UNITED STATES GOVERNMENT MEMORANDUM

To: Public Information (MS 5030)

Plans Section, Office of Field Operations (MS 5231)

Public Information copy of Exploration Plan Control # - N-09714 Type - Initial Exploration Plan Lease(s) - OCS-G33755 Block - 738 Mississippi Canyon Area OCS-G33757 Block - 782 Mississippi Canyon Area Operator - Noble Energy, Inc. Drill & Complete - MC 738 A, B, MC 782 A, B, C, D

DP Semisubmersible

Attached is a copy of the subject plan for public comments on issues that should be addressed in an Environmental Assessment.

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

Mohammad Ashfaq Plan Coordinator Description - Rig Type - Subject: From: June 11, 2013

## PUBLIC COPY April 9, 2013



# Initial Exploration Plan

Lease OCS-G 33755 & 33757 Mississippi Canyon 738 & 782 Prospect Name: Dantzler

Offshore: Louisiana and Alabama

Submitted by:

Noble Energy, Inc. 100 Glenborough Drive Suite 100 Houston, Texas 77067

Estimated start up date: J uly 2 8 , 2013

## Table of Contents

Noble Energy, Inc. Initial Exploration Plan

Lease OCS-G 33755 & 33757 Mississippi Canyon 738 & 782



### A. Plan Contents

a. Plan Summary b. Plan Information Form

c. Location d. Safety and Pollution Prevention Features

e. Storage Tanks and/or Production Vessels f. Additional Measures



### B. General Information

a. Applications and Permits b. Drilling Fluids

c. New or Unusual Technologies d. Bonding Statement

e. Oil Spill Financial Responsibility (OSFR) f. Deepwater Well Control Statement g. Blowout Scenario



### C. Geological and Geophysical Information

a. Geologic Description b. Structure Contour Maps

c. Interpreted 3-D Seismic Lines d. Geological Structure Cross Section

e. Shallow Hazards Report f. Shallow Hazards Assessment g. High Resolution Seismic Lines h. Stratigraphic Column i. Time vs. Depth Table



### D. Hydrogen Sulfide (H 2 

### S) Information

a. Concentration b. Classification



### E. Biological, Physical, and Socioeconomic Information

a. Chemosynthetic Communities Report b. Topographic Features Map

c. Topographic Features Statement (Shunting) d. Live Bottoms (Pinnacle Trend) Map

e. Live Bottoms (Low Relief) Map f. Potentially Sensitive Biological Features g. Remotely Operated Vehicle (ROV) Monitoring Survey Plan h. Threatened and Endangered Species Information, Critical Habitat, and Marine Mammal Information i. Archaeological Report

### F. Waste and Discharge Information a. Projected Generated Wastes & Projected Ocean Discharges



### G. Air Emissions Information a. Emissions Worksheets and Screening Questions



### H. Oil Spill Information

a. Oil Spill Response Planning b. Spill Response Sites

c. OSRO Information d. Worst-case Scenario Comparison

e. Oil Spill Response Discussion



### I. Environmental Monitoring Information

a. Monitoring Systems b. Incidental Takes

c. Flower Garden Banks National Marine Sanctuary



### J. Lease Stipulation Information



### K. Support Vessels and Aircraft Information

a. General b. Diesel Oil Supply Vessels

c. Solid and Liquid Wastes Transportation d. Vicinity Map



### L. Onshore Support Facilities Information

a. General b. Support Base Construction or Expansion

c. Waste Disposal



### M. Coastal Zone Management Act (CZMA) Information



### N. Environmental Impact Analysis (EIA)



### O. Administrative Information

a. Exempted Information Description b. Bibliography

## Section A Plan Contents

A. Plan Summary Noble Energy, Inc. proposes to drill and complete six well in Mississippi Canyon Blocks 738 and 782 utilizing a dynamically positioned semisubmersible rig and a subsea BOP. The anticipated spud date of the first well is Ju ly 28 , 2013. Noble anticipates it will take approximately 86 days to drill and 70 days to complete each well. If commercial quantities of hydrocarbons are discovered, a Development Operations Coordination Document will be submitted for approval.

B. Plan Information Form See attached OCS Plan Information Form – Form BOEM -137, included as Attachment A-1

.

C. Location Included as Attachment A-2 is a location map depicting the proposed surface locations of the new wells. Attachment A-3 is a bathymetry map showing the water depths at the surface location of each proposed well. Attachment A-4 is p roprietary information.

D. Safety and Pollution Prevention Features A description of the drilling unit is included on the OCS Plan Information Form. Rig specifications will be made part of each Application for Permit to Drill.

Safety features on the drilling unit will include well control, pollution prevention, and blowout prevention equipment as described in Title 30 CFR Part 250, Subparts C, D, E, and G; and as further clarified by BOEM Notices to Lessees, and current policy making invoked by the BOEM, Environmental Protection Agency and the U.S. Coast Guard. Appropriate life rafts, life jackets, ring buoys, etc., will be maintained on the facility at all times.

Pollution prevention measures include installation of curbs, gutters, drip pans, and drains on drilling deck areas to collect all contaminants and debris.

E. Storage Tanks and/or Production Vessels All facility tanks of 25 barrels or more.

Type of Storage Tank Type of Facility Tank Capacity (bbls) Number

of Tanks Total

Capacity (bbls) Fluid

Gravity (API)

Fuel Oil (Marine Diesel) DP Semisubmersible 3,461 2 6,922 32.4°

4,634 2 9,268 32.4°

Total 16,190



### F. Additional Measures Noble does not propose additional safety, pollution prevention, or early spill detection measures beyond those required by 30 CFR 250.

Noble Energy, Inc. Page A-1 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)

# a a a

' ' '

'

a a a

a

a a ) )

) 

## 738

782 A

A

B

C OCS-G-33755

OCS-G-33757 1 1BP 25593' 27316' Y=10,264,320'

Y=10,232,640' Y=10,248,480'X=1,219,680'X=1,235,520' 782 'A' S.L. X=1,224,943' Y=10,247,759' LAT. 28° 13' 59.05"N LON. 88° 17' 26.43"W WD 6576'

782 'B' S.L. X=1,226,029' Y=10,245,555' LAT. 28° 13' 37.34"N LON. 88° 17' 14.02"W WD 6560'
782 'C' S.L. X=1,224,265' Y=10,238,900' LAT. 28° 12' 31.25"N LON. 88° 17' 32.95"W WD 6542' 738 'A' S.L. X=1,224,346' Y=10,250,202' LAT. 28° 14' 23.18"N LON. 88° 17' 33.39"W WD 6572'

738 'A' S.L. 1722' FSL 4666' FWL

782 'A' S.L. 721' FNL 5263' FWL

782 'B' S.L. 2925' FNL 6349' FWL

782 'C' S.L. 6260' FSL 4585' FWL Proposed well locations Coordinates Public Information

D B 738 'B' S.L. X=1,224,427' Y=10,250,134' LAT. 28° 14' 22.51"N LON. 88° 17' 32.48"W WD 6572' 738 'B' S.L. 1654' FSL 4747' FWL

782 'D' S.L. X=1,224,918' Y=10,247,903' LAT. 28° 14' 0.47"N LON. 88° 17' 26.72"W WD 6576' 782 'D' S.L. 577' FNL 5238' FWL

DEEP WATER BUSINESS UNIT 

### MISSISSIPPI CANYON 738/782 LOUISIANA



### LOCATION PLAT

GEOL./GEOP.: Staff C.I.: FILENAME: DATE: 1/2013 0 2,000 4,000 6,000 8,000 1,000 Feet 

# ®

Projection: UTM Zone 16 North Datum: NAD 27 Distance Units: US Survey Feet

# a a a

' ' '

'

a a a

a

a a ) )

) 

## 738

782 A

A

B

C OCS-G-33755

OCS-G-33757 1 1BP 25593' 27316' Public Information 6250'

6500' 6750'



### 6750'

7000' D B

DEEP WATER BUSINESS UNIT 

### MISSISSIPPI CANYON 738/782 LOUISIANA



### BATHYMETRY PLAT

GEOL./GEOP.: Staff C.I.: 50’ FILENAME: DATE: 1/2013 0 2,000 4,000 6,000 8,000 1,000
Feet 

# ®

Projection: UTM Zone 16 North Datum: NAD 27 Distance Units: US Survey Feet Proposed well locations

738 'A' S.L. 1722' FSL 4666' FWL

738 'B' S.L. 1654' FSL 4747' FWL

782 'A' S.L. 721' FNL 5263' FWL

782 'B' S.L. 2925' FNL 6349' FWL

782 'C' S.L. 6260' FSL 4585' FWL

782 'D' S.L. 577' FNL 5238' FWL

## Section B General Information

A. Applications and Permits No additional applications or permits are required to conduct the activities proposed herein.

B. Drilling Fluids –

Type of Dril ling Fluid Estimated Volume of Drilling Fluid to be used per Well Water-based Please see table in Section F Page F-1 Synthetic-based Please see table in Section L Page L-2

C. New or Unusual Technology Noble does not propose to use any new or unusual technology to carry out the proposed exploration activities.

D. Bonding Statement The bond requirements for the activities and facilities proposed in this EP are satisfied by an area-wide bond, furnished and maintained according to 30 CFR 256, subpart I; NTL No. 2000-G16, "Guidelines for General Lease Surety Bonds;" and NTL No. 2008-N07, "Supplemental Bond Procedures".

E. Oil Spill Financial Responsibility (OSFR) Noble Energy, Inc., BOEM company number 02237, has demonstrated oil spill financial responsibility for the facilities proposed in this EP according to 30 CFR Part 253; and NTL No. 2008-N05, "Guidelines for Oil Spill Financial Responsibility for Covered Facilities".

F. Deepwater Well Control Statement Noble Energy, Inc., BOEM company number 02237, has the financial capability to drill a relief well and conduct other emergency well control operations.

G. Blowout Scenario T he NTL 2010-N06, worst case discharge package , is included as "Attachment B­1".

Noble Energy, Inc. Page B-1 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)

### 1

WCD Discharge Discussion OCS-G33757 Operator – Noble Energy, Inc. MC 782-A, Dantzler Prospect

Introduction

Noble Energy Inc. is planning to drill the Dantzler Prospect, MC 782 No.1well, to a depth of21,584’ MD to test the Middle Miocene sands updip of the Chevron Caterpillar Deep well (OCSG16648 MC 782 No. 1). Noble Energy, Inc. has calculated a Worst Case Discharge rate based on mapping the sands found in the Caterpillar well to the proposed location for the Dantzler prospect. The calculated worst case discharge is 173,214 BOPD + no water. Noble Energy, Inc. has the resources to respond to the estimated Worst Case Discharge rate.

WCD Hole Section

The MC 782-A WCD (NTL – 06) application is designed for the exploration well. The well consists of eight hole sections to a proposed total depth of 21,584’ MD.

WCD Geological Input

The WCD model was built using values based on well control from local fields and dry holes. Interpretation of lithology was based on both seismic character (amplitude response) and seismic ties to wells with lithology data. Seismic lines were tied to the following local wells: Chevron MC 782 #1 (Caterpillar Deep), Amoco MC 739 #1 (Hilbert), BP MC 696 #1 (Blind Faith) and Shell MC 608 #1 (East Anstey).

WCD Engineering Input

The petrophysical and fluid data used in the WCD calculations were based on both public data and proprietary analog data in the area. The rock values were calculated from the closest offset well log of Chevron MC 782 No. 1, also known as Caterpillar Deep.

Dantzler MC 782 # 1 WCD Calculation Results

Noble Energy, Inc. used a commercial available nodal analysis program (Prosper) to calculate a WCD value of 173,214 BOPD + no water.

Description of the Drilling Blowout Scenario

The MC 782-A WCD is based on a drilling blowout scenario whereby the well has been drilled to TD and it is assumed that the drill pipe will be out of the hole and the drilling riser is removed allowing the worst case discharge fluid to exit the well at the subsea wellhead. In this WCD scenario, the assumption is the well will produce unrestricted from the open hole section to the wellhead with a sea water gradient as backpressure at the wellhead, and expects a failure of the closing of the blowout preventers (BOP) and the absence of a riser.

### 2

Duration of the Worst Case Discharge

The duration of the WCD is dependent on the characteristics of the blow out. The WCD will persist until the well is contained, a relief well is drilled, or the well bridges over due to wellbore instability.

Scenarios exist in which the duration of the WCD has the potential to flow from hours to months depending on the condition of the well at the time of the discharge as outlined below:

 The well could bridge over due to wellbore instability which should happen relatively early in the WCD scenario.

 Containment blowout preventer equipment (BOPE) is installed and closed using a prescribed procedure shutting in the well and eliminating the discharge. This would require between several weeks to accomplish, provided no debris removal is required.

 Twisted riser material may need to be removed prior to any containment equipment installation, which could take considerable time depending on the amount and complexity of debris. It could take several weeks to a few months to clear a connection for the BOPE to eliminate fluid releases.

 If all intervention attempts are unsuccessful, the well could discharge until intercepted and killed by a relief well intervention. The estimated time to drill a relief well is approximately four months. The estimated worst case volume discharge in the worst case scenario described above is 20.8 million barrels.

In summary, the WCD duration may be short lived if it bridges over, last several days until the well is contained, or discharge for several months until the relief well kills the discharging well. Noble Energy, Inc. has recently participated in an unannounced offshore WCD drill with BSEE and successfully capped a deepwater well in one week which includes several days of weather downtime.

Potential of Open Hole to Bridge Over

Due to the unrestricted flow of a WCD scenario, the well has the potential to experience a downhole rock failure. The primary failure mechanism would be wellbore instability caused by the reduced wellbore pressure. The in situ stresses that exist in the reservoir rock are held in place by the hydrostatic pressure of the weighted drilling fluid in the wellbore. If the wellbore pressure is reduced, the high in situ stresses are no longer opposed by the weighted drilling fluid and the in situ rock may fail and collapse into the wellbore causing the wellbore to bridge over where the failed rock fragments accumulate and lodge downhole to prevent the well discharge from continuing.

### 3

Likelihood for Surface Intervention to Stop Blowout

There is a high likelihood that a combined surface and subsea intervention would stop a blowout of the MC 782-A well

. Noble Energy has access to and can deploy surface and subsea containment resources. Clean Gulf Associates (CGA) has the capability to provide efficient mobilization of necessary equipment and procedures to effectively mitigate numerous blowout scenarios.

Availability of Drilling Rig for a Relief Well

In the event of a WCD, Noble Energy has identified several dynamically positioned (DP) rigs that are capable of drilling the MC 782-A relief well to the appropriate depth and in 6,576’ of water. Depending on the activity and location of an equivalent rig at the time of the WCD, it may require several weeks before the rig is on location ready to spud the relief well.

Estimated Time to Drill a Relief Well

A deepwater drilling rig capable of drilling in +/- 6,600’ of water must be utilized for a relief well. In this scenario, drilling a relief well from a nearby platform is not feasible. The estimated time to drill a relief well is 120 days which allows 2 weeks for securing a DP rig and mobilize it to the lease

.

Measures for Blowout Prevention

Certain measures will be taken to prevent and reduce the likelihood of a blowout as described in the WCD discharge scenario. The blowout prevention measures provide additional assurance in improving the safety of offshore oil and gas drilling. Key measures taken for blowout prevention include but are not limited to:

 Complying with all Federal rules and regulations: CFRs, NTLs, and Final Rules.  Following provisions in API RP 65-Part 2 and API RP 53.  Utilizing Noble’s management systems: Global Management System (GMS), Safety and Environmental Management System (SEMS), Drilling Management System (DMS), Management of Change (MOC), and/or appropriate bridging documents to contractor’s Safety Management Systems.  Utilizing established well control practices, guidelines, and procedures.  Certifying that the BOPE that is fit for purpose.  Utilizing rig and equipment that is fit for purpose.

Early Intervention In the Event of a Blowout

Noble Energy has access to and can deploy surface and subsea containment resources to promptly respond to a blowout or loss of well control. Noble Energy has access to the following through the CGA:

 Subsea containment and capture equipment

### 4

 Subsea equipment to cut riser and perform various interventions  Dispersant injection equipment  Riser systems  Remotely operated vehicles  Capture vessels  Support vessels  Storage facilities

MC 782-A Containment

In the event of a WCD scenario blowout, the MC 782-A is designed to handle the worst-case shut in pressure and maintain full integrity. This wellbore integrity will allow the HFRS 10k subsea capping stack to be utilized for capping and killing the well in a timely manner.

Relief Well Arrangements

Noble Energy Inc. has taken additional measures for drilling a relief well to assist in conducting early and effective intervention of a blowout. Noble Energy Inc. has selected relief well locations with notional well designs to intercept the last drilling liner set prior to drilling the production hole section. The team has assessed the tangibles, equipment, and services necessary to drill a relief well and can source all of those requirements in the event of a blowout.

Summary

Noble Energy, Inc. calculates a Worst Case Discharge rate of 173,214 BOPD based on detailed engineering calculations using geological and geophysical inputs from nearby offset wells. Noble Energy, Inc. has the resources to respond to this Worst Case Discharge scenario in a timely

manner.

## Section C Geological and Geophysical Information

A. Geological Description Proprietary Data
B. Structure Contour Map Proprietary Data

C. Interpreted 3-D Seismic Lines Proprietary Data

D. Geological Structure Cross-Section Proprietary Data

E. Shallow Hazards Report A shallow hazards survey was conducted over Mississippi Canyon 738 and 782. Locations included are MC 738 A, MC 738 B, MC 782 A, MC 782 B, MC 782 C and MC 782 D.

F. Shallow Hazards Assessment Utilizing the 3D seismic exploration data, a shallow hazards assessment was prepared for the proposed surface locations, and is included as Attachment C-4. The shallow hazards assessment for the proposed well locations are included as report “Shallow Hazards Assessment Dantzler Prospect, Block 738, 782 and Vicinity (OCS-G-33755 and OCS-G-33757)”, Project No. 27.2012-2526.

G. High-Resolution Seismic Lines Proprietary Data

H. Stratigraphic Column Proprietary Data

I. Time vs. Depth Table Proprietary Data

Noble Energy, Inc. Page C-1 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)

## FUGRO GEOCONSULTING, INC.

Letter Report No. 27. 2012-2526-4 13 February 2013

Noble Energy, Inc. 100 Glenborough Houston, Texas 77069

Attention: Mr. Bill Hobbs

Wellsite Clearance Letter Proposed Wellsite MC 738-A Block 738, Mississippi Canyon Area

OCS-G-33755

Introduction. Fugro GeoConsulting, Inc. (FGCI) was contracted by Noble Energy Inc. (Noble) to prepare a wellsite clearance letter addressing shallow hazards for proposed Wellsite MC 738-A in Block 738, Mississippi Canyon Area (OCS-G-33755). The proposed well is planned to be vertical through the tophole section and will be drilled by a dynamically positioned rig. This letter is intended to address specific seafloor and shallow geologic conditions within 3,000 ft of the proposed wellsite to the top of salt reflector (about 3,579 ft BML). Shallow geologic conditions at the proposed wellbore are summarized on the attached Tophole Prognosis Chart. Annotated data examples of the nearest 3D exploration seismic survey lines, a sub-bottom profiler line, and four 1:12,000-scale charts showing the proposed wellsite are included. The 1:12,000-scale illustrations include a water depth and seafloor features chart, a side-scan sonar mosaic, a multibeam backscatter chart, and a sub-seafloor geologic features chart. A 2,000 ft radius circle around the proposed wellsite is shown, as per Bureau of Ocean Energy Management (BOEM) Notice to Lessees (NTL) 2009-G40. Please refer to Fugro Report No. 27.2012-2526, “Shallow Geohazards Assessment, Dantzler Prospect, Blocks 738 and 782, Mississippi Canyon Area, Gulf of Mexico,” for a comprehensive assessment of shallow geohazards within Blocks 738 and 782, and a complete list of references used in this investigation. Please refer to C&C Technologies, Inc. Project No. 120578, “Archaeological Assessment Report, Blocks 737, 738, 782 Mississippi Canyon Area, Gulf of Mexico,” for a description of the AUV geophysical data used in this report, as well as a comprehensive archaeological assessment.
3-D Seismic Survey Parameters . A pre-stack, time-migrated 3DX seismic data volume was used for this assessment. The 3DX survey is a subset of the WesternGeco “E-Manatee” reprocessing effort completed in August 2007 and is based in part on the “Mississippi Canyon Phase 11 (Ultra)” survey acquired in 1997 in a north-south orientation with a streamer length of 26,247 ft (8,000 m), 53 fold, 32.8 ft (10 m +1.5m) sound source depth, and 41.01 ft (12.5 m) by 131 ft (40 m) bin spacing. The 3DX data processing was performed by WesternGeco using Kirchhoff pre-stack time migration. The processed volume has a bin size of 41.01 ft (12.5 m) by 65.6 ft (20 m) and a sample rate of 4 milliseconds (Chart 1). The data exhibit no trace or sample decimation of the final processed volume. Inlines are oriented east-west, have a numerical increment of one, and are spaced at intervals of 41.01 ft (12.5 m). Crosslines are oriented north-south, have a numerical increment of 1, and are spaced at intervals of 65.6 ft (20 m). The seismic data set follows North American polarity convention and demonstrates a balanced, zero-phase wavelet based on analysis of the seafloor reflector, top of salt reflector, and low-impedance, high-amplitude anomalies indicative of gas sands.NOBLE ENERGY INC. SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012

- 2526 -4 2 3- D Seismic Frequency. Based on power spectra analysis of the 3D X seismic data at 50% power, the frequency bandwidth for the E

- Manatee data between the seafloor to about 1.0 s is approximately 15

- 64 Hz. Th is freque ncy bandwidth correspond s to a limit of separability of 29 ft, assuming a dominant frequency of 4 5 Hz and an average velocity of 5,400 ft/s in the shallow section. Other details regarding the data descriptions and limitations are found in Fugro Report No. 27.201 2-2 526

. High

- Resolution Geophysical Data

. A high

- resolution geophysical survey was provided by Noble for interpretation in this study. The survey was acquired by C&C in Sept ember 201 2 utilizing an autonomous underwater vehicle (AUV) system. The survey grid consists of 49 primary north

- south trending trac klines spaced 200 m apart and 14 east

- west trending tielines spaced 900 m apart. Navigational fixes (shot points) were recorded at 410 ft (125 m) intervals. Multibeam (MBES), side

- scan sonar (SS S), and sub

- bottom profiler (SBP) were acquired during this survey

. For further details concerning the survey, please refer to C&C Project No. 120578 delivered to Noble Energy in October of 201 2.

Depth Conversions. Water column time

- to

- depth conversions for the 3DX seismic volume are based on a velocity of about 1,480 ft/s. Water depths along AUV tracklines are based on a velocity model generated from real

- time velocimeter data. Comparison of the AUV water depths, and the water depths of the seismic volume showed the seismic was generally ~ 15 ft deeper. Sub

- seafloor depths for the 3DX seismic data are based on an interval velocity volume provided by Noble , and sub

- bottom profiler depths are based on a velocity of 5,250 ft/s

.

. Offset Well Data

. Noble provided well log data, daily drilling reports, scout tickets, and paleontological data for offset wells MC 738

- 1 (Caterpillar Deep) and MC 7 39 -1 ( Hilbert ). Well logs from MC 738

- 1 (Caterpillar Deep), located about 3.4 mi southeast of the proposed wellbore and MC 739

- 1 (Hilbert) , located about 4. 1 mi east

- northeast of the proposed wellbore, were utilized to calibrate sediment interpretations from seismic data

. Graphics. A Water Depth and Seafloor Features page

- size figure (1:12,000

- scale) showing the proposed wellsite, water depth contours and seafloor features, accompanies this wellsite assessment. A 2,000 ft radius circle around the proposed wellsite is shown as per BOEM NTL No. 2009

- G40. A Composite Sid e- Sca n Sonar Mosaic and a Multibeam Backscatter chart (1:12,000

- scale) showing the seafloor conditions in the vicinity of the wellsite are included. S hallow geologic conditions at the proposed wellsite are summarized on the attached Tophole Prognosis Chart. The nearest 3D X inline, 3D X crossline, and AUV SBP profiles are attached to illustrate shallow geologic conditions in the vicinity of the proposed location. A page

- size 1:12,000

- scale Sub

- Seafloor Geologic Features Chart is also included to illustrate geol ogic conditions in the vicinity of the proposed wellbore. The 3D X Seismic Power Spectrum is included as an assessment of the frequency content of the 3D X seismic data at the proposed wellbore

. Proposed Well Location. The surface location for proposed Wellsite MC 738 -A is located in northern MC Block 738 as follows:

Proposed Wellsite MC 738

- A Block 738 , Mississippi Canyon Area UTM Zone 16, NAD 1927 X = 1,224
, 346 ft Y = 10, 2 50
, 202 ft Latitude: 28° 14 ' 23 "N Longitude: 88° 17' 33 "W Nearest E

- Manatee Inline 1 4 1 65 Nearest E

- Manatee Crossline 37 25 4,666 ft FWL 1,722 ft F S LNOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-4 3 Water Depth and Seafloor Gradient. The MBES water depth at the proposed wellsite is predicted to be about 6572 ft with zero datum at sea surface. The local gradient is less than 1° to the north-northwest.

Seafloor Features . At the proposed MC 738-A wellsite, the local seafloor is smooth, featureless, and appears stable. One northwest-southeast trending seafloor fault is identified in the vicinity of the proposed wellsite. The seafloor fault scarp lies about 930 ft to the northeast, exhibits a seafloor relief of about 40 ft and is associated with seafloor gradient of less than 10°. This fault is identified on SBP records and 3DX seismic data and the fault plane will not be penetrated by the proposed wellbore. The seafloor fault scarp meets the 75 m (245 ft) standoff distance as outlined by the BOEM in NTL No. 2008-G05.

Potential High-density Benthic Communities. Two areas of high seafloor multibeam backscatter intensity indicative of possible hardground are located about 2,350 ft northwest and 3,500 ft southwest of the proposed MC 738-A wellsite. There is no geophysical evidence of hydrocarbon seepage sites or areas that could potentially support high-density benthic communities within 2,000 ft of the proposed location. Therefore, there is a negligible potential for high-density communities of benthic and/or chemosynthetic organisms within 2,000 ft of the proposed wellsite, in accordance with BOEM NTL 2009-G40.

Man-Made Obstructions. A search of Fugro’s GIS database conducted in February 2013 and a review of the SSS data from the high-resolution geophysical data set indicated closest man-made feature is one existing pipeline (Enterprise 20-24” SEG#15153) 1,700 ft south of the proposed wellsite.

The closest sonar targets (contacts # 21, # 24, and # 33) were detected about 2,400 ft northwest, 2,250 ft north, and 1,800 ft northeast of the proposed wellsite, respectively. These targets, and all the other targets farther from the proposed wellsite, are interpreted as unidentified debris as outlined in the archaeological assessment by C&C (Project No. 120578). Although no man-made features or other potentially hazardous seafloor conditions are identified in the SSS data, we recommend that an ROV be used to inspect the seafloor at the proposed wellsite immediately before spud-in to confirm that no seafloor obstructions have appeared since the SSS survey was acquired.

Stratigraphy. The seafloor and five subsurface horizons (10, 20, 30, 40 and 60) were mapped to divide the tophole section into five stratigraphic sequences (Sequence 1 through 5) of distinct seismic and inferred lithologic character at the proposed wellbore. Predicted depths and thicknesses associated with each of the mapped horizons and sequences are displayed on the attached Tophole Prognosis Chart for the proposed wellsite MC 738-A drilling location.

At the proposed wellbore, Sequence 1 is 274 ft thick and is divided into an upper 160 ft thick interval of parallel-stratified marine clays and thin, fine-grained MTDs and a lower 114 ft thick interval of sand-prone sediments. Sequence 2 is 220 ft thick and is comprised of mostly fine-grained sediments interbedded with thin, fine-grained MTDs and possible thin sands. The upper 25 ft of Sequence 2 consists of possible sand-prone channel and overbank deposits which are interpreted to be part of the Blue Unit (Ostermeier et al., 2000 and Winker et al., 2000).

Sequence 3 is cumulatively about 1,630 ft thick and is interpreted to represent the informally described Green Unit. The upper 255 ft of Sequence 3 consist of fine-grained MTDs interbedded with possible sand-prone sediments. The middle 550 ft of Sequence 3 are comprised of slope failure deposits consisting of fine-grained MTDs interbedded with sand-prone channel and overbank deposits. The lower 825 ft of Sequence 3 are composed of slope failure deposits consisting of sand-prone channel and overbank deposits interbedded with fine-grained MTDs. Sequence 4 is a 75 ft thick interval of possible sand-prone sediments underlain by Sequence 5, which is composed of 1,465 ft of faulted, sand-prone channel and overbank deposits interbedded with thin, fine-grained MTDs.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-4 4 Fault Penetrations. One buried fault plane will intersect the proposed wellbore at about 3,579 ft BML. This fault is presumed to be inactive and is not expected to present a constraint to drilling operations. However the sedimentary section within Sequence 5 is expected to be extensively fractured, and could create secondary porosity and permeability that could cause drilling fluid loss to formation.

Gas Hydrate and Gas Hazards. Temperature and pressure conditions are favorable for the presence of gas hydrates within the study area. The base of gas hydrate stability was modeled using the fundamental gas hydrate phase equilibrium curve, which requires input for temperature, pressure, gas mixture, and salinity (Sloan, 1990), and is estimated to be located within Sequence 3. Localized and disseminated gas hydrates, if present, may occur above the base of has hydrate stability. Massive gas hydrate accumulations at the proposed wellbore are not expected.

No high-amplitude anomalies interpreted to represent shallow gas will be penetrated in the tophole section by a vertical wellbore at the proposed wellsite. Interpreted anomalies representing possible shallow gas hazards in the tophole section within 3,000 ft of the proposed wellbore are located in Sequences 2 through 5. The closest amplitude anomalies to the proposed MC 738-A wellbore are located 706 ft to the southwest within upper Sequence 2 and 825 ft to the northeast within Sequence 3. Because of the sand-prone nature of lower Sequence 1 and upper Sequence 2, a low potential for shallow gas is assessed for the intervals of these Sequences between 160 ft and 299 ft BML. Because of the presence of possible sand-prone sediments within Sequences 3 through 5; a low potential for shallow gas is assessed for these Sequences between 494 ft and the base of the tophole section at 3,664 ft BML. Possible gas sands in the other stratigraphic units are located safely away from the borehole and should not pose any hazard or constraint to drilling. Therefore, the remainder of the tophole section is assessed a negligible potential for encountering significant gas accumulations.

Shallow-Water-Flow (SWF). A map presented by Pelletier and others (1999) shows the relative magnitude of shallow-water-flow (SWF) hazards in the Northern Gulf of Mexico. On this map, the study area falls within the moderate-risk zone. There are other reported cases of SWF in the general vicinity of the study area. The MMS Internet Database indicates that SWF has occurred in the following wells in the area: MC 696 (Blind Faith; very low severity event), MC 730-1 (moderate flow at 1,842 ft BML), MC 731-1 (low flow at 1,622 ft BML), MC 778-13 (low flow at 2,374 ft BML), MC 864-1 (moderate flow at 1,593 ft BML). Based on these documented SWF events and the geologic conditions present within the study area, we assess that the tophole section in MC 738 has the potential to be overpressured and that sand-prone intervals, if penetrated, could cause a SWF event if not contained or otherwise mitigated.

Sequence 1 is comprised of mostly fine-grained sediments and is assessed a negligible SWF potential. A lo w potential for SWF is assessed for the sand-prone intervals within lower Sequence 1, lower Sequence 2, and Sequence 5. Sand-prone channel deposits within upper Sequence 2, between 274 ft and 299 ft BML, are interpreted to be part of the Blue Unit sands (Ostermeier et al., 2000 and Winker et al., 2000) and are believed responsible for documented SWF occurrences at some wells in the area. Therefore, upper Sequence 2 is assessed a moderate potential for SWF. Sequence 3 is sand-prone and is interpreted to be part of the informally defined Green Unit sands inferred to have caused SWF events at other wells in the area; therefore, all of Sequence 3 between 494 ft and 2,124 ft BML is assessed a moderate potential for SWF at the proposed wellbore. Sequence 4 is interpreted to be sand-prone and is overlain by fine-grained MTDs within Sequence 3; therefore, Sequence 4 is assessed a moderate potential for SWF between about 2,124 ft and 2,199 ft BML.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-4 5 We appreciate the opportunity to work with you on this project and look forward to continuing as your geohazards consultants. If you have any questions concerning this assessment, please do not hesitate to call us (713-369-5600).

Sincerely, FUGRO GEOCONSULTING, INC.

Jennifer Katrib Senior Geoscientist

Hunter Danque Bruce Samuel Project Geoscientist Geoscience Group Manager

Attachments:

1. Water Depth and Seafloor Features, Dantzler Prospect, Block 738, Gulf of Mexico, Proposed Wellsite MC 738-A (1:12,000) 2. Side-Scan Sonar Mosaic, Dantzler Prospect, Block 738, Mississippi Canyon Area, Proposed Wellsite MC 738-A (1:12,000) 3. Multibeam Backscatter Rendering, Dantzler Prospect, Block 738, Mississippi Canyon, Proposed Wellsite MC 738-A 4. Sub-seafloor Geologic Features, Dantzler Prospect, Block 738, Mississippi Canyon Area, Proposed Wellsite MC 738-A (1:12,000) 5. Tophole Prognosis Chart, Proposed Wellsite MC 738-A, Dantzler Prospect, Block 738, Mississippi Canyon Area, Gulf of Mexico 6. E-MANATEE 3DX Seismic Profile, Inline 14165, Proposed Wellsite MC 738-A, Dantzler Prospect, Block 738, Mississippi Canyon Area, Gulf of Mexico 7. E-MANATEE 3DX Seismic Profile, Crossline 3725, Proposed Wellsite MC 738-A, Dantzler Prospect, Block 738, Mississippi Canyon Area, Gulf of Mexico 8. Sub-bottom Profile, Line 132, Proposed Wellsite MC 738-A, Dantzler Prospect, Block 738, Mississippi Canyon Area, Gulf of Mexico 9. 3DX Seismic Power Spectrum, Proposed Wellsite MC 738-A, Dantzler Prospect, Block 738, Mississippi Canyon Area, Gulf of Mexico

## FUGRO GEOCONSULTING, INC.

Letter Report No. 27. 2012-2526-5 8 March 2013

Noble Energy, Inc. 100 Glenborough Houston, Texas 77069

Attention: Mr. Bill Hobbs

Wellsite Clearance Letter Proposed Wellsite MC 738-B Block 738, Mississippi Canyon Area

OCS-G-33755

Introduction. Fugro GeoConsulting, Inc. (FGCI) was contracted by Noble Energy Inc. (Noble) to prepare a wellsite clearance letter addressing shallow hazards for proposed Wellsite MC 738-B in Block 738, Mississippi Canyon Area (OCS-G-33755). The proposed well is planned to be vertical through the tophole section and will be drilled by a dynamically positioned rig. This letter is intended to address specific seafloor and shallow geologic conditions within 3,000 ft of the proposed wellsite to the top of salt reflector (about 3,665 ft BML). Shallow geologic conditions at the proposed wellbore are summarized on the attached Tophole Prognosis Chart. Annotated data examples of the nearest 3D exploration seismic survey lines, a sub-bottom profiler line, and four 1:12,000-scale charts showing the proposed wellsite are included. The 1:12,000-scale illustrations include a water depth and seafloor features chart, a side-scan sonar mosaic, a multibeam backscatter chart, and a sub-seafloor geologic features chart. A 2,000 ft radius circle around the proposed wellsite is shown, as per Bureau of Ocean Energy Management (BOEM) Notice to Lessees (NTL) 2009-G40. Please refer to Fugro Report No. 27.2012-2526, “Shallow Geohazards Assessment, Dantzler Prospect, Blocks 738 and 782, Mississippi Canyon Area, Gulf of Mexico,” for a comprehensive assessment of shallow geohazards within Blocks 738 and 782, and a complete list of references used in this investigation. Please refer to C&C Technologies, Inc. Project No. 120578, “Archaeological Assessment Report, Blocks 737, 738, 782 Mississippi Canyon Area, Gulf of Mexico,” for a description of the AUV geophysical data used in this report, as well as a comprehensive archaeological assessment.
3-D Seismic Survey Parameters . A pre-stack, time-migrated 3DX seismic data volume was used for this assessment. The 3DX survey is a subset of the WesternGeco “E-Manatee” reprocessing effort completed in August 2007 and is based in part on the “Mississippi Canyon Phase 11 (Ultra)” survey acquired in 1997 in a north-south orientation with a streamer length of 26,247 ft (8,000 m), 53 fold, 32.8 ft (10 m +1.5m) sound source depth, and 41.01 ft (12.5 m) by 131 ft (40 m) bin spacing. The 3DX data processing was performed by WesternGeco using Kirchhoff pre-stack time migration. The processed volume has a bin size of 41.01 ft (12.5 m) by 65.6 ft (20 m) and a sample rate of 4 milliseconds. The data exhibit no trace or sample decimation of the final processed volume. Inlines are oriented east-west, have anumerical increment of one, and are spaced at intervals of 41.01 ft (12.5 m). Crosslines are oriented northsouth, have a numerical increment of 1, and are spaced at intervals of 65.6 ft (20 m). The seismic data set follows North American polarity convention and demonstrates a balanced, zero-phase wavelet based on analysis of the seafloor reflector, top of salt reflector, and low-impedance, high-amplitude anomalies indicative of gas sands.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-5 2 3-D Seismic Frequency. Based on power spectra analysis of the 3DX seismic data at 50% power, the frequency bandwidth for the E-Manatee data between the seafloor to about 1.0 s is approximately 15-64 Hz. This frequency bandwidth corresponds to a limit of separability of 29 ft, assuming a dominant frequency of 45 Hz and an average velocity of 5,400 ft/s in the shallow section. Other details regarding the data descriptions and limitations are found in Fugro Report No. 27.2012-2526.

High-Resolution Geophysical Data . A high-resolution geophysical survey was provided by Noble for interpretation in this study. The survey was acquired by C&C in September 2012 utilizing an autonomous underwater vehicle (AUV) system. The survey grid consists of 49 primary north-south trending tracklines spaced 200 m apart and 14 east-west trending tielines spaced 900 m apart. Navigational fixes (shot points) were recorded at 410 ft (125 m) intervals. Multibeam (MBES), side-scan sonar (SSS), and sub-bottom profiler (SBP) were acquired during this survey. For further details concerning the survey, please refer to C&C Project No. 120578 delivered to Noble Energy in October of 2012.

Depth Conversions. Water column time-to-depth conversions for the 3DX seismic volume are based on a velocity of about 1,480 m/s. Water depths along AUV tracklines are based on a velocity model generated from real-time velocimeter data. Comparison of the AUV water depths, and the water depths of the seismic volume showed the seismic was generally ~15 ft deeper. Sub-seafloor depths for the 3DX seismic data are based on an interval velocity volume provided by Noble, and sub-bottom profiler depths are based on a velocity of 5,250 ft/s.

. Offset Well Data. Noble provided well log data, daily drilling reports, scout tickets, and paleontological data for offset wells MC 738-1 (Caterpillar Deep) and MC 739-1 (Hilbert). Well logs from MC 738-1 (Caterpillar Deep), located about 3.4 mi southeast of the proposed wellbore and MC 739-1 (Hilbert), located about 4.1 mi east-northeast of the proposed wellbore, were utilized to calibrate sediment interpretations from seismic data.

Graphics. A Water Depth and Seafloor Features page-size figure (1:12,000-scale) showing the proposed wellsite, water depth contours and seafloor features, accompanies this wellsite assessment. A 2,000 ft radius circle around the proposed wellsite is shown as per BOEM NTL No. 2009-G40. Side-Scan Sonar Mosaic and Multibeam Backscatter charts (1:12,000-scale) showing the seafloor conditions in the vicinity of the wellsite are included. Shallow geologic conditions at the proposed wellsite are summarized on the attached Tophole Prognosis Chart. The nearest 3DX inline, 3DX crossline, and AUV SBP profiles are attached to illustrate shallow geologic conditions in the vicinity of the proposed location. A page-size 1:12,000-scale Sub-Seafloor Geologic Features Chart is also included to illustrate geologic conditions in the vicinity of the proposed wellbore. The 3DX Seismic Power Spectrum is included as an assessment of the frequency content of the 3DX seismic data at the proposed wellbore.

Proposed Well Location. The surface location for proposed Wellsite MC 738-B is located in northern MC Block 738 as follows:

Proposed Wellsite MC 738

- B Block 738, Mississippi Canyon Area UTM Zone 16, NAD 1927 X = 1,224,427 ft Y = 10,250,134 ft Latitude: 28° 14' 22"N Longitude: 88° 17' 32"W Nearest E-Manatee Inline 14164 Nearest E-Manatee Crossline 3727

4,747 ft FWL 1,654 ft FSLNOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-5 3 Water Depth and Seafloor Gradient. The MBES water depth at the proposed wellsite is predicted to be about 6571 ft with zero datum at sea surface. The local gradient is less than 1° to the north-northwest.

Seafloor Features . At the proposed MC 738-B wellsite, the local seafloor is smooth, featureless, and appears stable. One northwest-southeast trending seafloor fault is identified in the vicinity of the proposed wellsite. The seafloor fault scarp lies about 920 ft to the northeast, exhibits a seafloor relief of about 40 ft and is associated with seafloor gradient of less than 10°. This fault is identified on SBP records and 3DX seismic data and the fault plane will not be penetrated by the proposed wellbore. The seafloor fault scarp meets the 75 m (245 ft) standoff distance as outlined by the BOEM in NTL No. 2008-G05.

Potential High-density Benthic Communities. Two areas of high seafloor multibeam backscatter intensity indicative of possible hardground are located about 2,300 ft northwest and 3,440 ft southwest of the proposed MC 738-B wellsite. There is no geophysical evidence of hydrocarbon seepage sites or areas that could potentially support high-density benthic communities within 2,000 ft of the proposed location. Therefore, there is a negligible potential for high-density communities of benthic and/or chemosynthetic organisms within 2,000 ft of the proposed wellsite, in accordance with BOEM NTL 2009-G40.

Man-Made Obstructions. A search of Fugro’s GIS database conducted in March 2013 and a review of the SSS data from the high-resolution geophysical data set indicated closest man-made feature is one existing pipeline (Enterprise 20-24” SEG#15153) 1,625 ft south of the proposed wellsite.

The closest sonar targets (contacts # 21, # 24, and # 33) were detected about 2,420 ft northwest, 2,280 ft north, and 1,830 ft northeast of the proposed wellsite, respectively. These targets, and all the other targets farther from the proposed wellsite, are interpreted as unidentified debris as outlined in the archaeological assessment by C&C (Project No. 120578). Although no man-made features or other potentially hazardous seafloor conditions are identified in the SSS data, we recommend that an ROV be used to inspect the seafloor at the proposed wellsite immediately before spud-in to confirm that no seafloor obstructions have appeared since the SSS survey was acquired.

Stratigraphy. The seafloor and five subsurface horizons (10, 20, 30, 40 and 60) were mapped to divide the tophole section into five stratigraphic sequences (Sequence 1 through 5) of distinct seismic and inferred lithologic character at the proposed wellbore. Predicted depths and thicknesses associated with each of the mapped horizons and sequences are displayed on the attached Tophole Prognosis Chart for the proposed wellsite MC 738-B drilling location.

At the proposed wellbore, Sequence 1 is 271 ft thick and is divided into an upper 161 ft thick interval of parallel-stratified marine clays and thin, fine-grained MTDs and a lower 110 ft thick interval of sand-prone sediments. Sequence 2 is 219 ft thick and is comprised of mostly fine-grained sediments interbedded with thin, fine-grained MTDs and possible thin sands. The upper 29 ft of Sequence 2 consists of possible sand-prone channel and overbank deposits which are interpreted to be part of the Blue Unit (Ostermeier et al., 2000 and Winker et al., 2000).

Sequence 3 is cumulatively about 1,635 ft thick and is interpreted to represent the informally described Green Unit. The upper 260 ft of Sequence 3 consist of fine-grained MTDs interbedded with possible sand-prone sediments. The middle 550 ft of Sequence 3 are comprised of slope failure deposits consisting of fine-grained MTDs interbedded with sand-prone channel and overbank deposits. The lower 825 ft of Sequence 3 are composed of slope failure deposits consisting of sand-prone channel and overbank deposits interbedded with fine-grained MTDs. Sequence 4 is a 70 ft thick interval of possible sand-prone sediments underlain by Sequence 5, which is composed of 1,470 ft of faulted, sand-prone channel and overbank deposits interbedded with thin, fine-grained MTDs.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-5 4 Fault Penetrations. One buried fault plane will intersect the proposed wellbore at about 3,421 ft BML. This fault is presumed to be inactive and is not expected to present a constraint to drilling operations. However the sedimentary section within Sequence 5 is expected to be extensively fractured, and could create secondary porosity and permeability that could cause drilling fluid loss to formation.

Gas Hydrate and Gas Hazards. Temperature and pressure conditions are favorable for the presence of gas hydrates within the study area. The base of gas hydrate stability was modeled using the fundamental gas hydrate phase equilibrium curve, which requires input for temperature, pressure, gas mixture, and salinity (Sloan, 1990), and is estimated to be located within Sequence 3. Localized and disseminated gas hydrates, if present, may occur above the base of has hydrate stability. Massive gas hydrate accumulations at the proposed wellbore are not expected.

No high-amplitude anomalies interpreted to represent shallow gas will be penetrated in the tophole section by a vertical wellbore at the proposed wellsite. Interpreted anomalies representing possible shallow gas hazards in the tophole section within 3,000 ft of the proposed wellbore are located in Sequences 2 through 5. The closest amplitude anomalies to the proposed MC 738-B wellbore are located 830 ft to the northeast, 695 ft to the southwest, and 1,610 ft to the southwest within upper Sequence 2 and Sequence 3. Because of the sand-prone nature of lower Sequence 1 and upper Sequence 2, a low potential for shallow gas is assessed for the intervals of these Sequences between 161 ft and 300 ft BML. Because of the presence of possible sand-prone sediments within Sequences 3 through 5; a low potential for shallow gas is assessed for these Sequences between 490 ft and the base of the tophole section at 3,665 ft BML. Possible gas sands in the other stratigraphic units are located safely away from the borehole and should not pose any hazard or constraint to drilling. Therefore, the remainder of the tophole section is assessed a negligible potential for encountering significant gas accumulations.

Shallow-Water-Flow (SWF). A map presented by Pelletier and others (1999) shows the relative magnitude of shallow-water-flow (SWF) hazards in the Northern Gulf of Mexico. On this map, the study area falls within the moderate-risk zone. There are other reported cases of SWF in the general vicinity of the study area. The BOEM Internet Database indicates that SWF has occurred in the following wells in the area: MC 696 (Blind Faith; very low severity event), MC 730-1 (moderate flow at 1,842 ft BML), MC 731-1 (low flow at 1,622 ft BML), MC 778-13 (low flow at 2,374 ft BML), MC 864-1 (moderate flow at 1,593 ft BML). Based on these documented SWF events and the geologic conditions present within the study area, we assess that the tophole section in MC 738 has the potential to be overpressured and that sand-prone intervals, if penetrated, could cause a SWF event if not contained or otherwise mitigated.

Upper Sequence 1 is comprised of mostly fine-grained sediments and is assessed a negligible SWF potential. A lo w potential for SWF is assessed for the sand-prone intervals within lower Sequence 1, lower Sequence 2, and Sequence 5. Sand-prone channel deposits within upper Sequence 2, between 271 ft and 300 ft BML, are interpreted to be part of the Blue Unit sands (Ostermeier et al., 2000 and Winker et al., 2000) and are believed responsible for documented SWF occurrences at some wells in the area. Therefore, upper Sequence 2 is assessed a moderate potential for SWF. Sequence 3 is sand-prone and is interpreted to be part of the informally defined Green Unit sands inferred to have caused SWF events at other wells in the area; therefore, all of Sequence 3 between 490 ft and 2,125 ft BML isassessed a moderate potential for SWF at the proposed wellbore. Sequence 4 is interpreted to be sandprone and is overlain by fine-grained MTDs within Sequence 3; therefore, Sequence 4 is assessed a moderate potential for SWF between about 2,125 ft and 2,195 ft BML.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-5 5 We appreciate the opportunity to work with you on this project and look forward to continuing as your geohazards consultants. If you have any questions concerning this assessment, please do not hesitate to call us (713-369-5600).

Sincerely, FUGRO GEOCONSULTING, INC.

Jennifer Katrib Senior Geoscientist

Hunter Danque Bruce Samuel Project Geoscientist Geoscience Group Manager

Attachments:

1. Water Depth and Seafloor Features, Dantzler Prospect, Block 738, Gulf of Mexico, Proposed Wellsite MC 738-B (1:12,000) 2. Side-Scan Sonar Mosaic, Dantzler Prospect, Block 738, Mississippi Canyon Area, Proposed Wellsite MC 738-B (1:12,000) 3. Multibeam Backscatter Rendering, Dantzler Prospect, Block 738, Mississippi Canyon, Proposed Wellsite MC 738-B 4. Sub-seafloor Geologic Features, Dantzler Prospect, Block 738, Mississippi Canyon Area, Proposed Wellsite MC 738-B (1:12,000) 5. Tophole Prognosis Chart, Proposed Wellsite MC 738-B, Dantzler Prospect, Block 738, Mississippi Canyon Area, Gulf of Mexico 6. 3DX Seismic Profile, Inline 14164, Proposed Wellsite MC 738-B, Dantzler Prospect, Block 738, Mississippi Canyon Area, Gulf of Mexico 7. 3DX Seismic Profile, Crossline 3727, Proposed Wellsite MC 738-B, Dantzler Prospect, Block 738, Mississippi Canyon Area, Gulf of Mexico 8. Sub-bottom Profile, Line 132, Proposed Wellsite MC 738-B, Dantzler Prospect, Block 738, Mississippi Canyon Area, Gulf of Mexico 9. 3DX Seismic Power Spectrum, Proposed Wellsite MC 738-B, Dantzler Prospect, Block 738, Mississippi Canyon Area, Gulf of Mexico

## FUGRO GEOCONSULTING, INC.

Letter Report No. 27. 2012-2526-1 13 February 2013

Noble Energy, Inc. 100 Glenborough Houston, Texas 77069

Attention: Mr. Bill Hobbs

Wellsite Clearance Letter Proposed Wellsite MC 782-A Block 782, Mississippi Canyon Area

OCS-G-33757

Introduction. Fugro GeoConsulting, Inc. (FGCI) was contracted by Noble Energy Inc. (Noble) to prepare a wellsite clearance letter addressing shallow hazards for proposed Wellsite MC 782-A in Block 782, Mississippi Canyon Area (OCS-G-33757). The proposed well is planned to be vertical through the tophole section and will be drilled by a dynamically positioned rig. This letter is intended to address specific seafloor and shallow geologic conditions within 3,000 ft of the proposed wellsite to the top of salt reflector (about 3,260 ft BML). Shallow geologic conditions at the proposed wellbore are summarized on the attached Tophole Prognosis Chart. Annotated data examples of the nearest 3D exploration seismic survey lines, a sub-bottom profiler line, and four 1:12,000-scale charts showing the proposed wellsite are included. The 1:12,000-scale illustrations include a water depth and seafloor features chart, a side-scan sonar mosaic, a multibeam backscatter chart, and a sub-seafloor geologic features chart. A 2,000 ft radius circle around the proposed wellsite is shown, as per Bureau of Ocean Energy Management (BOEM) Notice to Lessees (NTL) 2009-G40. Please refer to Fugro Report No. 27.2012-2526, “Shallow Geohazards Assessment, Dantzler Prospect, Blocks 738 and 782, Mississippi Canyon Area, Gulf of Mexico,” for a comprehensive assessment of shallow geohazards within Blocks 738 and 782, and a complete list of references used in this investigation. Please refer to C&C Technologies, Inc. Project No. 120578, “Archaeological Assessment Report, Blocks 737, 738, 782 Mississippi Canyon Area, Gulf of Mexico,” for a description of the AUV geophysical data used in this report, as well as a comprehensive archaeological assessment.
3-D Seismic Survey Parameters . A pre-stack, time-migrated 3DX seismic data volume was used for this assessment. The 3DX survey is a subset of the WesternGeco “E-Manatee” reprocessing effort completed in August 2007 and is based in part on the “Mississippi Canyon Phase 11 (Ultra)” survey acquired in 1997 in a north-south orientation with a streamer length of 26,247 ft (8,000 m), 53 fold, 32.8 ft (10 m +1.5m) sound source depth, and 41.01 ft (12.5 m) by 131 ft (40 m) bin spacing. The 3DX data processing was performed by WesternGeco using Kirchhoff pre-stack time migration. The processed volume has a bin size of 41.01 ft (12.5 m) by 65.6 ft (20 m) and a sample rate of 4 milliseconds (Chart 1). The data exhibit no trace or sample decimation of the final processed volume. Inlines are oriented east-west, have a numerical increment of one, and are spaced at intervals of 41.01 ft (12.5 m). Crosslines are oriented north-south, have a numerical increment of 1, and are spaced at intervals of 65.6 ft (20 m). The seismic data set follows North American polarity convention and demonstrates a balanced, zero-phase wavelet based on analysis of the seafloor reflector, top of salt reflector, and low-impedance, high-amplitude anomalies indicative of gas sands.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-1 2 3-D Seismic Frequency. Based on power spectra analysis of the 3DX seismic data at 50% power, the frequency bandwidth for the E-Manatee data between the seafloor to about 1.0 s is approximately 15-64 Hz. This frequency bandwidth corresponds to a limit of separability of 29 ft, assuming a dominant frequency of 45 Hz and an average velocity of 5,400 ft/s in the shallow section. Other details regarding the data descriptions and limitations are found in Fugro Report No. 27.2012-2526.

High-Resolution Geophysical Data . A high-resolution geophysical survey was provided by Noble for interpretation in this study. The survey was acquired by C&C in September 2012 utilizing an autonomous underwater vehicle (AUV) system. The survey grid consists of 49 primary north-south trending tracklines spaced 200 m apart and 14 east-west trending tielines spaced 900 m apart. Navigational fixes (shot points) were recorded at 410 ft (125 m) intervals. Multibeam (MBES), side-scan sonar (SSS), and sub-bottom profiler (SBP) were acquired during this survey. For further details concerning the survey, please refer to C&C Project No. 120578 delivered to Noble Energy in October of 2012.

Depth Conversions. Water column time-to-depth conversions for the 3DX seismic volume are based on a velocity of about 1,480 ft/s. Water depths along AUV tracklines are based on a velocity model generated from real-time velocimeter data. Comparison of the AUV water depths, and the water depths of the seismic volume showed the seismic was generally ~15 ft deeper. Sub-seafloor depths for the 3DX seismic data are based on an interval velocity volume provided by Noble, and sub-bottom profiler depths are based on a velocity of 5,250 ft/s.

. Offset Well Data. Noble provided well log data, daily drilling reports, scout tickets, and paleontological data for offset wells MC 782-1 (Caterpillar Deep) and MC 739-1 (Hilbert). Well logs from MC 782-1 (Caterpillar Deep), located about 3 mi southeast of the proposed wellbore and MC 739-1 (Hilbert), located about 4.2 mi east-northeast of the proposed wellbore, were utilized to calibrate sediment interpretations from seismic data.

Graphics. A Water Depth and Seafloor Features page-size figure (1:12,000-scale) showing the proposed wellsite, water depth contours and seafloor features, accompanies this wellsite assessment. A 2,000 ft radius circle around the proposed wellsite is shown as per BOEM NTL No. 2009-G40. A Composite Side-Scan Sonar Mosaic and a Multibeam Backscatter chart (1:12,000-scale) showing the seafloor conditions in the vicinity of the wellsite are included. Shallow geologic conditions at the proposed wellsite are summarized on the attached Tophole Prognosis Chart. The nearest 3DX inline, 3DX crossline, and AUV SBP profiles are attached to illustrate shallow geologic conditions in the vicinity of the proposed location. A page-size 1:12,000-scale Sub-Seafloor Geologic Features Chart is also included to illustrate geologic conditions in the vicinity of the proposed wellbore. The 3DX Seismic Power Spectrum is included as an assessment of the frequency content of the 3DX seismic data at the proposed wellbore.

Proposed Well Location. The surface location for proposed Wellsite MC 782-A is located in northern MC Block 782 as follows:

Proposed Wellsite MC 7 82

- A Block 782, Mississippi Canyon Area UTM Zone 16, NAD 1927 X = 1,224,943 ft Y = 10,247,759 ft Latitude: 28° 13' 59.053"N Longitude: 88° 17' 26.422"W Nearest E-Manatee Inline 14128 Nearest E-Manatee Crossline 3740

5,263 ft FWL 721 ft FNLNOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-1 3 Water Depth and Seafloor Gradient. The MBES water depth at the proposed wellsite is predicted to be about 6576 ft with zero datum at sea surface. The local gradient is less than 1° to the east.

Seafloor Features . At the proposed MC 782-A wellsite, the local seafloor is smooth, featureless, and appears stable. Several northwest-southeast trending seafloor faults are identified in the vicinity of the proposed wellsite. The closest seafloor fault scarp lies about 2,070 ft to the southwest, exhibits a seafloor relief of about 10 ft and is associated with seafloor gradient of less than 4°. Another seafloor fault is about 2,360 ft northeast of the proposed wellsite, and the seafloor scarp defined by this fault has maximum relief of about 40 ft and a seafloor gradient of less than 10°. These faults are identified on SBP records and 3DX seismic data. No seafloor faults will be penetrated by the proposed wellbore, and the seafloor fault scarps meet the 75 m (245 ft) standoff distance as outlined by the BOEM in NTL No. 2008-G05.

Potential High-density Benthic Communities. Two areas of high seafloor multibeam backscatter intensity indicative of possible hardground are located about 2,050 ft and 2,600 ft southwest of the proposed MC 782-A wellsite. There is no geophysical evidence of hydrocarbon seepage sites or areas that could potentially support high-density benthic communities within 2,000 ft of the proposed location. Therefore, there is a negligible potential for high-density communities of benthic and/or chemosynthetic organisms within 2,000 ft of the proposed wellsite, in accordance with BOEM NTL 2009-G40.

Man-Made Obstructions. A search of Fugro’s GIS database conducted in February 2013 and a review of the SSS data from the high-resolution geophysical data set indicated closest man-made feature is one existing pipeline (Enterprise 20-24” SEG#15153) 694 ft north of the proposed wellsite.

The closest sonar target (contact # 37) was detected about 2,200 ft southeast of the proposed wellsite. This target, and all the other targets farther from the proposed wellsite, are interpreted as unidentified debris as outlined in the archaeological assessment by C&C (Project No. 120578). Although no man-made features or other potentially hazardous seafloor conditions are identified in the SSS data, we recommend that an ROV be used to inspect the seafloor at the proposed wellsite immediately before spud-in to confirm that no seafloor obstructions have appeared since the SSS survey was acquired.

Stratigraphy. The seafloor and five subsurface horizons (10, 20, 30, 40 and 60) were mapped to divide the tophole section into five stratigraphic sequences (Sequence 1 through 5) of distinct seismic and inferred lithologic character at the proposed wellbore. Predicted depths and thicknesses associated with each of the mapped horizons and sequences are displayed on the attached Tophole Prognosis Chart for the proposed wellsite MC 782-A drilling location.

At the proposed wellbore, Sequence 1 is 275 ft thick and is divided into an upper 165 ft thick interval of parallel-stratified marine clays and thin, fine-grained MTDs and a lower 110 ft thick interval of sand-prone sediments. Sequence 2 is 215 ft thick and is comprised of mostly fine-grained sediments interbedded with thin, fine-grained MTDs and possible thin sands. The upper 25 ft of Sequence 2 consists of possible sand-prone channel and overbank deposits which are interpreted to be part of the Blue Unit (Ostermeier et al., 2000 and Winker et al., 2000).

Sequence 3 is cumulatively about 1,730 ft thick and is interpreted to represent the informally described Green Unit. The upper 255 ft of Sequence 3 consist of fine-grained MTDs interbedded with possible sand-prone deposits. The middle 675 ft of Sequence 3 are comprised of slope failure deposits consisting of sand-prone channel and overbank deposits interbedded with fine-grained MTDs. The lower 800 ft of Sequence 3 consist of mostly fine-grained slope failure deposits with possible sand-prone sediment blocks. Sequence 4 is a 465 ft thick interval of faulted, fine-grained sediments underlain by Sequence 5, which is composed of 575 ft of faulted, sand-prone channel and overbank deposits interbedded with thin, fine-grained MTDs.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-1 4 Fault Penetrations. One buried fault plane will intersect the proposed wellbore at about 3,035 ft BML. This fault is presumed to be inactive and is not expected to present a constraint to drilling operations. However the sedimentary section within Sequences 4 and 5 is expected to be extensively fractured, and could create secondary porosity and permeability that could cause drilling fluid loss to formation.

Gas Hydrate and Gas Hazards. Temperature and pressure conditions are favorable for the presence of gas hydrates within the study area. The base of gas hydrate stability was modeled using the fundamental gas hydrate phase equilibrium curve, which requires input for temperature, pressure, gas mixture, and salinity (Sloan, 1990), and is estimated to be located within Sequence 3. Localized and disseminated gas hydrates, if present, may occur above the base of has hydrate stability. Massive gas hydrate accumulations at the proposed wellbore are not expected.

No high-amplitude anomalies interpreted to represent shallow gas will be penetrated in the tophole section by a vertical wellbore at the proposed wellsite. Interpreted anomalies representing possible shallow gas hazards in the tophole section within 3,000 ft of the proposed wellbore are located in Sequences 2 through 5. The closest amplitude anomalies to the proposed MC 782-A wellbore are located 310 ft to the south within upper Sequence 2 and 990 ft to the northwest within Sequence 3. Because of the sand-prone nature of lower Sequence 1 and upper Sequence 2, a low potential for shallow gas is assessed for the intervals of these Sequences between 165 ft and 300 ft BML. Because of the presence of possible sand-prone sediments within Sequences 3 and 5; a low potential for shallow gas is assessed for these Sequences between 490 ft and 2,220 ft BML and between 2,685 ft and 3,260 ft BML, respectively. Possible gas sands in the other stratigraphic units are located safely away from the borehole and should not pose any hazard or constraint to drilling. Therefore, the remainder of the tophole section is assessed a negligible potential for encountering significant gas accumulations.

Shallow-Water-Flow (SWF). A map presented by Pelletier and others (1999) shows the relative magnitude of shallow-water-flow (SWF) hazards in the Northern Gulf of Mexico. On this map, the study area falls within the moderate-risk zone. There are other reported cases of SWF in the general vicinity of the study area. The MMS Internet Database indicates that SWF has occurred in the following wells in the area: MC 696 (Blind Faith; very low severity event), MC 730-1 (moderate flow at 1,842 ft BML), MC 731-1 (low flow at 1,622 ft BML), MC 778-13 (low flow at 2,374 ft BML), MC 864-1 (moderate flow at 1,593 ft BML). Based on these documented SWF events and the geologic conditions present within the study area, we assess that the tophole section in MC 782 has the potential to be overpressured and that sand-prone intervals, if penetrated, could cause a SWF event if not contained or otherwise mitigated.

Sequences 1 and 4 are comprised of mostly fine-grained sediments and are assessed a negligible SWF potential. A lo w potential for SWF is assessed for the sand-prone intervals within lower Sequence 1, lower Sequence 2, and Sequence 5. Sand-prone channel deposits within upper Sequence 2, between 275 ft and 300 ft BML, are interpreted to be part of the Blue Unit sands (Ostermeier et al., 2000 and Winker et al., 2000) and are believed responsible for documented SWF occurrences at some wells in the area. Therefore, upper Sequence 2 is assessed a moderate potential for SWF. Sequence 3 is sand-prone and is interpreted to be part of the informally defined Green Unit sands inferred to have caused SWF events at other wells in the area; therefore, all of Sequence 3 between 490 ft and 2,220 ft BML is assessed a moderate potential for SWF at the proposed wellbore.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-1 5 We appreciate the opportunity to work with you on this project and look forward to continuing as your geohazards consultants. If you have any questions concerning this assessment, please do not hesitate to call us (713-369-5600).

Sincerely, FUGRO GEOCONSULTING, INC.

Jennifer Katrib Senior Geoscientist

Hunter Danque Bruce Samuel Project Geoscientist Geoscience Group Manager

Attachments:

1. Water Depth and Seafloor Features, Dantzler Prospect, Block 782, Gulf of Mexico, Proposed Wellsite MC 782-A (1:12,000) 2. Side-Scan Sonar Mosaic, Dantzler Prospect, Block 782, Mississippi Canyon Area, Proposed Wellsite MC 782-A (1:12,000) 3. Multibeam Backscatter Rendering, Dantzler Prospect, Block 782, Mississippi Canyon, Proposed Wellsite MC 782-A 4. Sub-seafloor Geologic Features, Dantzler Prospect, Block 782, Mississippi Canyon Area, Proposed Wellsite MC 782-A (1:12,000) 5. Tophole Prognosis Chart, Proposed Wellsite MC 782-A, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 6. E-MANATEE 3DX Seismic Profile, Inline 14128, Proposed Wellsite MC 782-A, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 7. E-MANATEE 3DX Seismic Profile, Crossline 3740, Proposed Wellsite MC 782-A, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 8. Sub-bottom Profile, Line 133-e-1, Proposed Wellsite MC 782-A, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 9. 3DX Seismic Power Spectrum, Proposed Wellsite MC 782-A, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico

## FUGRO GEOCONSULTING, INC.

Letter Report No. 27. 2012-2526-2 13 February 2013

Noble Energy, Inc. 100 Glenborough Houston, Texas 77069

Attention: Mr. Bill Hobbs

Wellsite Clearance Letter Proposed Wellsite MC 782-B Block 782, Mississippi Canyon Area

OCS-G-33757

Introduction. Fugro GeoConsulting, Inc. (FGCI) was contracted by Noble Energy Inc. (Noble) to prepare a wellsite clearance letter addressing shallow hazards for proposed Wellsite MC 782-B in Block 782, Mississippi Canyon Area (OCS-G-33757). The proposed well is planned to be vertical through the tophole section and will be drilled by a dynamically positioned rig. This letter is intended to address specific seafloor and shallow geologic conditions within 3,000 ft of the proposed wellsite to the top of salt reflector (about 3,426 ft BML). Shallow geologic conditions at the proposed wellbore are summarized on the attached Tophole Prognosis Chart. Annotated data examples of the nearest 3D exploration seismic survey lines, a sub-bottom profiler line, and four 1:12,000-scale charts showing the proposed wellsite are included. The 1:12,000-scale illustrations include a water depth and seafloor features chart, a side-scan sonar mosaic, a multibeam backscatter chart, and a sub-seafloor geologic features chart. A 2,000 ft radius circle around the proposed wellsite is shown, as per Bureau of Ocean Energy Management (BOEM) Notice to Lessees (NTL) 2009-G40. Please refer to Fugro Report No. 27.2012-2526, “Shallow Geohazards Assessment, Dantzler Prospect, Blocks 738 and 782, Mississippi Canyon Area, Gulf of Mexico,” for a comprehensive assessment of shallow geohazards within Blocks 738 and 782, and a complete list of references used in this investigation. Please refer to C&C Technologies, Inc. Project No. 120578, “Archaeological Assessment Report, Blocks 737, 738, 782 Mississippi Canyon Area, Gulf of Mexico,” for a description of the AUV geophysical data used in this report, as well as a comprehensive archaeological assessment.
3-D Seismic Survey Parameters . A pre-stack, time-migrated 3DX seismic data volume was used for this assessment. The 3DX survey is a subset of the WesternGeco “E-Manatee” reprocessing effort completed in August 2007 and is based in part on the “Mississippi Canyon Phase 11 (Ultra)” survey acquired in 1997 in a north-south orientation with a streamer length of 26,247 ft (8,000 m), 53 fold, 32.8 ft (10 m +1.5m) sound source depth, and 41.01 ft (12.5 m) by 131 ft (40 m) bin spacing. The 3DX data processing was performed by WesternGeco using Kirchhoff pre-stack time migration. The processed volume has a bin size of 41.01 ft (12.5 m) by 65.6 ft (20 m) and a sample rate of 4 milliseconds (Chart 1). The data exhibit no trace or sample decimation of the final processed volume. Inlines are oriented east-west, have a numerical increment of one, and are spaced at intervals of 41.01 ft (12.5 m). Crosslines are oriented north-south, have a numerical increment of 1, and are spaced at intervals of 65.6 ft (20 m). The seismic data set follows North American polarity convention and demonstrates a balanced, zero-phase wavelet based on analysis of the seafloor reflector, top of salt reflector, and low-impedance, high-amplitude anomalies indicative of gas sands.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-2 2 3-D Seismic Frequency. Based on power spectra analysis of the 3DX seismic data at 50% power, the frequency bandwidth for the E-Manatee data between the seafloor to about 1.0 s is approximately 15-64 Hz. This frequency bandwidth corresponds to a limit of separability of 29 ft, assuming a dominant frequency of 45 Hz and an average velocity of 5,400 ft/s in the shallow section. Other details regarding the data descriptions and limitations are found in Fugro Report No. 27.2012-2526.

High-Resolution Geophysical Data . A high-resolution geophysical survey was provided by Noble for interpretation in this study. The survey was acquired by C&C in September 2012 utilizing an autonomous underwater vehicle (AUV) system. The survey grid consists of 49 primary north-south trending tracklines spaced 200 m apart and 14 east-west trending tielines spaced 900 m apart. Navigational fixes (shot points) were recorded at 410 ft (125 m) intervals. Multibeam (MBES), side-scan sonar (SSS), and sub-bottom profiler (SBP) were acquired during this survey. For further details concerning the survey, please refer to C&C Project No. 120578 delivered to Noble Energy in October of 2012.

Depth Conversions. Water column time-to-depth conversions for the 3DX seismic volume are based on a velocity of about 1,480 ft/s. Water depths along AUV tracklines are based on a velocity model generated from real-time velocimeter data. Comparison of the AUV water depths, and the water depths of the seismic volume showed the seismic was generally ~15 ft deeper. Sub-seafloor depths for the 3DX seismic data are based on an interval velocity volume provided by Noble, and sub-bottom profiler depths are based on a velocity of 5,250 ft/s.

. Offset Well Data. Noble provided well log data, daily drilling reports, scout tickets, and paleontological data for offset wells MC 782-1 (Caterpillar Deep) and MC 739-1 (Hilbert). Well logs from MC 782-1 (Caterpillar Deep), located about 2.5 mi southeast of the proposed wellbore and MC 739-1 (Hilbert), located about 4.2 mi northeast of the proposed wellbore, were utilized to calibrate sediment interpretations from seismic data.

Graphics. A Water Depth and Seafloor Features page-size figure (1:12,000-scale) showing the proposed wellsite, water depth contours and seafloor features, accompanies this wellsite assessment. A 2,000 ft radius circle around the proposed wellsite is shown as per BOEM NTL No. 2009-G40. A Composite Side-Scan Sonar Mosaic and a Multibeam Backscatter chart (1:12,000-scale) showing the seafloor conditions in the vicinity of the wellsite are included. Shallow geologic conditions at the proposed wellsite are summarized on the attached Tophole Prognosis Chart. The nearest 3DX inline, 3DX crossline, and AUV SBP profiles are attached to illustrate shallow geologic conditions in the vicinity of the proposed location. A page-size 1:12,000-scale Sub-Seafloor Geologic Features Chart is also included to illustrate geologic conditions in the vicinity of the proposed wellbore. The 3DX Seismic Power Spectrum is included as an assessment of the frequency content of the 3DX seismic data at the proposed wellbore.

Proposed Well Location. The surface location for proposed Wellsite MC 782-B is located in northern MC Block 782 as follows:

Proposed Wellsite MC 782

- B Block 782, Mississippi Canyon Area UTM Zone 16, NAD 1927 X = 1,226,029 ft Y = 10,245,555 ft Latitude: 28° 13' 37"N Longitude: 88° 17' 14"W Nearest E-Manatee Inline 14094 Nearest E-Manatee Crossline 3723

6,349 ft FWL 2,925 ft FNLNOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-2 3 Water Depth and Seafloor Gradient. The MBES water depth at the proposed wellsite is predicted to be about 6560 ft with zero datum at sea surface. The local gradient is less than 1° to the north.

Seafloor Features . At the proposed MC 782-B wellsite, the local seafloor is smooth, featureless, and appears stable. Several northwest-southeast trending seafloor faults are identified in the vicinity of the proposed wellsite. The closest seafloor fault scarp lies about 1,560 ft to the southwest, exhibits a seafloor relief of about 10 ft and is associated with seafloor gradient of less than 4°. Another seafloor fault is about 2,960 ft northeast of the proposed wellsite, and the seafloor scarp defined by this fault has maximum relief of about 40 ft and a seafloor gradient of less than 10°. These faults are identified on SBP records and 3DX seismic data. No seafloor faults will be penetrated by the proposed wellbore, and the seafloor fault scarps meet the 75 m (245 ft) standoff distance as outlined by the BOEM in NTL No. 2008-G05.

Potential High-density Benthic Communities. Two areas of high seafloor multibeam backscatter intensity indicative of possible hardground are located about 2,200 ft and 2,800 ft west of the proposed MC 782-B wellsite. There is no geophysical evidence of hydrocarbon seepage sites or areas that could potentially support high-density benthic communities within 2,000 ft of the proposed location. Therefore, there is a negligible potential for high-density communities of benthic and/or chemosynthetic organisms within 2,000 ft of the proposed wellsite, in accordance with BOEM NTL 2009-G40.

Man-Made Obstructions. A search of Fugro’s GIS database conducted in February 2013 and a review of the SSS data from the high-resolution geophysical data set indicated closest man-made feature is one existing pipeline (Enterprise 20-24” SEG#15153) ~2,920 ft north of the proposed wellsite.

The closest sonar targets (contacts # 37 and #38) were detected about 1,750 ft northeast and ~1,800 ft east of the proposed wellsite, respectively. These targets, and all the other targets farther from the proposed wellsite, are interpreted as unidentified debris as outlined in the archaeological assessment by C&C (Project No. 120578). Although no man-made features or other potentially hazardous seafloor conditions are identified in the SSS data, we recommend that an ROV be used to inspect the seafloor at the proposed wellsite immediately before spud-in to confirm that no seafloor obstructions have appeared since the SSS survey was acquired.

Stratigraphy. The seafloor and five subsurface horizons (10, 20, 30, 40 and 60) were mapped to divide the tophole section into five stratigraphic sequences (Sequence 1 through 5) of distinct seismic and inferred lithologic character at the proposed wellbore. Predicted depths and thicknesses associated with each of the mapped horizons and sequences are displayed on the attached Tophole Prognosis Chart for the proposed Wellsite MC 782-B drilling location.

At the proposed wellbore, Sequence 1 is 290 ft thick and is divided into an upper 161 ft thick interval of parallel-stratified marine clays and thin, fine-grained MTDs and a lower 129 ft thick interval of sand-prone sediments. Sequence 2 is 200 ft thick and is comprised of mostly fine-grained sediments interbedded with thin, fine-grained MTDs and possible thin sands. The upper 21 ft of Sequence 2 consists of possible sand-prone channel and overbank deposits which are interpreted to be part of the Blue Unit (Ostermeier et al., 2000 and Winker et al., 2000).

Sequence 3 is cumulatively about 1,551 ft thick and is interpreted to represent the informally described Green Unit. The upper 246 ft of Sequence 3 consist of fine-grained MTDs interlayered with fine-grained MTDs and possible sand-prone deposits. The middle 350 ft of Sequence 3 are comprised of mostly fine-grained slope failure deposits interbedded with possible sand-prone sediments. The lower 955 ft of Sequence 3 consist of slope failure deposits consisting of sand-prone channel and overbank deposits interbedded with fine-grianed MTDs. Sequence 4 is a 600 thick interval of faulted, fine-grained sediments underlain by Sequence 5, which is composed of 785 ft of faulted, sand-prone channel and overbank deposits interbedded with thin, fine-grained MTDs.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-2 4 Fault Penetrations. The proposed wellbore will not penetrate any buried faults. However the sedimentary section within Sequences 4 and 5 is expected to be extensively fractured, and could create secondary porosity and permeability that could cause drilling fluid loss to formation.

Gas Hydrate and Gas Hazards. Temperature and pressure conditions are favorable for the presence of gas hydrates within the study area. The base of gas hydrate stability was modeled using the fundamental gas hydrate phase equilibrium curve, which requires input for temperature, pressure, gas mixture, and salinity (Sloan, 1990), and is estimated to be located within Sequence 3. Localized and disseminated gas hydrates, if present, may occur above the base of has hydrate stability. Massive gas hydrate accumulations at the proposed wellbore are not expected.

No high-amplitude anomalies interpreted to represent shallow gas will be penetrated in the tophole section by a vertical wellbore at the proposed wellsite. Interpreted anomalies representing possible shallow gas hazards in the tophole section within 3,000 ft of the proposed wellbore are located in Sequences 2 through 5. The closest amplitude anomalies to the proposed MC 782-B wellbore are located 372 ft to the southeast within upper Sequence 2 and 1,050 ft to the southwest within Sequence 3. Because of the sand-prone nature of lower Sequence 1 and upper Sequence 2, a low potential for shallow gas is assessed for the intervals of these Sequences between 161 ft and 311 ft BML. Because of the presence of possible sand-prone sediments within Sequences 3 and 5; a low potential for shallow gas is assessed for these Sequences between 490 ft and 2,041 ft BML and between 2,641 ft and 3,426 ft BML, respectively. Possible gas sands in the other stratigraphic units are located safely away from the borehole and should not pose any hazard or constraint to drilling. Therefore, the remainder of the tophole section is assessed a negligible potential for encountering significant gas accumulations.

Shallow-Water-Flow (SWF). A map presented by Pelletier and others (1999) shows the relative magnitude of shallow-water-flow (SWF) hazards in the Northern Gulf of Mexico. On this map, the study area falls within the moderate-risk zone. There are other reported cases of SWF in the general vicinity of the study area. The MMS Internet Database indicates that SWF has occurred in the following wells in the area: MC 696 (Blind Faith; very low severity event), MC 730-1 (moderate flow at 1,842 ft BML), MC 731-1 (low flow at 1,622 ft BML), MC 778-13 (low flow at 2,374 ft BML), MC 864-1 (moderate flow at 1,593 ft BML). Based on these documented SWF events and the geologic conditions present within the study area, we assess that the tophole section in MC 782 has the potential to be overpressured and that sand-prone intervals, if penetrated, could cause a SWF event if not contained or otherwise mitigated.

Sequences 1 and 4 are comprised of mostly fine-grained sediments and are assessed a negligible SWF potential. A lo w potential for SWF is assessed for the sand-prone intervals within lower Sequence 1, lower Sequence 2, and Sequence 5. Sand-prone channel deposits within upper Sequence 2, between 290 ft and 311 ft BML, are interpreted to be part of the Blue Unit sands (Ostermeier et al., 2000 and Winker et al., 2000) and are believed responsible for documented SWF occurrences at some wells in the area. Therefore, upper Sequence 2 is assessed a moderate potential for SWF. Sequence 3 is sand-prone and is interpreted to be part of the informally defined Green Unit sands inferred to have caused SWF events at other wells in the area; therefore, all of Sequence 3 between 490 ft and 2,041 ft BML is assessed a moderate potential for SWF at the proposed wellbore.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-2 5 We appreciate the opportunity to work with you on this project and look forward to continuing as your geohazards consultants. If you have any questions concerning this assessment, please do not hesitate to call us (713-369-5600).

Sincerely, FUGRO GEOCONSULTING, INC.

Jennifer Katrib Senior Geoscientist

Hunter Danque Bruce Samuel Project Geoscientist Geoscience Group Manager

Attachments:

1. Water Depth and Seafloor Features, Dantzler Prospect, Block 782, Gulf of Mexico, Proposed Wellsite MC 782-B (1:12,000) 2. Side-Scan Sonar Mosaic, Dantzler Prospect, Block 782, Mississippi Canyon Area, Proposed Wellsite MC 782-B (1:12,000) 3. Multibeam Backscatter Rendering, Dantzler Prospect, Block 782, Mississippi Canyon, Proposed Wellsite MC 782-B 4. Sub-seafloor Geologic Features, Dantzler Prospect, Block 782, Mississippi Canyon Area, Proposed Wellsite MC 782-B (1:12,000) 5. Tophole Prognosis Chart, Proposed Wellsite MC 782-B, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 6. E-MANATEE 3DX Seismic Profile, Inline 14094, Proposed Wellsite MC 782-B, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 7. E-MANATEE 3DX Seismic Profile, Crossline 3766, Proposed Wellsite MC 782-B, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 8. Sub-bottom Profile, Line 135, Proposed Wellsite MC 782-B, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 9. 3DX Seismic Power Spectrum, Proposed Wellsite MC 782-B, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico

## FUGRO GEOCONSULTING, INC.

Letter Report No. 27. 2012-2526-3 13 February 2013

Noble Energy, Inc. 100 Glenborough Houston, Texas 77069

Attention: Mr. Bill Hobbs

Wellsite Clearance Letter Proposed Wellsite MC 782-C Block 782, Mississippi Canyon Area

OCS-G-33757

Introduction. Fugro GeoConsulting, Inc. (FGCI) was contracted by Noble Energy Inc. (Noble) to prepare a wellsite clearance letter addressing shallow hazards for proposed Wellsite MC 782-C in Block 782, Mississippi Canyon Area (OCS-G-33757). The proposed well is planned to be vertical through the tophole section and will be drilled by a dynamically positioned rig. This letter is intended to address specific seafloor and shallow geologic conditions within 3,000 ft of the proposed wellsite to the top of salt reflector (about 3,018 ft BML). Shallow geologic conditions at the proposed wellbore are summarized on the attached Tophole Prognosis Chart. Annotated data examples of the nearest 3D exploration seismic survey lines, a sub-bottom profiler line, and four 1:12,000-scale charts showing the proposed wellsite are included. The 1:12,000-scale illustrations include a water depth and seafloor features chart, a side-scan sonar mosaic, a multibeam backscatter chart, and a sub-seafloor geologic features chart. A 2,000 ft radius circle around the proposed wellsite is shown, as per Bureau of Ocean Energy Management (BOEM) Notice to Lessees (NTL) 2009-G40. Please refer to Fugro Report No. 27.2012-2526, “Shallow Geohazards Assessment, Dantzler Prospect, Blocks 738 and 782, Mississippi Canyon Area, Gulf of Mexico,” for a comprehensive assessment of shallow geohazards within Blocks 738 and 782, and a complete list of references used in this investigation. Please refer to C&C Technologies, Inc. Project No. 120578, “Archaeological Assessment Report, Blocks 737, 738, 782 Mississippi Canyon Area, Gulf of Mexico,” for a description of the AUV geophysical data used in this report, as well as a comprehensive archaeological assessment.
3-D Seismic Survey Parameters . A pre-stack, time-migrated 3DX seismic data volume was used for this assessment. The 3DX survey is a subset of the WesternGeco “E-Manatee” reprocessing effort completed in August 2007 and is based in part on the “Mississippi Canyon Phase 11 (Ultra)” survey acquired in 1997 in a north-south orientation with a streamer length of 26,247 ft (8,000 m), 53 fold, 32.8 ft (10 m +1.5m) sound source depth, and 41.01 ft (12.5 m) by 131 ft (40 m) bin spacing. The 3DX data processing was performed by WesternGeco using Kirchhoff pre-stack time migration. The processed volume has a bin size of 41.01 ft (12.5 m) by 65.6 ft (20 m) and a sample rate of 4 milliseconds (Chart 1). The data exhibit no trace or sample decimation of the final processed volume. Inlines are oriented east-west, have a numerical increment of one, and are spaced at intervals of 41.01 ft (12.5 m). Crosslines are oriented north-south, have a numerical increment of 1, and are spaced at intervals of 65.6 ft (20 m). The seismic data set follows North American polarity convention and demonstrates a balanced, zero-phase wavelet based on analysis of the seafloor reflector, top of salt reflector, and low-impedance, high-amplitude anomalies indicative of gas sands.NO BLE ENERGY INC. SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27. 2012

- 2526 -3 2 3- D Seismic Frequency. Based on power spectra analysis of the 3D X seismic data at 50% power, the frequency bandwidth for the E

- Manatee data between the seafloor to about 1.0 s is approximately 15

- 64 Hz. Th is frequency bandwidth correspon ds to a limit of separability of 29 ft, assuming a dominant frequency of 4 5 Hz and an average velocity of 5,400 ft/s in the shallow section. Other details regarding the data descriptions and limitations are found in Fugro Report No. 27.201 2-2 526

. High

- Resolution Geophysical Data

. A high

- resolution geophysical survey was provided by Noble for interpretation in this study. The survey was acquired by C&C in Sept ember 201 2 utilizing an autonomous underwater vehicle (AUV) system. The survey grid cons ists of 49 primary north

- south trending trac klines spaced 200 m apart and 14 east

- west trending tielines spaced 900 m apart. Navigational fixes (shot points) were recorded at 410 ft (125 m) intervals. Multibeam (MBES), side

- scan sonar (SSS), and sub

- bottom profiler (SBP) were acquired during this survey

. For further details concerning the survey, please refer to C&C Project No. 120578 delivered to Noble Energy in October of 201 2.

Depth Conversions. Water column time

- to

- depth conversions for the 3DX seismic volume are based on a velocity of about 1,480 ft/s. Water depths along AUV tracklines are based on a velocity model generated from real

- time velocimeter data. Comparison of the AUV water depths, and the water depths of the seismic volume showed the seismic was generally ~ 15 ft deeper. Sub

- seafloor depths for the 3DX seismic data are based on an interval velocity volume provided by Noble , and sub

- bottom profiler depths are based on a velocity of 5,250 ft/s

.

. Offset Well Data

. Noble provided well log data, daily drilling reports, scout tickets, and paleontological data for offset wells MC 782

- 1 (Caterpillar Deep) and MC 7 39 -1 ( Hilbert ). Well logs from MC 782

- 1 (Caterpillar Deep), located about 1.6 mi southeast of the proposed w ellbore and MC 739

- 1 (Hilbert) , located about 5.2 mi northeast of the proposed wellbore, were utilized to calibrate sediment interpretations from seismic data

. Graphics. A Water Depth and Seafloor Features page

- size figure (1:12,000

- scale) showing the pro posed wellsite, water depth contours and seafloor features, accompanies this wellsite assessment. A 2,000 ft radius circle around the proposed wellsite is shown as per BOEM NTL No. 2009

- G40. A Composite Sid e- Scan Sonar Mosaic and a Multibeam Backscatter chart (1:12,000

- scale) showing the seafloor conditions in the vicinity of the wellsite are included. S hallow geologic conditions at the proposed wellsite are summarized on the attached Tophole Prognosis Chart. The nearest 3D X inline, 3D X crossline, and A UV SBP profiles are attached to illustrate shallow geologic conditions in the vicinity of the proposed location. A page

- size 1:12,000

- scale Sub

- Seafloor Geologic Features Chart is also included to illustrate geologic conditions in the vicinity of the proposed wellbore. The 3D X Seismic Power Spectrum is included as an assessment of the frequency content of the 3D X seismic data at the proposed wellbore

. Proposed Well Location. The surface location for proposed Wellsite MC 782 -C is located in northern MC Block 7 82 as follows:

Proposed Wellsite MC 782

- C Block 7 82 , Mississippi Canyon Area UTM Zone 16, NAD 1927 X = 1,22 4
, 265 ft Y = 10, 2 38
, 900 ft Latitude: 28° 1 2 ' 31 "N Longitude: 88° 17' 33 "W Nearest E

- Manatee Inline 1 3993 Nearest E

- Manatee Crossline 37 23 4,585 ft FWL 6,260 ft F S LNOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-3 3 Water Depth and Seafloor Gradient. The MBES water depth at the proposed wellsite is predicted to be about 6542 ft with zero datum at sea surface. The local gradient is less than 1° to the north.

Seafloor Features . At the proposed MC 782-C wellsite, the local seafloor is smooth, featureless, and appears stable. Several north-northwest south-southeast trending seafloor faults are identified in the vicinity of the proposed wellsite. The closest seafloor fault scarp lies about 320 ft to the west and the fault dips away from the proposed wellbore. This seafloor fault scarp exhibits a seafloor relief of about 10 ft and is associated with seafloor gradient of less than 4°. A cluster of seafloor fault scarps is located at least 2,400 ft west and southwest of the proposed wellsite, and the seafloor scarps defined by these faults have maximum relief of about 40 ft and a seafloor gradient of less than 10°. These faults are identified on SBP records and 3DX seismic data. No seafloor faults will be penetrated by the proposed wellbore, and the seafloor fault scarps meet the 75 m (245 ft) standoff distance as outlined by the BOEM in NTL No. 2008-G05.

Potential High-density Benthic Communities. One area of high seafloor multibeam backscatter intensity indicative of possible hardground is located about 3,400 ft southwest of the proposed MC 782-C wellsite. There is no geophysical evidence of hydrocarbon seepage sites or areas that could potentially support high-density benthic communities within 2,000 ft of the proposed location. Therefore, there is a negligible potential for high-density communities of benthic and/or chemosynthetic organisms within 2,000 ft of the proposed wellsite, in accordance with BOEM NTL 2009-G40.

Man-Made Obstructions. A search of Fugro’s GIS database conducted in February 2013 and a review of the SSS data from the high-resolution geophysical data set indicated closest man-made feature is one existing pipeline (Enterprise 20-24” SEG#15153) ~9,600 ft north of the proposed wellsite.

The closest sonar target (contact # 20) was detected about 2,800 ft southwest of the proposed wellsite. This target, and all the other targets farther from the proposed wellsite, is interpreted as unidentified debris as outlined in the archaeological assessment by C&C (Project No. 120578). Although no man-made features or other potentially hazardous seafloor conditions are identified in the SSS data, we recommend that an ROV be used to inspect the seafloor at the proposed wellsite immediately before spud-in to confirm that no seafloor obstructions have appeared since the SSS survey was acquired.

Stratigraphy. The seafloor and five subsurface horizons (10, 20, 30, 40 and 60) were mapped to divide the tophole section into five stratigraphic sequences (Sequence 1 through 5) of distinct seismic and inferred lithologic character at the proposed wellbore. Predicted depths and thicknesses associated with each of the mapped horizons and sequences are displayed on the attached Tophole Prognosis Chart for the proposed Wellsite MC 782-C drilling location.

At the proposed wellbore, Sequence 1 is 274 ft thick and is divided into an upper 159 ft thick interval of parallel-stratified marine clays and thin, fine-grained MTDs and a lower 115 ft thick interval of sand-prone sediments. Sequence 2 is 244 ft thick and is comprised of mostly fine-grained sediments interbedded with thin, fine-grained MTDs and possible thin sands. The upper 25 ft of Sequence 2 consists of possible sand-prone channel and overbank deposits which are interpreted to be part of the Blue Unit (Ostermeier et al., 2000 and Winker et al., 2000).

Sequence 3 is cumulatively about 1,460 ft thick and is interpreted to represent the informally described Green Unit. The upper 481 ft of Sequence 3 consist of sand-prone sediments interbedded with thin, fine-grained MTDs. The middle 520 ft of Sequence 3 are comprised of slope failure deposits consisting of sand-prone channel and overbank deposits interbedded with fine-grained MTDs. The lower 459 ft of Sequence 3 consist of faulted, fine-grained sediments interbedded with possible thin sands. Sequence 4 is a 690 ft thick interval of faulted, fine-grained sediments underlain by Sequence 5, which is composed of 350 ft of faulted, sand-prone channel and overbank deposits interbedded with thin, fine-grained MTDs.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-3 4 Fault Penetrations. One buried fault plane will intersect the proposed wellbore at about 2,699 ft BML. This fault is presumed to be inactive and is not expected to present a constraint to drilling operations. However the sedimentary section within Sequences 4 and 5 is expected to be extensively fractured, and could create secondary porosity and permeability that could cause drilling fluid loss to formation.

Gas Hydrate and Gas Hazards. Temperature and pressure conditions are favorable for the presence of gas hydrates within the study area. The base of gas hydrate stability was modeled using the fundamental gas hydrate phase equilibrium curve, which requires input for temperature, pressure, gas mixture, and salinity (Sloan, 1990), and is estimated to be located within Sequence 3. Localized and disseminated gas hydrates, if present, may occur above the base of has hydrate stability. Massive gas hydrate accumulations at the proposed wellbore are not expected.

No high-amplitude anomalies interpreted to represent shallow gas will be penetrated in the tophole section by a vertical wellbore at the proposed wellsite. Interpreted anomalies representing possible shallow gas hazards in the tophole section within 3,000 ft of the proposed wellbore are located in Sequences 2 through 5. The closest amplitude anomalies to the proposed MC 782-C wellbore are located 345 ft to the southwest within upper Sequence 2 and 1,100 ft to the north-northeast within Sequence 3. Because of the sand-prone nature of lower Sequence 1 and upper Sequence 2, a low potential for shallow gas is assessed for the intervals of these Sequences between 159 ft and 299 ft BML. Because of the presence of possible sand-prone sediments within Sequences 3 and 5; a low potential for shallow gas is assessed for these Sequences between 518 ft and 1,978 ft BML and between 2,668 ft and 3,018 ft BML, respectively. Possible gas sands in the other stratigraphic units are located safely away from the borehole and should not pose any hazard or constraint to drilling. Therefore, the remainder of the tophole section is assessed a negligible potential for encountering significant gas accumulations.

Shallow-Water-Flow (SWF). A map presented by Pelletier and others (1999) shows the relative magnitude of shallow-water-flow (SWF) hazards in the Northern Gulf of Mexico. On this map, the study area falls within the moderate-risk zone. There are other reported cases of SWF in the general vicinity of the study area. The MMS Internet Database indicates that SWF has occurred in the following wells in the area: MC 696 (Blind Faith; very low severity event), MC 730-1 (moderate flow at 1,842 ft BML), MC 731-1 (low flow at 1,622 ft BML), MC 778-13 (low flow at 2,374 ft BML), MC 864-1 (moderate flow at 1,593 ft BML). Based on these documented SWF events and the geologic conditions present within the study area, we assess that the tophole section in MC 782 has the potential to be overpressured and that sand-prone intervals, if penetrated, could cause a SWF event if not contained or otherwise mitigated.

Sequences 1 and 4 are comprised of mostly fine-grained sediments and are assessed a negligible SWF potential. A lo w potential for SWF is assessed for the sand-prone intervals within lower Sequence 1, lower Sequence 2, and Sequence 5. Sand-prone channel deposits within upper Sequence 2, between 274 ft and 299 ft BML, are interpreted to be part of the Blue Unit sands (Ostermeier et al., 2000 and Winker et al., 2000) and are believed responsible for documented SWF occurrences at some wells in the area. Therefore, upper Sequence 2 is assessed a moderate potential for SWF. Sequence 3 is sand-prone and is interpreted to be part of the informally defined Green Unit sands inferred to have caused SWF events at other wells in the area; therefore, all of Sequence 3 between 518 ft and 1,978 ft BML is assessed a moderate potential for SWF at the proposed wellbore.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-3 5 We appreciate the opportunity to work with you on this project and look forward to continuing as your geohazards consultants. If you have any questions concerning this assessment, please do not hesitate to call us (713-369-5600).

Sincerely, FUGRO GEOCONSULTING, INC.

Jennifer Katrib Senior Geoscientist

Hunter Danque Bruce Samuel Project Geoscientist Geoscience Group Manager

Attachments:

1. Water Depth and Seafloor Features, Dantzler Prospect, Block 782, Gulf of Mexico, Proposed Wellsite MC 782-C (1:12,000) 2. Side-Scan Sonar Mosaic, Dantzler Prospect, Block 782, Mississippi Canyon Area, Proposed Wellsite MC 782-C (1:12,000) 3. Multibeam Backscatter Rendering, Dantzler Prospect, Block 782, Mississippi Canyon, Proposed Wellsite MC 782-C 4. Sub-seafloor Geologic Features, Dantzler Prospect, Block 782, Mississippi Canyon Area, Proposed Wellsite MC 782-C (1:12,000) 5. Tophole Prognosis Chart, Proposed Wellsite MC 782-C, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 6. E-MANATEE 3DX Seismic Profile, Inline 13993, Proposed Wellsite MC 782-C, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 7. E-MANATEE 3DX Seismic Profile, Crossline 3723, Proposed Wellsite MC 782-C, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 8. Sub-bottom Profile, Line 132, Proposed Wellsite MC 782-C, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 9. 3DX Seismic Power Spectrum, Proposed Wellsite MC 782-C, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico

## FUGRO GEOCONSULTING, INC.

Letter Report No. 27. 2012-2526-6 8 March 2013

Noble Energy, Inc. 100 Glenborough Houston, Texas 77069

Attention: Mr. Bill Hobbs

Wellsite Clearance Letter Proposed Wellsite MC 782-D Block 782, Mississippi Canyon Area

OCS-G-33757

Introduction. Fugro GeoConsulting, Inc. (FGCI) was contracted by Noble Energy Inc. (Noble) to prepare a wellsite clearance letter addressing shallow hazards for proposed Wellsite MC 782-D in Block 782, Mississippi Canyon Area (OCS-G-33757). The proposed well is planned to be vertical through the tophole section and will be drilled by a dynamically positioned rig. This letter is intended to address specific seafloor and shallow geologic conditions within 3,000 ft of the proposed wellsite to the top of salt reflector (about 3,220 ft BML). Shallow geologic conditions at the proposed wellbore are summarized on the attached Tophole Prognosis Chart. Annotated data examples of the nearest 3D exploration seismic survey lines, a sub-bottom profiler line, and four 1:12,000-scale charts showing the proposed wellsite are included. The 1:12,000-scale illustrations include a water depth and seafloor features chart, a side-scan sonar mosaic, a multibeam backscatter chart, and a sub-seafloor geologic features chart. A 2,000 ft radius circle around the proposed wellsite is shown, as per Bureau of Ocean Energy Management (BOEM) Notice to Lessees (NTL) 2009-G40. Please refer to Fugro Report No. 27.2012-2526, “Shallow Geohazards Assessment, Dantzler Prospect, Blocks 738 and 782, Mississippi Canyon Area, Gulf of Mexico,” for a comprehensive assessment of shallow geohazards within Blocks 738 and 782, and a complete list of references used in this investigation. Please refer to C&C Technologies, Inc. Project No. 120578, “Archaeological Assessment Report, Blocks 737, 738, 782 Mississippi Canyon Area, Gulf of Mexico,” for a description of the AUV geophysical data used in this report, as well as a comprehensive archaeological assessment.
3-D Seismic Survey Parameters . A pre-stack, time-migrated 3DX seismic data volume was used for this assessment. The 3DX survey is a subset of the WesternGeco “E-Manatee” reprocessing effort completed in August 2007 and is based in part on the “Mississippi Canyon Phase 11 (Ultra)” survey acquired in 1997 in a north-south orientation with a streamer length of 26,247 ft (8,000 m), 53 fold, 32.8 ft (10 m +1.5m) sound source depth, and 41.01 ft (12.5 m) by 131 ft (40 m) bin spacing. The 3DX data processing was performed by WesternGeco using Kirchhoff pre-stack time migration. The processed volume has a bin size of 41.01 ft (12.5 m) by 65.6 ft (20 m) and a sample rate of 4 milliseconds. The data exhibit no trace or sample decimation of the final processed volume. Inlines are oriented east-west, have anumerical increment of one, and are spaced at intervals of 41.01 ft (12.5 m). Crosslines are oriented northsouth, have a numerical increment of 1, and are spaced at intervals of 65.6 ft (20 m). The seismic data set follows North American polarity convention and demonstrates a balanced, zero-phase wavelet based on analysis of the seafloor reflector, top of salt reflector, and low-impedance, high-amplitude anomalies indicative of gas sands.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-6 2 3-D Seismic Frequency. Based on power spectra analysis of the 3DX seismic data at 50% power, the frequency bandwidth for the E-Manatee data between the seafloor to about 1.0 s is approximately 15-64 Hz. This frequency bandwidth corresponds to a limit of separability of 29 ft, assuming a dominant frequency of 45 Hz and an average velocity of 5,400 ft/s in the shallow section. Other details regarding the data descriptions and limitations are found in Fugro Report No. 27.2012-2526.

High-Resolution Geophysical Data . A high-resolution geophysical survey was provided by Noble for interpretation in this study. The survey was acquired by C&C in September 2012 utilizing an autonomous underwater vehicle (AUV) system. The survey grid consists of 49 primary north-south trending tracklines spaced 200 m apart and 14 east-west trending tielines spaced 900 m apart. Navigational fixes (shot points) were recorded at 410 ft (125 m) intervals. Multibeam (MBES), side-scan sonar (SSS), and sub-bottom profiler (SBP) were acquired during this survey. For further details concerning the survey, please refer to C&C Project No. 120578 delivered to Noble Energy in October of 2012.

Depth Conversions. Water column time-to-depth conversions for the 3DX seismic volume are based on a velocity of about 1,480 m/s. Water depths along AUV tracklines are based on a velocity model generated from real-time velocimeter data. Comparison of the AUV water depths, and the water depths of the seismic volume showed the seismic was generally ~15 ft deeper. Sub-seafloor depths for the 3DX seismic data are based on an interval velocity volume provided by Noble, and sub-bottom profiler depths are based on a velocity of 5,250 ft/s.

. Offset Well Data. Noble provided well log data, daily drilling reports, scout tickets, and paleontological data for offset wells MC 782-1 (Caterpillar Deep) and MC 739-1 (Hilbert). Well logs from MC 782-1 (Caterpillar Deep), located about 3 mi southeast of the proposed wellbore and MC 739-1 (Hilbert), located about 4.2 mi east-northeast of the proposed wellbore, were utilized to calibrate sediment interpretations from seismic data.

Graphics. A Water Depth and Seafloor Features page-size figure (1:12,000-scale) showing the proposed wellsite, water depth contours and seafloor features, accompanies this wellsite assessment.A 2,000 ft radius circle around the proposed wellsite is shown as per BOEM NTL No. 2009-G40. SideScan Sonar Mosaic and Multibeam Backscatter charts (1:12,000-scale) showing the seafloor conditions in the vicinity of the wellsite are included. Shallow geologic conditions at the proposed wellsite are summarized on the attached Tophole Prognosis Chart. The nearest 3DX inline, 3DX crossline, and AUV SBP profiles are attached to illustrate shallow geologic conditions in the vicinity of the proposed location. A page-size 1:12,000-scale Sub-Seafloor Geologic Features Chart is also included to illustrate geologic conditions in the vicinity of the proposed wellbore. The 3DX Seismic Power Spectrum is included as an assessment of the frequency content of the 3DX seismic data at the proposed wellbore.

Proposed Well Location. The surface location for proposed Wellsite MC 782-D is located in northern MC Block 782 as follows:

Proposed Wellsite MC 782

- D Block 782, Mississippi Canyon Area UTM Zone 16, NAD 1927 X = 1,224,918 ft Y = 10,247,903 ft Latitude: 28° 14' 00"N Longitude: 88° 17' 26"W Nearest E-Manatee Inline 14130 Nearest E-Manatee Crossline 3739

5,238 ft FWL 577 ft FNLNOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-6 3 Water Depth and Seafloor Gradient. The MBES water depth at the proposed wellsite is predicted to be about 6576 ft with zero datum at sea surface. The local gradient is less than 1° to the east.

Seafloor Features . At the proposed MC 782-D wellsite, the local seafloor is smooth, featureless, and appears stable. Two northwest-southeast trending seafloor faults are identified in the vicinity of the proposed wellsite. The closest seafloor fault scarp lies about 2,130 ft to the southwest, exhibits a seafloor relief of about 10 ft and is associated with seafloor gradient of less than 4°. Another seafloor fault is about 2,300 ft northeast of the proposed wellsite, and the seafloor scarp defined by this fault has maximum relief of about 40 ft and a seafloor gradient of less than 10°. These faults are identified on SBP records and 3DX seismic data. No seafloor faults will be penetrated by the proposed wellbore, and the seafloor fault scarps meet the 75 m (245 ft) standoff distance as outlined by the BOEM in NTL No. 2008-G05.

Potential High-density Benthic Communities. Two areas of high seafloor multibeam backscatter intensity indicative of possible hardground are located about 2,030 ft and 2,750 ft southwest of the proposed MC 782-D wellsite. There is no geophysical evidence of hydrocarbon seepage sites or areas that could potentially support high-density benthic communities within 2,000 ft of the proposed location. Therefore, there is a negligible potential for high-density communities of benthic and/or chemosynthetic organisms within 2,000 ft of the proposed wellsite, in accordance with BOEM NTL 2009-G40.

Man-Made Obstructions. A search of Fugro’s GIS database conducted in February 2013 and a review of the SSS data from the high-resolution geophysical data set indicated closest man-made feature is one existing pipeline (Enterprise 20-24” SEG#15153) 577 ft north of the proposed wellsite.

The closest sonar target (contact # 37) was detected about 3,180 ft southeast of the proposed wellsite. This target, and all the other targets farther from the proposed wellsite, are interpreted as unidentified debris as outlined in the archaeological assessment by C&C (Project No. 120578). Although no man-made features or other potentially hazardous seafloor conditions are identified in the SSS data, we recommend that an ROV be used to inspect the seafloor at the proposed wellsite immediately before spud-in to confirm that no seafloor obstructions have appeared since the SSS survey was acquired.

Stratigraphy. The seafloor and five subsurface horizons (10, 20, 30, 40 and 60) were mapped to divide the tophole section into five stratigraphic sequences (Sequence 1 through 5) of distinct seismic and inferred lithologic character at the proposed wellbore. Predicted depths and thicknesses associated with each of the mapped horizons and sequences are displayed on the attached Tophole Prognosis Chart for the proposed wellsite MC 782-D drilling location.

At the proposed wellbore, Sequence 1 is 275 ft thick and is divided into an upper 165 ft thick interval of parallel-stratified marine clays and thin, fine-grained MTDs and a lower 110 ft thick interval of sand-prone sediments. Sequence 2 is 200 ft thick and is comprised of mostly fine-grained sediments interbedded with thin, fine-grained MTDs and possible thin sands. The upper 25 ft of Sequence 2 consists of possible sand-prone channel and overbank deposits which are interpreted to be part of the Blue Unit (Ostermeier et al., 2000 and Winker et al., 2000).

Sequence 3 is cumulatively about 1,730 ft thick and is interpreted to represent the informally described Green Unit. The upper 270 ft of Sequence 3 consist of fine-grained MTDs interbedded with possible sand-prone deposits. The middle 675 ft of Sequence 3 are comprised of slope failure deposits consisting of sand-prone channel and overbank deposits interbedded with fine-grained MTDs. The lower 785 ft of Sequence 3 consist of mostly fine-grained slope failure deposits with possible sand-prone sediment blocks. Sequence 4 is a 475 ft thick interval of faulted, fine-grained sediments underlain by Sequence 5, which is composed of 540 ft of faulted, sand-prone channel and overbank deposits interbedded with thin, fine-grained MTDs.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-6 4 Fault Penetrations. One buried fault plane will intersect the proposed wellbore at about 2,940 ft BML. This fault is presumed to be inactive and is not expected to present a constraint to drilling operations. However the sedimentary section within Sequences 4 and 5 is expected to be extensively fractured, and could create secondary porosity and permeability that could cause drilling fluid loss to formation.

Gas Hydrate and Gas Hazards. Temperature and pressure conditions are favorable for the presence of gas hydrates within the study area. The base of gas hydrate stability was modeled using the fundamental gas hydrate phase equilibrium curve, which requires input for temperature, pressure, gas mixture, and salinity (Sloan, 1990), and is estimated to be located within Sequence 3. Localized and disseminated gas hydrates, if present, may occur above the base of has hydrate stability. Massive gas hydrate accumulations at the proposed wellbore are not expected.

No high-amplitude anomalies interpreted to represent shallow gas will be penetrated in the tophole section by a vertical wellbore at the proposed wellsite. Interpreted anomalies representing possible shallow gas hazards in the tophole section within 3,000 ft of the proposed wellbore are located in Sequences 2 through 5. The closest amplitude anomalies to the proposed MC 782-D wellbore are located 552 ft to the southwest and 507 ft to the southeast within upper Sequence 2. Because of the sand-prone nature of lower Sequence 1 and upper Sequence 2, a low potential for shallow gas is assessed for the intervals of these Sequences between 165 ft and 300 ft BML. Because of the presence of possible sand-prone sediments within Sequences 3 and 5; a low potential for shallow gas is assessed for these Sequences between 475 ft and 2,205 ft BML and between 2,680 ft and 3,220 ft BML, respectively. Possible gas sands in the other stratigraphic units are located safely away from the borehole and should not pose any hazard or constraint to drilling. Therefore, the remainder of the tophole section is assessed a negligible potential for encountering significant gas accumulations.

Shallow-Water-Flow (SWF). A map presented by Pelletier and others (1999) shows the relative magnitude of shallow-water-flow (SWF) hazards in the Northern Gulf of Mexico. On this map, the study area falls within the moderate-risk zone. There are other reported cases of SWF in the general vicinity of the study area. The BOEM Internet Database indicates that SWF has occurred in the following wells in the area: MC 696 (Blind Faith; very low severity event), MC 730-1 (moderate flow at 1,842 ft BML), MC 731-1 (low flow at 1,622 ft BML), MC 778-13 (low flow at 2,374 ft BML), MC 864-1 (moderate flow at 1,593 ft BML). Based on these documented SWF events and the geologic conditions present within the study area, we assess that the tophole section in MC 782 has the potential to be overpressured and that sand-prone intervals, if penetrated, could cause a SWF event if not contained or otherwise mitigated.

Sequences 1 and 4 are comprised of mostly fine-grained sediments and are assessed a negligible SWF potential. A lo w potential for SWF is assessed for the sand-prone intervals within lower Sequence 1, lower Sequence 2, and Sequence 5. Sand-prone channel deposits within upper Sequence 2, between 275 ft and 300 ft BML, are interpreted to be part of the Blue Unit sands (Ostermeier et al., 2000 and Winker et al., 2000) and are believed responsible for documented SWF occurrences at some wells in the area. Therefore, upper Sequence 2 is assessed a moderate potential for SWF. Sequence 3 is sand-prone and is interpreted to be part of the informally defined Green Unit sands inferred to have caused SWF events at other wells in the area; therefore, all of Sequence 3 between 475 ft and 2,205 ft BML is assessed a moderate potential for SWF at the proposed wellbore.NOBLE ENERGY INC.

SHALLOW HAZARDS ASSESSMENT, DANTZLER PROSPECT MISSISSIPPI CANYON AREA, GULF OF MEXICO

FGCI Report No. 27.2012-2526-6 5 We appreciate the opportunity to work with you on this project and look forward to continuing as your geohazards consultants. If you have any questions concerning this assessment, please do not hesitate to call us (713-369-5600).

Sincerely, FUGRO GEOCONSULTING, INC.

Jennifer Katrib Senior Geoscientist

Hunter Danque Bruce Samuel Project Geoscientist Geoscience Group Manager

Attachments:

1. Water Depth and Seafloor Features, Dantzler Prospect, Block 782, Gulf of Mexico, Proposed Wellsite MC 782-D (1:12,000) 2. Side-Scan Sonar Mosaic, Dantzler Prospect, Block 782, Mississippi Canyon Area, Proposed Wellsite MC 782-D (1:12,000) 3. Multibeam Backscatter Rendering, Dantzler Prospect, Block 782, Mississippi Canyon, Proposed Wellsite MC 782-D 4. Sub-seafloor Geologic Features, Dantzler Prospect, Block 782, Mississippi Canyon Area, Proposed Wellsite MC 782-D (1:12,000) 5. Tophole Prognosis Chart, Proposed Wellsite MC 782-D, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 6. 3DX Seismic Profile, Inline 14130, Proposed Wellsite MC 782-D, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 7. 3DX Seismic Profile, Crossline 3739, Proposed Wellsite MC 782-D, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 8. Sub-bottom Profile, Line 133-e-1, Proposed Wellsite MC 782-D, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico 9. 3DX Seismic Power Spectrum, Proposed Wellsite MC 782-D, Dantzler Prospect, Block 782, Mississippi Canyon Area, Gulf of Mexico

## Section D Hydrogen Sulfide Information

A. Concentration Noble Energy, Inc. does not anticipate encountering any H2S during the proposed operations.

B. Classification In accordance with Title 30 CFR 250.490(c) and NTL No. 2003-G17, Noble requests that Mississippi Canyon 738 and 782 be classified by the BOEM as H2S absent.

Noble Energy, Inc. Page D-1 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)

## Section E Biological, Physical and Socioeconomic Information

A. Chemosynthetic Communities Report Activities proposed in this plan could disturb seafloor areas in deepwater, therefore, a report described in Attachment A of NTL No. 2009-G40 "Deepwater Benthic Communities" is provided below:

MAPS Submitted under separate cover are maps prepared using high resolution seismic information and/or 3-D seismic data depicting bathymetry, seafloor and shallow geological features, surface location of proposed well(s), and a radius circle of 2,000 feet around each such location.

ANALYSIS Using high-resolution seismic information and/or 3-D seismic information, all seafloor features and areas that could be disturbed by the activities proposed in this plan have been identified. The likelihood of these proposed activities disturbing these seafloor and shallow geologic features is discussed in the following summary statement:

No Associated Anchors – No Disturbances within 2,000 Feet of Chemosynthetic Communities Features or areas that could support high-density deepwater benthic communities are not located within 2,000 feet of each proposed muds and cuttings discharge location.

1. Sensitive Underwater Features The activities proposed in this plan will not take place within 500 feet of any identified topographic feature; therefore topographic features information is not required.

2. Marine Sanctuaries Mississippi Canyon 738 and 782 are not located within 100 feet of any pinnacle trend feature with vertical relief equal to or greater than 8 feet; therefore, live bottom information is not required.

B. Topographic Features Map Activities proposed in this EP do not fall within 305 meters (1,000 feet) of the “no activity zone”, therefore no map is required.

C. Topographic Features Statement (Shunting) All activities proposed under this EP will be conducted outside all Topographic Feature Protective Zones, therefore shunting of drill cuttings and drilling fluids is not required.

D. Live Bottoms (Pinnacle Trend) Map Mississippi Canyon 738 and 782 are not located within 61 meters (200 feet) of any pinnacle trend feature with vertical relief equal to or greater than 8 feet; therefore, live bottom information is not required.

E. Live Bottoms (Low Relief) Map Mississippi Canyon 738 and 782 are not located within 100 feet of any pinnacle trend feature with vertical relief equal to or greater than 8 feet; therefore, live bottom (low relief) maps are not required.

Noble Energy, Inc. Page E-1 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)

### F. Potentially Sensitive Biological Features

Mississippi Canyon 738 and 782 are not located within 30 meters (100 feet) of potentially sensitive biological features; therefore, biologically sensitive area maps are not required.

G. Remotely Operated Vehicle (ROV) Monitoring Survey Plan Pursuant to NTL No. 2008-G06, operators may be required to conduct remotely operated vehicle (ROV) surveys during pre-spudding and post-drilling operations for the purpose of biological and physical observations.

Mississippi Canyon 738 and 782 fall within Grid No. 17, an area which BOEM classifies as having inadequate ROV survey coverage; therefore a plan for an ROV monitoring survey is required.

Surveys will be conducted immediately prior and upon completion of drilling operations.

A rig based ROV equipped with video imaging capabilities will be used. The survey pattern will consist of six transects centered on the well location 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.

Biological and physical observations as described in the subject NTL and Form BOEM-141 will be made prior to commencing drilling operations and also following the completion of drilling operations, but prior to moving the rig off location. The observations will be documented using Form BOEM-141 or a facsimile and submitted to the BOEM within 60 days after the second survey is completed.

H . Threatened and Endangered Species Information, Critical Habitat, and Marine Mammal Information Under Section 7 of the Endangered Species Act (ESA) all federal agencies must ensure that any actions they authorize, fund, or carry out are not likely to jeopardize the continued existence of a listed species, or destroy or adversely modify its designated critical habitat.

In accordance with the 30 CFR 250, Subpart B, effective May 14, 2007, and further outlined in Notice to Lessees (NTL) 2008-G04, lessees/operators are required to address site-specific information on the presence of federally listed threatened or endangered species and critical habitat designated under the ESA and marine mammals protected under the Marine Mammal Protection Act (MMPA) in the area of proposes activities under this plan.

NOAA Fisheries currently lists the Sperm Whale, Leatherback Turtle, Green Turtle, Hawksbill Turtle, and the Kemp’s Ridley Turtle as endangered and the Loggerhead Turtle and Gulf Sturgeon as threatened. Currently there are no designated critical habitats for the listed species in the Gulf of Mexico Outer Continental Shelf, however, it is possible that one or more of these species could be seen in the area of our operations.

I . Archaeological Report An Archaeological Survey for Mississippi Canyon 738 and 782 was performed by C&C Technologies Survey Services and it is being submitted with this plan.

Noble Energy, Inc. Page E-2 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)

## Section F Waste and Discharge Information
A. Projected Generated Wastes & Projected Ocean Discharges See Table 1 below All discharges associated with operations proposed in this Exploration Plan will be in accordance with regulations implemented by Bureau of Ocean Energy Management (BOEM), U. S. Coast Guard (USCG) and the U.S. Environmental Protection Agency (EPA).

Projected generated waste Projected ocean discharges Projected Downhole Disposal

Type of Waste Composition Projected Amount Discharge

rate Discharge Method Answer yes or no Will drilling occur ? If yes, you should list muds and cuttings

EXAMPLE: Cuttings wetted with synthetic based fluid Cuttings generated while using synthetic based drilling fluid. X bbl/well X bbl/day/ well discharge overboard No Water-based drilling fluid Seawater 20476 2047 Riserless at sea floor No

Synthetic based drilling fluids or muds Internal Olefine 217 2.3 Discharge overboard with cuttings No

Cuttings wetted with water-based fluid Cuttings generated while using water based drilling

fluid. 4989 498 Riserless at sea floor No

Cuttings wetted with synthetic-based fluid Cutting generated while using synthetic based drilling fluid. 3152 33 Discharge overboard No Will humans be there? If yes, expect conventional waste

EXAMPLE: Sanitary waste water Sanitary waste from living quarters X bbl/well X bbl/hr/well chlorinate and discharge overboard No Domestic waste – gray water Food waste disposal 300 lbs/day 30 lbs/min Discharge overboard No

Sanitary waste Human Waste 2,312 gal/day 96.3 GPH Chlorinated No Is there a deck? If yes, there will be Deck Drainage Deck Drainage Rain Water N/A N/A Closed loop system No Will you conduct well treatment, completion, or workover?

Well treatment fluids 8.6 ppg potassium chloride based well treatment fluid 500 bbls/well 500 bbl

treatment discharge overboard No

Well completion fluids 12.4 lb/gal Calcium Chloride/Calcium Bromide 10,000 bbls 500 bbls < 500 bbls discharge overboard. Remainder - 25% lost to formation during completion/ 75% reclaimed and sold back to vendor No

Workover fluids N/A N/A N/A N/A N/A Miscellaneous discharges. If yes, only fill in those associated with your activity. Desalinization unit discharge Seawater 46,656/day 1,950 GPH Discharge overboard No

Blowout prevent fluid Erifon 1,500 gal at 4% Stack No

Ballast water Seawater 72,000 gal/day 1,200 GPM Pump No Bilge water N/A N/A N/A N/A No

Excess cement at seafloor Type 1 Cement 120 BBLS 8 BPM Pump No

Fire water Seawater 0 bbls – only use in case of fire 800 GPM Discharge overboard No

Cooling water Seawater 5,760,000 gal/day 240,000

gal/hr Pump No Will you produce hydrocarbons? If yes fill in for produced water. Produced water N/A N/A N/A N/A N/A Will you be covered by an individual or general NPDES permit ? General 

### Noble Energy, Inc. Page F-1 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)

### Noble Energy, Inc. Page G-1

Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757 

## Section G Air Emissions Information

A. Emissions Worksheets and Screening Questions

Screen Procedures for EP’s Yes No Is any calculated Complex Total (CT) Emission amount (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)? X

Do your emission calculations include any emission reduction measures or modified emission factors? X

Are your proposed exploration activities located east of 87.5° W longitude? X Do you expect to encounter H 2 

### S at concentrations greater than 20 parts per million (ppm)? X

Do you propose to flare or vent natural gas for more than 48 continuous hours from any proposed well? X

Do you propose to burn produced hydrocarbon liquids? X



### If you answer no to all of the above screening questions, then provide the following: There are no existing facilities or activities co-located with the currently proposed activities, therefore the Complex Total Emissions are the same as the Plan Emissions and are provided in the table below.

Air Pollutant Plan Emission Amounts 1 

### (tons) Calculated

Exemption Amounts 2 

### (tons) Calculated

Complex Total Emission Amounts 3 

### (tons) Carbon Monoxide (CO) 462.36 59928.50 462.36 Particular matter (PM) 61.65 2464.20 61.65 Sulphur dioxide (SO 2 

### ) 282.81 2464.20 282.81 Nitrogen oxides (NO x 

### ) 2119.14 2464.20 2119.14 Volatile organic compounds (VOC) 63.57 2464.20 63.57

1 For activities proposed in your EP, list the projected emissions calculated from the worksheets.

2 List the exemption amounts for your proposed activities calculated by using the formulas in 30 CFR 250.303(d). 3 List the complex total emissions associated with your proposed activities calculated from the worksheets



### Contact Information: Name: Nicole Bueno Email: NBueno@nobleenergyinc.com Office Number: 281-872-2593

## Section H Oil Spill Information

A. Oil Spill Response Planning Noble Energy, Inc.’s (BOEM Operator Number 02237) Regional Oil Spill Response Plan (OSRP) was approved on March 28, 2013. Activities proposed in this EP will be covered by the Regional OSRP in accordance with 30 CFR 254.

Surface Containment – In the event of an oil spill, resources have been contracted and are available to deploy ocean boom to collect product on the water and direct it to skimmers for recovery or to conduct in-situ burn operations. By utilizing multiple contractors over 100,000 feet of ocean boom is available for use within 48 hours.

If product continues to move closer to shore both collection and protection booming strategies can be utilized to minimize impact to the Coastal Zone. In the near-shore environment over 250,000 feet of 18” hard boom is available within 48 hours. The primary focus is to collect and/or remove the product from the surface of the water via mechanical recovery and/or in-situ burning.

The final protection is beach boom and would need to be deployed very strategically based on the conditions observed and the movement of the product. Utilizing the same 48 hour window of availability 5,000 feet is available. Based on the WCD information Plaquemines, LA has an 11% chance of impact within the first 30 days. All other parishes on the coastline have a 2% or less chance in the same period.

Noble Energy has taken extra steps to ensure resources are available quickly from around the Gulf of Mexico to respond to a release from Mississippi Canyon 738 & 782 and to the extent possible minimize potential impacts to the Coastal Zone by engaging the product early in the offshore and near-shore environments.

B. Spill Response Sites

Primary Response Equipment Location Preplanned Staging Location Houma/ Venice/ Belle Chasse, LA Houma/ Fourchon/ Venice, LA; Theodore, AL

C. OSRO Information Noble has two equipment providers, Clean Gulf Associates (CGA) and Marine Spill Response Corporation (MSRC). The Marine Spill Response Corporation’s (MSRC) STARS network will provide closest available personnel, as well as an MSRC supervisor to operate the equipment.

Noble Energy, Inc. Page H-1 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)

### D. Worst-Case Scenario Comparison

Category Regional OSRP WCD EP WCD
Type of Activity Drilling Drilling Facility Location (Area/Block) MC 699 MC 782

Facility Designation Location D Location A
Distance to Nearest Shoreline (miles) 80 74

Volume Storage tanks (total) Uncontrolled blowout Total Volume 265,500 173,214 Type of Oil(s) (crude, condensate, diesel) Crude Crude

API Gravity 30.95° 26.30°

The Regional OSRP for exploratory worst case discharge was reviewed and accepted under plan R-5205 for the Mississippi Canyon Block 699.

Since Noble Energy Inc. has the capability to respond to the worst-case spill scenario included in our regional OSRP approved on March 28, 2013 and since the worst-case scenario determined for our EP does not replace the appropriate worst-case scenario in our regional OSRP, Noble Energy Inc. has certified that it has the capability to respond, to the maximum extent practicable, to a worst-case discharge, or a substantial threat of such a discharge, resulting from the activities proposed in this EP.

E. Oil Spill Response Discussion See attachment H-1.

Noble Energy, Inc. Page H-2 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)

### Page 1 of 18 SPILL RESPONSE DISCUSSION

For the purpose of NEPA and Coastal Zone Mana gement Act analysis, the largest spill volume originating from the proposed activity would be a well bl owout during drilling operations, estimated to be 173,214 barrels of crude oil with an API gravity of 26.3°.

Land Segment and Resource Identification

Trajectories of a spill and the probability of it impacting a land segment have been projected utilizing information in the BS EE Oil Spill Risk Analysis Model (OSRAM) for the Central and Western Gulf of Mexico available on th e BSEE website. The re sults are shown in Figure 1. The BSEE OSRAM identifies an 11% probability of impact to the shorelines of Plaquemines Parish, Louisiana within 30 days. Plaquemines Parish includes Barataria Bay, the Mississippi River Delta, Breton Sound and the affiliated islands and bays. This region is an extremely sensitive habitat and serves as a migratory, breeding, feedi ng and nursery habitat fo r numerous species of wildlife. Beaches in this area vary in grain particle size and can be classified as fine sand, shell or perched shell beaches. Sandy and muddy tidal flats are also abundant.

Response

Noble Energy, Inc. will make every effort to respond to the Worst Case Discharge as effectively as practicable. A description of the response equi pment under contract to contain and recover the Worst Case Discharge is shown in Figure 2.

Using the estimated chemical and physical charact eristics of crude oil, an ADIOS weathering model was run on a similar product from the ADIO S oil database. The results indicate 20% or approximately 34,643 barrels of crude oil would be evaporated/dispersed w ithin 24 hours, with approximately 138,571 barrels remaining.

Spill Response MC 782, Well Location A Barrels of Oil
WCD Volume 173,214
Less 20% natural evaporation/dispersion 34,643 Remaining volume 138,571



### Figure 2 outlines equipment, personnel, materials and support vessels as well as temporary storage equipment available to respond to a sp ill of approximately 138,571 barrels. The volume accounts for the amount remaining after evaporatio n/dispersion at 24 hours. The list estimates individual times needed for proc urement, load out, travel time to the site and deployment. Figure 2 also indicates how operations will be supported.

Noble Energy, Inc.’s Oil Spill Response Plan includes alternative response technologies such as dispersants and in-situ burn. Stra tegies will be decide d by Unified Command based on the size of the spill, weather and potential impacts. If aerial dispersants are util ized, 8 sorties (9,600 gallons) from two of the DC-3 aircraft s and 4 sorties (8,000 gallons) from the Basler aircraft would

### Page 2 of 18 provide a daily dispersant capab ility of 7,540 barrels. If the condi tions are favorable for in-situ burning, the proper approvals have been obtained and the proper planning is in place, in-situ burning of oil may be attempted. Slick containm ent boom would be immediately called out and on-scene as soon as possible. Offshore response strategies may include attempting to skim utilizing from CGA and MSRC, with a to tal derated skimming capacity of 286,244 barrels. Temporary storage associated with skimming equipment equals 207,202 barrels. If additional storage is needed, a 25,000 barrel storage barg e, a 20,000 barrel storage barge, and two 23,000 barrel storage barges may be mobilized and cen trally located to provide temporary storage allowing the skimmers to stay in the ar ea of operations as much as possible. Safety is first priority. Air monitoring will be accomplished and operations deemed safe prior to any containment/skimming attempts.

If the spill went unabated, shoreline impact in Plaquemines Parish, Louisiana would depend upon existing environmental conditions. Shorelin e protection would include the use of CGA’s near shore and shallow water skimmers with a totaled derated sk imming capacity of 92,753 barrels. Temporary storage asso ciated with skimming equipm ent equals 1,198 barrels. If additional storage is needed, a 47,000 barrel storag e barge, a 23,000 barrel storage barge, and two 20,000 barrel storage barges may be mobilized and centrally located to provide temporary storage allowing the skimmers to stay in the ar ea of operations as much as possible. Onshore response may include the deployment of shor eline boom on beach areas, or protection and sorbent boom on vegetated areas. Master Service Agreements with AMPOL and OMI Environmental will ensure access to 147,000 f eet of 18” shoreline protection boom. Figure 2 outlines individual times needed for procurement, load out, travel time to the site and deployment. Strategies would be based upon surveilla nce and real time traj ectories that depict areas of potential impact given actual sea and w eather conditions. The Stat e of Louisiana Initial Oil Spill Response Plan for Plaquemines Parish and Unified Command would be consulted to ensure that environmental and special economic resources would be co rrectly identified and prioritized to ensure optimal protection. Shorel ine protection strategies depict the protection response modes applicable for o il spill clean-up operati ons. The State of Louisiana Initial Oil Spill Response Plan provides detailed shoreline protection strategies for this area, and it describes necessary action to keep the oil spill from entering Louisiana’s coastal wetlands, based on the assumption that removal of the released oil will be much easier and less damaging to fragile coastal ecosystems if done in the open waters of the Gulf of Mexico. Supervisory personnel have the option to modify the deploym ent and operation of equipment allowing a more effective response to site-specific circumst ances. Noble Energy, Inc.’s contract Spill Management Team holds a copy of the State of Louisiana Initial O il Spill Response Plan.

Based on the anticipated worst case discharge scen ario, Noble Energy, Inc. can be onsite with contracted oil spill recovery equipment with ad equate response capacity to contain and recover surface hydrocarbons, and prevent land impact, to the maximum extent practicable, within an estimated 62 hours (based on the equipment’s Ef fective Daily Recovery Capacity (EDRC)).

### Page 3 of 18 Initial Response Considerations Actual actions taken during an oil spill response will be based on many factors which include but are not limited to:

• Weather

• Equipment and materials availability

• Ocean currents and tides

• Location of the spill

• Product spilled

• Amount spilled

• Environmental risk assessments

• Trajectory and product analysis

• Well status, i.e., shut in or continual release

Noble Energy, Inc. will take action to provide a safe, aggressive response to contain and recover as much of the spilled oil as quick ly as it is safe to do so. In an effort to protect the environment, response actions will be designed to provide an “in-depth” protection strategy meant to recover as much oil as possible as far from environmenta lly sensitive areas as possible. Safety will take precedence over all other considerations during these operations.

Coordination of response assets will be supe rvised by the designation of a SIMOPS group as necessary for close quarter vessel response activitie s. Most often, this gr oup will be used during source control events that require a significant nu mber of large vessels operating independently, but in coordination to complete a common objec tive, in a small area and in close coordination and support of each other. This group must also monitor the subsurface activ ities of each vessel (ROV, dispersant application, well control sup port, etc.). The SIMOPS group leader reports to the Source Control Section Chief.

In addition, these activities will be monitored by the spill mana gement team (SMT) and Unified Command via a structured Common Operating Picture (COP) esta blished to track resource and slick movement in real time.

Upon notification of a spill, the following actions will be taken:

• Information will be confirmed

• An assessment will be made and initial objectives set

• OSROs and appropriate agen cies will be notified

• ICS 201, Initial Report Form will be completed

• Initial Safety plan will be written and published

• Unified Command will be established

o Overall safety plan developed to reflect the operational situa tion and coordinated objectives

o Areas of responsibility esta blished for Source Control a nd each surface operational site

o On-site com mand and control established

### Page 4 of 18 Decanting Strategy Recovered oil and water mixtures will typically se parate into distinct phases when left in a quiescent state. When separati on occurs, the relatively clean water phase can be siphoned or decanted back to the recovery point with minima l, if any, impact. Decanting therefore increases the effective on-site oil storage capacity a nd equipment operating time. FOSC/SOSC approval will be requested prior to decanting operations. This practice is routinely used for oil spill recovery.
Offshore Response Actions

Equipment Deployment Surveillance

• Surveillance Aircraft will be deployed within two hours of Qu alified Individual (QI) notification, or at first light

• Provide trained observer to pr ovide on site status reports

• Provide command and control platfo rm at the site if needed

• Continual surveillance of oil movement by remote sensing systems, aerial photography and visual confirmation

• Continual monitoring of vessel assets using vessel monitoring systems

Dispersant application assets

• Put Airborne Support Inc. (ASI) on standby

• With the Federal On-Scene Coordinator (FOSC), conduct analysis to determine appropriateness of dispersant application

• Gain FOSC approval for use of dispersants on the surface

• Deploy aircraft in accordance with a plan developed for the actual situation

• Coordinate movement of dispersants, ai rcraft, and support equipment and personnel

• Confirm dispersant availability fo r current and long range operations

• Start ordering dispersa nt stocks required for expected operations

Containment boom

• Call out early and expedite deployment to be on scene ASAP

• Ensure boom handling and mooring equipment is deployed with boom

• Provide continuing reports to vessels to expedite their arrival at sites that will provide for their most effective containment

• Use Vessels of Opportunity (VOO) to deploy and maintain boom

Dedicated off-shore skimming systems General

• Deployed to the highest concentration of oil

• Assets deployed at safe distance from aer ial dispersant and in-situ burn operations

### Page 5 of 18 CGA HOSS Barge

• Use in areas with heaviest oil concentrations

• Consider for use in areas of known debris (seaweed, and other floating materials)

CGA FRUs

• To the area of the thickest oil

• Use as far off-shore as allowed

• VOOs 140’ – 180’ in length

• VOOs with minimum of 18’ x 38’ or 23’ x 50’ of optimum deck space

• VOOs in shallow water should have a dr aft of <10 feet when fully loaded

MSRC Oil Spill Response Vessels (OSRV)

• Use in areas with heaviest oil concentrations

• Use as far off-shore as allowed

MSRC Responders

• Use in areas with heaviest oil concentrations

• Consider for use in areas of known debris (seaweed, and other floating materials)

Storage Vessels

• Establish availability of CGA contracted assets

• Early call out (to allow for tug boa t acquisition and deployment speeds)

• Phase mobilization to allow storage vessels to arrive at the same time as skimming systems

• Position as closely as possible to ski mming assets to minimize offloading time

Vessels of Opportunity (VOO)

• Use Noble Energy, Inc.’s contract ed resources as applicable

• Industry vessels are usually best for deployment of Vessel of Opportunity Skimming Systems (VOSS)

• Acquire additional resources as needed

• Consider use of local assets, i.e. fishing and pleasure craft

• Expect mission specific and sa fety training to be required

• Plan with the US Coast Guard for vessel inspections

### Page 6 of 18 In-situ Burn assets

• Determine appropriateness of in-situ burn ope ration in coordination with the FOSC and affected State On-Scene Coordinator (SOSC)

• Determine availability of fire boom and selected ignition systems

• Start ordering fire boom stocks required for expected operations

• Contact boom manufacturer to provide training if required

• Determine assets to perform on water operation

• Build operations into safety plan

• Conduct operations in accordance with an approved plan

Adverse Weather Operations:

In adverse weather, when seas are > 3 feet, the use of larger recovery and storage vessels, oleophilic skimmers, and large offshore boom will be maximized. Safety will be the overriding factor in all operations and will cease at the order of the Unified Command, vessel captain, or in an emergency, ”stop work” may be directed by any crew member.

### Page 7 of 18 Near Shore Response Actions

Timing

• Place near shore assets on standby and depl oy in accordance with planning based on the actual situation, actual traj ectories and oil budgets

• VOO identification and training in advance of spill nearing shoreline if possible

• Outfitting of VOOs for specific missions

• Deployment of assets based on actual movement of oil

Considerations

• Water depth, vessel draft

• Shoreline gradient

• State of the oil

• Use of VOOs

• Distance of surf zone from shoreline

Equipment Deployment Surveillance

• Provide trained observer to direct skimming operations

• Continual surveillance of oil movement by remote sensing systems, aerial photography and visual confirmation

• Continual monitoring of vessel assets

Dispersant Use

• Generally will not be approved within 3 miles of shore or with less than 10 meters of water depth

• Approval would be at Regional Re sponse Team level (Region 6)

Vessel Deployment Dedicated Near Shore skimming systems

• Fast Response Vessels (FRV)

• Egmopol and Marco Shallow Water Skimmer (SWS)

• Operate with aerial spotter directi ng systems to observed oil slicks

VOO

• Use Noble Energy, Inc.’s contract ed resources as applicable

• Industry vessels are usually best for deployment of Vessel of Opportunity Skimming Systems (VOSS)

• Acquire additional resources as needed

• Consider use of local assets, i.e. fishing and pleasure craft

• Expect mission specific and sa fety training to be required

• Plan with the US Coast Guard for vessel inspections

• Operate with aerial spo tter directing systems to oil patches

### Page 8 of 18 Shoreline Protection Operations

Response Planning Considerations

• Environmental risk assessments (ERA) to determine priorities for area protection

• Time to acquire personnel and eq uipment and their availability

• Previous contingency planning contained in the appropriate Area Contingency Plan, and currently for Louisiana, The State of Loui siana Initial Oil Spill Response Plan, Deep Water Horizon, dated 2 May 2010

Actions

Placement of boom

• Position boom in accordance with the ERA based on the actual situation or the appropriate ACP

• Assess timing of booming operations to ensure it is where it needs to be at time of impact. Consider:

o Trajectories

o Weather forecast

o Oil Impact forecast

o Verified spill movement

o Boom, manpower and vessel (shallow draft) availability

o Near shore boom and support material, (stakes, anchors, line)

Beach Preparation

Considerations and Actions

• Use of a 10 mile go/no go line to determine timing of beach cleaning

• Shoreline Cleanup and Assessment Team Reports and recommendations

• Determination of Archeological site s and gaining authority to enter

• Monitoring of tide tables and weather to determine extent of high tides

• Pre cleaning of beaches by moving waste above high tide lines to minimize waste

• Staging of equipment and housing of respons e personnel as close to the job site as possible to maximize on-site work time

• Boom tending, repair, replacement and security (u se of local assets may be advantageous)

• Constant awareness of weather and oil moveme nt for resource redeployment as necessary

• In-situ burn may be considered when marshes have been impacted

• Passive clean up of marshes should be consider ed and appropriate stoc ks of sorbent boom and/or sweep obtained

• Earthen berms and shoreline protection boom may be considered to protect sensitive inland areas

### Page 9 of 18 Decanting Strategy Recovered oil and water mixtures will typically se parate into distinct phases when left in a quiescent state. When separati on occurs, the relatively clean water phase can be siphoned or decanted back to the recovery point with minima l, if any, impact. Decan ting therefore increases the effective on-site oil storage capacity a nd equipment operating time. FOSC/SOSC approval will be requested prior to decanting operations. This practice is routinely used for oil spill recovery.
CGA Equipment Limitations The capability for any spill response equipment, whether a dedicated or portable system, to operate in differing weather conditions will be directly in rela tion to the capabilities of the vessel the system in placed on. Most importantly, however, the decision to operate will be based on the judgment of the Unified Command a nd/or the Captain of the vessel, who will ultimately have the final say in terminating operations. Skimming equipment listed below may have operational limits which exceed those safety thresholds. As was seen in the Deepwater Horizon (DWH) oil spill response, vessel skimming opera tions ceased when seas reache d 5-6 feet and vessels were often recalled to port when those conditions were exceeded. Systems below are some of the most up-to-date systems available and were employed during the DWH spill.

Boom 3 foot seas, 20 knot winds Dispersants Winds more than 25 knots Visibility less than 3 nautical miles Ceiling less than 1,000 feet. FRU 8 foot seas HOSS Barge/OSRB 8 foot seas Koseq Arms 8 foot seas OSRV 4 foot seas

### Page 10 of 18 Environmental Conditions in the GOM Louisiana is situated between the easterly and westerly wind belts, and therefore, experiences westerly winds during the wint er and easterly winds in the summer. Average wind speed is generally 14-15 mph along the coast. Wave he ights average 4 and 5 feet. However, during hurricane season, Louisiana has recorded wave heights ranging from 40 to 50 feet high and winds reaching speeds of 100 mph. Because much of southern Louisiana lies below sea level, flooding is prominent.

Surface water temperature ranges between 70 and 80  ̊ F during the summer months. During the winter, the average temperatur e will range from 50 and 60  ̊ F.

The Atlantic and Gulf of Mexico hurricane seas on is officially from 1 June to 30 November. 97% of all tropical activity occurs within this window. The Atlant ic basin shows a very peaked season from August through October, with 78% of the tropical storm days, 87% of the minor (Saffir-Simpson Scale categories 1 and 2) hurricane days, and 96% of the major (Saffir-Simpson categories 3, 4 and 5) hurricane days occurri ng then. Maximum activity is in early to mid September. Once in a few years there may be a hurri cane occurring "out of season" - primarily in May or December. Globally, September is the mo st active month and May is the least active month.

### Page 11 of 18 FIGURE 1 TRAJECTORY BY LAND SEGMENT

Trajectory of a spill and the probability of it impacting a land segment have been projected utilizing Noble Energy, Inc.’s WCD and inform ation in the BSEE Oil Spill Risk Analysis Model (OSRAM) for the Central and Western Gulf of Mexico av ailable on the BSEE website using 30 day impact. The results are tabulated below.

Area/Block OCS-G Launch Area Land Segment and/or Resource Conditional Probability (%) within 30 days

Exploratory Drilling

MC 782, Well Location A

74 miles from shore G33757 C59 Cameron, LA Vermilion, LA Terrebonne, LA Lafourche, LA Jefferson, LA Plaquemines, LA

St. Bernard, LA Walton, FL

Bay, FL 1 1 2 2 1 11 2 1 1Page 12 of 18WCD Scenario– BASED ON WELL BLOWOUT DURING DRILLING OPERATIONS(74 miles from shore)138,571 bbls of crude oil (Volume considering natural weathering)API Gravity 26.3°FIGURE 2 – Equipment ResponseTime to MC 782, Well Location ADispersants/SurveillanceDispersant/SurveillanceDispersantCapacity (gal)StorageCapacityPersonsReq.FromHrs toProcureHrs toLoadoutTravel tositeTotal HrsCGABasler 67T2000NA 2 Houma 11 0.92.9ASIDC 31200NA 2 Houma 11 1.13.1DC 31200NA 2 Houma 11 1.13.1Aero CommanderNANA 2 Houma 11 0.92.9Offshore ResponseOffshore Equipment EDRCStorageCapacityVOOPersonsRequiredFromHrs toProcureHrs toLoadoutHrs toGOMTravel toSpill SiteHrs toDeployTotalHrsCGAHOSS Barge43000 4000 3 Tugs 8Harvey7 0 5 9.8 1 22.8Enterprise Marine Services LLC (available through contract with CGA)CTCo 2603NA 25000 1 Tug 6Amelia4 12 4 25 1 46CTCo 2606NA 20000 1 Tug 6Amelia4 12 4 25 1 46CTCo 2607NA 23000 1 Tug 6Amelia4 12 4 25 1 46CTCo 2608NA 23000 1 Tug 6Amelia4 12 4 25 1 46Page 13 of 18Offshore EquipmentPre-determined StagingEDRCStorageCapacityVOOPersonsRequiredFromHrs toProcureHrs toLoadoutHrs toGOMTravel toSpill SiteHrs toDeployTotalHrsMSRCLouisiana ResponderLFF 100 Brush + OSRV2,640’ 44” Sea Sentry II Boom5,280’ 67” LAMOR18086 4000 NA 14 Fort Jackson 2 0 1 4.4 1 8.4MSRC 452 Offshore Barge1 Crucial Disk 88/301,980’ 44” Sea Sentry II Boom660 ‘ 67” LAMOR11122 45000 3 Tugs 6 Fort Jackson 2 0215.7 1 20.7Mississippi ResponderTransrec 350 + OSRV5,280’ 44” Sea Sentry II Boom2,640’ 67” LAMOR10567 4000 NA 14 Pascagoula 2 0 1 5.6 1 9.6MSRC 402 Offshore Barge2 Crucial Disk 88/30660’ 44” Sea Sentry II Boom1,980‘ 67” LAMOR22244 40300 3 Tugs 6 Pascagoula 2 0 2 20 1 25Deep Blue ResponderLFF 100 Brush + OSRV6,600’ 44” Sea Sentry II Boom660’ 67” LAMOR18086 4000 NA 14 Fourchon 2 0 1 10.8 1 14.8PSV – HOS Centerline1 Crucial Disk 88/301,320’ EFC (cont inflate)11122 10626 NA 14 Fourchon 12 12 1 10.8 1 36.8PSV – HOS Strongline1 Crucial Disk 88/301,320’ EFC (cont inflate)11122 10626 NA 14 Fourchon 12 12 1 10.8 1 36.8PSV – C-Freedom1 LFF 100 Brush1,320’ EFC (cont inflate)18086 6000 NA 14 Fourchon 12 12 1 10.8 1 36.8PSV – C-Leader1 LFF 100 Brush1,320’ EFC (cont inflate)18086 6000 NA 14 Fourchon 12 12 1 10.8 1 36.8PSV – Allysa Chouest1 LFF 100 Brush1,320’ EFC (cont inflate)18086 6000 NA 14 Fourchon 12 12 1 10.8 1 36.8Page 14 of 18Offshore EquipmentPre-determined StagingEDRCStorageCapacityVOOPersonsRequiredFromHrs toProcureHrs toLoadoutHrs toGOMTravel toSpill SiteHrs toDeployTotalHrsMSRCMSRC Lightning2 LORI Brush Pack5000 50 3 Tugs 6 Tampa 2 0 2 13.6 1 18.6Gulf Coast ResponderTransrec 350 + OSRV5,280’ 44” Sea Sentry II Boom2,640’ 67” LAMOR10567 4000 NA 14 Lake Charles 2 0 1 12.8 1 16.8Texas ResponderTransrec 350 + OSRV4,620’ 44” Sea Sentry II Boom3,300’ 67” LAMOR10567 4000 NA 14 Galveston 2 0 1 16 1 20MSRC 570 Offshore Barge2 Crucial Disk 88/302,640’ 44” Sea Sentry II Boom22244 56900 3 Tugs 6 Galveston 2 0 2 57.1 1 62.1Page 15 of 18Staging Area: VeniceOffshore Equipment WithStagingEDRCStorageCapacityVOOPersonsReq.FromHrs toProcureHrs toLoadoutTravel toStagingTravel toSiteHrs toDeployTotalHrsCGAFRU (1) + 100 bbl Tank (2) 4251 200 1 Utility 6 Morgan City 1 2 3 6.7 1 13.7FRU (1) + 100 bbl Tank (2) 4251 200 1 Utility 6 Galveston 1 2 8 6.7 1 18.7FRU (2) + 100 bbl Tank (4) 8502 400 2 Utility 12 Leeville 1 2 3.5 6.7 1 14.2FRU (1) + 100 bbl Tank (1) 4251 100 1 Utility 6Harvey1 2 1.5 6.7 1 12.2FRU (1) + 100 bbl Tank (2) 4251 200 1 Utility 6 Ingleside 1 2 11 6.7 1 21.7FRU (1) + 100 bbl Tank (2) 4251 200 1 Utility 6 Lake Charles 1 2 5.5 6.7 1 16.2FRU (2) + 100 bbl Tank (4) 8502 400 2 Utility 12 Venice1 2 0 6.7 1 10.742” Auto Boom (5000’)NA NA 10 Crew 20 Galveston 1 2 8 6.7 1 18.742” Auto Boom (10000’)NA NA 20 Crew 40 Harvey1 2 1.5 6.7 1 12.242” Auto Boom (2500’)NA NA 6 Crew 12 Ingleside 1 2 11 6.7 1 21.742” Auto Boom (5000’)NA NA 10 Crew 20 Lake Charles 1 2 5.5 6.7 1 16.242” Auto Boom (2500’)NA NA 6 Crew 12 Pascagoula 1 2 4 6.7 1 14.71000’ Hydro-Fire BoomNA NA 8 Utility 40 Harvey1 4 1.5 6.7 6 19.2MSRC44” Sea Sentry II Boom (2860’) NA NA 6 Crew 12 Ingleside 1 2 11 6.7 1 21.744” Sea Sentry II Boom (4290’) NA NA10 Crew 20 Galveston 1 2 8 6.7 1 18.744” Sea Sentry II Boom (6679’) NA NA 10 Crew 20 Lake Charles 1 2 5.5 6.7 1 16.244” Sea Sentry II Boom (1980’) NA NA 6 Crew 12 Fort Jackson 1 2 .5 6.7 1 11.244” Sea Sentry II Boom (3190’) NA NA10 Crew 20 Pascagoula 1 2 4 6.7 1 14.72000’ Hydro-Fire BoomNA NA 16 Utility 80 Lake Charles 1 4 5.5 6.7 6 23.2Page 16 of 18Nearshore ResponseNearshore EquipmentPre-determined StagingEDRCStorageCapacityVOOPersonsRequiredFromHrs toProcureHrs toLoadoutHrs toGOMTravel toSpill SiteHrs toDeployTotalHrsCGATrinity SWS21500 249 NA 4 Morgan City 1 2 24.8 1 10.8Trinity SWS21500 249 NA 4Leeville1 2 22 1 8Trinity SWS21500 249 NA 4Venice1 2 22 1 846’ FRV5000 65 NA 4 Leeville 1 0 2 2.8 0 5.846’ FRV5000 65 NA 4 Lake Charles 1 0 1 9.8 0 11.846’ FRV5000 65 NA 4 Venice 1 0 1 2.0 0 4.0Enterprise Marine Services LLC (Available through contract with CGA)CTCo 2604NA 20000 1 Tug 6Amelia4 12 4 15.63 1 36.63CTCo 2605NA 20000 1 Tug 6Amelia4 12 4 15.63 1 36.63CTCo 2609NA 23000 1 Tug 6Amelia4 12 4 15.63 1 36.63CTCo 5001NA 47000 1 Tug 6Amelia4 12 4 15.63 1 36.63Staging Area: VeniceNearshore and InlandSkimmers With StagingEDRCStorageCapacityVOOPersonsReq.FromHrs toProcureHrs toLoadoutTravel toStagingTravel toDeploymentHrs toDeployTotalHrsCGASWS Egmopol3000 100 NA 3 Galveston 1 2820 13SWS Egmopol3000 100 NA 3Houma 1 2320 8SWS Marco 3588 34 NA 3 Houma 1 2 3 2 0 8SWS Marco 3588 20 NA 3 Lake Charles 1 2 5.5 2 0 10.5Rope Mop77 2 0 3 Belle Chasse 1 2220 7Page 17 of 18Shoreline ProtectionStaging Area: Venice18” ShorelineProtection BoomVOOPersonsReq.Storage/WarehouseLocationHrs toProcureHrs toLoadoutTravel toStagingTravel toDeploymentHrs to Deploy Total HrsAMPOL (available through MSA)42,000’ 18” Boom 16 Crew 40 New Iberia, LA2242122220,000’ 18” Boom 8 Crew 20 New Orleans, LA2222614OMI Environmental (available through MSA)10,000’ 18” Boom 4 Crew 10 New Iberia, LA114231110,000’ 18” Boom 4 Crew 10Houston, TX11 7.52314.510,000’ 18” Boom 4 Crew 10 Port Arthur, TX11 6.252313.2520,000’ 18” Boom 8 Crew 20 Belle Chasse, LA11 1.752611.7510,000’ 18” Boom 4 Crew 10 Port Allen, LA11 3.52310.510,000’ 18” Boom 4 Crew 10Houma, LA11 3.52310.515,000’ 18” Boom 6 Crew 14 Gretna, LA (Warehouse) 2222412Beach BoomEDRCStorageCapacityVOOPersonsReq.FromHrs toProcureHrs toLoadoutTravel toStagingTravel toDeploymentHrs toDeployTotalHrsCGABeach Boom (2000’)NA NA NA 6 Galveston 1 2812 14Beach Boom (1000’)NA NA NA 4 Ingleside 1 2 1112 17Beach Boom (2000’)NA NA NA 6 Pascagoula 1 2412 10Page 18 of 18Staging Area: VeniceWildlife Response EDRCStorageCapacityVOOPersonsReq.FromHrs toProcureHrs toLoadoutTravel toStagingTravel toDeploymentHrs toDeployTotalHrsCGAWildlife Support Trailer NA NA NA 2Houma1 2312 9Bird Scare Guns (24)NA NA NA 2 Belle Chasse 1 2212 8Bird Scare Guns (12)NA NA NA 2 Galveston 1 2812 14Bird Scare Guns (24)NA NA NA 2Houma1 2312 9Bird Scare Guns (12)NA NA NA 2 Ingleside 1 2 1112 17Bird Scare Guns (24)NA NA NA 2 Lake Charles 1 2 5.512 11.5Bird Scare Guns (24)NA NA NA 2 Pascagoula 1 2412 10Response AssetTotalOffshore EDRC286,244Offshore Recovered Oil Storage298,202Nearshore / Shallow Water EDRC92,753Nearshore / Shallow Water Recovered Oil Storage111,198

## Section I Environmental Monitoring and Mitigation Information

A. Monitoring Systems There are no environmental monitoring systems currently in place or planned for the proposed activities.

B. Incidental Takes There is no reason to believe that protected species may be incidentally taken by the activities proposed in this Initial Exploration Plan. However, Noble will comply with Joint NTL No. 2012-G01 “Vessel Strike Avoidance and Injured/Dead Protected Species Reporting” BSEE No. 2012-G01 “Marine Trash and Debris Awareness and Elimination”.

C. Flower Garden Banks National Marine Sanctuary Mississippi Canyon 738 and 782 are not located in the Flower Garden Banks National Marine Sanctuary; therefore, the requested information is not required in this EP.

Noble Energy, Inc. Page I-1 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)

## Section J Lease Stipulations Information

Exploration activities are subject to the following stipulations attached to Lease OCS-G 333755 & 33757, Mississippi Canyon 738 & 782.

Marine Protected Species Lease Stipulation No. 8 is meant to reduce the potential taking of marine protected species. Noble will operate in accordance with NTL 2003-G10 which has been superseded by NTL 2007-G04 and Joint NTL 2012-G01, to minimize the risk of vessel strikes to protected species and report observations of injured or dead protected species, and NTL 2003-G11 which has been superseded by NTL 2007-G03 and BSEE NTL 2012-G01 to prevent intentional and/or accidental introduction of debris into the marine environment.

Noble Energy, Inc. Page J-1 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)

## Section K Support Vessels and Aircraft Information

A. General The most practical, direct route from the shorebase as permitted by weather and traffic conditions will be utilized.

Type Maximum Fuel Tank Capacity Maximum

Number in Area at Any Time Trip Frequency

or Duration

Supply Boat 9,588 bbls 2 2 trips per week Supply Boat 7,082 bbls 1 4 trips per week
Crew Boat 809 bbls 1 4 trips per week Helicopter S-92 764 gals 1 4 trips per week

B. Diesel Oil Supply Vessels

Size of Fuel Supply Vessel Capacity of Fuel

Supply Vessel Frequency of Fuel Transfers Route Fuel Supply

Vessel Will Take Norbert Bouziga - 280 Feet 310,000 gals Once a month From the shore base in Fourchon, LA to MC 738 & 782 Field then to Fourchon , LA Gary Chouest - 276 Feet 300,000 gals Once every 3 months From the shore base in

Fourchon, LA to MC 738 & 782 Field then to Fourchon , LA

C. Solid and Liquid Wastes Transportation See section F, Waste and Discharge Information and Section L, Onshore Support Facilities Information, Waste Disposal.

D. Vicinity Map Enclosed as Attachment K-1 is a vicinity map showing the location of the activities proposed herein relative to the shoreline with the distance of the proposed activities from the shoreline and the primary route(s) of the support vessels and aircraft that will be used when traveling between the onshore support facilities and the drilling unit.

Noble Energy, Inc. Page K-1 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)Distance from Dantzier to Fourchon (roughly) 210 km 130 mi 113 nmi Distance from Dantzier to shore (roughly) 118 km 74 mi 64 nmi VENICE CAMERON

FOURCHON GRAND ISLE FRESHWATER CITY INTRACOASTAL CITY

MC 738/782 

## LOUISIANA TEXAS

DEEP WATER BUSINESS UNIT 

### MISSISSIPPI CANYON 738/782 LOUISIANA



### VICINITY PLAT

GEOL./GEOP.: Staff C.I.: FILENAME: DATE: 1/2013 

## Public Information

## Section L Onshore Support Facilities Information

A. General Provide a listing in the table below of the onshore facilities that will be used to provide supply and service support for the proposed activities:

Name of Shorebase Location Existing/New/Modified C Port 1 Slip 4 Port Fourchon, LA Existing PHI Heliport Houma, LA Existing

B. Support Base Construction or Expansion There will be no new construction of an onshore support base, nor will we expand the existing shore base as a result of the operations proposed in this Exploration Plan.

Noble Energy, Inc. Page L-1 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)

### C. Waste Disposal

Provide information in the table below on the onshore facilities you will use to store and dispose of any solid and liquid wastes generated by the proposed activities.

Type of Waste Composition Solid and Liquid Wastes Transport Method Name/Location

of Facility Amount Disposal Method Will drilling occur ? If yes, fill in the muds and cuttings.

EXAMPLE: Synthetic-based drilling fluid or mud internal olefin, ester Below deck storage tanks on offshore support vessels Newport Environmental Services Inc., Ingleside, TX X bbl/well Recycled

Oil-based drilling fluid or mud N/A N/A N/A N/A N/A

Synthetic-based drilling fluid or mud Internal Olefin 25 bbl transport US Fluids Port Fourchon 273 bbls Injection

Synthetic-based drilling fluid or mud Internal Olefin Boat tank Baroid Port Fourchon, LA 10,938 bbls Reclamation

Cuttings wetted with Water-based fluid Cuttings generated while using water based drilling fluid. Seafloor N/A N/A N/A

Cuttings wetted with Syntheticbased fluid Interfaces, cement contamination Cutting boxes Newpark Environmental Fourchon, LA 309 bbls Injection

Cuttings wetted with oil-based fluids N/A N/A N/A N/A N/A Will you produce hydrocarbons? If yes fill in for produced sand.

Produced sand N/A N/A N/A N/A N/A
Will you have additional wastes that are not permitted for discharge? If yes, fill in the appropriate rows. Lbs/ month

Recyclables Plastic, paper, aluminum Approved

Compactor Bags Tech Oil, New Iberia, LA 2,500 lbs Recycled

Trash and debris Household Debris Approved Compactor Bags C Port 1 Fourchon, LA 300,000 lbs Landfill/Disposal

Used oil 40 wt, 90 wt & hyd DOT approved tote tank American

Recovery Houma, LA 11,050 gals Recycled

Scrap Irons Iron, Copper, Brass & Stainless 4’ x 8’ Solid Bin Basket C Port Chouest

Offshore Fourchon, LA 60,000 lbs Recycled

Chemical product wastes Paint, Oily Rags, Gloves & Tyvek Suits DOT approved drum American Recovery Houma, LA 11,250 lbs Processed, Recycled/Disposed

Spent, dirty completion fluid Calcium Bromide Offshore Support Vessels Newpark

Environmental Fourchon, LA 2,000 bbls Injection

Completion fluid filtration media & wash water Diatomaceous Earth and Water 25-bbl Cuttings Boxes Newpark

Environmental Fourchon, LA 800 bbls Injection



### Noble Energy, Inc. Page L-2 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)

## Section M Coastal Zone Management Act (CZMA) Information

Relevant enforceable policies were considered in certifying consistency for Louisiana. A certificate of Coastal Zone Management Consistency for the state of Louisiana is enclosed as Attachment M-1

.

Noble Energy, Inc. Page M-1 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)

### Noble Energy, Inc. Page M-2

Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757) For Alabama:
Alabama Coastal Zone Management Consistency Certification Initial Exploration Plan Mississippi Canyon Block 738 & 782 OCS-G 33755 & 33757

The OCS related oil and gas development activities having potential impact on the Alabama Coastal Zone are based on the location of the proposed facilities, access to those sites, best practical techniques for operations and production equipment, guidelines for the prevention of adverse environmental effects, effective environmental protection, emergency plans and contingency plans. Alabama policies have been addressed below or are cross referenced to the appropriate sections of the plan:
Topic Cross Reference to the

Initial Exploration Plan Comments

Coastal Resource Use Policies Coastal Development Dock and port facilities in LA will be used. There will be no new construction, dredging, or filling in Alabama state waters. There will be no new commercial development or capital improvements in Alabama’s coastal zone, nor will there be any employment effects. Mineral Resource Exploration and Extraction Proposed petroleum exploration operations will take place approximately 135 miles offshore of the Alabama State Waters boundary in Federal waters. Commercial Fishing Sections H – Oil Spill

Response Planning, & Section N – Environmental Impact Analysis (C.8.1 Recreational and Commercial Fishing) There will be little or no impact on commercial fishing under normal operations. A worst case discharge (WCD) could result in fishery closures depending of the duration of the discharge, meteorological conditions at the time, and the effectiveness of spill response measures.

Hazard Management Section C – Geological and

Geophysical Information A Shallow Hazards Assessment, Benthic Communities Evaluation, and Archeological Resource Survey has been submitted to BOEM in order to identify and assess the seafloor and shallow geologic conditions in this block. No significant geological hazards or archeological resources are reported. Shoreline Erosion Proposed petroleum exploration operations will take place approximately 135 miles from Alabama’s coastal waters and 138 miles from the actual Alabama coastline. Dock and port facilities will be located in LA and vessels will follow the shortest direct route to the project area. There will be no new construction, dredging, or filling in Alabama state waters and this project will have no

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Initial Exploration Plan Comments

impact on Alabama coastal erosion Recreation Section N – Environmental

Impact Analysis (C.8.4 Recreation and Tourism) There are no known recreational uses of the lease area. Recreational resources and tourism in coastal areas would not be affected by any routine activities due to the distance from shore. Compliance with the new BSEE 2012-G01 NTL will minimize the chance of trash or debris being lost overboard from the drilling rig and subsequently washing up on beaches.

Based on the revised 120 day OSRA modeling (BOEMRE, 2011; and BOEM, 2012 as summarized in attachment H-1 Oil Spill Response Discussion, there is a 1% or less chance that oil from a spill in this lease area would reach shorelines in Baldwin Co., Alabama within 30 days.. Transportation Section N – Environmental

Impact Analysis (C.8.6 Other Marine Uses) The lease area is not located within any USCG-designated fairway or shipping lane and there are no impacts to Alabama transportations routes or infrastructure. Natural Resource Protection Policies Biological Productivity Sections E – Waste

Discharge Information, and Section N – Environmental Impact Analysis (C.1.2 Water Quality) There will be no impacts to the coastal waters or shorelines of Alabama under normal operations during this project.

A worst case discharge (WCD) could result in temporary losses in water column productivity within the offshore and nearshore waters of Alabama depending of the duration of the discharge, meteorological conditions at the time, and the effectiveness of spill response

measures.
Based on the revised 120 day OSRA modeling (BOEMRE, 2011, and BOEM 2012) as summarized in attachment H-1 Oil Spill Response Discussion, there is a 1% or less chance that oil from a spill in this lease area would reach shorelines in Baldwin Co., within 30 days.

### Noble Energy, Inc. Page M-4

Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757) Topic Cross Reference to the

Initial Exploration Plan Comments

Water Quality Section N – Environmental

Impact Analysis (C.1.2 Water Quality) There would be no impacts to water quality within Alabama coastal waters under normal operating conditions during this project.

The impact producing factors (IPFs) potentially affecting water quality are effluent discharges and two types of accidents: a small diesel fuel spill and a large oil spill (WCD).

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 during exploratory drilling.

Treated sanitary and domestic wastes may have a slight transient effect on water quality in the immediate vicinity of these discharges. All NPDES permit limitations and requirements will be met, therefore, little or no impact on water quality is anticipated.

A small diesel 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. The area of the sea surface 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 large spill would 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.

Due to the lease area location (138 miles from the Alabama shoreline), it is expected that most water quality

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Initial Exploration Plan Comments

impacts would occur in offshore waters, especially in the event of a spill lasting less than 30 days. Based on the revised 120 day OSRA modeling (BOEMRE, 2011, and BOEM 2012) as summarized in attachment H-1 Oil Spill Response Discussion, there is a 1% or less chance that oil from a spill in this lease area would reach shorelines in Baldwin Co., within 30 days. Water Resources Proposed petroleum exploration operations will take place approximately 135 miles from Alabama’s coastal waters and 138 miles from the actual Alabama coastline. Dock and port facilities will be located in LA and all supplies including fresh water will be purchased there. There will be no new construction, dredging, or filling in Alabama state waters and this project will have no impact on Alabama coastal water resources. Air Quality Section G – Air Emissions

Information, and Section N – Environmental Impact Analysis (C.1.1 Air Quality) The Air Quality Emissions Report (see EP Section G) prepared 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 pollutants.

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 Wetlands and Submerged Grassbeds Section A – Plan Contents,

and Section N – Environmental Impact Analysis (C.7 Coastal Habitats and Protected Areas) There will be no estuarine, fresh water, or near shore operations associated with this project and there will be no impacts to Alabama wetlands or submerged grass beds under normal operations.

Based on the revised 120 day OSRA modeling (BOEMRE, 2011, and BOEM 2012) as summarized in attachment H-1 Oil Spill Response Discussion, there is a 1% or less chance that oil from a spill in this lease area would reach shorelines in Baldwin Co., within 30 days. Beach and Dune Protection Section H – Oil Spill

Information, and Section N – Environmental Impact Analysis (C.7 Coastal Habitats and Protected There would be no impacts to Alabama beaches and dunes under normal operations.

In the event of a major oil spill (WCD) the initial response would be staged out of existing facilities, with

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Initial Exploration Plan Comments

Areas) no effect on Alabama land use. A large spill could have limited temporary impacts on Alabama coastal lands if additional staging areas were needed. These areas would eventually return to their original state after the response is demobilized. Wildlife Habitat Protection Section E - Biological,

Physical, and Socioeconomic Information; Section H – Oil Spill Information; and Section N – Environmental Impact Analysis (C.7 Coastal Habitats and Protected Areas) Due to the distance from shore, there are no IPFs associated with routine activities that are likely to affect beaches and dunes, wetlands, seagrass beds, coastal wildlife refuges, wilderness areas, or any other managed or protected coastal area.

Potential spill impacts on coastal habitats from a large oil spill (WCD) are discussed in recent EISs (MMS, 2007b, 2008, BOEMRE 2011, and BOEM 2012). 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.

Based on the revised 120 day OSRA modeling (BOEMRE, 2011, and BOEM 2012) as summarized in attachment H-1 Oil Spill Response Discussion, there is a 1% or less chance that oil from a spill in this lease area would reach shorelines in Baldwin Co., within 30 days. Endangered Species Section H – Oil Spill

Information, Section I – Environmental Monitoring Information, and, Section N – Environmental Impact Analysis (C.3 Threatened, Endangered, and Protected Species and Critical Habitat) As mandated by the ESA, BOEM consulted with NMFS and FWS on possible and potential impacts from the proposed leasing in the Central Gulf of Mexico Planning Area on endangered/threatened species and their designated critical habitat (MMS, 2007a,b,). A biological assessment was prepared for each consultation. The formal ESA consultation with NMFS was concluded with receipt of the Biological Opinion on 3 July 2007 (NMFS, 2007b). The Biological Opinion concludes that the proposed lease sales and associated activities in the Gulf of Mexico in the current 5-Year Program are not likely to jeopardize the continued existence of threatened and endangered species under NMFS jurisdiction or destroy or adversely modify designated critical habitat.

Following the Macondo oil spill the BOEMRE requested reinitiating of ESA consultation with both NMFS and FWS on 30 July 2010. The NMFS responded with a

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letter to BOEMRE on 24 September 2010. The FWS responded with a letter to BOEMRE on 27 September 2010. The reinitiated consultations are not complete at this time, although BOEM is in discussions with both agencies. The existing consultations remain in effect until the reinitiated consultations are completed (BOEMRE, 2012). Cultural Resources Protection Section E – H.

Archaeological Report and Section N – Environmental Impact Analysis (C.6 Archaeological Resources) Mississippi Canyon Blocks 738 & 782 are on the list of Lease Blocks with high potential for containing archaeological properties (shipwrecks). Beginning in 2011 archeological scurvies are now required prior to any new construction before a permit will be issued by BOEM.

A site clearance letter report is submitted under separate cover in the Initial Exploration Plan. No evidence of shipwrecks or other potential archeological resources was found in Mississippi Canyon Blocks 738 & 782.

An oil spill entering shallow coastal waters of Alabama could conceivably contaminate an archaeological and cultural resources along the shoreline. Based on the revised 120 day OSRA modeling (BOEMRE, 2011, and BOEM 2012) as summarized in attachment H-1 Oil Spill Response Discussion, there is a 1% or less chance that oil from a spill in this lease area would reach shorelines in Baldwin Co., within 30 days.

As 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

A certificate of Coastal Management Consistency for the State of Alabama is enclosed as Attachment M-2

.

## Section N Environmental Impact Analysis (EIA)

See attachment N – 1.

Noble Energy, Inc. Page N-1 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)

# Environmental Impact Analysis

INITIAL EXPLORATION PLAN

for Mississippi Canyon Block 738 (OCS-G 33755) and Mississippi Canyon Block 782 (OCS-G 33757)

Offshore Alabama

March 2013

Prepared for:

Noble Energy, Inc. 100 Glenborough Drive, Suite 100 Houston, Texas 77067 Telephone: (381) 872-3100

Prepared by:

CSA Ocean Sciences Inc. 8502 SW Kansas Avenue Stuart, Florida 34997 Telephone: (772) 219-3000Mississippi Canyon Blocks 738 and 782 March 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............................................................................................................ 8 A.7 Marine Debris............................................................................................................................ 9 A.8 Support Vessel and Helicopter Traffic ........................................................................................ 9 A.9 Accidents................................................................................................................................... 9 A.9.1 Types of Accidents Evaluated ......................................................................................... 9 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 ........................................................................ 15



### B. Affected Environment...........................................................................................16

C. Impact Analysis.....................................................................................................18 C.1 Physical/Chemical Environment............................................................................................... 18 C.1.1 Air Quality .................................................................................................................... 18 C.1.2 Water Quality............................................................................................................... 20 C.2 Seafloor Habitats and Biota ..................................................................................................... 22 C.2.1 Soft Bottom Benthic Communities................................................................................ 22 C.2.2 High-Density Deepwater Benthic Communities ............................................................ 25 C.2.3 Designated Topographic Features................................................................................. 27 C.2.4 Pinnacle Trend Area Live Bottoms ................................................................................ 27 C.2.5 Eastern Gulf Live Bottoms ............................................................................................ 28 C.3 Threatened, Endangered, and Protected Species and Critical Habitat ...................................... 28 C.3.1 Sperm Whale (Endangered).......................................................................................... 30 C.3.2 West Indian Manatee (Endangered) ............................................................................. 34 C.3.3 Endangered Mysticete Whales ..................................................................................... 36 C.3.4 Non-Endangered Marine Mammals (Protected) ........................................................... 36 C.3.5 Sea Turtles (Endangered/Threatened) .......................................................................... 39 C.3.6 Piping Plover (Threatened) ........................................................................................... 42 C.3.7 Whooping Crane (Endangered)..................................................................................... 45 C.3.8 Gulf Sturgeon (Threatened).......................................................................................... 45 C.3.9 Smalltooth Sawfish (Endangered)................................................................................. 46 C.3.10 Beach Mice (Endangered)............................................................................................. 47 C.3.11 Elkhorn Coral (Endangered).......................................................................................... 47

## Contents (Continued)

Page

Mississippi Canyon Blocks 738 and 782 March 2013 Environmental Impact Analysis for Initial Exploration Plan Page iii C.4 Coastal and Marine Birds......................................................................................................... 48 C.4.1 Marine Birds................................................................................................................. 48 C.4.2 Shorebirds and Coastal Nesting Birds............................................................................ 50 C.5 Fisheries Resources ................................................................................................................. 53 C.5.1 Pelagic Communities and Ichthyoplankton ................................................................... 53 C.5.2 Essential Fish Habitat.................................................................................................... 55 C.6 Archaeological Resources ........................................................................................................ 58 C.6.1 Shipwreck Sites ............................................................................................................ 58 C.6.2 Prehistoric Archaeological Sites .................................................................................... 59 C.7 Coastal Habitats and Protected Areas ...................................................................................... 60 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....................................................................................................................... 68 D.3 Currents and Waves ................................................................................................................ 68



### E. Alternatives ..........................................................................................................69

F. Mitigation Measures .............................................................................................69

G. Consultation .........................................................................................................69

H. Preparers..............................................................................................................69

I. References .............................................................................................................70Mississippi Canyon Blocks 738 and 782 March 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 Environmental 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)..................................................................... 12

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 Wildlife refuges, wilderness areas, and State and National parks within the

geographic range of the potential shoreline contacts after 120 days (From: BOEM, 2012b) ............................................................................................................................. 61



## List of Figures

Figure Page

1 Location of Mississippi Canyon Blocks 738 and 782 ............................................................ 2

2 Bathymetric map of the lease area showing the surface hole locations of Wells A

and B in Mississippi Canyon Block 738 and A, B, C, and D in Mississippi Canyon Block 782 ......................................................................................................................... 17

3 Location of selected environmental features in relation to the lease area ........................ 44Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page v



## Acronyms and Abbreviations

ADIOS2 Automated Data Inquiry for Oil Spills 2 bbl barrel BOEM Bureau of Ocean Energy Management BOEMRE Bureau of Ocean Energy Management,

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 positioning 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 Fugro Fugro Geoconsulting, Inc. GMFMC Gulf of Mexico Fishery Management

Council GPS global positioning system H 2 S hydrogen sulfide HAPC Habitat Area of Particular Concern HOSS high-volume open sea skimmer IPF impact-producing factor MARPOL International Convention for the

Prevention of Pollution from Ships MC Mississippi Canyon MMC Marine Mammal Commission MMPA Marine Mammal Protection Act MMS Minerals Management 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 Noble Noble Energy, Inc. NPDES National Pollutant Discharge

Elimination System NPS National Park Service NRDA Natural Resource Damage Assessment NTL Notice to Lessees and Operators NWR National Wildlife Refuge OBM oil-based mud OCS Outer Continental Shelf OSAT Operational Scientific Advisory 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 Sperm 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 dischargeMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 1 

## Introduction

Noble Energy, Inc. (Noble) is submitting an Initial Exploration Plan (EP) for Mississippi Canyon (MC) Blocks 738 and 782 (MC 738 and 782). The EP includes six exploratory well locations: A, B and D in MC 738 and A, B, and C, in MC 782. The surface hole locations (SHLs) for the six wells will be located in the respective blocks, MC 738 or MC 782

. This Environmental Impact Analysis (EIA) provides information on the exploratory wells based on the SHLs.

The lease area is 74 miles (119 km) southeast of the nearest shoreline, 131 miles (211 km) from the onshore support base at Port Fourchon, Louisiana, and 173 miles (279 km) from the helicopter base at Houma, Louisiana ( Figure 1 ). Water depths at the wellsites range from 1,994 to 2,004 m (6,542 to 6,576 ft). The drilling rig will be a similar dynamic positioning (DP) semisubmersible rig. This EIA 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 Noble’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. 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 entire OCS are not anticipated" (BOEM, 2012b).

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 Enforcement’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.Mississippi Canyon Blocks 738 and 782 March 2013 Environmental Impact Analysis for Initial Exploration Plan Page 2 Figure 1. Location of Mississippi Canyon Blocks 738 and 782.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 3 Noble’s Regional Oil Spill Response Plan (OSRP) was originally approved by the MMS on 7 December 2009, and a revised and updated OSRP was submitted to BOEMRE on August 1, 2010. The OSRP details Noble’s plan for response to rapidly and effectively manage oil spills that may result from drilling and production operations. Noble has designed its response program based on a regional capability of response to spills ranging from small operational spills to a worst case discharge (WCD) from a well blowout. Noble’s spill response program meets the response planning requirements of the relevant coastal states and applicable Federal oil spill planning regulations and also includes information regarding Noble’s regional oil spill organization and dedicated response assets, potential spill risks, and local environmental sensitivities. The OSRP describes personnel and equipment mobilization, the incident management team organization, and an overview of actions and notifications to be taken in the event of a spill. All activities planned for MC 738 and 782 are covered under this regional OSRP in accordance with 30 CFR Part 254.

This EIA is organized into Sections A through I corresponding to the information required by NTL 2008-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

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 of 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 marine 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 Archaeological Resource Surveys and Reports Provides new information of which Outer Continental Shelf (OCS) blocks require archaeological surveys and reports and required survey line spacing in each block. This NTL augments NTL 2005-G07.

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 must 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 BOEM 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.Table 1. (Continued).

Mississippi Canyon Blocks 738 and 782 March 2013 Environmental Impact Analysis for Initial Exploration Plan Page 4

NTL Title Summary

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 Guidance 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 Guidance for avoiding and protecting biologically sensitive 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 Military 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 the 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 Guidance on the information requirements for OCS plans, including EIA requirements and information regarding compliance with the provisions of the Endangered Species Act and Marine Mammal Prote ction 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 protecting archaeological resources.Mississippi Canyon Blocks 738 and 782 March 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-0142. 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 seafloor

 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 drilling rig proposed for this EP is will be a DP semisubmersible rig. DP semisubmersible rigs use a global positioning system (GPS), specific computer software, and sensors in conjunction with 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 required station-keeping adjustment. This allows operations at sea where mooring or anchoring is not feasible.

The drilling rig for the wells proposed in this EP will be on site for an estimated 156 days per well. The physical presence of the drilling rig in the ocean can attract pelagic fishes and other 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 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 Physical Disturbance to the Seafloor

In water depths of 600 m (1,969 ft) or greater, DP semisubmersibles 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 ha (0.62 ac) (MMS, 2007a).Mississippi Canyon Blocks 738 and 782 March 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 Onshore

Waste Disposal Marine

Debris Support

Vessel/Helo Traffic Accidents

Small 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.Mississippi Canyon Blocks 738 and 782 March 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 zone of the Flower Garden Banks, or the 3-mi zone of Stetson Bank; (b) 1,000-m, 1-mi, or 3-mi 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 400 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), Noble is requesting that BOEM classify the lease area as “H 2 S absent.” (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 shipwrecks 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 on the list of archaeology survey blocks (BOEM, 2012c) but 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. The geohazards and archaeological assessments indicate multiple sonar contacts in the lease area, but none are interpreted to be historic shipwrecks. A dynamic positioning semisubmersible rig 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 habitats.

 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.Mississippi Canyon Blocks 738 and 782 March 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 requirements 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 installation 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, non-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 organisms. The current NPDES General Permit No. GMG290000 does not specify requirements for existing facilities (those that started construction before 16 July 2006). The DP drilling rig being considered for use in this EP is a “new” facility as defined by the NPDES permit and therefore triggers the cooling water intake regulations. The drilling rig will be in compliance with all cooling water intake requirements of the general NPDES permit. 

## A.6 Onshore Waste Disposal

Wastes generated during drilling are tabulated in EP Section F . A total of approximately 204,000 lbs of trash will be generated over the life of this project. The trash will be transportedMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 9 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

Noble 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 Helicopter Traffic

Noble 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 three supply vessels. The crew boat will make four round-trips per week, and the supply vessels will make two round-trips per week. The boats typically will move to the project area via the most direct route from the shorebase.

A helicopter will make an estimated four 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. Helicopters 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 properties. 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, 2012d).


## 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

 the WCD for this EP, which is an oil spill resulting from an uncontrolled blowout.
The following subsections summarize assumptions about the sizes and fates of these spills, as well as Noble’s spill response plans. Impacts are analyzed in Section C

.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 10 MMS (2007b) and BOEM (2012b) analyzed 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 (2012a), 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, 2012b). The median size for spills <1 bbl is 0.024 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. Operational 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 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, given 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, 2012b).
The water-soluble fractions of diesel are dominated by two- and three-ringed polycyclic aromatic hydrocarbons (PAHs), which are moderately volatile (National Research Council, 2003a). 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, 2003a) 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).
For purposes of this EIA, the fate of a small diesel fuel spill was estimated using NOAA’s Automated Data Inquiry for Oil Spills 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.
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 74 miles (119 km)from the nearest shoreline. Modeling results discussed below indicate that a spill in the lease area would 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 Noble’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) and rapidly spread out, evaporate and disperse into the water column (BOEM, 2012b). Because of the distance of these potential spills on the OCS and their lack of persistence, it is unlikely that a spill would make landfall prior to dissipation (BOEM, 2012b).Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 11 Spill Response. 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 Noble’s response to a spill.


### A.9.3 Crude Oil Spill (Worst Case Discharge)
Spill Size. In accordance with requirements of NTL 2010-N06, Noble has estimated a WCD for this EP as 173,214 barrels of oil. The detailed analysis of this calculation can be found in EP Section H

. 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 recent Macondo event; however, significant changes to the spill rates for the entire OCS are not anticipated (BOEMRE, 2011a; BOEM, 2012d). 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 Noble’s calculations and information as required by NTL 2010-N06, including descriptions of measures to prevent a blowout, reduce the likelihood of a blowout, and conduct effective and early intervention in the event of a blowout. Noble will also comply with NTL 2010-N10 and the Final Drilling Safety Rule, which specifies additional safety measures for OCS activities.
Spill Trajectory. 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 currents 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 results 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 did 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 size but has generally been used by the BOEM to evaluate contact probabilities for spills greater than 1,000 bbl.
To address this criticism, a special OSRA run was conducted for the recent BOEM Western and Central Gulf of Mexico Planning Area Supplemental EISs (BOEMRE, 2011a; BOEM, 2012b) 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 emphasized modeling a spill that continued for 90 consecutive days, with each trajectory tracked for up to 120 days.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 12 The OSRA model run for this revised analysis was conducted for five hypothetical launch points in the Central and Western Gulf of Mexico Planning Areas. These launch points were deliberately located in areas 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 area west of the Mississippi 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. Western 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

. Table 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).

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, Texas -- -- -- 2 -- -- -- -- -- -- -- 2 -- -- -- 2 Willacy, Texas -- -- -- 3 -- -- -- -- -- -- -- 2 -- -- -- 3 Kenedy, Texas -- -- -- 8 -- -- -- 1 -- -- -- 9 -- -- -- 5 Kleberg, Texas -- -- 1 6 -- -- -- -- -- -- -- 4 -- -- 1 6 Nueces, Texas -- -- 1 6 -- -- -- -- -- -- -- 2 -- -- 1 2 Aransas, Texas -- -- -- 5 -- -- -- 1 -- -- -- 3 -- -- -- 2 Calhoun, Texas -- -- 1 6 -- -- -- -- -- -- -- 6 -- -- 1 4 Matagorda, Texas -- -- 2 17 -- -- 3 4 -- -- -- 11 -- -- 1 6 Brazoria, Texas -- -- 3 12 -- -- 1 3 -- -- 2 8 -- -- 1 5 Galveston, Texas -- -- 3 10 -- -- 3 6 -- -- 2 5 -- -- 1 4 Jefferson, Texas -- -- 1 4 -- -- 7 9 -- -- 1 1 -- -- -- 2 Cameron, Louisiana -- -- 1 4 -- -- 11 12 -- 1 1 4 -- -- -- 4 Vermilion, Louisiana -- -- 1 2 -- -- 5 6 -- 1 1 2 -- -- -- -- Iberia, Louisiana -- -- -- 1 -- -- 4 4 -- -- -- -- -- -- -- -- Terrebonne, Louisiana -- 1 2 3 -- 4 12 14 -- -- -- 2 -- -- -- -- Lafourche, Louisiana -- -- 1 1 -- 2 8 10 -- -- 1 2 -- -- -- -- Jefferson, Louisiana -- -- -- 1 -- -- 2 2 -- -- 1 1 -- -- -- -- Plaquemines, Louisiana -- -- -- 1 -- 2 10 12 -- -- 1 2 -- -- -- -- Jackson, Mississippi -- -- -- -- -- -- 1 1 -- -- -- -- -- -- -- -- Baldwin, Alabama -- -- -- -- -- -- 1 1 -- -- -- -- -- -- -- -- Bay, Florida -- -- -- -- -- -- -- 1 -- -- -- -- -- -- -- -- Franklin, Florida -- -- -- 1 -- -- -- -- -- -- -- -- -- -- -- -- Monroe, Florida -- -- -- -- -- -- -- -- -- -- -- 1 -- -- -- 1 Dade, Florida -- -- -- -- -- -- -- -- -- -- -- 1 -- -- -- -- "—" = Values <1.0%. Areas where there is <0.5% chance of contact within 120 days are not shown.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 13 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 aerial 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.

Weathering. 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 ecosystems. 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, 2003a).

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 in the oil on the water surface.

Spill Response. BOEM has issued recent NTLs following the Macondo spill that clarify additional oil-spill prevention and response planning requirements. These NTLs are summarized in Table 2
, and additional BOEM (2012b) 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 regional 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 preparation 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 Information 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 evaluate 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 intendsMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 14

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: This NTL, effective 18 June 2010, explains the procedures for the lessee or operator to submit supplemental information for new or previously submitted EPs, Development and Production Plans, or Development Operations Coordination Documents. 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 methods of the third requirement could actually include the surface and subsea containment resources 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 loss of well control.

Noble submitted an updated Gulf of Mexico Regional OSRP to BOEMRE on 29 September 2011. The OSRP provides a detailed plan for Noble to respond to rapidly and effectively manage oil spills that may result from drilling and production operations.
In the event of a WCD, Noble has access to surface and subsea response/containment capabilities that could be implemented through various organizations under contract. Noble'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 oleophilic brush pack skimming systems operating in troughs built into the hulls, below-deck storage, and marine electronics packages including marine, aircraft and company-frequency radios; radar; moving map plotters; GPS; satellite phones; and depth finders. CGA also offers nine Fast Response Systems staged throughout the Gulf of Mexico 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 HOSS 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 their website: http://www.cleangulfassoc.com/

. Noble 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 oilMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 15 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/

.
See EP Section H for a detailed description of Noble’s site-specific response to the WCD for this plan.


### 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 sulfide (H 2 S) release. There are no other site-specific issues for the drilling of the wells 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 quantity 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, 2011a; BOEM, 2012b).

Riser Disconnect SBM Spills. In deepwater drilling, SBMs are preferred over petroleum oil-based muds (OBMs) due to the superior environmental properties of SBMs. The synthetic base fluids 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-1990s, 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 accidental riser disconnects may result in the release of medium (238 to 2,380 bbl) to large (>2,380 bbl) quantities of drilling fluids. Riser disconnect accidents are of particular concern when SBMs are in use (BOEMRE, 2011b).

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 platforms in the OCS resulted in diesel spills, and in several collision incidents, fires 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 lease 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 collisions. Human error accounted for approximately half of all reported vessel collisions from 2006 to 2009. As summarized in MMS (2007b) and BOEM (2012b), vessel collisions occasionally occur during routine operations. Some of these collisions have caused spills of diesel fuel or chemicals. Noble will comply with all USCG- and BOEM-mandated safety requirements to minimize the potential for vessel collisions.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 16 Loss of Well Control. A loss of well control is the uncontrolled flow of a reservoir fluid that may result in the release 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 risk 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. Noble has a robust system in place to prevent loss of well control. Measures 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 package 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 safety measures for OCS activities.

H 2 S Release. Pursuant to 30 CFR 250.490(c), Noble is requesting in the EP that the BOEM Regional Supervisor, Field Operations, classify the area in the proposed drilling operations as H 2 S absent.



## B. Affected Environment

The lease area is in the central Gulf of Mexico, 74 miles (119 km) from the nearest shoreline, and 131 miles (211 km) from the onshore support base at Port Fourchon, Louisiana ( Figure 1 ).
Based on the site clearance survey conducted by Fugro Geoconsulting, Inc. (Fugro) (2013) water depth at the wellsites is anticipated to be 1,994 to 2,004 m (6,542 to 6,576 ft) ( Figure 2 ). The seafloor at the proposed wellsites is smooth, featureless, and appears stable. However, there are several seafloor faults in the vicinity of the proposed wellsites. No seafloor faults will be penetrated by the proposed wellbores, and the seafloor fault scarps meet the 75 m (245 ft) standoff distance as outlined by the BOEM in NTL No. 2008-G05. There is an existing pipeline in the lease area. There is no evidence of fluid expulsion features, or high-density deepwater benthic communities near the wellsites (Fugro, 2013). A detailed description of the regional affected environment, including meteorology, oceanography, geology, air and water quality, benthic communities, threatened and endangered species, biologically sensitive resources, archaeological resources, socioeconomic conditions, and other marine uses is provided in recent lease sale EISs (MMS, 2007b; BOEM, 2012b). These regional 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 in Section C

. The Macondo spill resulted in impacts to water quality in the area of the spill. In addition to the oil slick on the sea surface, plumes of submerged oil droplets were produced when subsea dispersants were applied at the wellhead (Camilli et al., 2010; Hazen et al., 2010; Joint Analysis Group, 2010a,b,c). Despite limited information on the water quality of deep water, it is clear that conditions in the offshore waters of the Gulf of Mexico were altered by the Macondo event. Various monitoring efforts and environmental studies are in progress, but it is not currently possible to precisely estimate the long-term impacts the spill will have on offshore water quality (BOEMRE, 2011a; BOEM, 2012a).Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 17 Figure 2. Bathymetric map of the lease area showing the surface hole locations of Wells A and B in

Mississippi Canyon Block 738 and A, B, C, and D in Mississippi Canyon Block 782.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 18 The lease area is located approximately 34 miles (54 km) south-southeast of the Macondo spill site. Based on an analysis of satellite imagery, the surface slick did extend over the lease area, and there is the possibility that water quality in the lease area was briefly affected. Prior to the Macondo incident, water quality in deep, offshore waters of the Gulf of Mexico was expected to be good, with low levels of contaminants (Kennicutt, 2000). Based on the information currently available, there is no reason to expect any long-term change in water quality conditions in the lease area from those predicted in the recent lease sale EISs (MMS, 2007b; BOEM, 2012a,b,d).



## C. Impact Analysis

This section analyzes 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 Areas (MMS, 2007b; BOEM, 2012b). The information in these documents is incorporated by reference. Potential site-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 for 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 unclassified because there is no provision in the Clean Air Act for classification of areas outside State waters (MMS, 2007b).

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 substantial new information was found that would alter the potential impacts on air quality presented in previous lease sale EISs (BOEMRE, 2011a; 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, pumps, 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. As described in recent lease sale EISs, the incremental contribution to cumulative impacts from activities similar to Noble’s proposed activities is not significant and will not cause or contribute to a violation of anyMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 19 National Ambient Air Quality Standard (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 Noble’s proposed EP are not likely to contribute 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 effects on temperature, 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 emissions from reasonably foreseeable activities in the Gulf of Mexico area and would not significantly alter any of the climate change impacts evaluated in the lease sale EIS (MMS, 2007b) or Programmatic EIS (MMS, 2007a).

Because of the distance from shore, routine operations in the project area are not expected to have any impact on air quality conditions along the coast, including nonattainment areas. As noted in the lease sale EIS (MMS, 2007b), emissions of air pollutants from routine activities in the Central 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 ) prepared 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 pollutants. No further analysis or control measures are required.
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 quality 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 sources 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 100 miles (161 km) from the Breton Wilderness Area, and no air quality impacts on the Wilderness Area are expected. Noble will comply with all BOEM requirements regarding air emissions.


### Impacts of a Small Fuel Spill
Potential impacts of a small spill on air quality are expected to be consistent with those analyzed and discussed in EISs prepared for recent lease sales (MMS, 2007b; BOEM, 2012b,d). The probability of a small spill would be minimized by Noble’s preventative measures during routine operations, including fuel transfer. In the unlikely event of a spill, implementation of Noble’s OSRP will 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.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 20 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. 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 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 those analyzed and discussed in recent lease sale EISs (MMS, 2007b; BOEM, 2012b,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 included 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.

Because of the lease area location (74 miles [119 km])from the nearest shoreline, most air quality impacts would occur in offshore waters with minimal chance 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 a recent lease sale EIS (MMS, 2007b), deepwater areas in the northern Gulf of Mexico are relatively 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-surface sediments and up through the water column.
The lease area is located approximately 34 miles (54 km) from 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 affected briefly.

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 toMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 21 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, little 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. Based 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 water quality are expected to be consistent with those analyzed and discussed in recent EISs (MMS, 2007b; BOEM, 2012a,b). The probability of a small spill would be minimized by Noble’s preventative measures during routine operations, including fuel transfer. In the unlikely event of a spill, implementation of Noble’s OSRP will 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.

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 ). 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.

The water-soluble fractions of diesel are dominated by two- and three-ringed PAHs, which are moderately volatile (National Research Council, 2003a). 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 and 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, 2003a) 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).Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 22 A small fuel spill would not affect coastal water quality because the spill would not be expected to make 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 water quality are expected to be consistent with those analyzed and discussed in recent lease sale EISs (MMS, 2007b; BOEM, 2012b,d). A large spill would 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 sediments and be removed from the water column (Operational Scientific Advisory Team [OSAT], 2010).

Because of the lease area location ( 74 miles [116 km] from the nearest shoreline), it is 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

Water depth at the proposed project area is approximately 1,994 to 2,004 m (6,542 to 6,576 ft). The seafloor at the proposed wellsites is smooth, featureless and stable. The immediate regions around the proposed well locations show several seafloor faults in the vicinity of the proposed wellsites. These seafloor faults will not be penetrated by the proposed wellbores. No areas of possible hard bottom or microseepages were seen within 610 m (2,000 ft) of any of the wellsites (Fugro, 2013).

Based on the absence of hard bottom areas detected by side-scan sonar during the site clearance survey, the seafloor within 610 m (2,000 ft) of the wellsites is expected to consist 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. No areas of gaseous sediments or possible hydrocarbon seepage were defined within 610 m (2,000 ft) of the wellsites, and the presence of chemosynthetic communities is considered negligible (Fugro, 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.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 23 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 from: Wei, 2006; Rowe and Kennicutt, 2009).

Station Water Depth

(m) Abundance

Meiofauna (individuals/m 2 ) Macroinfauna

(individuals/m 2 ) Megafauna

(individuals/ha) S37 2,384 291,179 2,192 1,451 S36 1,828 799,963 4,481 359 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 (1,994 to 2,004 m [6,542 to 6,576 ft] ) typically range from approximately 84,000 to 800,000 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 Mexico 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 1,550 individuals/m 2

. Polychaetes are typically 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 horizontally. The lease area is in Zone 3E which includes the west flank of the lower Mississippi Fan, lower Mississippi Canyon, lower De Soto Canyon, lower West Florida Terrace, deep Mississippi Fan and one location at the base of the Sigsbee Escarpment with stations ranging in depth from 2,275 to 3,314 m (7,464 and 10,873 ft). The most abundant species in Zone 3E were the polychaetes Paraonella monilaris and Tharyx marioni ; the bivalves Heterodonta spp. B and C; and the isopod Macrostylis sp.
Megafaunal densities from nearby stations ranged from 359 to 1,600 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 terms 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.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 24 

### Physical Disturbance to the Seafloor
In water depths such as are encountered in the lease area, DP semisubmersibles disturb the seafloor only around the wellbore (SHL) where the bottom template and BOP are located. Depending upon the specific well configuration, this area is generally about 0.25 ha (0.62 ac).

The areal extent of these impacts from the DP rig will be small compared to the lease area itself, and these type soft bottom communities are ubiquitous along the northern Gulf of Mexico continental slope (Gallaway, 1988; Gallaway et al., 2003; Rowe and Kennicutt, 2009). Impacts from the physical disturbance of the seafloor during this project 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 components 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 years.

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 conducted 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 both 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 Associates, 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.

The 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 the 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.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 25 

### Impacts of 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) estimated 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) could 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).

Recent lease sale EISs (MMS, 2007a, 2008) indicated 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 contact the seafloor and affect benthic communities beyond the 300-m (984-ft) radius 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, 2003a).


### C.2.2 High-Density Deepwater Benthic Communities
As defined by NTL 2009-G40, high-density deepwater benthic communities are features or areas that could support high-density chemosynthetic communities, or features 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 66 miles (106 km) north-northeast of the lease area in Viosca Knoll Block 826. The nearest identified deep water coral communities are in MC 426, 24 miles (39 km) north-northwest 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 (Fugro, 2013).

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.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 26 

### Physical Disturbance to the Seafloor
In water depths such as are encountered in the lease area, DP semisubmersibles disturb the seafloor only around the wellbore (SHL) where the bottom template and BOP are located. Depending upon the specific well configuration, this area is generally about 0.25 ha (0.62 ac).

The areal extent of these impacts from the DP rig will be small, and NTL 2009-G40 requires that high-density deepwater benthic communities and features or areas that could support high-density chemosynthetic communities, or deepwater corals communities be avoided. Based on the Fugro (2013) report, there will be no impacts on chemosynthetic or deepwater coral communities from this project.


### Impacts of Effluent Discharges The site clearance survey (Fugro, 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. Monitoring 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 deepwater 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 high-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 biological 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) reported changes in plume hydrocarbon composition with distance from the source. Incubation 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.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 27 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 constant 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; change 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 temperature 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 measuring 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 that the observed coral injuries likely resulted from exposure to the subsurface oil plume (White et al., 2012).


### C.2.3 Designated Topographic Features
The block is not within or near a designated topographic feature or a no-activity zone as identified in NTL 2009-G39. The nearest designated topographic feature is Sackett Bank in the West Delta Area, South Addition, Block 147, 79 miles (128 km) west-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.



### C.2.4 Pinnacle Trend Area Live Bottoms
The lease area is not covered by the Live Bottom (Pinnacle Trend) Stipulation. As defined by NTL 2009-G39, the nearest pinnacle trend is Viosca Knoll Block 778, 66 miles (107 km) north of the lease area.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 28 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 lease 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, 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.



### 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 depths of 100 m (328 ft) or less and portions of Pensacola and Destin Dome Area blocks 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 85 miles (136 km) north-northeast 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 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. 

## 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 Coast are listed in Table 5 . The table also indicates the location of critical habitat (if designated in the Gulf of Mexico). Critical 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-listed cetaceans, sea turtles, and fishes in the Gulf of Mexico. The USFWS has jurisdiction for ESA-listed birds and the West Indian manatee.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 29 Table 5. Federally listed endangered and threatened species potentially occurring in the lease area and along the northern Gulf Coast.

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 = 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.

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 Biological Assessment 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 of threatened and endangered species under NMFS jurisdiction or destroy or adversely modify designated critical habitat. The informal ESA consultation with USFWS was concluded with aMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 30 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 reinitiate 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 the USFWS responded with a letter to BOEMRE on 27 September 2010. At present, the NMFS and USFWS have placed the consultation process on hold because they feel the environmental baseline information needs to be updated for the post-Macondo spill environment based on the results of the Natural Resource Damage Assessment (NRDA) process. The NRDA data have yet to be released, and the existing consultation remains in effect (BOEM, 2012b). 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 mouse. 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 Pelican) discussed in the MMS (2007b) and BOEM (2012b) lease sale EISs are no longer federally listed as endangered or threatened. These are discussed in Section C.4.2
, Shorebirds and Coastal Nesting Birds

. 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 leatherback 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 has 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 sperm whales occur within the Gulf of Mexico; a species description is presented in a recent lease sale EIS (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 Fisheries (Waring et al., 2012). No critical habitat for the sperm whale has been designated in the Gulf of Mexico.Mississippi Canyon Blocks 738 and 782 March 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 Loop 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 groups was 10 individuals (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 Mexico population (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.

Current threats to sperm whale populations worldwide are discussed in a final recovery plan for the sperm whale recently published by NOAA (NMFS, 2010a). 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, 2011a; BOEM, 2012b).


### 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. As discussed in Section A.1 , the bandwidth of sounds generated by the drilling rig is approximately 100 to 500 Hz. The anatomy of the sperm whale ear suggests that it hears in the ultrasonic (>20 kHz) range. The sperm whale may possess better low frequency hearing than some of the other odontocetes, although not as low as many baleen whale species that produce sounds within a bandwidth between 30 Hz and greater than 5 kHz (Wartzok and Ketten, 1999). Southall et al. (2007) lists sperm whales in the same hearing group (mid-frequency cetaceans), as “dolphins,” toothed whales, beaked whales, and bottlenose whales (estimated hearing range of 150 Hz to 160 kHz). Generally, most of the acoustic energy from sperm whales is present at frequencies below 4 kHz, although diffuse energy up to and past 20 kHz has been reported, with source levels up to 236 dB re 1 μPa at 1 m. Other studies indicate sperm whales’ wideband clicks contain energy between 0.1 and 20 kHz (Weilgart and Whitehead, 1993; Goold and Jones, 1995).Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 32 Some sounds produced by the drilling rig may be emitted at levels that could potentially disturb individual whales or mask the sounds animals would normally produce or hear. Observations of sperm whales near offshore oil and gas operations suggest an inconsistent response to anthropogenic noise (Jochens et al., 2008). Barkaszi et al. (2012) showed that Gulf of Mexico sightings distances and surface activity durations were greater for sperm whales during full power seismic surveys than during no-firing periods on seismic vessels, indicating a potential avoidance response to some sound sources. In contrast, Davis et al. (2000) noted that sighting frequency in the northern Gulf of Mexico did not differ significantly among different acoustic levels, including vessel traffic and active seismic surveys. Most observations of behavioralresponses of marine mammals to anthropogenic sounds, in general, have been limited to shortterm behavioral responses, which included the cessation of feeding, resting, or social interactions (NMFS, 2009). Sounds produced during drill rig operations are generally constant (rather than pulsed or intermittent) and at levels that may be louder than, and of a similar frequency to, the auditory signal received by sperm whales. Animals can determine the direction from which a sound arrives based on cues, such as difference in arrival times, sound levels, and phases at the two ears. Thus, an animal’s directional hearing capabilities have a bearing on its vulnerability to masking (National Research Council, 2003b). Behavioral changes for marine mammals such as the sperm whale to auditory masking sounds may include producing more calls, longer calls, or shifting the frequency of the calls (NMFS, 2009). For example, killer whales, also a mid-frequency odontocete, increased the amplitude of their calls to avoid masking by boat noise (Holt et al. 2009).

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 intensity) 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 Opinion 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).

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 hearing or behavioral effects to sperm whales.

Drilling rig lighting and rig presence are not identified as IPFs for sperm whales in recent lease sale EISs (MMS, 2007b; BOEM, 2012a,b,d) or the NMFS (2007) Biological Opinion.


### 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). DataMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 33 concerning the frequency of vessel strikes are presented in a recent lease sale EIS (MMS, 2007b). To reduce the potential for vessel strikes, the BSEE and BOEM issued NTL 2012-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. 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 expected 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 maintain a distance of 91 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) documented 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 that the observed reactions to brief overflights by the aircraft were short-term and probably of no long-term biological significance.
While 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 (Smultea et al., 2008), the NMFS (2007) and BOEM (2012d) concluded that this 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 recent lease sale EISs (MMS, 2007b; BOEM, 2012a,b,d) and by NMFS (2007). 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 Noble’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Noble’s OSRP will mitigate and lessen the potential for impacts on sperm whales. Given the open oceanMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 34 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 whales, 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 recent EISs (MMS, 2007b; BOEM, 2012a,b,d) and by 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, noise, 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; 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.

In the event of a large spill, the level of vessel and aircraft activity associated with spill response could disturb 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 Manatee (Endangered)
Most 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 recent lease sale EIS (MMS, 2007b) and in the recovery plan for this species (USFWS, 2001).Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 35 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, as the lease area is approximately 74 miles (119 km)from the nearest shoreline (Louisiana). 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 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 2012-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 altitudes 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 exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, 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 of social structure, changing prey availability and foraging distribution and/or patterns, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 2011).

In the event that a large spill reached coastal waters where manatees were present, 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 reduce the potential for striking or disturbing these animals, and therefore no significant impacts are expected.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 36 

### 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 scope 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 recent lease sale EISs (MMS, 2007b; 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 of marine mammals that may be found in the Gulf of Mexico, including 2 species of mysticete whales, dwarf and pygmy sperm whales, 4 species of beaked whales, and 14 species of delphinids. All marine mammals are protected species under the MMPA. The most common nonendangered 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 additional information on these groups is presented in a recent lease sale EIS (MMS, 2007b).

Mysticete whales. Two species of nonendangered 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 Mexico, 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 dwarf 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.

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 Ziphius spp.). In the northern Gulf of Mexico, they are broadly distributed in water depths greater than 1,000 m (3,281 ft) overMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 37 lower slope and abyssal landscapes (Davis et al., 2000). Any of these species could occur in the lease area.

Delphinids. 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 ), false killer whale ( Pseudorca crassidens ), Fraser’s dolphin ( Lagenodelphis hosei ), killer whale ( Orcinus orca ), melon-headed whale ( Peponocephala electra ), pantropical spotted dolphin ( Stenella attenuata ), pygmy killer whale ( Feresa attenuata ), short-finned pilot whale ( Globicephala macrorhynchus ), Risso’s dolphin ( Grampus griseus ), rough-toothed dolphin ( Steno bredanensis ), spinner dolphin ( Stenella longirostris ), and striped dolphin ( Stenella coeruleoalba ). Any of these species could occur in the lease area. The most common nonendangered cetaceans in the deepwater environment are the pantropical spotted dolphin, spinner dolphin, and Clymene dolphin.
Bottlenose dolphins. The bottlenose dolphin ( Tursiops truncatus ) is a common inhabitant of the northern Gulf of Mexico, particularly 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 bottlenose 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., 2012). NMFS (2013) has proposed to 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

 for which the level of direct human-caused mortality exceeds the potential biological removal level;

 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 listed 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 has 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 been 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.


### 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 during 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 noise alone (LGL Ecological Research Associates, Ltd., 2006) but are dependent on variables relating to thrusterMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 38 type and usage. It is expected that marine mammals within or near the lease area would be able to detect the 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 otherwise 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 insignificant to marine mammal populations.

Drilling rig lighting and rig presence are not identified as IPFs for marine mammals in recent lease sale EISs (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 a recent lease sale EIS (MMS, 2007b). To reduce the potential for vessel strikes, BSEE and BOEM issued NTL 2012-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. Vessel operators 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 cetaceans are observed near an underway vessel, when safety permits. Compliance with NTL 2012-JOINT-G01 will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing marine mammals, and therefore no significant impacts are expected.
Aircraft traffic also has the potential to disturb marine mammals (Würsig 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 significant impacts are expected (BOEM, 2012a,d).


### Impacts of a Small Fuel Spill Potential spill impacts on marine mammals are discussed in recent EISs (MMS, 2007b; BOEM, 2012a,b), and 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.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 39 The probability of a fuel spill will be minimized by Noble’s preventative measures during fuel transfer. In the unlikely event of a spill, implementation of Noble’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 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 (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 marine mammals, no significant impacts would be expected.


### Impacts of a Large Oil Spill (WCD)
Potential spill impacts on marine mammals are discussed in recent EISs (MMS, 2007b; 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, 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 of social structure, changing prey availability and foraging distribution and/or patterns, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 2011).

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)
Five species of endangered or threatened sea turtles may be found near the lease area. Leatherback 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 2010, NMFS and USFWSMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 40 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 coast of Mexico breeding populations, which are listed as endangered. Species descriptions are presented in MMS (2007b).
Leatherback and loggerhead turtles 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 nearshore species, unlikely to occur near the lease area as adults. Hatchlings or juveniles of any of the sea turtle species may be present in deepwater 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 numbers 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 leatherback turtles infrequently nest on Florida Panhandle beaches (Florida Fish and Wildlife Conservation Commission, 2012);

 Kemp’s ridley turtles – The main Kemp’s ridley nesting site is Rancho Nuevo beach, Tamaulipas, 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.


### Impacts 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 disruption 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 produced 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, these 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 rely 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 inMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 41 the Gulf of Mexico (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 inclement weather. To reduce the potential for vessel strikes, BSEE and BOEM issued NTL 2012-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.


### Impacts of a Small Fuel Spill Potential spill impacts on sea turtles are discussed in recent EISs (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 Noble’s preventative measures during fuel transfer. In the unlikely event of a spill, implementation of Noble’s OSRP is expected to minimize potential impacts on sea turtles. 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 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 (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, as the lease area is 74 miles (119 km)from the nearest shoreline (Louisiana). 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, andMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 42 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 Noble’s OSRP is expected to minimize the potential for these types of impacts on sea turtles. EP Section H provides 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 effects 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 impaired movement and normal bodily functions (NMFS, 2007).
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 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.
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 USFWS on 30 July 2010. The NMFS responded with a letter to BOEMRE on 24 September 2010, and the USFWS responded with a letter to BOEMRE on 27 September 2010. However, NMFS and the USFWS 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 remains in effect (BOEM, 2012b).
BOEMRE (2011a) and BOEM (2012b) reexamined the impacts analyses 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 impacts 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 Piping 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 ofMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 43 hunting, habitat loss and modification, predation, 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 invertebrates 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 a recent lease sale EIS (MMS, 2007b).
A large oil spill (WCD) is the only IPF potentially affecting Piping Plovers. 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 ).


### Impacts of a Large Oil Spill (WCD) The lease area is 73 miles (118 km) from the nearest shorelines 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 physically 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. Noble has extensive resources available to protect and rehabilitate wildlife in the event of a spill reaching the shoreline, as detailed in the OSRP.Mississippi Canyon Blocks 738 and 782 March 2013 Environmental Impact Analysis for Initial Exploration Plan Page 44 Figure 3. Location of selected environmental features in relation to the lease area.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 45 

### C.3.7 Whooping Crane (Endangered)
The Whooping Crane ( Grus americana ) is an omnivorous wading bird and an endangered species. There are three wild populations 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; this 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 nonmigrating 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 fields (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 recent lease sale EISs (MMS, 2007b; 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 497 miles (800 km) from its critical habitat designated in the Aransas NWR. The revised OSRA modeling (BOEM, 2012b) predicts that there is a 3% or less probability that an oil spill originating in the lease area would reach the Aransas NWR within 30 days and a 17% 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 fishes. It is possible that some Whooping Crane deaths could occur. In the event of a spill, Noble would work with the applicable State and Federal agencies to prevent impacts from a spill.


### 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) to Suwannee Sound, Florida (Levy County) (NMFS, 2010b) ( Figure 3 ). A species description is presented in a lease sale EISMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 46 (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 recent lease sale EISs (MMS, 2007b; BOEM, 2012a,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 133 miles (214 km) from the nearest Gulf sturgeon critical habitat. The revised OSRA modeling (BOEM, 2012b) predicts that 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, subadult and adult 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 Smalltooth Sawfish (Endangered)
Smalltooth sawfish ( Pristis pectinata ) are found in the tropical and subtropical Atlantic Ocean. In the Western 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 approximately 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 coastal habitat. The two units are located along the southwestern coast of Florida between Charlotte 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)
Potential spill impacts on smalltooth sawfish are similar to those discussed for other coastal and estuarine species in recent lease sale EISs (MMS, 2007b; BOEM, 2012a) and by the NMFS (2007) in its Biological Opinion. For this EP, there are no unique site-specific issues with respect to smalltooth sawfish.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 47 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 petroleum products through the gills.


### C.3.10 Beach Mice (Endangered)
Four subspecies of endangered beach mouse ( Peromyscus polionotus ) occur on the barrier islands of Alabama and the Florida Panhandle. They are the Alabama, Choctawhatchee, 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 a recent lease sale EIS (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 recent lease sale EISs (MMS, 2007b, 2008; BOEMRE, 2011a; 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 lease area is about 137 miles (220 km) north from the nearest beach mouse critical habitat. 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 tissues, 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 nests. 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.


### C.3.11 Elkhorn Coral (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, elkhorn 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. AlthoughMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 48 subsurface plumes were reported following the Macondo spill, these plumes resulted from the use of subsea dispersants 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). Seabirds 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 shorebirds 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 shorebirds 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, four 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 Mexico, 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 offshore structures because of the lights and the fish populations that aggregate around these structures.

IPFs potentially affecting marine and pelagic birds 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 the birds due to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility 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 rigs may be exposed to contaminants including air pollutants and routine discharges, but significant impacts are unlikely due to rapid dispersion. Birds migrating over water have been known to strike offshore structures, resulting in death or injury (Wiese et al.,Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 49 2001; Russell, 2005). Mortality of migrant birds 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, navigation 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 spring (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.

A study in the North Sea indicated that rig lighting causes circling behavior in various birds, especially on cloudy nights; apparently the birds’ geomagnetic compasses are upset by the red part of the spectrum from the lights currently in use (Nederlandse Aardolie Maatschappij, 2007). The numbers varied greatly, from none at all to some tens of thousands of birds per night per rig, with an apparent effect radius of up to 3 miles (5 km). The OSPAR workshop (OSPAR Commission, 2012) noted that this circling increases the risk of collisions leading to traumas and deaths and may interrupt their migration. A study in the Gulf of Mexico also noted the phenomenon but did not recommend mitigation (Russell, 2005). Factors to consider in evaluating this impact in the Gulf of Mexico would include the lower incidence of cloudy and foggy days in the Gulf of Mexico versus the North Sea. In laboratory experiments, Poot et al. (2008) found the magnetic compass of migratory birds to be wavelength dependent. Migratory birds require light from the blue-green part of the spectrum for magnetic compass orientation, whereas red light (visible long-wavelength) disrupts their magnetic orientation. They designed a field study to test if and how changing light color influenced migrating birds under field conditions. During field studies they found that nocturnally migrating birds were disoriented and attracted by red and white light (containing visible long-wavelength radiation), whereas they were clearly less disoriented by blue and green light (containing less or no visible long-wavelength radiation) (Poot et al., 2008). Due to the limited scope and short duration of drilling activities proposed in this EP, lighting impacts, collisions, or other adverse effects are unlikely, and no significant impacts are expected.


### Impacts of Support Vessel and Helicopter 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 significant.


### Impacts of a Small Fuel Spill Potential spill impacts on marine birds are discussed in recent EISs (MMS, 2007b; BOEM, 2012 a,b,d). 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 Noble’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Noble’s OSRP will reduce the potential for impacts on marine and 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.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 50 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.

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 a small fuel spill, secondary impacts due to ingestion of oil via contaminated prey or reductions in prey abundance 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 recent EISs (MMS, 2007b; 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 analyses for coastal and marine birds presented in MMS (2007b, 2008) and determined that no new information was found that would alter the potential impacts on marine and pelagic birds (BOEMRE, 2011a; BOEM, 2012b).
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 <10 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 recent 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 numbers of birds affected by the spill.


### C.4.2 Shorebirds 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 Coast, including diving birds, shorebirds, 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, barrier 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 recent lease sale EISs (MMS, 2007b; BOEM, 2012a).Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 51 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, 2011), and as a species of special concern by the State of Florida (Florida Fish and Wildlife Conservation Commission, 2011). 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 offshore waters (Fritts and Reynolds, 1981; Peake, 1996; Hess and Ribic, 2000). Nearly half the southeastern population of Brown Pelicans lives in the northern Gulf Coast, generally nesting on protected islands (USFWS, 2010b).
The Southern Bald Eagle ( Haliaeetus 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 Coast is inhabited by both wintering migrant and resident Bald Eagles (Johnsgard, 1990; Ehrlich et al., 1992).

IPFs potentially affecting shorebirds 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 shorebirds or coastal nesting birds, as the lease area is 74 miles (119 km)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 near Port Fourchon and Houma, Louisiana, where shorebirds 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 pathways; 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 Noble’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 designated 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 exposures 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. 91-36DMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 52 recommends 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 overflights 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 Large Oil Spill (WCD)
Data from the Macondo spill provide additional information about the species of coastal birds that may be affected in the event of a catastrophic spill of a similar nature and duration. This information supplements the analysis presented in the lease sale EIS (MMS, 2007b). According to USFWS (2010d) and based on the latest reports, about 5,000 dead birds have been collected since the spill began, and about 1,900 of the dead animals were visibly oiled. In addition, over 2,000 oiled birds have been collected alive and about 1,200 released (NMFS, 2010c). According to the USFWS (2011), bird species that have been treated for oiling include the following:

 Brown Pelican

 White Pelican

 Masked Booby

 Magnificent Frigatebird

 Laughing Gull

 Herring Gull

 Northern Gannet

 Black Crowned Night Heron

 Tri-colored Heron

 Green Heron

 Cattle Egret

 Snowy Egret

 Reddish Egret

 Least Bittern

 Common Tern

 Royal Tern

 Caspian Tern  Sandwich Tern

 Forster’s Tern

 Black Tern

 Gull-billed Tern

 Least Tern

 Black Skimmer

 Black Oystercatcher

 White Ibis

 Roseate Spoonbill

 Willet

 Sanderling

 Dunlin

 Semipalmated Sandpiper

 Killdeer

 King Rail

 Clapper Rail

 Virginia Rail

According to the USFWS (2010d), species with the largest numbers of dead oiled birds were Laughing Gull, Northern Gannet, Brown Pelican, Royal Tern, Black Skimmer, Least Tern, unidentified Gull, and unidentified Tern. There are no reports of Bald Eagle oiling.

While the Macondo spill had direct and indirect impacts to coastal and marine birds, it is premature to conclude impacts over a long period (BOEM, 2012b). Modeling of Macondo spill related bird impacts is underway by NRDA, but results have not yet been released. Antonio et al. (2011) modeled bird-mortality from the Macondo spill showing cumulative carcass numbers and mortality rate increasing exponentially from the start of the Macondo spill until the mortality rate began to decline after the 97th day of the spill. Note that the collected animals would be a small subset of the total number of impacted birds and therefore, the collected animals would represent an underestimated measure of the overall impact of the Macondo event (BOEM, 2012b).Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 53 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, 2010e). Oil interferes with the water repellency of feathers and can cause hypothermia in the right conditions. As birds groom themselves, they can ingest and inhale the oil on their bodies. Scavengers such as Bald Eagles and gulls can be exposed 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 nest.

As noted above, the Brown Pelican was recently removed from the Federal endangered species list. Over 300 dead Brown Pelicans were collected in the Gulf following the Macondo spill, (USFWS, 2010d). These data indicate that Brown Pelicans may be particularly at risk of oiling in the event of a catastrophic spill reaching coastal waters. Issues for Brown Pelicans include direct contact with oil, disturbance by cleanup activities, and long-term habitat contamination.



## C.5 Fisheries 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 influence 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 mesoscale 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, depending 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 spill (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 feeding of epipelagic predators by attracting 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
Treated 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,Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 54 organic matter, and chlorine, but should be diluted rapidly to undetectable 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. Deck 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 undetectable 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 water, 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 rig. The rig considered for use for activities described in this EP is a "new" facility as defined by the NPDES permit and therefore will comply with the cooling water intake regulations for Phase III facilities under Section 316(b) of the Clean Water Act.

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, any 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 resources are discussed in recent EISs (MMS, 2007b; BOEM, 2012a,d). For this EP, there are no unique site-specific issues with respect to spill impacts.
The probability of a fuel spill will be minimized by Noble’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Noble’s OSRP will 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.

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 naturallyMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 55 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 water 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 necessary 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 (2012b) has reexamined the analysis for fish resources and EFH presented in recent lease EISs (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, shrimps, stone crab, spiny lobster, reef fishes, 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). The EFH for most of these GMFMC-managed species is on the continental 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 58 miles (93 km) north of the lease area along the shelf edge south of Louisiana.
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):Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 56  Atlantic bluefin tuna (spawn, eggs, larvae)

 Bigeye tuna (juveniles, adults)

 Bigeye thresher shark (all)

 Blue marlin (juveniles, adults)

 Longbill spearfish (juveniles, adults)

 Longfin mako shark (all)  Oceanic whitetip shark (all)

 Skipjack tuna (spawn)

 Swordfish (larvae, juveniles, adults)

 White marlin (juveniles, adults)

 Yellowfin tuna (spawn, juveniles, adults)

 Whale shark (all)

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 species. 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 foraging in June through March off the eastern U.S. and Canadian coasts, followed by migration to the Gulf of Mexico to spawn in April, 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 spawning 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, 2009a,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 above will be followed (BOEMRE, 2011a; BOEM, 2012b).
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, Pulley Ridge, and several individual reefs and banks of the northwestern Gulf of Mexico ( Figure 3 ). The nearest HAPC is Jakkula Bank, located approximately 201 miles (323 km) to the 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).


### Impacts of Drilling Rig Presence, Noise, and Lights
The drilling rig, as a floating structure in the deepwater environment, will act as an FAD. In oceanic waters, the FAD effect would be most pronounced for epipelagic fishes such as tunas,Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 57 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 impacts 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 drainage, 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 fishes 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 Noble’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Noble’s OSRP will help diminish the potential for impacts on EFH. 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.
Potential spill impacts on EFH are discussed in recent EISs (MMS, 2007b; BOEM, 2012a,d). For 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 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 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.

A small fuel spill would not affect EFH for corals and coral reefs, the nearest EFH being the topographic features located approximately 58 miles (93 km) from the lease area along the shelf edge south of Louisiana. A small fuel spill would float and dissipate on the sea surface and would not contact these features.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 58 

### Impacts of a Large Oil Spill (WCD)
Potential spill impacts on EFH are discussed in recent EISs (MMS, 2007b; BOEM, 2012a,d). For this EP, there are no unique site-specific issues with respect to EFH.

An oil 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 shrimps, 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 biota 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.
The 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 58 miles (93 km) north of the lease area, are designated 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 (2012b) reexamined the analyses for archaeological resources presented in MMS (2007b, 2008), based on additional information available since the publication of these two documents and in consideration of the Macondo oil spill. Substantial new information that 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 discovered 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 on the list of OCS blocks with a high potential for historic shipwrecks (BOEM, 2012c). Two sonar contacts interpreted as unidentified debris on the seafloor lie within 610 m (2,000 ft) of the proposed wellsites. There were no indications of wrecks or other archaeological resources detected during the site clearance survey (Fugro, 2013). Noble will abide by the applicable requirements of NTL 2005-G07, which stipulate that work be 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.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 59 Because there are no shipwreck sites in the lease area, there are no routine IPFs that are likely to affect shipwrecks. Impacts 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) estimated 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 shipwreck 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 their condition or preservation. Should there be any indication that potential shipwreck sites could be affected, in accordance with NTL 2005-G07 Noble will immediately halt operations, take steps to ensure that the site is not disturbed in any way, and contact the BOEM Regional Supervisor, Leasing and Environment, within 48 hours of its discovery. Noble 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. As 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 91 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 years 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) below the present-day sea level (Coastal Environments, Inc., 1977, 1982). On this basis, the continental shelf shoreward of the 45- to 60-m (148- to 197-ft) bathymetric contours has potential for 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 adoptedMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 60 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 1,994 to 2,004 m (6,542 to 6,576 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 Coast, 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 also 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 recent EISs (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. Generally, 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. The support bases at Port Fourchon and Houma, Louisiana, are not in wildlife refuges or wilderness areas. Potential impacts of support vessel traffic are addressed briefly below.
A small fuel spill in the lease area would be unlikely to affect coastal habitats, as the lease area is 74 miles (119 km)from the nearest shoreline (Louisiana). 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 in 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 operations, including crew boats and supply boats as detailed in EP Section K , may have a minor incremental impact on coastal habitats or protected areas. Impacts will be minimized by following the speed and wake restrictions in harbors and channels.Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 61 

### Impacts of a Large Oil Spill (WCD) Potential spill impacts on coastal habitats are discussed in recent EISs (MMS, 2007b; 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 during winter there is a 17% probability of oil from a spill in the lease area reaching shorelines in Texas within 120 days, and a 14% probability in spring of oil reaching Louisiana 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 recent lease sale EISs (MMS, 2007b; BOEM, 2012b) and Noble’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. Wildlife refuges, wilderness areas, and State and National parks within the geographic range of the potential shoreline contacts after 120 days (From: BOEM, 2012b).

County or Parish, State W ildlife Refuge, Wilderness Area, or State/National Park

Cameron County, Texas Laguna Atascosa National Wildlife Refuge Padre Island National Seashore Isla Blanca Park Andy Bowie County Park Laguna Madre Estuarine and Coastal Marine Area

Willacy County, Texas Lower Rio Grande Valley National Wildlife Reserve Laguna Atascosa National Wildlife Reserve Padre Island National Seashore Laguna Madre Estuarine And Coastal Marine Area
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 Big Boggy National Wildlife Refuge Aransas National Wildlife Refuge Mad Island Wildlife Management Area San Bernard National Wildlife Refuge

Brazoria County, Texas San Bernard National Wildlife Refuge Peach Point Wildlife Management AreaTable 6. (Continued).

Mississippi Canyon Blocks 738 and 782 March 2013 Environmental Impact Analysis for Initial Exploration Plan Page 62

County or Parish, State W ildlife Refuge, Wilderness Area, or State/National Park Brazoria National Wildlife Refuge Christmas Bay Coastal Preserve and Christmas Bay State Park

Galveston County, Texas Galveston Island State Park Brazoria National Wildlife Refuge Apffel Park Seawolf Park Old Fort Travis Park Atkinson Island Wildlife Management Area Ft. Anahuac Park 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 Cameron 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 Louisiana Rockefeller Wildlife Management Area Paul J. Rainey Wildlife Management Area

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

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 that 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 will 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 aboveMississippi Canyon Blocks 738 and 782 March 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 activities 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 and 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. No new information was found that would alter the potential impacts on commercial fishing (BOEMRE, 2011a; BOEM, 2012b).

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. In August 2000, the Federal government closed two areas in the northeastern Gulf of Mexico to longline fishing (65 FR 47214, 1 August 2000). The lease is outside of the closure

areas.
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 such as fronts or downwellings, with 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 targeted 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). Tilefishes (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) (Continental Shelf Associates, Inc., 1997, 2002). In deeper water, the main attraction to recreational fishers would be petroleum rigs offshore Texas and Louisiana. Due to the distance from shore, it is unlikely that recreational fishing activity is occurring in the lease area.
The only routine IPF potentially affecting fisheries is drilling rig presence (including noise and lights). Two types of potential accidents are also addressed below – a small fuel spill and a large oil spill (WCD).Mississippi Canyon Blocks 738 and 782 March 2013

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### 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 expected.

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 Noble’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Noble’s OSRP will potentially mitigate and reduce the potential for impacts. 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.

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 would 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 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 spill impacts on fishing activities are discussed in recent EISs (MMS, 2007b; 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 spill 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 recent 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, 2010d). 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 Safety
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 Noble’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Noble’sMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 65 OSRP will potentially alleviate the potential for impacts. EP Section H provides 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 74 miles (119 km) from the nearest shoreline (Louisiana) and nearly all 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 recent 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, 2010a). 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 wildlife-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 prevalence 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 Employment 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 facilities 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 Noble’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Noble’sMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 66 OSRP will potentially mitigate and reduce the potential for impacts. 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 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 recent EISs (MMS, 2007b; 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 part 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 analyses presented by MMS (2007b, 2008) and BOEM (2012b), a recent study explored the economic impacts of the Macondo spill on oil and gas industry employment due to suspension of deepwater drilling (Inter-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 analyses 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 impacts on recreation and tourism (BOEMRE, 2011a; BOEM, 2012b).

There are no known recreational uses of the lease area. Recreational resources and tourism in coastal 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.


### Impacts of a Small Fuel Spill
The probability of a fuel spill will be minimized by Noble’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Noble’s OSRP will potentially help mitigate and reduce the potential for impacts. 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.Mississippi Canyon Blocks 738 and 782 March 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 recent EISs (MMS, 2007b; 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 recreation 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 17% probability in winter of oil from a spill in the lease area reaching shorelines in Texas and a 14% chance in spring of contacting shorelines in Louisiana within 120 days.
In addition to the analysis presented by MMS (2007b; BOEMa,b,d), recent and ongoing studies have explored 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 Coast is discussed in recent lease sale EISs (MMS, 2007b; BOEM, 2012a,b,d). There are no routine IPFs potentially 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, will 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 shorebases.
A large oil spill (WCD) is the 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 response is demobilized.Mississippi Canyon Blocks 738 and 782 March 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. Noble will comply with BOEM requirements and lease stipulations to avoid impacts on uses of the area by military vessels and aircraft.

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. The blocks are not located within any USCG-designated fairway or shipping lane or Military Warning Area. In the event of a large spill requiring numerous response vessels, coordination would be required to manage the vessel traffic for safe operations. Noble will comply with BOEM requirements and lease stipulations to avoid impacts on uses of the area by military vessels and aircraft.

In the event of a large spill requiring numerous vessels in the area, coordination would be required 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 Fugro (2013) concluded that the wellsites are free of any significant geological hazards and are suitable for the proposed 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

Metocean 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., caused by Loop Current eddies and intrusions) and large waves were considered in the design criteria for the drilling rig underMississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 69 consideration for this project. High waves during a severe storm could disrupt support activities (i.e., 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.



## E. Alternatives

No formal alternatives were evaluated in this EIA for an EP. However, various technical and operational options, including the location of the wellsites and the selection of a drilling unit, were considered by Noble 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 Federal, State, and local requirements concerning air pollutant emissions, discharges to water, and solid waste disposal. All project activities will be conducted under guidance by Noble’s OSRP and will include the measures described in EP Section H

.



## 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:

 C. Chandool, Ph.D. (Senior Scientist);

 C. Kalloo (Senior Scientist);

 M. John Thompson (Senior Scientist);

 Neal Phillips, Ph.D. (Senior Scientist);

 Keith VanGraafeiland (GIS/Remote Sensing Specialist);

 Kristen L. Metzger (Library and Information Services Director); and

 Pamela S. Jones (Technical Editor).Mississippi Canyon Blocks 738 and 782 March 2013

Environmental Impact Analysis for Initial Exploration Plan Page 70 

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## Section O Administrative Information

A. Exempted Information Description The proposed bottom-hole locations of the planned wells have been removed from the public information copy of the EP as well as any discussions of the target objectives, geologic or geophysical data, and any interpreted geology.

B. Bibliography Not applicable.

Noble Energy, Inc. Page O-1 Initial Exploration Plan 04/09/2013 Mississippi Canyon 738 & 782 (OCS-G 33755 & 33757)