulf (Sooty Tern, Least Tern, Sandwich Tern, Magnificent Frigatebird); winter residents (gannets, gulls, jaegers); and permanent resident species (Laughing Gulls, Royal Terns, Bridled Terns) (Hess and Ribic, 2000). The GulfCet II study did not estimate bird densities; however, Powers (1987) indicates that seabird densities over the open ocean typically are <10 birds/km 2

.

The distributions and relative densities of seabirds within the deepwater areas of the Gulf of

Mexic o, including the project area, vary temporally (i.e., seasonally) and spatially. In GulfCet II studies, species diversity and densities varied by hydrographic environment and by the presence and relative location of mesoscale features such as Loop Current eddies that may enhance nutrient levels and productivity of surface waters where these seabird species forage ( Hess and
Ribic

, 2000 ).

Trans

- Gulf migrant birds including shorebirds, wading birds, and terrestrial birds may also be present in the lease area. Migrant birds may use offshore structures and rigs for resting, feeding, or as temporary shelter from inclement weather (Russell, 2005). Some birds may be
attracted to o ffshore structures because of the lights and the fish populations that aggregate
around these structures.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 48 IPFs potentially affecting marine and pelagic birds include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two t ypes of accidents – a small fuel spill and a large oil spill ( WCD ) . Effluent discharges are likely to have negligible impacts on the birds due to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the
mobili ty of these animals. Compliance with NTL 2012

- BSEE

- G01 will minimize the potential for
marine debris

- related impacts on birds.



### Impacts of Drilling Rig Presence, Noise, and Lights

Birds that frequent rig s may be exposed to contaminants including air pollut ants and routine discharges, but significant impacts are unlikely due to rapid dispersion. Birds migrating over water have been known to strike offshore structures, resulti ng in death or injury (Wiese et al., 2001; Russell, 2005). Mortality of migrant bi rds at tall towers and other land

- based structures has been reviewed extensively, and the mechanisms involved in rig collisions appear to be similar. In some cases, migrants simply do not see a part of the rig until it is too late. In other cases, naviga tion may be disrupted by noise (Russell, 2005). On the other hand, offshore structures are suitable stopover habitats for most trans

- Gulf migrant species, and most of the migrants that stop over on rigs probably benefit from their stay, particularly in sp ring (Russell, 2005). Due to the limited scope and short duration of drilling activities described in this EP, any impacts on populations of either seabirds or trans

- Gulf migrant birds are not expected to be significant.



### Impacts of Support Vessel and Heli copter Traffic

Support vessels and helicopters are unlikely to significantly disturb pelagic birds in open, offshore waters. It is likely that individual birds would experience, at most, only short

- term behavioral disruption

, and the impact would not be s ignificant.



### Impacts of a Small Fuel Spill

Potential spill impacts on marine birds are discussed in MMS ( 2007b ) and BOEM ( 2012 a,b ,d ).

F or this EP , there are no unique site

- specific issues with respect to spill impacts on these
animals.

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP could reduce the potential for impacts on marine a nd pelagic birds.

EP Section H provides detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanog raphic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The sea surface area wit h diesel fuel on it would range from 0.5 to 5 ha (1.2 to

12 ac)

, depending on sea state and weather conditions.

Birds exposed to oil on the sea surface could experience direct physical and physiological effects including skin irritation; chemical burns of skin, eyes, and mucous membranes; and inhalation of toxic fumes. Due to the limited areal extent and short duration of water quality impacts from aAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 49 small fuel spill, secondary impacts due to ingestion of oil via contaminated prey or reductions in prey abu ndance are unlikely. Due to the low densities of birds in open ocean areas, the small area affected, and the brief duration of the surface slick, no significant impacts on pelagic birds would be expected.



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine and pelagic birds are discussed in MMS ( 2007b ) and BOEM ( 2012 a,b ,d ). For this EP , there are no unique site

- specific issues with respect to spill impacts on
these animals.

BOEM has reexamined the analys e s for coastal and marine birds pr esented in MMS (2007b, 2008) and determined that no new information was found that would alter the potential impact s on marine and pelagic birds ( BOEMRE, 2011 a ; BOEM, 2012 b ).

Pelagic seabirds could be exposed to oil from a spill at the project area. Hess and Ribic (2000) reported that terns, storm

- petrels, shearwaters, and jaegers were the most frequently sighted seabirds in the deepwater Gulf of Mexico (>200 m [<656 ft] ). Powers (1987) indicates that seabird densities over the open ocean typically are <1 0 birds/km 2 . The number of pelagic birds that could be affected in open, offshore waters would depend on the extent and persistence of
the oil slick.

The Macondo spill provides relevant information about the species of pelagic birds that may be affected in the event of a large oil spill. Birds that have been treated for oiling include several pelagic species such as the Northern Gannet

, Magnificent Frigatebird, and Masked Booby ( USFWS, 2011 ). The Northern Gannet is among the species with the largest numb ers of birds affected by the spill.



### C.4.2 Shorebird s and Coastal Nesting Birds

Threatened and endangered bird species (Piping Plover and Whooping Crane) have been discussed previously in Section C.3 . Various species of non

- endangered birds are also found along the northern Gulf C oast, including diving birds, shorebird s, marsh birds, wading birds, and
waterfowl. Gulf Coast marshes and beaches also provide important feeding grounds and nesting habitats. Species that breed on beaches, flats, dunes, bars, ba rrier islands, and similar habitats include the Sandwich Tern, Wilson’s Plover, Black Skimmer, Forster’s Tern, Gull

- Billed Tern, Laughing Gull, Least Tern, and Royal Tern (USFWS, 2010b). Additional information is presented in MMS ( 2007b ) and BOEM ( 2012a ).

The Brown Pelican ( Pelecanus occidentalis ) was delisted from Federal endangered status in 2009 (USFWS, 2010c). However, this species remains listed as endangered on the Louisiana list of Endangered Species (Louisiana Department of Wildlife and Fisheries, 2013), is listed as a species of greatest conservation need by the State of Mississippi (Mississippi Department of Wildlife, Fisheries and Parks, 20 05 ), and a s a species of special concern by the State of Florida (Florida
Fish and Wildlife Conservation Co mmission, 201 2 ). Brown Pelicans inhabit coastal habitats and forage within both coastal waters and waters of the inner continental shelf. Aerial and shipboard surveys, including GulfCet and GulfCet II, indicate that Brown Pelicans do not occur in deep of fshore waters (Fritts and Reynolds, 1981; Peake, 1996; Hess and Ribic, 2000). Nearly half the southeastern population of Brown Pelicans live s in the northern Gulf Coast, generally nesting on protected islands (USFWS, 2010 b ).Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 50 The Southern Bald Eagle ( Halia eetus leucocephalus ) was delisted from its threatened status in
the lower 48 states on 28 June 2007. The Bald Eagle is a terrestrial raptor widely distributed across the southern U.S., including coastal habitats along the Gulf of Mexico. The Gulf C oast i s inhabited by both wintering migrant and resident Bald Eagles (Johnsgard, 1990; Ehrlich et al., 1992).

IPFs potentially affecting shorebird s and coastal nesting birds include support vessel and helicopter traffic and a large oil spill (WCD). A small fuel spill in the lease area would be unlikely
to affect shorebird s or coastal nesting birds , due to the lease area’s distance from the nearest
shoreline. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall

or reach coastal waters prior to breaking up. Compliance with NTL 2012

- BSEE

- G01 will minimize the potential for marine debris

- related impacts on shorebirds.



### Impacts of Support Vessel and Helicopter Traffic

Support vessels and helicopters will transit coastal areas n ear Port Fourchon and Houma, Louisiana, where shorebird s and coastal nesting birds may be found. These activities could periodically disturb individuals or groups of birds within sensitive coastal habitats (e.g., wetlands that may support feeding, resting, or breeding birds).

Vessel traffic may disturb some foraging and resting birds. Flushing distances vary between species and between individuals (Rodgers and Schwikert, 2002). The disturbances will be limited to flushing birds away from vessel p athways; known distances are from 20 to 49 m (65 to 160 ft) for personal watercraft and 23 to 58 m (75 to 190 ft) for an outboard

- powered boat (Rodgers and Schwikert, 2002). Flushing distances may be similar or less for the support
vessels to be used for Anadarko ’s project, and some species such as gulls are attracted to boats. Support vessels will not approach nesting or breeding areas on the shoreline, so disturbances to nesting birds, eggs, and chicks are not expected. Vessel operators will use design ated navigation channels and comply with posted speed and wake restrictions while transiting sensitive inland
waterways. Due to the limited scope and short duration of drilling activities, any short

- term impacts are not expected to be biologically significant to coastal bird populations.

Aircraft traffic can cause some disturbance to birds onshore and offshore. Responses are highly dependent on the type of aircraft, the bird species, the activities that animals were previously engaged in, and previous exp osures to overflights (Efroymson et al., 2000). Helicopters seem to cause the most intense responses over other human disturbances for some species (Bélanger and Bédard, 1989). However, Federal Aviation Administration Advisory Circular No. 91

- 36D

recomme nds that pilots maintain a minimum altitude of 610 m (2,000 ft) when flying over

noise

- sensitive areas such as wildlife refuges, parks, and areas with wilderness characteristics. This is greater than the distance (slant range) at which aircraft overflight s have been reported to cause behavioral effects on most species of birds studied (Efroymson et al., 2000). With these guidelines in effect, it is likely that individual birds would experience, at most, only short

- term
behavioral disruption.



### Impacts of La rge Oil Spill (WCD)

Coastal birds can be exposed to oil as they float on the water surface, dive during foraging, or wade in oiled coastal waters. Oiled birds can lose the ability to fly, dive for food, or float on the water, which could lead to drowning (USFWS, 2010 d ). Oil interferes with the water repellency of feathers and can cause hypothermia in the right conditions. As birds groom themselves, theyAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 51 can ingest and inhale the oil on their bodies. Scavengers such as Bald Eagles and gulls can be

expose d to oil by feeding on carcasses of contaminated fish and wildlife. While ingestion can kill animals immediately, more often it results in lung, liver, and kidney damage, which can lead to death. Bird eggs may be damaged if an oiled adult sits on the nes t.

As noted above, the Brown Pelican was removed from the Federal endangered species list. Brown Pelicans are especially at risk from direct and indirect impacts from spilled oil within inner shelf and inshore waters, such as embayments . The range of this species is generally limited to these waters and surrounding coastal habitats. Brown Pelicans feed on mid

- sized fish that they capture by diving from above (“plunge diving”) and then scooping the fish into their expandable gular pouch . This behavior makes them susceptible to plumage oiling if they feed in areas with surface oil or an oil sheen. They may also capture prey that has been physically contaminated with oil or has ingested oil. Issues for Brown Pelicans include direct cont act with oil, disturbance by cleanup activities, and long

- term habitat contamination. The Bald Eagle may also be at risk from direct and indirect impacts from spilled oil. This species often captures fish within shallow water areas (snatching prey from the surface or wading into shallow areas to capture prey with their bill) and so may be susceptible to plumage oiling and, as with the Brown
Pelican , they may also capture prey that has been physically contaminated with oil or has ingested oil.



## C.5 Fisherie s Resources

C.5.1 Pelagic Communities and Ichthyoplankton

Biggs and Ressler (2000) reviewed the biology of pelagic communities in the deepwater environment of the northern Gulf of Mexico. The biological oceanography of the region is dominated by the influ ence of the Loop Current, whose surface waters are among the most oligotrophic in the world’s oceans. Superimposed on this low

- productivity condition are productive " hot spots " associated with entrainment of nutrient

- rich Mississippi River water and

mesos cale oceanographic features. Anticyclonic and cyclonic hydrographic features play an important role in determining biogeographic patterns and controlling primary productivity in the northern Gulf of Mexico (Biggs and Ressler, 2000).

Most fishes inhabiting shelf or oceanic waters of the Gulf of Mexico have planktonic eggs and larvae (Ditty, 1986; Ditty et al., 1988; Richards et al., 1989, 1993). Pelagic eggs and larvae become part of the planktonic community for various lengths of time (10 to 100 days, dep ending on the species) (MMS, 2007b).

IPFs potentially affecting pelagic communities and ichthyoplankton include drilling rig presence, noise, and lights; effluent discharges; water intakes; and two types of accidents – a small fuel spill and a large oil sp ill ( WCD).



### Impacts of Drilling Rig Presence, Noise, and Lights

The drilling rig, as a floating structure in the deepwater environment, will act as a fish

- attracting device (FAD). In oceanic waters, the FAD effect would be most pronounced for epipelagic fishes such as tunas, dolphin, billfishes, and jacks, which are commonly attracted to fixed and drifting surface structures (Holland et al., 1990; Higashi, 1994; Relini et al., 1994 ; MMS, 2000, 2007b,

2008 ). This FAD effect could possibly enhance the feed ing of epipelagic predators by attractingAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 52 and concentrating smaller fish species. Because the drilling rig is a single, temporary structure, impacts on fish populations, whether beneficial or adverse, are considered minor.



### Impacts of Effluent Discharges

T reated sanitary and domestic wastes may have a slight effect on the pelagic environment in the immediate vicinity of these discharges. These wastes may have elevated levels of nutrients, organic matter, and chlorine, but should be diluted rapidly to undet ectable levels within tens to hundreds of meters from the source. Minimal impacts on water quality, plankton, and nekton are anticipated.

Deck drainage may have a slight effect on the pelagic environment in the immediate vicinity of these discharges. Dec k drainage from contaminated areas will be passed through an
oil

- and

- water separator prior to release, and discharges will be monitored for visible sheen. The discharges may have slightly elevated levels of hydrocarbons but should be diluted rapidly to

un detectable levels within tens to hundreds of meters from the source. Minimal impacts on water quality, plankton, and nekton are anticipated.

Other discharges in accordance with the NPDES permit, such as desalination unit brine and uncontaminated cooling w ater, fire water, and ballast water

, are expected to be diluted rapidly and have little or no impact on water column biota.



### Impacts of Water Intakes

Seawater will be drawn from the ocean for once

- through, non

- contact cooling of machinery

on the drilling ri g. The drilling rig ultimately chosen for this project will be in compliance with all cooling water intake requirements.

The intake of seawater for cooling water will entrain plankton. The low intake velocity should allow most strong

- swimming juvenile fishes and smaller adults to escape entrainment or impingement. However, drifting plankton would not be able to escape entrainment with the exception of a few fast

- swimming larvae of certain taxonomic groups. Those organisms entrained may be stressed or killed, primarily through changes in water temperature during the route from cooling intake structure to discharge structure and mechanical damage (turbulence in pumps and condensers). Due to the limited scope and short duration of drilling activities , an y short

- term impacts of entrainment are not expected to be biologically significant to plankton or ichthyoplankton populations.



### Impacts of a Small Fuel Spill

Potential spill impacts on fisheries resource s are discussed in MMS ( 2007b ) and

BOEM ( 2012a, d). F or this EP , there are no unique site

- specific issues with respect to spill impacts.

The probability of a fuel spill will be minimized by Anadarko’ s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP could mitigate the potential for impacts on pelagic communities

, including ichthyoplankton. EP Section H provides detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 53 A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The sea surface area with diesel fuel on it would range from 0.5 to 5 ha (1.2 to

12 ac)

, depending on sea state and weather conditions.

A small fuel spill could have localized impacts on phytoplankton, zooplankton, and nekton.

Due to the limited areal extent and short duration of water quality impacts, a small fuel spill would be unlikely to produce detectable impacts on pelagic communities.



### Impacts of a Large Oil Spill (WCD)

A large oil spill could affect wate r column biota including phytoplankton, zooplankton, ichthyoplankton, and nekton. A large spill that persisted for weeks or months would be more likely to affect these communities. While adult and juvenile fishes may actively avoid a large spill, planktonic eggs and larvae would be unable to avoid contact. Eggs and larvae of fishes are especially vulnerable to oiling because they inhabit the upper layers of the water column, and they will die if exposed to certain toxic fractions of spilled oil. Impacts potentially would be greater if local

- scale currents retained planktonic larval assemblages (and the floating oil slick)
within the same water mass.



### C.5.2 Essential Fish Habitat

Essential Fish Habitat (EFH) is defined as those waters and substrate necessa ry to fish for spawning, breeding, feeding, and growth to maturity. Under the Magnuson

- Stevens Fishery Conservation and Management Act, as amended, Federal agencies are required to consult on activities that may adversely affect EFH designated in Fishery Management Plans developed by the regional Fishery Management Councils.

The BOEM (201 2b ) has reexamined the analysis for fish resources and EFH presented in MMS ( 2007a,b) in consideration of the Macondo event. No substantial new information was found
that would alter the impact conclusions for fish resources and EFH presented in MMS (2007a,b)

.
The Gulf of Mexico Fishery Management Council (GMFMC) has prepared Fishery Management Plans for corals and coral reefs, shrimp s , stone crab, spiny lobster, reef fish es, coastal migratory pelagic fishes, and red drum. In 2005, the EFH for these managed species was redefined in Generic Amendment No. 3 to the various Fishery Management Plans (GMFMC, 2005). T he EFH
for most of these GMFMC

- managed species is on the conti nental shelf in waters shallower than

183 m (600 ft). The shelf edge is the outer boundary for coastal migratory pelagic fishes, reef fishes, and shrimps. EFH for corals and coral reefs includes some shelf

- edge topographic
features on the Texas

- Louisiana OCS, the nearest of which are located approximately 56 miles (90 km) north

- northwest of the lease area.

Highly migratory pelagic fishes, which occur as transients in the lease area, are the only remaining group for which EFH has been identified in the deepwater Gulf of Mexico. Species in this group, including tunas, swordfishes, billfishes, and sharks, are managed by NMFS. Highly migratory species with EFH at or near the lease area include the following species and life stages (NMFS, 2009):Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 54 • Atlantic bluefin tuna (spawn, eggs,
larvae , adults )

• Bigeye tuna (juveniles , adults )

• Bigeye thresher shark (all)

• Blue marlin (juveniles, adults)

• Longbill spearfish (juveniles, adults)

• Longfin mako shark (all) • Oceanic whitetip shark (all)

• Sailfish (adult)

• Silky shark (all)

• Skipjack tuna (spawn , adults )

• Swordfish (larvae, juveniles, adults)

• White marlin (juveniles, adults)

• Yellowfin tuna (spawn, juveniles, adults)

Recent research indicates the central and western Gulf of Mexico may be important spawning habitat for Atlantic bluefin tuna, and NMFS (2009) has designated a Habitat Area of Particular Concern (HAPC) for this specie s. The HAPC covers much of the deepwater Gulf of Mexico, including the lease area ( Figure 3 ). The areal extent of the HAPC is approximately 300,000 km 2 (15,000 mi 2 ). The prevailing assumption is that Atlantic bluefin tuna follow an annual cycle of forag ing in June through March off the eastern U.S. and Canadian coasts, followed by migration to the Gulf of Mexico to spawn in Apr il, May, and June (NMFS, 2009).

On 27 May 2011, after an extensive scientific review, NOAA announced that Atlantic bluefin tuna currently do not warrant species protection under the ESA

. However, NOAA did classify
the bluefin tuna as a species of concern, effectively placing the species on a watch list as the agency awaits new data on the impact of a stricter international management regimen

.

A new amendment to the original EFH Generic Amendment was finalized in 2005 (GMFMC, 2005). One of the most significant proposed changes in this amendment reduced the extent of EFH relative to the 1998 Generic Amendment by removing the EFH description and
identification from waters between 100 fathoms and the seaward limit of the Exclusive

Economic Zone ( EEZ )

. The Highly Migratory Species Fisheries Management Plan was amended

in 2009 to update EFH and HAPC to include the bluefin tuna sp awning area ( NMFS , 2009).

There are current NTLs (2009

- G39 and 2009

- G40) that provide guidance and clarification of the regulations with respect to biologically sensitive underwater features and areas and benthic

communities that are considered EFH (MMS, 2 009 a,b ). A new EFH consultation has been initiated between BOEM’s Gulf of Mexico Region and NOAA’s Southeastern Region. Some

EFH requirements may change with the new agreement. Until the new agreement is in place, the 1999 Programmatic Consultation with the elements described a bove will be followed ( BOEMRE, 2011 a ; BOEM, 2012 b ).

Other HAPCs have been identified by the GMFMC (2005). These include the Florida Middle Grounds, Madison

- Swanson Marine Reserve, Tortugas North and South Ecological Reserves,
Pull ey Ridge, and several individual reefs and banks of the northwestern Gulf of Mexico ( Figure 3 ). The nearest HAPC is Jakkula Bank, located approximately 153 miles (246 km) west of
the lease area.

IPFs potentially affecting EFH include drilling rig presence, noise, and lights; effluent discharges; water intakes; and two types of accidents – a small fuel spill and a large oil spill (WCD).Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 55 

### Impacts of Drilling Rig Presence, Noise, and Lights

The drilling rig, as a floating structure in the deepwater environment, will act as a n FAD. In oceanic waters, the FAD effect would be most pronounced for epipelagic fishes such as tunas, dolphin, billfishes, and jacks, which are commonly attracted to fixed and drifting surface structures (Holland et al., 1990; Higashi, 1994; Relini et al., 1994 ; MMS, 2000, 2007b, 2008 ). This FAD effect would possibly enhance feeding of epipelagic predators by attracting and concentrating smaller fish species. Because the drilling rig is a single, temporary structure, any impact s on EFH for highly migratory pelagic fishes are considered minor.



### Impacts of Effluent Discharges

Other effluent discharges affecting EFH by diminishing ambient water quality include drilling muds and cuttings, treated sanitary and domestic wastes, deck dr ainage, and miscellaneous discharges such as desalination unit brine and uncontaminated cooling water, fire water, and ballast water. Impacts on water quality have been discussed previously. No significant impacts

on EFH for highly migratory pelagic fish es are expected from these discharges.



### Impacts of Water Intakes

As noted previously, cooling water intake will cause entrainment and impingement of plankton, including fish eggs and larvae (ichthyoplankton). Due to the limited scope and short duration of drilling activities , any short

- term impacts on EFH for highly migratory pelagic fishes are not expected to be biologically significant.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures duri ng routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP could help diminish the potential for impacts on EFH. EP Section H provides
detail on spill response measures. Given the open ocean locati on of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

Potential spill impacts on EFH are discussed in MMS ( 2007b ) and BOEM ( 2012a, d)

. F or this EP

, there are no unique site

- specific issues with respect to spill impacts.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteor ological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The sea surface area with diesel fuel on it would range from 0.5 to 5 ha (1.2 to

12 ac)

, depending on sea state and weather conditions.

A small fuel spill could have localized impacts on EFH for highly migratory pelagic fishes, including tunas, swordfishes, billfishes, and sharks. These species occur as transients in the
lease area. A spill would also produce short

- term impact on water quality in the HAPC for spawning bluefin tuna, which covers much of the deepwater Gulf of Mexico. The areal extent of
the affected area would represent a negligible portion of the HAPC.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 56 A small fuel spill would not affect EFH for corals and coral reefs, as the nearest EFH is located approximately 56 miles (90 km) from the lease area. A small fuel spill would float and dissipa te

on the sea surface and would not contact these features.



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on EFH are discussed in MMS ( 2007b ) and BOEM ( 2012a, d ). For this EP

, there are no unique site

- specific issues with respect to EFH.

An oi l spill in offshore waters would temporarily increase hydrocarbon concentrations on the water surface and potentially in the subsurface as well. Given the extent of EFH designations in the Gulf of Mexico (GMFMC, 2005; NMFS, 2009), some impact on EFH would be unavoidable.

A large spill could affect the EFH for many managed species including shrimp s , stone crab, spiny lobster, reef fishes, coastal migratory pelagic fishes, and red drum. It would result in adverse impacts on water quality and water column bi ota including phytoplankton, zooplankton, and nekton. In coastal waters, sediments could be contaminated and result in persistent degradation of the seafloor habitat for managed demersal fish and shellfish species.

T he lease area is within the HAPC for spawning Atlantic bluefin tuna (NMFS, 2009). A large spill could temporarily degrade the HAPC due to increased hydrocarbon concentrations in the water column, with the potential for lethal or sublethal impacts on spawning tuna. Potential impacts would depend in part on the timing of a spill, as this species migrates to the Gulf of Mexico to spawn in April, May, and June (NMFS, 2009).

The topographic features

, located 56 miles (90 km) north

- northwest of the lease area

, are design ated as EFH under the corals and coral reefs management plan. An accidental spill would be unlikely to affect this area, since a surface slick would not reach these features due to their depth

.



## C.6 Archaeological Resources

C.6.1 Shipwreck Sites

The BOEM ( 201 2b ) reexamined the analys e s for archaeological resources presented in

MMS (2007b, 2008), b ased on additional information available since the publication of these
two documents and in consideration of the Macondo oil spill

. Substantial new information t hat alters the impact conclusion for archaeological resources presented in MMS (2007b, 2008) has come to light as a result of BOEM

- sponsored studies and industry surveys. Specifically, evidence of damage to significant cultural resources (i.e., historic shipwrecks) has been shown to have occurred because of an incomplete knowledge of seafloor conditions in lease areas >200 m (656 ft) deep that have been exempted from high

- resolution surveys. Since significant historic shipwrecks have recently been discov ered outside the previously designated high

- probability areas (some of which show evidence of impacts from permitted activities prior to their discovery), a survey is now required for exploration and development projects.

The lease area is not on the list of OCS blocks with a high potential for historic shipwrecks (BOEM, 2012c ). The site clearance surveys conducted by Gardline (2013) found no items of archaeological significance within 610 m (2,000 ft) of any of the proposed wellsites. Anadarko
will abide by the applicable requirements of NTL 2005

- G07, which stipulate that work beAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 57 stopped at the project site if any previously undetected archaeological resource is discovered after work has begun until appropriate surveys and evaluations have been completed.

Because there are no shipwreck sites in the lease area, there are no routine IPFs that are likely to affect shipwrecks. I mpacts of a large oil spill (WCD) are the only IPFs considered. A small fuel spill would not affect shipwrecks because the oil would float and dissipate on the sea surface.



### Impacts of a Large Oil Spill (WCD)

MMS (2007b) estimate d that a severe subsurface blowout could resuspend and disperse
sediments within a 300

- m (984

- ft) radius. Because there are no historic shipwrecks in the lease area, this impact would not be relevant.

Previous analyses (MMS, 2007a, 2008) concluded that oil spills would be unlikely to affect archaeological sites beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 22 miles ( 35 km ) from the wellsite and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could have the potential to contact
sh ipwreck sites beyond the 300

- m (984

- ft) radius estimated by MMS (2007a, 2008)

, depending on its extent, trajectory, and persistence. If oil from a subsea spill should come into contact with wooden shipwrecks on the seafloor

, it could adversely affect thei r condition or preservation. Should there be any indication that potential shipwreck sites could be affected, in accordance
with NTL 2005

- G07 Anadarko will immediately halt operations, take steps to ensure that the site is not disturbed in any way

, and co ntact the BOEM Regional Supervisor, Leasing and Environment, within 48 hours of its discovery. Anadarko would cease all operations within

305 m (1,000 ft) of the site until the Regional Supervisor provides instructions on steps to take
to assess the site’ s potential historic significance and protect it.

A spill entering shallow coastal waters could conceivably contaminate an undiscovered shipwreck site. A s noted by MMS (2007b), should an oil spill contact a coastal historic site, such as a fort or a lighthouse, the major impact would be a temporary, reversible visual impact from
oil contact and contamination of the site and its environment.



### C.6.2 Prehistoric Archaeological Sites

Available evidence suggests that sea level in the northern Gulf of Mexico was at least 9 1 m ( 300 ft), and possibly as much as 130 m (427 ft), lower than present sea level during the period 20,000 to 17,000 years Before Present (B.P.) (Nelson and Bray, 1970). Sea level in the northern Gulf reached its present stand around 3,500 year s B.P. (Pearson et al., 1986).

During periods that the continental shelf was exposed above sea level, the area was open to habitation by prehistoric peoples. The advent of early man into the Gulf of Mexico region is currently accepted to be around 12,000 years B.P. (Aten, 1983). The sea

- level curve for the
northern Gulf of Mexico proposed by Coastal Environments, Inc. suggests that sea level at 12,000 years B.P. would have been approximately 45 to 60 m (148 to 197 ft) bel ow the
present

- day sea level (Coastal Environments, Inc.

, 1977

, 1982). On this basis, the contine ntal
shelf shoreward of the 45 - to 60

- m (148 - to 197

- ft) bathymetric contours has potential forAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 58 prehistoric sites dating after 12,000 years B.P. Because of inherent uncertainties in both the depth of sea level and the entry date of prehistoric man into North America, the MMS adopted
the 60

- m (197

- ft) water depth as the seaward extent for archaeological site potential in Gulf of

Mexico region

.
With a water depth between 1,270 and 1,351 m (4 ,167 and 4,433 ft)

, the lease area is well beyond the 60

- m (197

- ft) depth contour used by the BOEM as the seaward extent for prehistoric archaeological site potential in the Gulf of Mexico. Because prehistoric archaeological sites are not found in the lease area, the only relevant IPF is a large oil spill (WCD). A small fuel spill would not affect prehistoric archaeological resources because the oil would float and dissipate on the sea surface.



### Impacts of a Large Oil Spill (WCD)

Because prehistoric archaeological sites are not found in the lease area, they would not be affected by the physical effects of a subsea blowout. The MMS (2007b) estimates that a severe subsurface blowout could resuspend and disperse sediments within a 300

- m (984

- ft) radius.

Along the northern Gulf C oast, prehistoric sites occur frequently along the barrier islands and mainland coast and along the margins of bays and bayous (MMS, 2007b). If a spill did reach a prehistoric site along these shorelines it could coat fragile artifacts or site features and compromise the potential for radiocarbon dating organic materials in a site (although other dating methods are available and it is possible to decontaminate an oiled sample for radiocarbon dating). Coastal prehistoric sites could als o be damaged by spill cleanup operations (e.g., by destroying fragile artifacts and disturbing the provenance of artifacts and site features).



## C.7 Coastal Habitats and Protected Areas

Coastal habitats in the northeastern Gulf of Mexico that may be affected by oil and gas activities
are described in MMS ( 2007b ), BOEM ( 2012a,b, d), and in a literature review by Collard and Way (1997). Coastal habitats inshore of the project area include barrier beaches and dunes, wetlands, and submerged seagrass beds. Genera lly, most of the northeastern Gulf is fringed by barrier beaches, with wetlands and/or submerged seagrass beds occurring in sheltered areas
behind the barrier islands and in estuaries.

Due to the distance from shore, the only IPF associated with routine activities in the lease area
that potentially may affect beaches and dunes, wetlands, seagrass beds, coastal wildlife refuges, wilderness areas, or any other managed or protected coastal area relate to support vessel
traffic . T he support bases at Port Fourchon and Houma, Louisiana

, are not in wildlife refuge s or wilderness area s . Potential impacts of support vessel traffic are addressed briefly below.

A small fuel spill in the lease area would be unlikely to affect coastal habi tats due to the lease area’s distance from the nearest shoreline. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.



### Impacts of Support Vessel Traffic

For OCS activities i n general, support operations, including crew boats and supply boats, may have a minor incremental impact on coastal habitats. Over time with a large number of vessel trips, vessel wakes can erode shorelines along inlets, channels, and harbors. Support

o perations, including crew boats and supply boats as detailed in EP Section K

, may have a minorAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 59 incremental impact on coastal habitats or protected areas. Impacts will be minimized by following the speed and wake restrictions in harbors and channels.



### Impac ts of a Large Oil Spill (WCD)

Potential spill impacts on coastal habitats are discussed in MMS ( 2007b ) and BOEM ( 2012a,b, d ). Coastal habitats inshore of the project area include barrier beaches and dunes, wetlands, and submerged seagrass beds. For this EP , there are no unique site

- specific issues with respect to
coastal habitats.

The revised OSRA modeling summarized in Table 3 predicts that there is a 17 % probability of oil from a spill in the lease area reaching shorelines in Texas within 120 days, a 14 % probability of oil reaching Louisiana shorelines within 120 days , and a 1% chance of oil from a spill from the lease area reaching Mississippi shorelines within 120 days

.
The shorelines within the geographic range predicted by the OSRA modeling ( Table 3 ) include extensive barrier beaches and wetlands, with submerged seagrass beds occurring in sheltered
areas behind the barrier islands and in estuaries. NWRs and other protected areas along the
coast are discussed in MMS ( 2007b ), BOEM ( 2012b ), and Anadarko’ s OSRP. Coastal and near
coastal wildlife refuges, wilderness areas , and State and National parks within the geographic range of the potential shoreline contacts after 120 days are presented in Table 6

.

Table 6. W ildlife refuges, w ilderness areas, and State and National parks within the geographic range of the potential shoreline contacts after 120 days (From: BOEM , 2012 b).

County or Parish, State W ildlife Refuge, Wilderness Area, or State/National Park

Kenedy County, Texas Padre Island National Seashore Laguna Madre Estuarine And Coastal Marine Area

Kleberg County, Texas Padre Island National Seashore Laguna Madre Estuarine And Coastal Marine Area

Nueces County, Texas Laguna Madre Estuarine And Coastal Marine Area Mustang Island State Park Lake Corpus Christi State Park

Port Aransas Park

Mission

- Aransas National Estuarine Research Reserve

Aransas County, Texas Mission

- Aransas National Estuarine Research Reserve Aransas National Wildlife Refuge

Goose Island State Park

Calhoun County, Texas Mission

- Aransas National Estuarine Research Reserve Aransas National Wildlife Refuge Matagorda Island State Park Guadalupe Delta Wildlife Management Area

Welder Flats Coastal Preserve

Matagorda County, Texas Aransas National Wildlife Refuge Mad Island Wildlife Management Area Big Boggy National Wildlife Refuge San Bernard National Wildlife RefugeTable 6. (Continued).

Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 60 County or Parish, State W ildlife Refuge, Wilderness Area, or State/National Park

Brazoria County, Texas San Bernard National Wildlife Refuge Peach Point Wildlife Management Area

Bra zoria National Wildlife Refuge Christmas Bay State Park Christmas Bay Coastal Preserve

Galveston County, Texas Brazoria National Wildlife Refuge

Galveston Island State Park Apffel Park
Seawolf Park

Old Fort Travis Park Atkinson Island Wildlife Management Area

Ft. Anahuac Park Anahuac National Wildlife Refuge McFaddin National Wildlife Refuge Candy Abshier Wildlife Management Area Atkinson Island Wildlife Management Area

Chambers County, Texas Anahuac National Wildlife Refuge McFaddin National Wildlife Refuge

Jefferson County, Texas McFaddin National Wildlife Refuge

Sea Rim State Park Murphree Wildlife Management Area Texas Point National Wildlife Refuge

Cameron Parish, Louisiana Sabine National Wildlife Refuge

Camer on Prairie National Wildlife Refuge Lacassine National Wildlife Refuge

Little Pecan Island Natural Area

Peveto Woods Natural Area Lower Neches Wildlife Management Area Rockefeller Wildlife Management Area

Vermilion Parish, Louisiana Rockefeller Wildlife Management Area Paul J. Rainey Wildlife Management Area

Iberia Parish, Louisiana Marsh Island Wildlife Management Area Cypremort Point State Park Shell Keys National Wildlife Refuge

St. Mary Parish, Louisiana Atchafalaya Delta Wildlife Management Area Bayoue Teche National Wildlife Refuge

Terrebonne Parish, Louisiana Atchafalaya Delta Wildlife Management Area Mandalay National Wildlife Refuge

Isles Dernieres Barrier Islands Refuge Point Au Chein Wildlife Management Area

Lafourche Parish, Louisiana Point Au Chein Wildlife Management Area Wisner Wildlife Management Area

Jefferson Parish, Louisiana Grand Isle State Park
Salvador Wildlife Management Area
Jean Lafitte National Historical Park and Preserve
Lafitte Woods Natural AreaTable 6. (Continued).

Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 61 County or Parish, State W ildlife Refuge, Wilderness Area, or State/National Park

Plaquemines Parish, Louisiana Salvador Wildlife Management Area
Jean Lafitte National Historical Park and Preserve Delta National Wildlife Refuge

Pass A Loutre Wildlife Management Area Breton National Wildlife Refuge

St. Bernard State Park

St. Bernard Parish, Louisiana Breton National Wildlife Refuge

St. Bernard State Park Biloxi Wildlife Management Area Bayou Sauvage National Wildlife Refuge

Hancock and Harrison Counties, Mississippi Hancock County Coastal Marsh Reserve

Buccaneer State Park

Jourdan River Coastal Reserve

Biloxi River Coastal Reserve
Gulf Islands National Seashore Bayou Sauvage National Wildlife Refuge Big Branch Marsh National Wildlife Refuge Pearl River Wildlife Management Area
Wolf River Coastal Reserve Grand Bayou Coastal Preserve Bayou Portage Coastal Reserve

Biloxi Marshes State Coastal Preserve

Deer Island State Coastal Preserve

Jackson County, Mississippi Gulf Islands National Seashore Davis Bayou Coastal Preserve Mississippi Sandhill Crane National Wildlife Refuge Pascagoula River Coastal Reserve Grand Bay National Estuarine Research Reserve Grand Bay National Wildlife Refuge

Grand Bay Savannah Coastal Preserve

Deer Island State Coastal Preserve Old Fort Bayou Coastal Reserve
Bellefontaine Point Coastal Reserve Graveline Bay Coastal Reserve

Mobile County, Alabama Grand Bay National Wildlife Refuge The Grand Bay Savanna Tract
Penalver State Park Bon Secour National Wildlife Refuge W.L. Holland Wildlife Management Area

Baldwin County, Alabama Bon Secour National Wildlife Refuge

Meaher State Park Weeks Bay National Estuarine Research Reserve
Gulf State Park Lillian Swamp Mitigation Area Tarklin Bayou State Preserve W.L. Holland Wildlife Management AreaTable 6. (Continued).

Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 62 County or Parish, State W ildlife Refuge, Wilderness Area, or State/National Park

Escambia County, Florida Perdido Key State Recreation Area Big Lagoon State Recreation Area Fort Pickens State Park Aquatic Preserve
Gulf Islands National Seashore Pensacola Bay SWIM Area Yellow River Wildlife Management Area

Okaloosa County, Florida Gulf Islands National Seashore Pensacola Bay SWIM Area Choctawatchee Bay SWIM Area

Walton County, Florida Choctawatchee Bay SWIM Area

Henderson State Park Point Washington Outstanding Florida Water

Deer Lake State Park Grayton Beach State Park Outstanding Florida Water St. Andrew Bay Watershed SWIM Area

Bay County, Florida Point Washington Outstanding Florida Water St. Andrew Bay Watershed SWIM Area St. Andrews State Park Aquatic Preserve

St. Andrews State Park

Gulf County, Florida St. Andrew Bay Watershed SWIM Area St. Joseph Peninsula State Park St. Joseph Bay State Buffer Preserve

Franklin County, Florida St. Vincent National Wildlife Refuge Apalachicola National Estuarine Research Reserve Apalachicola Bay Aquatic Preserve Outstanding Florida Water Apalachicola River and Bay SWIM Area Apalachicola River Wildlife and Environmental Area St. George Island State Park

The level of impacts from oil spills on coastal habitats depends on many factors, including the oil characteristics, the geographic location of the landfall, and the weather and oceanographic conditions at the time (MMS, 2007b). Oil that makes it to beaches may be either liquid weathered oil, an oil

- and

- water mousse, or tarballs (MMS, 2007b). Oil is generally deposited on beaches in lines defined by wave action at the time of landfall. Oil t hat remains on the beach will thicken as its volatile components are lost. Thickened oil may form tarballs or aggregations that incorporate sand, shell, and other materials into its mass. Tar may be buried to varying depths under the sand. On warm days, both exposed and buried tarballs may liquefy and ooze. Oozing may also serve to expand the size of a mass as it incorporates beach materials. Oil on beaches may be cleaned up manually, mechanically, or both. Some oil can remain on the beach at varying depths and may persist for several years as it slowly biodegrades and volatilizes.

Wetlands are highly sensitive to oiling. The MMS (2007b) predicted that for every 50 bbl of oil contacting wetlands, approximately 2.7 ha (6.7 ac) of wetland vegetation wil l experience dieback. Thirty percent of these damaged wetlands are assumed to recover within 4 years, and 85% within 10 years. About 15% of the contacted wetlands are expected to be converted permanently to open

- water habitat. The critical concentration of oil is that concentration aboveAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 63 which impacts to wetlands will be long

- term and recovery will take longer than two growing seasons, and which causes plant mortality and some permanent wetland loss. Critical concentrations of various oils are expected to vary broadly for wetland types and wetland plant species. Louisiana wetlands are assumed to be more sensitive to oil contact than elsewhere in the Gulf because of high cumulative stress (MMS, 2007b). In addition to the direct impacts of oil, cleanup a ctivities in marshes may accelerate rates of erosion and retard recovery rates, which have been reported to require from years to decades following a spill (MMS, 2007b ; BOEMRE, 2011a; BOEM, 2012b ).



## C.8 Socioeconomic and Other Resources

C.8.1 Recreational a nd Commercial Fishing

BOEM has reexamined the analysis for recreational and commercial fishing presented in

MMS (2007b, 2008) based on additional information and in consideration of the Macondo spill.

N o new information was found that would alter the pote ntial impact s on commercial fishing ( BOEMRE, 2011 a ; BOEM, 2012 b).

The main commercial fishing activity in deep waters of the northern Gulf of Mexico is pelagic longlining for tunas, swordfishes, and other billfishes (Continental Shelf Associates, Inc., 2002). Pelagic longlining has occurred historically in the project area, primarily during spring and

summer

.
Longline gear consists of monofilament line deployed from a moving vessel and generally allowed to drift for 4 to 5 hours (Continental Shelf Associates, Inc., 2002). As the mainline is put out, baited leaders and buoys are clipped in place at regular intervals. It takes 8 to 10 hours to deploy a longline and about the same time to retrieve it. Longlines are often set near oceanographic features s uch as fronts or downwellings, w ith the aid of sophisticated on board temperature sensors, depth finders, and positioning equipment. Vessels typically are 10 to 30 m (33 to 98 ft) long, and their trips last from about 1 to 3 weeks. The main Gulf of Mexico homeports for longlining vessels are in Louisiana (Dulac and Venice) and Florida (Destin, Madeira Beach, and Panama City).

It is unlikely that any commercial fishing activity other than longlining occurs at or near the project area. Benthic species targe ted by commercial fishers occur on the upper continental slope, well inshore of the project area. Royal red shrimp ( Pleoticus robustus ) are caught by trawlers in water depths of about 250 to 550 m (820 to 1,804 ft). Tilefish es (primarily Lophalotilus chamaeleonticeps ) are caught by bottom longlining in water depths from about

165 to 450 m (540 to 1,476 ft) (Continental Shelf Associates, Inc., 2002).

Most recreational fishing activity in the region occurs in water depths less than 200 m (656 ft) (Continent al Shelf Associates, Inc., 1997, 2002). In deeper water, the main attraction to recreational fishers would be petroleum rig s offshore Texas and Louisiana. Due to the distance from shore, it is unlikely that recreational fishing activity is occurring in t he lease area.

The only routine IPF potentially affecting fisheries is drilling rig presence (including noise and lights)

. T wo types of potential accidents are also addressed below – a small fuel spill and a large oil spill (WCD).Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 64 

### Impacts of Drilling Rig Presence

There is a slight possibility of pelagic longlines becoming entangled in the drilling rig. For example, in January 1999, a portion of a pelagic longline snagged on the acoustic Doppler current profiler of a drillship working in the Gulf of Mexico (Continental Shelf Associates, Inc., 2002). The line was removed without incident. Generally, longline fishers use radar and are aware of offshore structures and ships when placing their sets. Therefore, little or no impact on pelagic longlining is exp ected.

Because it is unlikely that any recreational fishing activity is occurring in the project area, no adverse impacts are anticipated. Other factors such as effluent discharges are likely to have negligible impacts on commercial or recreational fisheries due to rapid dispersion, the small area of ocean affected, and the intermittent nature of the discharges.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko’s preventative measures during routine operations incl uding fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP could potentially mitigate and reduce the potential for impacts

. EP Section H provide s detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

Pelagic longlining activities in the lease area, if any, could be interrupted in the event of a small fuel spill. The sea surface area with diesel fuel on it wo uld range from 0.5 to 5 ha (1.2 to 12 ac)

, depending on sea state and weather conditions. Fishing activities could be interrupted due to the activities of response vessels operating in the lease area. A small fuel spill would not affect coastal water qua lity because the spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on fishing activities are discussed in MMS ( 2007b ) and BOEM ( 2012b,d )

. For this EP , there are no unique site

- specific issues with respect to this activity.

Pelagic longlining activities in the lease area and other fishing activities in the northern Gulf of Mexico could be interrupted in the event of a large oil spill. A s pill may or may not result in fishery closures, depending on the duration of the spill, the oceanographic and meteorological conditions at the time, and the effectiveness of spill response measures. The Macondo spill provides information about the maximum potential extent of fishery closures in the event of a large oil spill in the Gulf of Mexico (NMFS, 2010 c ). At its peak on 12 July 2010, closures encompassed 217,821 km 2 (84,101 mi 2 ), or 34.8% of the U.S. Gulf of Mexico EEZ.



### C.8.2 Public Health and Safet y

There are no IPFs associated with routine operations that are expected to affect public health and safety. Impacts of a small fuel spill and a large oil spill (WCD) are addressed below.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation ofAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 65 Anadarko ’s OSRP could potentially alleviate the potential for impa cts. EP Section H provide s detail on spill response measures.

A small fuel spill would not have any impacts on public health and safety because it would affect only a small area of the open ocean 71 miles (114 km) from the nearest shoreline

, and nearly al l of the diesel fuel would evaporate or disperse naturally within 24 hours. Response crews would be equipped with appropriate safety equipment to avoid injury and health effects. A small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

In the event of a large spill from a blowout, the main safety and health concerns are those of the offshore personnel involved in the incident and those responding to the spill. The drilling rig maintains a Shipboard Oil Pollution Emergency Plan as required under MARPOL 73/78.

Depending on the spill rate and duration, the physical/chemical characteristics of the oil, meteorological and oceanographic conditions at the time, and the effectiveness of spill response measures, the public could be exposed to oil on the water and along the shoreline, including skin contact or breathing VOCs . Crude oil is a highly flammable material

, and any smoke or vapors from a crude oil fire can cause irritation, and in large quantities may pose a health
hazard.

Data from the Macondo spill provide relevant information about the types of health issues that may occur in the event of a large oil spill (Centers for Disease Control and Prevention, 2 010a). Wildlife cleaning and rehabilitation workers have reported concerns including scrapes and cuts, itchy or red skin or rash, and symptoms of headache or feeling faint, dizzy, or fatigued. Hand, shoulder, or back pain was also reported by some wildl ife

- cleaning workers. Personnel working on offshore vessels or providing direct oversight to offshore vessels, including USCG personnel, civilian contractors, and other responders who were exposed to oil and dispersants

, had a 7 to

12 times higher prevale nce of upper respiratory symptoms and cough than those not exposed (Centers for Disease Control and Prevention, 2010b). Another potential occupational hazard for spill response workers in general was heat stress from work in a hot and humid environment. Initial symptoms from cleanup workers who sought medical care in Louisiana were typical of acute exposure to hydrocarbons or H 2 S , e.g., headaches, dizziness, nausea, vomiting, cough, respiratory distress, and chest pain (Solomon and Janssen, 2010).



### C.8.3 E mployment and Infrastructure

There are no IPFs associated with routine operations that are expected to affect employment and infrastructure. The project involves drilling with support from existing shorebase facilities in

Louisiana . No new or expanded fa cilities will be constructed, and no new employees are expected to move permanently into the area. The project will have a negligible impact on socioeconomic conditions such as local employment, existing offshore and coastal infrastructure (including major sources of supplies, services, energy, and water), and minority and lower income groups. Impacts of a small fuel spill and a large oil spill (WCD) are addressed below.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by An adarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation ofAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 66 Anadarko ’s OSRP could potentially mitigate and reduce the potential for impacts. EP Section H provide s detail on spill r esponse measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill that is dissipated within a few days would have little or no economic impact, as the spill response would use existing facilities, resources, and personnel.



### Impacts of a Large Oil Spill (WCD)

Potential socioeconomic impacts of an oil spill are discussed in MMS ( 2007b ) and

BOEM ( 2012a,b ,d ). For this EP , there are no unique site

- specific issues with respect to employment and coastal infrastructure. A large spill could cause economic impacts in several ways: it could result in extensive fishery closures that put fishermen out of work; it could result in temporary employment as par t of the response effort; it could result in adverse publicity that affects employment in coastal recreation and tourism industries; and it could result in another suspension of OCS drilling activities, including service and support operations that are an important part of local economies.

In addition to the analys e s presented by MMS (2007b, 2008 ) and BOEM (201 2b ), a recent study explored the economic impacts of the Macondo spill on oil and gas industry employment due to suspension of deepwater drilling (In ter

- Agency Economic Report, 2010). The study indicates that during the moratorium, the number of oil industry workers in the Gulf of Mexico fell by about 2,000 and may have indirectly caused a temporary loss of 8,000 to 12,000 jobs along the
Gulf Coast. Total spending by drilling operators is estimated to have declined by $1.8 billion

over a six

- month period; this direct reduction in spending affected employment in the industries that supply the Gulf drilling industry and in all other industries affected by declines in consumer and business spending (Inter

- Agency Economic Report, 2010)

.



### C.8.4 Recreation and Tourism

BOEM has reexamined the analys e s for recreation and tourism presented in MMS (2007b, 2008)
based on additional information and in consideration of the Macondo oil spill event. No new information was found that would alter the potential impact s on recreation and tourism ( BOEMRE, 2011 a ; BOEM, 2012 b ).

There are no known recreational uses of the lease area. Recreational resources and tourism in

coa stal areas would not be affected by any routine activities due to the distance from shore. Compliance with NTL 2012

- BSEE

- G01 will minimize the chance of trash or debris being lost overboard from the drilling rig and subsequently washing up on beaches.



### Imp acts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP could potentially help mitigate and reduce the potential for impacts.

EP Section H provide s detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 67 A small fuel spill in the lease area would be unlikely to affect recreation and tourism. There are no known recreational or tourism activities occurring in the lease area, and as explained in
Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.



### Impacts of a Large Oil Spill (WCD)

Potential impacts of an oil spill on recreation and tourism are discussed in MMS ( 2007b ) and

BOEM ( 2012a ,b,d ). For this EP , there are no unique site

- specific issues with respect to these impacts.

Impacts on recreation and tourism would vary depending on the duration of the spill and its fate including the effectiveness of response measures. A large spill that reached coastal waters and shorelines could adversely affect recreatio n and tourism by contaminating beaches and wetlands, resulting in negative publicity that encourages people to stay away. Based on the revised OSRA modeling (BOEM, 2012b) as summarized in Section A.9.3 ( Table 3 ), there is a

12 % probability of oil from a spill in the lease area reaching shorelines in Louisiana within 30 days and a 17 % chance of oil contacting shorelines in Texas within 120 days.

In addition to the analysis presented by MMS (2007b ; BOEMa,b,d), recent and ongoing studies have exp lored the economic impacts of the Macondo spill including tourism and " brand " damage (IEM, 2010; Oxford Economics, 2010). The U.S. Travel Association has estimated the economic impact of the Macondo spill on tourism across the Gulf Coast over a three

- year period at $22.7 billion (Oxford Economics, 2010)

.



### C.8.5 Land Use

Land use along the northern Gulf C oast is discussed in MMS ( 2007b ) and BOEM ( 2012a,b ,d ). There are no routine IPFs potential ly affecting land use. The project will use existing onshore support facilities in Louisiana . The land use at the existing shorebase sites is industrial. The project will not involve any new construction or changes to existing land use and, therefore, wil l not have any impacts. Levels of boat and helicopter traffic, as well as demand for goods and services including scarce coastal resources, will represent a small fraction of the level of activity occurring at the shorebase s.

A large oil spill (WCD) is th e only relevant IPF. A small fuel spill would not have any impacts on land use, as the response would be staged out of existing shorebases and facilities.



### Impacts of a Large Oil Spill (WCD)

The initial response for a large oil spill would be staged out of existing facilities, with no effect on land use. A large spill could have limited temporary impacts on land use along the coast if additional staging areas were needed. For example, during the Macondo spill, temporary staging areas were established in Louisiana, Mississippi, Alabama, and Florida for spill response and cleanup efforts. In the event of a large spill in the lease area, similar temporary staging areas could be needed. These areas would eventually return to their original use as the

respons e is demobilized.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 68 

### C.8.6 Other Marine Uses

The lease area is not located within any USCG

- designated fairway or shipping lane or Military Warning Area. Anadarko will comply with BOEM requirements and lease stipulations to avoid impacts on uses of the area by military vessels and aircraft.

Existing seafloor pipelines are present within 610 m (2,000 ft) of proposed wellsites AT 19

- KV,

AT 19

- EE, and AT 19

- KK. Existing wells are present within 610 m (2,000 ft) of p roposed wellsites

AT 18 -GG, AT 18 -GV , and AT 18

- QQ

. Anadarko will avoid existing infrastructure during the proposed exploratory drilling operations

.
There are no IPFs from routine project activities that are likely to affect other marine uses of the lease area. A large oil spill (WCD) is the only relevant accident IPF. A small fuel spill would not have any impacts on other marine uses because spill response activities would be mainly within
the lease area and the duration would be brief.



### Impacts of a Large Oil Spill (WCD)

An accidental spill would be unlikely to significantly affect shipping or other marine uses

. In the event of a large spill requiring numerous response vessels, coordination would be required to manage the vessel traffic for safe operations and to ensure that no anchoring or
seafloor

- disturbing activities occur near the existing pipelines and flowlines

.



## D. Environmental Hazards

D.1 Geologic Hazards

The site clearance surveys conducted by Gardline (2013) found a slight risk of shallow gas and a slight

- to

- moderate risk of shallow wate r flow across the lease area. A high risk for shallow water
flow was identified at proposed wellsite A T 18

- DD between 450 and 1,127 m (1,478 and 2,697 ft) below mud line ( BML )

. Gardline also identified a high risk for shallow water flow at proposed wellsite AT 19

- KK between 521 and 751 m (1,710 and 2,463 ft BML) , and for proposed
wellsite AT 18

- QQ between 683 and 898 m (2,239 and 2,946 ft BML). Gardline recommended drilling with caution and implementing appropriate drilling methodologies to contain possible
shallow water flow events in these two intervals (Gardline, 2013)

.
There are several seafloor faults in the vicinity of the proposed wellsites. A vertical wellbore at

AT 19

- DD will penetrate a fault at 4,497 ft BML. This fault appears to exhibit connectivity to the seabed and could cause drilling fluid circulation and wellbore stability problems

, especially if pressures over hydrostatic are exerted by the wellbore. A vertical wellbore at A T 19

- KK will penetrate a fault at 1,016 m (3,333 ft) BML. Gardline (2013) concluded that drilling fluid circulation problems could occur as a result of this fault penetration

, if pressures over background level are exerted by the drilling fluid column.

A vertical wellbore will penetrate three faults at well AT 18

- CC. The upper fault is located at

881 m (2,889 ft) BML and extends back to the seafloor; thereby representing a significant risk for drilling fluid recirculation and wellbore stability. The risk can be mitigated by preventing pressures exerted by the drilling fluid column from exceeding hydrostatic. The deeper twoAtwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 69 faults occur at 1,147 and 1,420 m (3,764 and 4,658 ft) BML , respectively

. These two faults have a limited vertical extent and could cause minor drilling fluid circulation and wellbore stab ility problems i f pressures exerted by the drilling fluid column exceed hydrostatic. Vertical wellbores at all other proposed wellsites will not penetrate any seafloor faults (Gardline, 2013).

Gardline (2013) con cluded that the wellsites are suitable for the propose d activities.

See EP Section C for supporting geological and geophysical information.



## D.2 Severe Weather

Under most circumstances, weather is not expected to have any effect on the proposed activities. Extreme weather, including high winds, strong currents, and large waves, was considered in the design criteria for the drilling rigs under consideration for this project . High winds and limited visibility during a severe storm could disrupt support activities (vessel and helicopter traffic) and make it necessary to suspend some activities on the drilling rig for safety
reasons until the storm or weather event passes. In the event of a hurricane, procedures as
outlined in the Hurricane Evacuation Plan would be adhered to.



## D.3 Currents and Waves

M etocean conditions such as sea states, wind speed, ocean currents, etc.

, will be continuously
monitored. Under most circumstances, physical oceanographic conditions are not expected to have any effect on the proposed activities. Strong currents (e.g., ca used by Loop Current eddies and intrusions) and large waves were considered in the design criteria for the drilling rig under consideration for this project. High waves during a severe storm could disrupt support activities (i.e., vessel and helicopter tr affic) and make it necessary to suspend some activities on the drilling rig for safety reasons until the storm or weather event passes.



## E. Alternatives

N o formal alternatives we re evaluated in this EIA for an EP . However, various technical and operation al options

, including the location of the wellsite s and the selection of a drilling unit, were considered by Anadarko in developing the proposed action.



## F. Mitigation Measures

The proposed action includes numerous mitigation measures required by laws, regulations, and

BOEM lease stipulations and NTLs. The project will comply with all applicable F ederal, S tate, and local requirements concerning air pollutant emissions, discharges to water, and solid waste disposal. All project activities will be conducted under guidance by Anadarko ’s OSRP and will
include the measures described in EP Section H

.Atwater Valley Blocks 18 and 19 December 2013 Environmental Impact Analysis for Initial Exploration Plan Page 70 

## G. Consultation

No persons or agencies were consulted during the preparation of this EIA.



## H. Preparers

The EIA was prepared by CSA Ocean Sciences Inc. Contributors included :

• M. John Thompson (Senior Scientist);

• John M. Tiggelaar II (Project Scientist);

• Keith VanGraafeiland (Geospatial Manager);

• Kevin Noack (Geospatial Coordinator);

• Kristen L. Metzger (Library and Information Services Director);

• LeslieAnn Weekes (Technical Editor).



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Aten, L.E. 1983. Indians of the upper Texas coast. New York, NY: Academic Press. 370 pp.
Barkuloo, J.M. 1988. Report on the conservation status of the Gulf of Mexico sturgeon, Acipenser oxyrinchus
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, The State of Deep Coral Ecosystems of the United States. NOAA Tech. Memo. CRCP

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, and 247. Final Envir onmental Impact Statement. U.S. Department of the Interior, Bureau of Ocean Energy Management, Gulf of Mexico OCS Region. OCS EIS/EA BOEM 2012

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. 2012 b. Gulf of Mexico OCS Oil and Gas Lease Sale: 2012. Cen tral Planning Area Lease Sale 216/222. Final Supplemental Environmental Impact Statement. U.S. Department of the Interior, Bureau of Ocean Energy Management. Gulf of Mexico OCS Region. New Orleans, LA. 2 volumes. OCS EIS/EA BOEM 2012

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