700.0

2271.0

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2271.0

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2271.0

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2271.0

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2271.0

1200.0

2271.0

30000 35000 40000 45000 50000 55000 60000

1.300

1.400

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1.900

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3.000

3.100

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877.0

1900.0

877.0

2000.0

877.0

2100.0

877.0

2200.0

877.0

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877.0

2400.0

877.0

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877.0

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877.0

2700.0

15000 20000 25000 30000 35000 40000 45000

1.400

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3.400

Line:

Trace: Horizontal

Distance (ft):

EB

689

Figure EB689-GG-1. Inline 877 and Crossline 2271 Showing Conditions Beneath Proposed Wellsite EB689-GG

NORTH SOUTH

CROSSLINE 2271 TW

O-WAY TRAVEL TIME (SEC)

PROPOSED

WELLSITE EB689-GG

TW

O-WAY TRAVEL TIME (SEC)

WEST EAST

Filename: 122148_fig_EB689-GG-1.cdr

PROPOSED

WELLSITE EB689-GG

Project No. 1012-2148

INLINE 877

Line:

Trace:

Horizontal

Distance (ft):

EB

690

EB

689

SEAFLOOR

HORIZON 10

HORIZON 20

HORIZON 30

HORIZON 40

100ms

(~250 ft)

Scale

5000 ft

100ms

(~250 ft)

Scale

5000 ft

Peak

Trough

RELATIVE AMPLITUDE

EB

645

STUDY AREA

STUDY AREA

SEAFLOOR

HORIZON 10

HORIZON 30

HORIZON 40

HORIZON 20

Peak

Trough

RELATIVE AMPLITUDE

HUMPHRIES

BASIN

EB

688

EB

601
877.0

2200.0

877.0

2300.0

30000 35000

1.4001.5001.6001.7001.8001.9002.0002.1002.2002.3002.4002.5002.6002.7002.8002.9003.0003.1003.2003.3003.400

Line:

Trace:

Horizontal

Distance (ft):

TWO-WAY TRAVEL TIME (SEC)

WATER

FLOW AND

GAS

POTENTIAL

Shallow Water Flow and Gas Potential

HIGH

0 1 2 3

0 = NEGLIGIBLE

1 = LOW2 = MODERATE

3 = HIGH

HORIZON 30

-3,881

NEGLIGIBLE

Horizon Lithology/Stratigraphy

Figure EB689-GG-2. Tophole Prognosis Chart, Proposed Wellsite EB689-GG, East Breaks 

Project No. 1012-2148 

Water

Flow

Gas

3-D Seismic Section Through

Proposed Wellsite EB689-GG

X = 1,155,272 FT; Y = 9,915,635 FT

Inline 877 at Crossline 2271

W E

383

Horizon

TWT

(sec, bml)

Depth

(ft, bml)

Depth

(ft, bss)

INLINE 877

HORIZON 20

-4,264 0.132-6,386 0.799 2,505

EB

689

Proposed

Wellsite EB689-GG

-6,042 0.697 2,161

Horizon

TWT

(sec, bsl)

1.591

1.7232.390

2.288

SEAFLOOR

HORIZON 10HORIZON 40

-4,547 0.227 1.818 666

INTERFACE -7,345 1.074 2.665 3,464

-8,473 1.384 2.975 4,592

-9,697 1.709 3.300 5,816

LIMIT OF

INVESTIGATION

FAULT /

INTERFACE

FAULT /

INTERFACE

-5,298 0.469 2.060 1,417

EB

690

There commNegliModeLow ModeLow 

Stratified hemipelagic silts and clays with thin, muddyturbidities.Predominantly clay-rich mass-transport deposits.Interbedded mass-transport and channel deposits.Clay-rich, contains silts and probable thin sand seams.Interbedded slope-fan, turbidite and mass-transportdeposits. Likely contains silts and possible thin sandseams.Clay-rich mass-transport deposits with thin possiblesands and silts.

NegliModeLow 

Predominantly clay-rich turbidites and gravity flow deposits, with possible thin sand layers or seams.Potential sand-prone turbidite deposits.

Trough Peak

RELATIVE AMPLITUDE

Low 

Clay-rich mass-transport deposits with thin possible sands and silts.Potential sand-prone turbidite deposits. Mode

5,4283,019

724

-9,309-6,900-4,605

1.6070.9480.246

3.1982.5391.837

FAULT

FAULT /

INTERFACE

FAULT
10615 Shadow Wood Drive 

Suite 200 

Houston, Texas 77043 

(713) 468-1410 (o) 

(713) 468-1438 (f) 

www.gemsinc.com

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March 28, 2012 Project No. 0212-2051 

Anadarko Petroleum Corporation 

1201 Lake Robbins Drive 

The Woodlands, TX 77380 

Attention: Mr. Rick Kincaid 

Site Clearance Letter 

Proposed Wellsite EB690-FF 

Block 690 (OCS G-22296) 

East Breaks Area, Gulf of Mexico 

Anadarko Petroleum Corporation, (Anadarko) plans to drill an exploration well in Block 690 of the East 

Breaks (EB) area, Gulf of Mexico. This letter addresses specific seafloor and subsurface geologic and 

stratigraphic conditions to a depth of approximately 5,425 ft below the mudline (bml) at the Proposed 

Wellsite EB690-FF location. The following discussion is based on findings provided within the geohazard 

reports “Geologic and Stratigraphic Assessment, Block 689 and 690, East Breaks Area, Gulf of Mexico” 

(GEMS Report No. 0610-1788), “Geologic and Stratigraphic Assessment, Blocks 602 and 645, East 

Breaks Area, Gulf of Mexico” (GEMS Report No. 0409-1634), and “Geologic and Stratigraphic Assessment, 

Block 646 (OCS G-20725), East Break Area, Gulf of Mexico” (GEMS Report No. 0607-1352). The report 

findings are supplemented with AUV subbottom profiler and side-scan sonar data acquired by C & C 

Technologies, Inc. in 2011. The AUV data covers much of eastern EB 645 and western EB 646, but only 

the northern 1,700 ft of blocks EB 689 and 690. 

The surface location for Proposed Wellsite EB690-FF is in the northwest corner of Block 690, East Breaks 

area, Gulf of Mexico. The coordinates for the proposed location are as follows: 

Proposed Wellsite EB690‐FF

Spheroid & Datum: Clarke 1866, NAD27 

Projection: UTM Zone 15 North, U.S. ft 

Line 

Reference 

Block Calls 

EB 690 

X: 1,161,353 ft Latitude: 27o 18' 57.24333"N Inline 869 5,033 ft FWL 

Y: 9,915,070 ft Longitude: 94o 28' 32.74711"W Crossline 2419 770 ft FNL 

Anadarko may drill this well using a moored vessel. An exact anchor pattern for the proposed well location 

is undetermined at this time. An anchor radius representing a typical maximum length of chain and anchor 

on bottom is displayed at 12,000 ft from the proposed wellsite. A 1,000 ft buffer zone beyond the limits of 

the anchor radius is also included, NTL 2009-G40 (MMS, 2010). 

Attachments 

The 1:12,000 scale-maps and page-size figures accompanying this letter have been extracted from the 

main report’s original maps and 3-D data volume and centered on the proposed well location. 

Map EB690-FF-1: Bathymetry Map 

Map EB690-FF-2: Seafloor Rendering 

Map EB690-FF-3: Seafloor Amplitude Rendering 

Map EB690-FF-4: Geologic Features Map 

Figure EB690-FF-1: Inline 869 and Crossline 2419 Showing Conditions Beneath Proposed 

Wellsite EB690-FF 
Project No. 0212-2051 

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Figure EB690-FF-2: Tophole Prognosis Chart, Proposed Wellsite EB690-FF, East Breaks 

Block 690 

Figure EB690-FF-3: Side-Scan Sonar Mosaic Showing Seafloor Conditions in the Vicinity of 

Proposed Wellsite EB690-FF 

Figure EB690-FF-4: Subbottom Profiler Line 719 Showing Near-Surface Conditions Beneath 

Proposed Wellsite FF 

NTL Requirements

The following report complies with the Bureau of Ocean Energy Management (BOEM; formerly the MMS) 

Notice to Lessees (NTL’s) 2009-G40, 2008-G04, and 2008-G05 (MMS, 2010 and 2008a, b). The proposed 

wellsite will be required to follow NTL 2008-G06 with respect to pre- and post-spud ROV visual inspection 

surveys (MMS, 2008c). The Federal lease block EB 690 is not included in the listing of archaeologically 

significant blocks (BOEM, 2011b); therefore, survey requirements for archaeological assessments as set 

forth in NTL 2005-G07 (MMS, 2005) are not necessary. To comply with pre-seabed disturbance mitigation 

requirements (BOEM, 2011a), Anadarko elected to perform a high-resolution geophysical survey in the 

area utilizing an autonomous underwater vehicle (AUV). C & C Technologies, Inc. prepared an 

archaeological assessment using these data (C & C Technologies Inc., 2011). 

Power Spectrum. According to NTL 2008-G05 (MMS, 2008b), 3-D seismic reflection data may be used for 

shallow hazard assessments with approval from the BOEM, Gulf of Mexico Region. A power spectrum analysis 

was conducted from the 3-D seismic data cube provided by Anadarko to illustrate the data parameters. The 

power spectrum curve (below) was generated within a 500-ft radius of the intersection of the inline and crossline 

at the proposed wellsite location. 

Power Spectrum Analysis Curve, EB 690 Proposed Wellsite FF 

The 3-D seismic volume used to assess the shallow hazards for this assessment possesses frequencies of 

50 Hz and above. The same volume was used for wellsites previously permitted and drilled in adjacent 

blocks by Anadarko. 
Project No. 0212-2051 

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Man-Made Features

Anadarko’s Nansen SPAR is the closest platform to the proposed wellsite. The SPAR is located in the 

southern portion of EB 602 approximately 3.56 miles north-northeast of the proposed wellsite. The SPAR 

is the surface location to several wells in the Nansen field and serves as the hub for several infield and 

export pipelines within and around the Nansen field (BOEM, 2012a). Several existing well locations are 

located near the proposed wellsite (Maps EB690-FF-1 through FF-4). Existing locations within a 13,000-ft 

radius around the proposed location include: 

Surface Area /

Block

Well Name Operator Well Status Distance / Direction

from Proposed

Surface Location

EB 690 001 

Anadarko 

Petroleum 

Corporation 

Completed 4,000 ft/Southsoutheast 

EB 646 SS001 

Anadarko 

Petroleum 

Corporation 

Completed 4,630 ft/Northwest 

EB 646 SS006 

Anadarko 

Petroleum 

Corporation 

Plugged and 

Abandoned 4,658 ft/Northwest 

EB 645 001 

Maxus (U.S.) 

Exploration 

Company 

Plugged and 

Abandoned 7,654 ft/Northwest 

EB 689 001 

Shell 

Deepwater 

Development 

Inc. 

Plugged and 

Abandoned 

8,700 ft/Southsouthwest 

Several pipelines and umbilicals lie near the Proposed EB690-FF wellsite location (Maps EB690-FF-1 

through FF-4). Anadarko’s 4-inch umbilical and 6-inch oil and gas pipelines lie from 1,022 ft to 2,200 ft 

southwest of the proposed location. The pipelines and umbilical originate from Anadarko’s EB 690 #001 

well and trend to the northwest to the Anadarko SS006/001 well completions in EB 646. The lines then 

continue northeast through EB 646 to the Nansen SPAR in EB 602. Another umbilical originates from the 

SPAR and extends back to the same well completion in EB 646. 

Anadarko’s 3-inch umbilical and 6-inch oil pipeline also tie-in at the Anadarko SS006/001 well completions 

in EB 646. These structures originate from the EB 646 SS007/SS008 well completions in the north-central 

portion of EB 646 and trend to the southwest to the SS006/001 well completions. The EB 646 

SS007/SS008 well completions are approximately 13,850 ft to the north of the proposed wellsite and are 

outside the 13,000 ft radius around the proposed wellsite. However, the southern portions of the pipeline 

and umbilical extending from these structures will be within this area. The pipeline and umbilical lie 2,783 ft 

and 3,394 ft northwest of the proposed wellsite, respectively. 

Williams Field Services’ 12-inch oil and 12-inch gas export pipelines are located 8,350 ft and 8,562 ft, 

respectively, west of the proposed location in the northwest portion of EB 690. The pipelines start at a well 

completion in EB 599 and trend southeast across EB 644 and into EB 689. In EB 689 the pipelines curve 

to a northeast heading across the eastern portion of EB 645 and northwestern portion of EB 646. The 

pipelines stay on this north-easterly heading to the termination point with the Nansen SPAR in EB 602. 

The pipelines are visible on the side-scan sonar data (Figure EB690-FF-3). Anchor scars extending from 

previous wellsites and possibly pipeline barges occur along the seafloor near the proposed EB 690-FF 

wellsite (Figure EB690-FF-3). 

Eleven military warning areas are located within the Gulf of Mexico. These areas represent regions where 

the U.S. Department of Defense conducts various testing and training operations. Lessees within military 

warning areas are required to enter into an agreement with the appropriate command headquarters 

concerning the control of electromagnetic emissions and the use of boats and aircraft within the warning 

area (NTL 2009-G06, MMS 2009). East Breaks Block 690 is within the active W-602 and W-147E Military 
Project No. 0212-2051 

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Warning Areas. Coordination of field operations with the appropriate commands may be necessary. The 

command headquarters information is:

Military Warning Area W-602 

Strategic Command Wing 1, Fleet Area Reconnaissance 4; Operations Department 

Tinker Air Force Base 

Oklahoma City, Oklahoma 73145-8704 

Telephone: (405) 739-5700/4527 

Military Warning Area W-147E 

Air Field Management 

14657 Sneider St. 

Houston, Texas 77034-5586 

Telephone: (281) 929-2142 

Wellsite Conditions 

The surface location is clear of any constraining geologic conditions within a 2,000 ft radius from the 

proposed wellsite. 

Water Depth and Seafloor Conditions. The water depth at the proposed location is approximately -

4,139 ft (Map EB690-FF-1). The seafloor slopes to the east at about 3. The proposed location lies on the 

western side of Humphries Basin and east of the highly faulted region along the rim of the basin (Maps 

EB690-FF-1 through FF-4). The seafloor at the proposed site is relatively smooth and featureless. The 

near-surface sediments are expected to be normally-consolidated, soft clays, forming a drape over the 

area. 

Deepwater Benthic Communities. No significant chemosynthetic or other benthic type communities are 

reported within EB 690 (MMS, 2010). The nearest recorded community to the proposed wellsite location is 

in the northwest portion of EB 602, over 5 miles to the northwest. The 3-D seismic data show no 

indications of hydrocarbon seepage within 2,000 ft of the proposed EB690-FF wellsite location (Figures 

EB690-FF-1 and FF-2). The Seafloor Amplitude Rendering (Map EB690-FF-3) shows normal (ambient) 

background amplitudes at the seafloor around this location. Subbottom profiler and side-scan sonar data 

covering much of the 2,000 ft radius show no evidence of near-surface gassy sediments, high-backscatter, 

or other indications of benthic communities near the proposed location (Figures EB690-FF-3 and FF-4). 

AUV data was not collected in the southern third of the 2,000 ft radius (Figure EB690-FF-3). No mounds, 

depressions, or hard bottom features occur within a 2,000 ft radius around the proposed wellsite. The 

potential for high-density chemosynthetic and other benthic communities within 2,000 ft of the proposed 

location is negligible. 

Stratigraphy. The stratigraphy at the proposed well location is illustrated on Figures EB690-FF-1, FF-2, 

and FF-4. 

The subbottom profiler data show approximately 350 ft of well-stratified, hemipelagic, clay-rich, sediments 

beneath the seafloor at the proposed location (Figure EB690-FF-4). The nearly transparent drape of 

presumably very soft, high water content pelagic clays is approximately 10 ft thick at the proposed location. 

The soils beneath the drape will gradually increase in strength and decrease in water content with depth. 

The Tophole Prognosis Chart (Figure EB690-FF-2) shows the inline annotated with calculated depths to 

the various horizons and predicted lithology of the sequences, along with their potential for shallow water 

flow and shallow gas. In general, the sediments between the seafloor and the limit of investigation (about 

5,425 ft bml) consist of hemipelagic silts and clays, bedded turbidites, slope-fan, and mass-transport 

deposits. The shallow section, seafloor to Horizon 20 (0 ft to 797 ft bml) will likely consist of predominantly 

clays and silts. Similar sediments interbedded with thin sand layers are likely in the Horizon 20 to Horizon 

30 unit (797 ft to 1,952 ft bml). Sands are possible from Horizon 30 to the limit of investigation (5,425 ft 

bml). Potentially thick sand layers may occur within turbidites and mass-transport deposits in the upper 

portion of the Horizon 30 to Horizon 40 sequence between 1,952 ft to 2,766 ft bml. The slope-fan deposits 

may correspond to the regional slope-fan sequence known as the GB Orange Unit. Thick sand layers may 

also be encountered between 3,950 ft and 4,396 ft bml. 
Project No. 0212-2051 

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Faults. No seafloor or buried faults will be penetrated by the well bore beneath the proposed EB690-FF 

wellsite between the seafloor and at least 5,425 ft bml, the limit of investigation (Figures EB690-FF-1, FF-2, 

and FF-4). 

Shallow Gas and Shallow Water Flow. The potential for shallow gas and shallow water flow at this well 

location varies from negligible to moderate at the proposed wellsite (Figure EB 690-FF-2). 

Shallow Gas. A vertical well bore at the proposed well location will not penetrate any high-amplitude 

anomalies between the seafloor and at least 5,425 ft bml, the limit of investigation; Map EB690-FF-4. The 

potential for encountering shallow gas at the Proposed Wellsite EB690-FF is low to moderate in zones from 

Horizon 20 (797 ft bml) to the limit of investigation (Figure EB690-FF-2). A moderate potential for 

encountering shallow gas exists in the intervals between 1,952 ft to 2,766 ft bml and 3,950 ft to 4,396 ft 

bml. The potential for encountering interbedded sand layers near the proposed wellsite is likely in these 

intervals. A low potential occurs in the intervals between 797 ft to 1,952 ft bml, 2,766 ft to 3,950 ft bml, and 

4,396 ft to 5,425 ft bml (limit of investigation). There is a negligible potential for encountering shallow gas 

in the sequences from the seafloor to Horizon 20 (797 ft bml). 

Shallow Water Flow. There is a moderate potential for shallow water flow within three sand-prone 

units (Figure EB690-FF-2). The shallowest unit is from 797 ft to 1,952 ft bml (Horizon 20 to Horizon 30). 

This stratigraphic interval likely contains sand-prone, bedded turbidite deposits. Drilling reports indicate the 

Maxus EB 645 #001 well, approximately 7,654 ft south-southeast of the proposed wellsite, experienced 

shallow water flow conditions within this shallow turbidite sequence (BOEM, 2012b). Similar stratigraphic 

conditions can also be correlated to the Anadarko SS007/SS008 wells in the northwestern portion of 

EB 646, the SS006/001 wells in the southwestern portion of the block, and the Anadarko #001 in the northcentral portion of EB 690. These wells did not report shallow water flow from the shallow sequence 

(BOEM, 2012b). However, we recommend designing your casing program to take into account the 

potential for shallow water flow within this interval. 

The next stratigraphic interval with a moderate potential for shallow water flow is between 1,952 ft to 

2,766 ft and consists of stacked, slope-fan and turbidite deposits. These deposits may correlate with the 

regional, slope fan sequence known as the Garden Banks (GB) Orange Unit. A moderate potential for 

shallow water flow also exists within the sand-prone interval between 3,950 ft and 4,396 ft bml 

(Figure EB690-FF-2). Although existing wells within and adjacent to EB 690 did not report shallow water 

flow from similar intervals, continuous sand seams could be present, some of which may be overpressured. 

The potential for shallow water flow is low from 2,766 ft to 3,950 ft bml and below 4,396 ft to the limit of 

investigation at 5,425 ft bml. Sands may be present within these intervals; however, they are not likely to 

be significantly overpressured. The remaining stratigraphic sequences at the proposed wellsite have a 

negligible potential for encountering shallow water flow. 

The potential for shallow water flow is low from 2,161 ft to 2,988 ft bml and below 3,546 ft to the limit of 

investigation at 5,825 ft bml. Sands may be present within these intervals; however, they are not likely to 

be significantly overpressured. The remaining stratigraphic sequences at the proposed wellsite have a 

negligible potential for encountering shallow water flow. 

Anchor Locations 

A 13,000-ft radius (12,000 ft maximum anchor spread as required during hurricane season plus a 1,000 ft 

buffer zone) is outlined on Maps EB690-FF-1 through FF-4 to represent an area that may be impacted by a 

generic anchoring configuration. The radius is the basis for clearance of seafloor conditions relating to 

anchoring considerations. 

Water depths within the potential 13,000 ft mooring area range from about -3,300 ft to -4,750 ft (Map 

EB690-FF-1). The northwest portion of the anchor radius is highly-faulted and irregular. The irregular 

seafloor conditions in these areas are associated with several seafloor faults that occur within a large, 

northeast-southwest trending fault system along the western flank of Humphries Basin (Map EB690-FF-2). 

Seafloor mounds are also present. The seafloor across the western, southern, and eastern areas is 

generally smooth and featureless. 
Project No. 0212-2051 

Anadarko Petroleum Corporation // March 28, 2012

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Slopes along the various fault escarpments range from approximately 3° to 46°. Irregular and mounded 

seafloor downdip of the faults, particularly in the north-central portion of the anchor radius, are likely the 

result of localized slumping from oversteepening along the faults. 

The seafloor in the far western portion of the radius gently dips to the southwest in EB 645 and southeast in 

the northern portion of EB 689. The seafloor in the southern portion dips to the northeast across most of 

EB 689 and to the east in EB 690 at about 2° to 5°. The northeast dipping seafloor in EB 689 is the result 

of a topographic high centered in block EB 733 to the south. The seafloor in the eastern portion of the 

radius dips to the east into Humphries Basin. Average gradients within this area range from 2o to 5o. 

There is one small seafloor amplitude anomaly observed within the probable radius for this wellsite 

(Map 690-FF-3). This anomaly lies along a fault in EB 646 approximately 2.2 miles north-northwest of the 

proposed wellsite. AUV side-scan sonar and subbottom profiler data reveal high-backscatter intensity and 

near-surface acoustic voids near the anomaly. Benthic communities are possible within these patches; 

however, significant high-density communities are unlikely. We recommend that the anomaly be avoided 

by at least 500 ft when planning an anchor mooring pattern. Four seafloor mounds exist along the 

downthrown side of two seafloor fault escarpments along the eastern margin of EB 645, approximately 

10,500 ft to 13,000 ft northwest of the proposed wellsite. No elevated amplitude responses at the seafloor 

are associated with these features in the 3D data. High-resolution AUV data reveals high-sonar 

backscatter and near-surface acoustic voids, indicating gassy sediment near these seafloor mounds. We 

recommend that the mounds be avoided by at least 500 ft when planning an anchor mooring pattern at this 

location. 

Closing 

The Proposed Wellsite FF in East Breaks Block 690 appears suitable for exploration drilling operations. 

However, caution is advised while drilling through potentially sand-prone intervals identified between 797 ft 

and 4,396 ft bml. Shallow water flow is more likely to be encountered within these stratigraphic units. 

We recommend avoiding the seafloor mounds to the northwest of the proposed wellsite when planning an 

anchor mooring pattern for this location. 

We appreciate the opportunity to be of service to Anadarko Petroleum Corporation and look forward to 

working closely with you on other projects. 

 Sincerely, 

 GEOSCIENCE EARTH & 

 MARINE SERVICES, INC. ®

Lisa A. Majzlik Daniel Lanier 

Geoscientist Vice President - Geoscience 

Attachments: (4 Maps and 4 Figures) 

Distribution: Mr. Rick Kincaid, Anadarko Petroleum Corporation, The Woodlands, TX (6 copies) 

References: 

Bureau of Ocean Energy Management (BOEM), 2011a, Pre-Seabed Disturbance Survey Mitigation 

<http://www.gomr.boemre.gov/homepg/regulate/environ/archaeological/Conditional-Archaeological-Mitigation.pdf. 

BOEM (Bureau of Ocean Energy Management), 2011b, Notice to lessees and operators (NTL) of federal oil and gas 

leases and pipeline right-of-way (ROW) holders on the outer continental shelf (OCS), Revisions to the list of OCS lease 

blocks requiring archaeological resource surveys and reports: U. S. Department of the Interior, Bureau of Ocean 

Energy Management, Bureau of Safety and Environmental Enforcement Gulf of Mexico Region (GOMR), NTL 2011-

JOINT-G01. Effective Date December 29, 2011. 
Project No. 0212-2051 

Anadarko Petroleum Corporation // March 28, 2012

Geoscience Earth & Marine Services, Inc. ® // 7 

FORUM ENERGY TECHNOLOGIES, INC.

BOEM (Bureau of Ocean Energy Management), 2012a, ASCII Data Files, published on the BOEMRE Gulf of Mexico 

Region Homepage: <http://www.gomr.boem.gov/homepg/pubinfo/freeasci/freedesc.html >, Accessed Jan, 2012. 

BOEM (Bureau of Ocean Energy Management), 2012b, Safety performance review-Shallow Waterflows Can Pose 

Significant hazards to deepwater drilling, http://www.gomr/mms.gov/homepg/offshore/sftey/watrflow.html website 

accessed Jan, 2012. 

C & C Technologies, Inc., 2011, Archaeological Assessment Report; Nansen, Eriksson, and Mawson Exploration 

Prospect, Blocks 602 (OCS-G-14205), 645 (OCS-G-32822), and 646 (OCS-G-20725), East Breaks Area, Gulf of 

Mexico, Project No. 110397. 

Geoscience Earth & Marine Services, Inc.®

 (GEMS), 2010, Geologic and stratigraphic assessment, blocks 689 and 

690, East Breaks Area, Gulf of Mexico, Project No. 0610-1788. 

Geoscience Earth & Marine Services, Inc.® (GEMS), 2007, Geologic and stratigraphic assessment, block 646 (OCS G20725), East Breaks Area, Gulf of Mexico, Project No. 0607-1352. 

Geoscience Earth & Marine Services, Inc.® (GEMS), 2009, Geologic and stratigraphic assessment, blocks 602 and 

645, East Breaks Area, Gulf of Mexico, Project No. 0409-1634. 

Minerals Management Service, 2005, Notice to lessees and operators of federal oil, gas, and sulphur leases and 

pipeline right-of-way holders in the outer continental shelf, Gulf of Mexico OCS region, Archaeological resource surveys 

and reports: U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2005-G07. 

Minerals Management Service, 2008a, Notice to lessees and operators of federal oil, gas, and sulphur leases and 

pipeline right-of-way holders in the outer continental shelf, Gulf of Mexico OCS region, information requirements for 

exploration plans and development operations coordination documents: U. S. Department of the Interior, Minerals 

Management Service, Gulf of Mexico, NTL 2008-G04. 

Minerals Management Service, 2008b, Notice to lessees and operators of federal oil, gas, and sulphur leases and 

pipeline right-of-way holders in the outer continental shelf, Gulf of Mexico OCS region, shallow hazards requirements: 

U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2008-G05. 

Minerals Management Service, 2008c, Notice to lessees and operators of federal oil, gas, and sulphur leases in the 

outer continental shelf, Gulf of Mexico OCS region; remotely operated vehicle surveys in deepwater, U. S. Department 

of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2008-G06. 

Minerals Management Service, 2009, Notice to lessees and operators of federal oil and gas leases and pipeline rightof-way holders on the outer continental shelf, Gulf of Mexico OCS region, Military Warning and Water Test Areas: U. 

S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2009-G06. Effective Date April 22, 

2009. 

Minerals Management Service, 2010, Notice to lessees and operators of federal oil and gas leases in the outer 

continental shelf, Gulf of Mexico OCS region, deepwater benthic communities: U. S. Department of the Interior, 

Minerals Management Service, Gulf of Mexico, NTL 2009-G40. Effective Date January 27, 2010. 

Line:

Trace:

Horizontal

Distance (ft):

Figure EB690-FF-1. Inline 869 and Crossline 2419 Showing Conditions Beneath Proposed Wellsite EB690-FF

NORTH SOUTH

CROSSLINE 2419

TWO-WAY 

TRAVEL 

TIME (SEC)

PROPOSED 

WELLSITE EB690-FF

TWO-WAY 

TRAVEL 

TIME (SEC)

WEST EAST

Filename: 122051_fig_EB690-FF-1.cdr

PROPOSED 

WELLSITE EB690-FF

Project No. 0212-2051

INLINE 869

Line:

Trace:

Horizontal

Distance (ft):

EB

690

EB

646

SEAFLOOR

HORIZON 10

HORIZON 20

HORIZON 30

HORIZON 40

100ms

(~250 ft)

Scale

5000 ft

SEAFLOOR

HORIZON 10

HORIZON 20

HORIZON 30

HORIZON 40

100ms

(~250 ft)

Scale

5000 ft

Peak

Trough

RELATIVE AMPLITUDE

Peak

Trough

RELATIVE AMPLITUDE

EB

690 STUDY AREA

STUDY AREA

HUMPHRIES

BASIN
Line:

Trace:

Horizontal

Distance (ft): TWO-WAY TRAVEL TIME (SEC)

WATER

FLOW AND

GAS

POTENTIAL

Shallow Water Flow and Gas Potential

HIGH

0 1 2 3

0 = NEGLIGIBLE

1 = LOW

2 = MODERATE

3 = HIGH

HORIZON 30

-4,139

NEGLIGIBLE

Horizon Lithology/Stratigraphy

Figure EB690-FF-2. Tophole Prognosis Chart, Proposed Wellsite EB690-FF, East Breaks Block 690

Potential Drilling

Constraints

Project No. 0212-2051 Filename: 122051_fig_EB690-FF-2.cdr

Water 

Flow

Gas

3-D Seismic Section Through

Proposed Wellsite EB690-FF

X = 1,161,353 FT; Y = 9,915,070 FT

 Inline 869 at Crossline 2419

W E

469

Horizon

TWT

(sec, bml)

Depth

(ft, bml)

Depth

(ft, bss)

INLINE 869

HORIZON 20

-4,608 0.161

-7,468 3,329 1.036

Proposed

Wellsite EB690-FF

-6,905 2,766 0.875

Horizon

TWT

(sec, bss)

1.694

1.855

2.730

2.569

SEAFLOOR

HORIZON 10

HORIZON 40

-4,936 797 0.270 1.964

-6,091 1,952 0.634 2.328

INTERFACE -8,089 3,950 1.209 2.903

-8,535 4,396 1.331 3.025

-9,564 5,425 1.606 3.300

LIMIT OF

INVESTIGATION

INTERFACE

INTERFACE

EB

690

There is a negligible potential for high-density benthic 

communities within 2,000 ft of the proposed location.

Negligible potential for shallow water flow and shallow gas.

Moderate potential for shallow water flow. 

Low potential for shallow gas.

Low potential for shallow water flow and shallow gas.

Moderate potential for shallow water flow and shallow 

gas.

Low potential for shallow water flow and shallow gas.

Stratified hemipelagic silts and clays with thin, muddy

turbidities. 

Predominantly clay-rich mass-transport deposits. 

Interbedded mass-transport and channel deposits. 

Clay-rich, contains silts and probable thin sand seams.

Interbedded turbidites and mass-transport deposits. 

Clay-rich, contains silts and possible thin sand seams.

Slope-fan turbidite deposits interbedded with clay-rich 

mass-transport deposits. Potential sand seams likely. 

Unit may correlate to regional GB Orange Unit.

Clay-rich mass-transport deposits with thin possible 

sands and silts. 

Negligible potential for shallow water flow and shallow gas.

Moderate potential for shallow water flow and shallow 

gas.

Potential sand-prone turbidite deposits.

Trough Peak

RELATIVE AMPLITUDE

Predominantly clay-rich turbidites and gravity flow 

deposits, with possible thin sand layers or seams.

Low potential for shallow water flow.

Negligible potential for shallow gas.
10615 Shadow Wood Drive 

Suite 200 

Houston, Texas 77043 

(713) 468-1410 (o) 

(713) 468-1438 (f) 

www.gemsinc.com

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March 28, 2012 Project No. 0212-2051 

Anadarko Petroleum Corporation 

1201 Lake Robbins Drive 

The Woodlands, TX 77380 

Attention: Mr. Rick Kincaid 

Site Clearance Letter 

Proposed Wellsite EB690-JJ 

Block 690 (OCS G-22296) 

East Breaks Area, Gulf of Mexico 

Anadarko Petroleum Corporation, (Anadarko) plans to drill an exploration well in Block 690 of the East 

Breaks (EB) area, Gulf of Mexico. This letter addresses specific seafloor and subsurface geologic and 

stratigraphic conditions to a depth of approximately 5,717 ft below the mudline (bml) at the Proposed 

Wellsite EB690-JJ location. The following discussion is based on findings provided within the geohazard 

reports “Geologic and Stratigraphic Assessment, Block 689 and 690, East Breaks Area, Gulf of Mexico” 

(GEMS Report No. 0610-1788), “Geologic and Stratigraphic Assessment, Blocks 602 and 645, East 

Breaks Area, Gulf of Mexico” (GEMS Report No. 0409-1634), and “Geologic and Stratigraphic Assessment, 

Block 646 (OCS G-20725), East Break Area, Gulf of Mexico” (GEMS Report No. 0607-1352). The report 

findings are supplemented with AUV subbottom profiler and side-scan sonar data acquired by C & C 

Technologies, Inc. in 2011. The AUV data covers much of eastern EB 645 and western EB 646, but only 

the northern 1,700 ft of blocks EB 689 and 690. 

The surface location for Proposed Wellsite EB690-JJ is in the northwest corner of Block 690, East Breaks 

area, Gulf of Mexico. The coordinates for the proposed location are as follows: 

Proposed Wellsite EB690‐JJ

Spheroid & Datum: Clarke 1866, NAD27 

Projection: UTM Zone 15 North, U.S. ft 

Line 

Reference 

Block Calls 

EB 690 

X: 1,156,904 ft Latitude: 27o 18' 58.85917"N Inline 872 584 ft FWL 

Y: 9,915,286 ft Longitude: 94o 29' 22.10101"W Crossline 2311 554ft FNL 

Anadarko may drill this well using a moored vessel. An exact anchor pattern for the proposed well location 

is undetermined at this time. An anchor radius representing a typical maximum length of chain and anchor 

on bottom is displayed at 12,000 ft from the proposed wellsite. A 1,000 ft buffer zone beyond the limits of 

the anchor radius is also included, NTL 2009-G40 (MMS, 2010). 

Attachments 

The 1:12,000 scale-maps and page-size figures accompanying this letter have been extracted from the 

main report’s original maps and 3-D data volume and centered on the proposed well location. 

Map EB690-JJ-1: Bathymetry Map 

Map EB690-JJ-2: Seafloor Rendering 

Map EB690-JJ-3: Seafloor Amplitude Rendering 

Map EB690-JJ-4: Geologic Features Map 

Figure EB690-JJ-1: Inline 872 and Crossline 2311 Showing Conditions Beneath Proposed 

Wellsite EB690-JJ 
Project No. 0212-2051 

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FORUM ENERGY TECHNOLOGIES, INC.

Figure EB690-JJ-2: Tophole Prognosis Chart, Proposed Wellsite EB690-JJ, East Breaks Block 

690 

Figure EB690-JJ-3: Side-Scan Sonar Mosaic Showing Seafloor Conditions in the Vicinity of 

Proposed Wellsite EB690-JJ 

Figure EB690-JJ-4: Subbottom Profiler Line 2002 Showing Near-Surface Conditions Beneath 

Proposed Wellsite JJ 

NTL Requirements

The following report complies with the Bureau of Ocean Energy Management (BOEM; formerly the MMS) 

Notice to Lessees (NTL’s) 2009-G40, 2008-G04, and 2008-G05 (MMS, 2010 and 2008a, b). The proposed 

wellsite will be required to follow NTL 2008-G06 with respect to pre- and post-spud ROV visual inspection 

surveys (MMS, 2008c). The Federal lease block EB 690 is not included in the listing of archaeologically 

significant blocks (BOEM, 2011b); therefore, survey requirements for archaeological assessments as set 

forth in NTL 2005-G07 (MMS, 2005) are not necessary. To comply with pre-seabed disturbance mitigation 

requirements (BOEM, 2011a), Anadarko elected to perform a high-resolution geophysical survey in the 

area utilizing an autonomous underwater vehicle (AUV). C & C Technologies, Inc. prepared an 

archaeological assessment using these data (C & C Technologies Inc., 2011). 

Power Spectrum. According to NTL 2008-G05 (MMS, 2008b), 3-D seismic reflection data may be used for 

shallow hazard assessments with approval from the BOEM, Gulf of Mexico Region. A power spectrum analysis 

was conducted from the 3-D seismic data cube provided by Anadarko to illustrate the data parameters. The 

power spectrum curve (below) was generated within a 500-ft radius of the intersection of the inline and crossline 

at the proposed wellsite location. 

Power Spectrum Analysis Curve, EB 690, Proposed Wellsite JJ 

The 3-D seismic volume used to assess the shallow hazards for this assessment possesses frequencies of 

50 Hz and above. The same volume was used for wellsites previously permitted and drilled in adjacent 

blocks by Anadarko. 
Project No. 0212-2051 

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Man-Made Features

Anadarko’s Nansen SPAR is the closest platform to the proposed wellsite. The SPAR is located in the 

southern portion of EB 602 approximately 3.75 miles north-northeast of the proposed wellsite. The SPAR 

is the surface location to several wells in the Nansen field and serves as the hub for several infield and 

export pipelines within and around the Nansen field (BOEM, 2012a). Several existing well locations are 

located near the proposed wellsite (Maps EB690-JJ-1 through JJ-4). Existing locations within a 13,000-ft 

radius around the proposed location include: 

Surface Area /

Block

Well Name Operator Well Status Distance / Direction

from Proposed

Surface Location

EB 646 SS001 

Anadarko 

Petroleum 

Corporation 

Completed 2,111 ft/Northnortheast 

EB 646 SS006 

Anadarko 

Petroleum 

Corporation 

Plugged and 

Abandoned 

2,165 ft/Northnortheast 

EB 645 001 

Maxus (U.S.) 

Exploration 

Company 

Plugged and 

Abandoned 3,993 ft/Northwest 

EB 689 001 

Shell 

Deepwater 

Development 

Inc. 

Plugged and 

Abandoned 4,471 ft/Southwest 

EB 690 001 

Anadarko 

Petroleum 

Corporation 

Completed 7,392 ft/Southeast 

Several pipelines and umbilicals lie near the Proposed EB690-JJ wellsite location (Maps EB690-JJ-1 

through JJ-4). Anadarko’s 4-inch umbilical and 6-inch oil and gas pipelines lie from 732 ft to 1995 ft 

northeast of the proposed location. The pipelines and umbilical originate from Anadarko’s EB 690 #001 

well and trend to the northwest to the Anadarko SS006/001 well completions in EB 646. The lines then 

continue northeast through EB 646 to the Nansen SPAR in EB 602. Another umbilical originates from the 

SPAR and extends back to the same well completion in EB 646. 

An Anadarko 3-inch umbilical and a 6-inch oil pipeline also tie-in at the Anadarko SS006/001 well 

completions in EB 646. These structures originate from the EB 646 SS007/SS008 well completions in the 

north-central portion of EB 646 and trend to the southwest to the SS006/001 well completions. The EB 646 

SS007/SS008 well completions are approximately 2.8 mi north-northeast of the proposed wellsite and are 

outside the 13,000 ft radius around the proposed wellsite. However, the southern portions of the pipeline 

and umbilical extending from these structures will be within this area. The pipeline and umbilical lie 2,009 ft 

and 2,209 ft east and northeast of the proposed wellsite, respectively. 

Williams Field Services’ 12-inch oil and 12-inch gas export pipelines are located 4,170 ft and 4,376 ft, 

respectively, west-northwest of the proposed location in the northwest portion of EB 690. The pipelines 

start at a well completion in EB 599 and trend southeast across EB 644 and into EB 689. In EB 689 the 

pipelines curve to a northeast heading across the eastern portion of EB 645 and northwestern portion of 

EB 646. The pipelines stay on this north-easterly heading to the termination point with the Nansen SPAR 

in EB 602. 

The pipelines are visible on the side-scan sonar and subbottom profiler data (Figures EB690-JJ-3 and 

JJ-4). Anchor scars extending from previous wellsites and possibly pipeline barges occur along the 

seafloor near the proposed EB 690-JJ wellsite (Figure EB690-JJ-3). 

Eleven military warning areas are located within the Gulf of Mexico. These areas represent regions where 

the U.S. Department of Defense conducts various testing and training operations. Lessees within military 

warning areas are required to enter into an agreement with the appropriate command headquarters 

concerning the control of electromagnetic emissions and the use of boats and aircraft within the warning 
Project No. 0212-2051 

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area (NTL 2009-G06, MMS 2009). East Breaks Block 690 is within the active W-602 and W-147E Military 

Warning Areas. Coordination of field operations with the appropriate commands may be necessary. The 

command headquarters information is:

Military Warning Area W-602 

Strategic Command Wing 1, Fleet Area Reconnaissance 4; Operations Department 

Tinker Air Force Base 

Oklahoma City, Oklahoma 73145-8704 

Telephone: (405) 739-5700/4527 

Military Warning Area W-147E 

Air Field Management 

14657 Sneider St. 

Houston, Texas 77034-5586 

Telephone: (281) 929-2142 

Wellsite Conditions 

The surface location is clear of any constraining geologic conditions within a 2,000 ft radius from the 

proposed wellsite. 

Water Depth and Seafloor Conditions. The water depth at the proposed location is approximately -

3,944 ft (Map EB690-JJ-1). The seafloor slopes to the east at about 2.2. The proposed location lies on 

the western side of Humphries Basin and east of the highly faulted region along the rim of the basin (Maps 

EB690-JJ-1 through JJ-4). The seafloor at the proposed site is relatively smooth and featureless. The 

near-surface sediments are expected to be normally-consolidated, soft clays, forming a drape over the 

area. 

Deepwater Benthic Communities. No significant chemosynthetic or other benthic type communities are 

reported within EB 690 (MMS, 2010). The nearest recorded community to the proposed wellsite location is 

in the northwest portion of EB 602, over 5 miles to the northwest. The 3-D seismic data show no 

indications of hydrocarbon seepage within 2,000 ft of the proposed EB690-JJ wellsite location (Figures 

EB690-JJ-1 and JJ-2). The Seafloor Amplitude Rendering (Map EB690-JJ-3) shows normal (ambient) 

background amplitudes at the seafloor around this location. Subbottom profiler and side-scan sonar data 

covering much of the 2,000 ft radius show no evidence of near-surface gassy sediments, high-backscatter, 

or other indications of benthic communities near the proposed location (Figures EB690-JJ-3 and JJ-4). 

AUV data was not collected in the southern third of the 2,000 ft radius (Figure EB690-JJ-3). No mounds, 

depressions, or hard bottom features occur within a 2,000 ft radius around the proposed wellsite. The 

potential for high-density chemosynthetic and other benthic communities within 2,000 ft of the proposed 

location is negligible. 

Stratigraphy. The stratigraphy at the proposed well location is illustrated on Figures EB690-JJ-1, JJ-2, 

and JJ-4. 

The subbottom profiler data show approximately 350 ft of well-stratified, hemipelagic, clay-rich, sediments 

beneath the seafloor at the proposed location (Figure EB690-JJ-4). The nearly transparent drape of 

presumably very soft, high water content pelagic clays is approximately 7 ft thick at the proposed location. 

The soils beneath the drape will gradually increase in strength and decrease in water content with depth. 

The Tophole Prognosis Chart (Figure EB690-JJ-2) shows the inline annotated with calculated depths to the 

various horizons and predicted lithology of the sequences, along with their potential for shallow water flow 

and shallow gas. In general, the sediments between the seafloor and the limit of investigation (about 

5,717 ft bml) consist of hemipelagic silts and clays, bedded turbidites, slope-fan, and mass-transport 

deposits. The shallow section, seafloor to Horizon 20 (0 ft to 724 ft bml) will likely consist of predominantly 

clays and silts. Similar sediments interbedded with thin sand layers are likely in the Horizon 20 to Horizon 

30 unit (724 ft to 1,577 ft bml). Sands are possible from Horizon 30 to the limit of investigation (5,717 ft 

bml). Potentially thick sand layers may occur within turbidites and mass-transport deposits in the Horizon 

30 to Horizon 40 sequence between 1,577 ft to 2,731 ft bml. The slope-fan deposits may correspond to the 

regional slope-fan sequence known as the GB Orange Unit. Thick sand layers may also be encountered 

from 3,075 ft to 3,646 ft bml and 4,733 ft to 5,717 ft bml (limit of investigation). 
Project No. 0212-2051 

Anadarko Petroleum Corporation // March 28, 2012

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Faults. The near-surface section shows numerous faults (Figure EB690-JJ-4). The proposed location is 

approximately 650 ft west of a buried fault. The proposed site is on the upthrown side of the buried fault; 

therefore, the surface casing will not intersect the fault plane. No faults will be intersected in the upper 

~350 ft bml (Figure EB690-JJ-4). Two seafloor faults and one buried fault will be penetrated by a vertical 

well bore in the shallow section between the seafloor and 5,717 ft bml (limit of investigation) at the 

Proposed Wellsite EB690-JJ location (Figures EB690-JJ-1 and JJ-2). The seafloor faults will be penetrated 

at 855 ft and 2,649 ft bml. The faults are about 856 ft and 2,243 ft west of the proposed wellsite location. 

The fault generally trends north to south and is downthrown to the east towards the proposed wellsite 

(Maps EB690-JJ-2 through JJ-4). 

The buried fault will be penetrated at about 5,044 ft bml. 

Potential high-amplitude zones occur along some of these faults, but not directly at the well bore/fault 

intersections. The “brightening” of amplitudes within the subsurface is an indication that gas/fluid is 

potentially migrating along the faults. We recommend caution while drilling through these faults as there is 

an increased potential for encountering gas. 

Shallow Gas and Shallow Water Flow. The potential for shallow gas and shallow water flow at this well 

location varies from negligible to moderate at the proposed wellsite (Figure EB690-JJ-2). 

Shallow Gas. A vertical well bore at the proposed well location will not penetrate any high-amplitude 

anomalies between the seafloor and at least 5,717 ft bml, the limit of investigation; Map EB690-JJ-4. The 

potential for encountering shallow gas at the Proposed Wellsite EB690-JJ is low to moderate in zones from 

Horizon 20 (724 ft bml) to the limit of investigation (Figure EB690-JJ-2). A moderate potential for 

encountering shallow gas exists in the intervals between 1,577 ft to 2,731 ft bml, 3,075 ft to 3,646 ft bml, 

and 4,733 ft to 5,717 ft bml (limit of investigation). The potential for encountering interbedded sand layers 

near the proposed wellsite is likely in these intervals. A low potential occurs in the intervals between 724 ft 

to 1,577 ft bml, 2,731 ft to 3,075 ft bml, and 3,646 ft to 4,733 ft bml. There is a negligible potential for 

encountering shallow gas in the sequences from the seafloor and Horizon 20 (724 ft bml). 

Shallow Water Flow. There is a moderate potential for shallow water flow within four sand-prone units 

(Figure EB690-JJ-2). The shallowest unit is from 724 ft to 1,577 ft bml (Horizon 20 to Horizon 30). This 

stratigraphic interval likely contains sand-prone, bedded turbidite deposits. Drilling reports indicate the 

Maxus EB 645 #001 well, approximately 3,993 ft northwest of the proposed wellsite, experienced shallow 

water flow conditions within this shallow turbidite sequence (BOEM, 2012b). Similar stratigraphic 

conditions can also be correlated to the Anadarko SS007/SS008 wells in the northwestern portion of 

EB 646, the SS006/001 wells in the southwestern portion of the block, and the Anadarko #001 in the northcentral portion of EB 690. These wells did not report shallow water flow from the shallow sequence 

(BOEM, 2012b). However, we recommend designing your casing program to take into account the 

potential for shallow water flow within this interval. 

The next stratigraphic interval with a moderate potential for shallow water flow is between 1,577 ft to 

2,731 ft bml and consists of stacked, slope-fan and turbidite deposits. These deposits may correlate with 

the regional, slope fan sequence known as the Garden Banks (GB) Orange Unit. A moderate potential for 

shallow water flow also exists within the sand-prone intervals from 3,075 ft to 3,646 ft bml and from 4,733 ft 

to the limit of investigation at 5,717 ft bml (Figure EB690-JJ-2). Although existing wells within and adjacent 

to EB 690 did not report shallow water flow from similar intervals, continuous sand seams could be present, 

some of which may be overpressured. 

The potential for shallow water flow is low from 2,731 ft to 3,075 ft bml and 3,646 ft to 4,733 ft bml. Sands 

may be present within these intervals; however, they are not likely to be significantly overpressured. The 

remaining stratigraphic sequences at the proposed wellsite have a negligible potential for encountering 

shallow water flow. 

Anchor Locations 

A 13,000-ft radius (12,000 ft maximum anchor spread as required during hurricane season plus a 1,000 ft 

buffer zone) is outlined on Maps EB690-JJ-1 through JJ-4 to represent an area that may be impacted by a 

generic anchoring configuration. The radius is the basis for clearance of seafloor conditions relating to 

anchoring considerations. 
Project No. 0212-2051 

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Water depths within the potential 13,000 ft mooring area range from about -3,290 ft to -4,580 ft (Map 

EB690-JJ-1). The northwest portion of the anchor radius is highly-faulted and irregular. The irregular 

seafloor conditions in these areas are associated with several seafloor faults that occur within a large, 

northeast-southwest trending fault system along the western flank of Humphries Basin (Map EB690-JJ-2). 

Seafloor mounds are also present. The seafloor across the western, southern, and eastern areas is 

generally smooth and featureless. 

Slopes along the various fault escarpments range from approximately 3° to 46°. Irregular and mounded 

seafloor downdip of the faults, particularly in the north-central portion of the anchor radius, are likely the 

result of localized slumping from oversteepening along the faults. 

The seafloor in the far western portion of the radius gently dips to the southwest in EB 645 and southeast in 

the northern portion of EB 689. The seafloor in the southern portion dips to the northeast across most of 

EB 689 and to the east in EB 690 at about 2° to 5°. The northeast dipping seafloor in EB 689 is the result 

of a topographic high centered in block EB 733 to the south. The seafloor in the eastern portion of the 

radius dips to the east into Humphries Basin. Average gradients within this area range from 2o to 5o. 

There is one small seafloor amplitude anomaly observed within the probable radius for this wellsite 

(Map 690-JJ-3). This anomaly lies along a fault in EB 646 approximately 2 miles north-northeast of the 

proposed wellsite. AUV side-scan sonar and subbottom profiler data reveal high-backscatter intensity and 

near-surface acoustic voids near the anomaly. Benthic communities are possible within these patches; 

however, significant high-density communities are unlikely. We recommend that the anomaly be avoided 

by at least 500 ft when planning an anchor mooring pattern. Four seafloor mounds exist in the 

northwestern quadrant of the anchor radius along the eastern margin of EB 645. These mounds occur 

along the downthrown side of the seafloor fault escarpments, approximately 7,920 ft to 10,913 ft northnorthwest of the proposed wellsite. No elevated amplitude responses at the seafloor are associated with 

these features in the 3D data. High-resolution AUV data reveals high-sonar backscatter and near-surface 

acoustic voids, indicating gassy sediment near these seafloor mounds. We recommend that the mounds 

be avoided by at least 500 ft when planning an anchor mooring pattern at this location. 

Elevated amplitudes within the southeast quadrant of the anchor radius are data artifacts and do not 

represent any potential hazards that require avoidance. 

Closing 

The Proposed Wellsite JJ in East Breaks Block 690 appears suitable for exploration drilling operations. 

However, caution is advised while drilling through potentially sand-prone intervals identified from 724 ft to 

2,731 ft bml, 3,075 ft to 3,646 ft bml, and from 4,733 ft to the limit of investigation at 5,717 ft bml. Shallow 

water flow is more likely to be encountered within these stratigraphic units. 

Caution is advised while drilling through the faults at 855 ft, 2,649 ft, and 5,044 ft bml where gas may be 

encountered along the fault planes. We recommend avoiding the seafloor mounds north-northwest of the 

proposed wellsite when planning an anchor mooring pattern for this location. 

We appreciate the opportunity to be of service to Anadarko Petroleum Corporation and look forward to 

working closely with you on other projects. 

 Sincerely, 

 GEOSCIENCE EARTH & 

 MARINE SERVICES, INC. ®

Lisa A. Majzlik Daniel Lanier 

Geoscientist Vice President - Geoscience 

Attachments: (4 Maps and 4 Figures) 
Project No. 0212-2051 

Anadarko Petroleum Corporation // March 28, 2012

Geoscience Earth & Marine Services, Inc. ® // 7 

FORUM ENERGY TECHNOLOGIES, INC.

Distribution: Mr. Rick Kincaid, Anadarko Petroleum Corporation, The Woodlands, TX (6 copies) 

References: 

Bureau of Ocean Energy Management (BOEM), 2011a, Pre-Seabed Disturbance Survey Mitigation 

<http://www.gomr.boemre.gov/homepg/regulate/environ/archaeological/Conditional-Archaeological-Mitigation.pdf. 

BOEM (Bureau of Ocean Energy Management), 2011b, Notice to lessees and operators (NTL) of federal oil and gas 

leases and pipeline right-of-way (ROW) holders on the outer continental shelf (OCS), Revisions to the list of OCS lease 

blocks requiring archaeological resource surveys and reports: U. S. Department of the Interior, Bureau of Ocean 

Energy Management, Bureau of Safety and Environmental Enforcement Gulf of Mexico Region (GOMR), NTL 2011-

JOINT-G01. Effective Date December 29, 2011. 

BOEM (Bureau of Ocean Energy Management), 2012a, ASCII Data Files, published on the BOEMRE Gulf of Mexico 

Region Homepage: <http://www.gomr.boem.gov/homepg/pubinfo/freeasci/freedesc.html >, Accessed Jan, 2012. 

BOEM (Bureau of Ocean Energy Management), 2012b, Safety performance review-Shallow Waterflows Can Pose 

Significant hazards to deepwater drilling, http://www.gomr/mms.gov/homepg/offshore/sftey/watrflow.html website 

accessed Jan, 2012. 

C & C Technologies, Inc., 2011, Archaeological Assessment Report; Nansen, Eriksson, and Mawson Exploration 

Prospect, Blocks 602 (OCS-G-14205), 645 (OCS-G-32822), and 646 (OCS-G-20725), East Breaks Area, Gulf of 

Mexico, Project No. 110397. 

Geoscience Earth & Marine Services, Inc.®

 (GEMS), 2010, Geologic and stratigraphic assessment, blocks 689 and 

690, East Breaks Area, Gulf of Mexico, Project No. 0610-1788. 

Geoscience Earth & Marine Services, Inc.® (GEMS), 2007, Geologic and stratigraphic assessment, block 646 (OCS G20725), East Breaks Area, Gulf of Mexico, Project No. 0607-1352. 

Geoscience Earth & Marine Services, Inc.® (GEMS), 2009, Geologic and stratigraphic assessment, blocks 602 and 

645, East Breaks Area, Gulf of Mexico, Project No. 0409-1634. 

Minerals Management Service, 2005, Notice to lessees and operators of federal oil, gas, and sulphur leases and 

pipeline right-of-way holders in the outer continental shelf, Gulf of Mexico OCS region, Archaeological resource surveys 

and reports: U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2005-G07. 

Minerals Management Service, 2008a, Notice to lessees and operators of federal oil, gas, and sulphur leases and 

pipeline right-of-way holders in the outer continental shelf, Gulf of Mexico OCS region, information requirements for 

exploration plans and development operations coordination documents: U. S. Department of the Interior, Minerals 

Management Service, Gulf of Mexico, NTL 2008-G04. 

Minerals Management Service, 2008b, Notice to lessees and operators of federal oil, gas, and sulphur leases and 

pipeline right-of-way holders in the outer continental shelf, Gulf of Mexico OCS region, shallow hazards requirements: 

U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2008-G05. 

Minerals Management Service, 2008c, Notice to lessees and operators of federal oil, gas, and sulphur leases in the 

outer continental shelf, Gulf of Mexico OCS region; remotely operated vehicle surveys in deepwater, U. S. Department 

of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2008-G06. 

Minerals Management Service, 2009, Notice to lessees and operators of federal oil and gas leases and pipeline rightof-way holders on the outer continental shelf, Gulf of Mexico OCS region, Military Warning and Water Test Areas: U. 

S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2009-G06. Effective Date April 22, 

2009. 

Minerals Management Service, 2010, Notice to lessees and operators of federal oil and gas leases in the outer 

continental shelf, Gulf of Mexico OCS region, deepwater benthic communities: U. S. Department of the Interior, 

Minerals Management Service, Gulf of Mexico, NTL 2009-G40. Effective Date January 27, 2010.