15055.0

13800.0

35000 40000

1.700

1.800

1.900

2.000

2.100

2.200

2.300

2.400

2.500

2.600

2.700

2.800

2.900

3.000

3.100

3.200

3.300

3.400

Line:

Trace:

WATER

FLOW AND

GAS

POTENTIAL

Shallow Water Flow and Gas Potential

HIGH

0 1 2 3

0 = NEGLIGIBLE

1 = LOW

2 = MODERATE

3 = HIGH

NEGLIGIBLE

Horizon Lithology/Stratigraphy

Illustration MC554-A-2. Tophole Prognosis Chart, Proposed Wellsite MC554-A, Mississippi Canyon, Block 554

Potential Drilling

Constraints

Project No. 0712-2117b Filename: 122117b_ill_MC554-A-2.cdr

Water 

Flow

Gas

3-D Seismic Section Through

Proposed Wellsite MC554-A

X = 1,108,169 FT; Y = 10,319,561 FT

 Inline 15055 at Crossline 13849 

NW SE

Horizon

TWT

(sec, bsl)

Depth

(ft, bml)

Depth

(ft, bsl)

INLINE 15055

TWO-WAY TIME TRAVEL (SEC)

SEAFLOOR

HORIZON 10

HORIZON 30

HORIZON 40

0.086

1.611

0.476

0.961

205

4,819

1,260

2,732

-4,647

-4,852

-9,466

-5,907

-7,379

Proposed 

Wellsite MC554-A

INTERFACE 2 0.707 -6,595 1,948

Distance (ft):

Horizontal

Hemipelagic clay- to silt-rich sediments. 

Silt- to sand-prone turbidites. Mud-dominated rotated

slide blocks possible. 

Muddy- to sandy turbidites. Mass-transport deposits

and thick continuous sands possible. 

Moderate potential for encountering overpressured sands

and low potential for minor shallow gas.

Horizon

TWT

(sec, bml)

1.889

1.975

3.500

2.365

2.850

2.596

Sand-prone channel system. 

Mass-transport deposits underlain by muddy- to sandy

turbidites. Sand-prone erosional remnants possible

within the MTD. 

 LIMIT OF

INVESTIGATION

HORIZON 20 2.171 0.282 -5,361 714

Negligible potential for encountering overpressured sands

Mass-transport deposits (MTD) interlayered by silty- and shallow gas.

to silty-clay turbidites.

Moderate potential for encountering overpressured sands

and low potential for minor shallow gas.

Low potential for encountering overpressured sands

and minor shallow gas.

The Seafloor slopes less than 1° to the SE. There is no

potential for benthic communities within 2,000 ft of the

wellsite. The closest well lies 1.4 miles southeast of the

proposed location. No shallow water flow conditions

were reported at this location.

INTERFACE 1 2.432 0.543 -6,103 1,456 Mud-dominated turbidites. Low potential for encountering overpressured sands

and minor shallow gas.

MC 554 MC 555

UNIT 1

UNIT 2

UNIT 3

UNIT 4

UNIT 5
Project No. 0712-2117b Filen

Green circle repreradius and outer 

(A)

Expulsion 

features Faults

Grid

North

Buried rafted 

blocks

MC 554 MC 555

BACKSCATTER

Buried slump

Buried 

slump

Buried rafted 

blocks

(C) MC554-A

Faults

Grid

North

MC 554 MC 555

SEAFLOOR REND

Potential for Benthic Communities

radius and outer circle represents 11anchor radius.1,000 ft buffer beanchor radius

(A) MC554-A 1,000 ft

Illustration MC554-A-3. 

(B) MC554-A

Expulsion 

features

Faults

1,000 ft

Buried rafted 

blocks

Grid

North

SIDE-SCAN SONAR MOSAIC

MC 554 MC 555

Buried slump

High reflectivity on backscatter data irregular rocky topography on sonar dof carbonate hard grounds at expulsiomultibeam bathymetry (C), show sofeatures (mounds and depressions) radius. The presence of hard grounds growth and support of potential benthic The mound-like features associated wilack hard returns. This validates that hydrocarbon related.
10615 Shadow Wood Drive, Suite 200 

 Houston, Texas 77043

713.468.1410[o] 713.468.1438 [f] 

www.gemsinc.com 

February 20, 2013 Project No. 0712-2117b 

Apache Deepwater LLC 

2000 W. Sam Houston Parkway South 

Suite 1600 

Houston, TX 77042 

Attention: Mr. John Worthen 

Site Clearance Letter 

Proposed Wellsite MC555-B 

Block 555 (OCS-G-34445) 

Mississippi Canyon Area 

Gulf of Mexico 

Apache Deepwater LLC (Apache) contracted Geoscience Earth & Marine Services, Inc.®, (GEMS) to 

prepare a Site Clearance Letter for the proposed well location in Block 555 (OCS G-34445), Mississippi 

Canyon (MC) Area. This letter addresses specific seafloor and subsurface geologic conditions around 

the proposed location (2,000 ft radius) to the limit of investigation, 4,664 ft below the mudline (bml). 

Apache will drill the proposed MC555-B with a semi-submersible or dynamically positioned (DP) 

semi-submersible. The seabed conditions within an 11,500 ft mooring radius plus an additional 1,000 ft 

buffer zone are discussed to satisfy seabed disturbance guidelines. 

Surface conditions are clear at the proposed wellsite; however, moorings or other seabed disturbance 

activities need to avoid a potential shipwreck, possible unexploded ordnance sites, and potential sites for 

benthic communities. Sandy units with potential for shallow water flow occur at 603 ft bml (388 ft thick) 

and 1,153 ft bml (410 ft thick). 

This letter provides the following details specific to the well location: available data, attachments 

(accompanying the letter), Notice to Lessees (NTL) requirements, man-made features and archaeological 

assessment, wellsite conditions, anchoring considerations, and the conclusions and recommendations. 

Proposed Well Location and Available Data 

The proposed MC555-B surface location lies in the southern portion of MC 555 (Figure MC555-B-1). 

Apache provided the following coordinates: 

Proposed Wellsite MC555-B 

Spheroid & Datum: Clarke 1866, NAD27 

Projection: UTM Zone 16 North Line Reference Block Calls 

MC 555 

X: 1,116,591 ft Latitude: 28o 25’ 04.7836” N Inline 15110 7,791 ft FWL 

Y: 10,316,301 ft Longitude: 88o 37’ 48.1618” W Crossline 13647 4,461 ft FSL 

The details provided in this letter are based on the findings from a geohazard assessment performed by 

GEMS (GEMS, 2012). The report which was submitted to Apache in December, 2012 described the 

geologic and archaeological conditions within the Guadalupe Prospect (in Blocks 554 and 555) and 

vicinity. Apache provided two sets of geophysical data for this assessment: a conventional, 

3-D exploration seismic volume and a high-resolution Autonomous Underwater Vehicle (AUV) data. 

The detailed data specifications are provided in the main report (GEMS, 2012). Well logs and drilling 

reports from the closest existing well (ExxonMobil #1 in MC 555) to the proposed location were also 
Proposed Wellsite MC555-B Clearance Letter 

Apache Deepwater LLC // February 20, 2013

Geoscience Earth & Marine Services, Inc. ® // 2 

FORUM ENERGY TECHNOLOGIES, INC. 

provided by Apache. Integrating these data allowed a thorough analysis of potential drilling hazards 

within the suprasalt stratigraphy at the proposed wellsite. 

Attachments 

The page-size maps and accompanying illustrations were extracted from the available data provided by 

Apache. A maximum anchor radius of 11,500 ft and an additional 1,000 ft buffer zone are included on the 

maps should Apache use a moored rig to drill. The figures embedded within the body text are also 

provided below. 

Map No. MC555-B-1: Bathymetry Map 

 Map No. MC555-B-2: Seafloor Features Map 

Map No. MC555-B-3: Side-Scan Sonar Mosaic 

Map No. MC555-B-4: Geologic Features Map 

Illustration MC555-B-1: Portions of Inline 15110 and Crossline 13647 Showing Conditions Beneath 

Proposed Wellsite MC555-B 

Illustration MC555-B-2: Tophole Prognosis Chart, Proposed Wellsite MC555-B, Mississippi Canyon, 

Block 555 

Illustration MC555-B-3: Potential for Benthic Communities 

Figure MC555-B-1: Regional Rendering of Mississippi Canyon Area, Gulf of Mexico 

Figure MC555-B-2: Power Spectrum Analysis Curve, Proposed Wellsite MC555-B 

Figure MC555-B-3: Seafloor Conditions at the Proposed Wellsite 

Figure MC555-B-4: Suprasalt Stratigraphy between the Proposed Wellsite and ExxonMobil #1 

Figure MC555-B-1. Regional Rendering of Mississippi Canyon Area, Gulf of Mexico 

MC554-A

MC555-A

MC555-B

Grid

North

MISSISSIPPI CANYON

AREA

3 miles

Survey Area

AUV Survey Area

High-potential 

Archaeological Area

Chemosynthetic Area

Shallow Water flow Area

Ordnance Disposal Area

Existing Platform

Existing Well 

Proposed Well Location

Existing Pipeline/

Umbilical

MENSA

Mass-wasting Pathway

Erosional Remnants
Proposed Wellsite MC555-B Clearance Letter 

Apache Deepwater LLC // February 20, 2013

Geoscience Earth & Marine Services, Inc. ® // 3 

FORUM ENERGY TECHNOLOGIES, INC. 

NTL Requirements

The following letter complies with the Bureau of Ocean Energy Management (BOEM) Notice to Lessees 

(NTL’s) 2008-G04, 2008-G05, and 2009-G40, (MMS, 2008a, b and 2010). The requirements set forth in 

NTL 2005-G07 are applicable because the Federal lease block MC 555 is considered to be a high 

probability archaeological block (MMS, 2005 and BOEM, 2011). In compliance with NTL 2005-G07, the 

required archaeological assessment was performed by GEMS and included as an appendix in the main 

report (GEMS, 2012). 

According to NTL 2008-G05 (MMS, 2008b), 3D 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 Apache to illustrate the data parameters 

(Figure MC555-B-2). The power spectrum curve was generated within a 500 ft radius of the intersection 

of the inline and crossline at the proposed wellsite. We converted the amplitude vs. frequency spectrum, 

generated by the SMT software, to power vs. frequency by squaring the amplitude values as described by 

J. A. Coffeen, 1978. 

Figure MC555-B-2. Power Spectrum Analysis Curve, Proposed Wellsite MC555-B 

Man-Made Features and Archaeological Assessment

The surface location is clear of any wells, pipelines, or platforms within a 2,000 ft radius from the 

proposed wellsite. The closest existing well (ExxonMobil #1) is located approximately 1 mile southwest of 

the proposed wellsite location in MC 555 (Map MC555-B-1). The well was an exploratory well and is 

currently temporarily abandoned. 

GEMS delineated 15 unidentified side-scan sonar contacts in the digital data within 12,500 ft (11,500 ft 

maximum anchor radius plus 1,000 ft buffer) of the proposed MC555-B (Maps MC555-B-2 and 555-B-3). 

Side-Scan Sonar Contact Number 54 appears to represent a potential shipwreck. The contact is located 

approximately 3,350 ft southeast of the proposed wellsite and a 1,000 ft archaeological avoidance is 

recommended around the contact. No known shipwrecks or objects exist within the area of potential 

effect for the proposed well location. 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 10 20 30 40 50 60 70 80 90 100 110 120

Power (Amp

2

)

Frequency (Hz)

POWER SPECTRUM
Proposed Wellsite MC555-B Clearance Letter 

Apache Deepwater LLC // February 20, 2013

Geoscience Earth & Marine Services, Inc. ® // 4 

FORUM ENERGY TECHNOLOGIES, INC. 

None of the other 14 contacts appear to represent cultural resources. A 100 ft shallow hazard avoidance 

is recommended around these contacts. 

Table 1. Sonar Contacts Located Within 12,500 ft of MC555-B. 

No. Area Block Length 

(ft) 

Width 

(ft) 

Height 

(ft) Shape 

X

NAD27 

(ft) 

Y

NAD27 

(ft) 

Avoidance 

Radius (ft) 

50 MC 555 11.52 4.74 0.00 Irregular 1112644.89 10312564.17 100 

51 MC 555 10.50 8.70 0.00 Linear 1113273.53 10315889.23 100 

52 MC 555 11.52 2.48 0.00 Linear 1116727.29 10314034.61 100 

53 MC 555 20.24 5.06 0.00 Linear 1118118.76 10326028.12 100 

54 MC 555 42.49 24.57 0.00 Irregular 1119186.80 10314174.41 1,000 

83 MC 598 10.86 2.65 0.00 Linear 1106972.13 10311235.93 100 

86 MC 599 17.16 18.29 0.00 Irregular 1110651.55 10309177.14 100 

87 MC 599 14.68 5.20 0.00 Linear 1111038.82 10307413.92 100 

89 MC 599 15.74 5.94 0.00 Linear 1113261.85 10308889.05 100 

90 MC 599 14.45 5.44 0.00 Irregular 1113277.50 10307382.10 100 

92 MC 599 24.83 10.87 0.00 Irregular 1114680.48 10304007.50 100 

96 MC 599 23.71 3.62 0.00 Linear 1118313.18 10307641.22 100 

97 MC 599 20.33 12.87 0.00 Irregular 1119403.37 10304658.58 100 

101 MC 599 14.27 1.82 0.00 Linear 1120853.43 10311828.55 100 

105 MC 599 11.97 2.04 0.00 Linear 1121888.67 10309038.72 100 

*Blue indicates a recommended archaeological avoidance. 

Wellsite Conditions

The proposed surface location is clear of any constraining seafloor geologic conditions as defined by the 

available geophysical data. MC555-B is expected to intersect a buried fault. The potential for encountering 

significant amounts of shallow gas is low. However, there is a moderate potential for encountering shallow 

water flow within possible overpressured sands. 

Water Depth and Seafloor Conditions

The water depth at the proposed surface location is approximately -4,760 ft and the seafloor slopes 

southeast at less than 3° (Map MC555-B-1). Side-scan sonar data show that the seabed in the vicinity of 

the proposed wellsite is primarily characterized by uniform low reflectivity (Map MC555-B-3). The low 

reflectivity is likely associated with very soft clays. 

The proposed wellsite MC555-B is located along a relatively shallow mass-wasting pathway trending 

northwest-southeast across the Survey Area (Figure MC555-B-1 and Map MC555-B-2). The hummocky 

topography within the vicinity of the proposed location represents the seafloor expression of buried slumps. 

The slumps are buried by more than 100 ft of strata (Figure MC555-B-3, GEMS, 2012). Mound-like 

features in the same area are associated with rafted blocks within the mass-transport deposits (MTD) matrix 

and are not hydrocarbon related (GEMS, 2012). A drainage feature (gully) located approximately 547 ft to 

the southwest suggests low-level sediment transport activities in the recent geologic past (> 10,000 yrs), 

Figure MC555-B-1. 
Proposed Wellsite MC555-B Clearance Letter 

Apache Deepwater LLC // February 20, 2013

Geoscience Earth & Marine Services, Inc. ® // 5 

FORUM ENERGY TECHNOLOGIES, INC. 

Figure MC555-B-3. Seafloor Conditions at the Proposed Wellsite 

Deepwater Benthic Communities 

BOEM and BSEE did not designate Federal lease Block MC 555 as having high-density deepwater 

benthic communities (MMS, 2010). There are no apparent geophysical indicators at the seafloor or at 

depth that would suggest conditions capable of supporting significant deepwater benthic communities 

within 2,000 ft of the proposed wellsite (Maps MC555-B-2 and MC555-B-3). 

Stratigraphy 

Stratigraphic conditions are shown on Illustrations MC555-B-1 and 555-B-2. The lithology at the 

proposed wellsite was inferred by integrating the seismic facies with the well log response at the existing 

well, ExxonMobil #1. Generally, the suprasalt seismic facies were correlated across both locations; 

however, the interlayered silty-sandy layer within Unit 5 appears thinner at the proposed location 

(Figure MC555-B-4). The sediments below the seafloor to the limit of investigation (4,664 ft bml or 

-9,423 ft bsl) consist primarily of hemipelagic clays, muddy- to sand-prone turbidites, slope fan deposits, 

and mass-transport deposits. 

The shallow stratigraphy (Seafloor to Horizon 10, Unit 1) is interpreted to be hemipelagic clay- to silt-rich 

sediments down to approximately 198 ft bml. The sediment units between Horizon 10 and Horizon 30 

(Units 2 and 3) are dominated by mass-transport deposits (MTD) with intermittent silty- to sandy turbidites 

to approximately 991 ft bml. Sand-prone erosional remnants from older strata are possible within the 

MTD matrix. Unit 3 is associated with a regional basin-floor fan system known as the “Blue Unit” (GEMS, 

2012). The low gamma ray log response (inferring sand) at ExxonMobil #1 suggests that there is a high 

potential for sandy turbidites within the Blue Unit between 603 ft bml and 991 ft bml (Figure MC555-B-4). 

A sand-prone slope fan system occurs in the middle portion of Unit 4 (Horizon 30 to Horizon 40). 

A vertical borehole at the proposed location will intersect the slope fan sediments from approximately 

1,153 ft bml to 1,563 ft bml. The upper portion of the strata (between 991 ft bml to 1,153 ft bml) 

comprises of mud-dominated turbidites, while the lower portion (between 1,563 ft bml to 2,036 ft bml) 

comprises of mud-dominated rotated slide blocks and silt- to sand-prone turbidites. The underlying 

Proposed Wellsite MC555-B

126 ft north of AUV Line 125

Portion of AUV Line 125

Seafloor expression 

of rafted block

500 ft

Assumed velocity: 5,000 ft/sec

W E

Two-way travel time (secs)

Horizontal

Distance (ft)

10 ft

INDEX MAP

AUV Line 125

Seafloor expression of 

rafted blocks

Seafloor Rendering

Grid

North

1,000 ft

Buried slump

MC555-B 

MC 555

Mound

Fault

Circle represents

2,000 ft radius around

proposed wellsite

Gully

Buried seep features ? Mound-like features at the seabed

represent the seafloor expression of

rafted blocks within buried slumps.

The slumps are buried by more than

100 ftof strata.

The lack of direct hydrocarbon

indicators (DHI) at these sites confirm

that the features are not hydrocarbon

related. See the main report for more

details (GEMS, 2012).

Amorphous layer

Well-layered 

unit

Shallow strata comprises of

hemipelagic clay- to silt-rich

sediments.
Proposed Wellsite MC555-B Clearance Letter 

Apache Deepwater LLC // February 20, 2013

Geoscience Earth & Marine Services, Inc. ® // 6 

FORUM ENERGY TECHNOLOGIES, INC. 

strata, Unit 5 (Horizon 40 to the limit of investigation) comprises of muddy- to sandy turbidites and 

possibly MTDs. Thick, continuous sand layers are possible within this sediment unit (between 2,036 ft 

bml and 4,664 ft bml), Figure MC555-B-4. 

Figure MC555-B-4. Suprasalt Stratigraphy between the Proposed Wellsite and ExxonMobil #1 

Faults 

No seafloor faults will be encountered at the proposed wellsite location (Map MC555-B-2). However, a 

vertical wellbore at proposed wellsite MC555-B will penetrate a buried fault at approximately 3,217 ft bml 

(-7,976 ft bsl), Illustrations MC555-B-1 and 555-B-2. The fault is downthrown northwest towards the 

wellbore and is buried by up to 2,000 ft of sediments. 

Shallow Gas and Shallow Water Flow 

The scout tickets from ExxonMobil # 1 did not report any shallow geohazard conditions related to shallow 

water flow and/or shallow gas. As a result, significant shallow gas is not expected at the proposed 

wellsite; however, a moderate potential for shallow water flow is possible within the identified sand prone 

sequences (Illustration MC555-B-2). 

Shallow Gas. There are no apparent subsurface high-amplitude anomalies directly below the proposed 

location (Map MC555-B-4). Elevated amplitude responses associated with the slope fan system is more 

likely lithology related. However, minor amounts of biogenic gas accumulation could be encountered. 

There is a low potential for encountering significant accumulations of shallow gas within these sand-prone 

slope fan sediments as well as within possible sand layers between 991 ft bml to the limit of investigation 

(4,664 ft bml). The potential for encountering shallow gas is considered negligible in the clay-prone unit 

between the Seafloor and 603 ft bml. 

INDEX MAP

Seafloor Rendering

Grid

North

MC 554

2,000 ft

MC555-B 

Circle represents 2,000 ft 

radius around proposed 

wellsite

ExxonMobil #1

MC 555

MC 599

Two-way travel time (secs)

Horizontal

Distance (ft)

Proposed Wellsite 

MC555-B ExxonMobil #1

MC 555 MC 599

Arbitrary Line A-A`

5,000 ft NE SW

Seafloor

Horizon 10

Horizon 20

Horizon 30

GR R

GR - Gamma Ray

R - Resistivity

Generally, the suprasalt stratigraphy at the

existing well location (ExxonMobil #1) and the

proposed wellsite MC555-B is similar. One of

the differences observed is within Unit 5 where

the interlayered silty-sandy layer appears

thinner at the proposed location.

The 22” casing got stuck and was later jarred

free at ExxonMobil #1. The casing was stuck in

possibly clay-prone sediments within the

channel system in Unit 4.

UNIT 1

UNIT 2

UNIT 3

UNIT 4

UNIT 5

Horizon 40

SALT

Channel

Blue 

Unit

Relative Amplitude

Low High

22” casing stuck
Proposed Wellsite MC555-B Clearance Letter 

Apache Deepwater LLC // February 20, 2013

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

FORUM ENERGY TECHNOLOGIES, INC. 

Shallow Water Flow. There is a moderate potential for encountering overpressured sands within the 

Blue Unit, Unit 3 (603 ft bml to 991 ft bml) and the underlying slope fan system (1,153 ft bml to 

1,563 ft bml), Illustration MC555-B-2. Although, numerous wells in the Mississippi Canyon Area have 

experienced water flow within the Blue Unit, no such occurrence was reported at ExxonMobil #1. 

Potential overpressures may have been mitigated while drilling the well, and hence not reported. 

A low potential for shallow water flow is interpreted between 991 ft bml to 1,153 ft bml and beneath 

1,563 ft bml. The shallow, clay-rich sediments (Seafloor to 603 ft bml) are considered to have a negligible 

potential for shallow water flow. 

Anchoring Considerations

The 11,500 ft radius outlined on the accompanying maps represents the area of potential effect for 

anchoring. An additional 1,000 ft buffer zone is also included. The following discussions address the 

seafloor conditions related to anchoring considerations within the total 12,500 ft radius. 

Water Depth and Seafloor Conditions

Water depths within the potential mooring area range from about -4,580 ft to -4,984 ft (Map MC555-B-1). 

The seafloor slopes southeast with shallow water depths in the western portion of the mooring radius. 

Seafloor gradients within the mooring radius range from nearly flat to approximately 42° (GEMS, 2012). 

Most of the seafloor has low gradients (less than 3°). 

Irregular seafloor morphology within the potential mooring area is associated with erosion-related features 

(e.g. gullies and erosional scarps) and seep-related features (e.g. mounds and pockmarks), 

Map MC555-B-2. The hummocky seafloor across most of the remaining area represents shallow buried 

slumps and the mound-like features within the slumps represent buried rafted blocks (Figure MC555-B-3). 

Seafloor slopes associated with the erosion-related and seep-related features range from 5° to 13° 

(GEMS, 2012).

Seafloor faulting is located in the northeastern portion of the radius in central MC 555. The faults trend 

northeast-southwest, are downthrown mainly to the northeast, and bound the expulsion features. 

Seafloor offsets associated with the faults are up 50 ft with associated slopes reaching 42°. 

Deepwater Benthic Communities 

The expulsion features that exhibit high backscatter reflectivity and “rocky” topography on sonar data are 

likely associated with carbonate hard grounds (conditions conducive for benthic communities), 

Map MC555-B-3 and Illustration MC555-B-3. These expulsion features have a high potential for 

supporting densely populated benthic communities and are shown as orange polygons on 

Map MC555-B-2. The features lacking irregular topography but still exhibit high backscatter and sonar 

reflectivity represent limited hard ground areas. These sites have a lower potential for supporting seep 

communities and are shown as green polygons on Map MC555-B-2. 

BOEM requires at least a 250 ft buffer around potential benthic community sites for all proposed seafloor 

disturbances (including those caused by anchors and anchor chains), MMS, 2010. However, if seafloor 

disturbances occur within 500 ft of these sites, Apache is required to submit an as-placed anchor plat to 

BOEM. We recommend conducting an ROV investigation to confirm or deny the existence of deepwater 

benthic communities at the potential hard grounds if these areas occur near the proposed anchors or 

anchor chains. 
Proposed Wellsite MC555-B Clearance Letter 

Apache Deepwater LLC // February 20, 2013

Geoscience Earth & Marine Services, Inc. ® // 8 

FORUM ENERGY TECHNOLOGIES, INC. 

Conclusions and Recommendations

We appreciate the opportunity to be of service to Apache and look forward to working with Apache on 

future projects. The conclusions and recommendations from this assessment are as follows: 

Wellsite Conditions 

No major seafloor hazards or constraints are defined by the available data within 2,000 ft radius of the 

proposed location. Caution and possible mitigation is recommended when encountering potential 

overpressured sands between 603 ft bml to 991 ft bml, and 1,153 ft bml to 1,563 ft bml. 

Anchor Maximum Radius Conditions 

The potential seafloor constraints within the mooring radius include possible hard grounds that could 

support benthic communities and a potential shipwreck. A minimum of a 250 ft radius is recommended 

around the potential benthic communities’ sites. Other recommendations include, a 1,000 ft 

archaeological avoidance around Side-Scan Sonar Contact Number 54, and a 100 ft shallow hazard 

avoidance for the remaining 14 side-scan sonar contacts. Care should be taken near the debris trail of 

potential unexploded ordnance in MC 554 and 598. All operations must cease and BOEM notified within 

48 hours should any potentially historic materials such as textiles, wood, ceramics, or other items be 

uncovered during operations in the area. 

Sincerely, 

GEOSCIENCE EARTH & MARINE 

SERVICES, INC.®

Oluwayomi Oyedele Daniel Lanier 

Geoscientist Vice President-Geosciences 

Erin Williams Janes 

Project Manager/Senior Geoscientist 

Attachments (4 Maps and 3 Illustrations) 

Distribution: 

Mr. John Worthen, Apache Deepwater LLC (3 copies) 

REFERENCES 

Bureau of Ocean Energy Management, 2013, ASCII Data Files, published on the BOEM Gulf of Mexico Region 

Homepage, <http://www.gomr.boem.gov/homepg/pubinfo/freeasci/freedesc.html>, accessed January, 2013. 

Bureau of Ocean Energy Management, 2012, Seismic Water Bottom Anomalies Map Gallery, published on the 

BOEM Homepage, <http://www.boem.gov/Oil-and-Gas-Energy-Program/Mapping-and-Data/Map-Gallery/SeismicWater-Bottom-Anomalies-Map-Gallery.aspx>, accessed November, 2012. 

Bureau of Ocean Energy Management, 2011, 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. 
Proposed Wellsite MC555-B Clearance Letter 

Apache Deepwater LLC // February 20, 2013

Geoscience Earth & Marine Services, Inc. ® // 9 

FORUM ENERGY TECHNOLOGIES, INC. 

Coffeen, J. A., 1978, Seismic Exploration Fundamentals: Tulsa, the Petroleum Publishing Co., p. 125. 

Geoscience Earth & Marine Services, Inc.® (GEMS), 2012, Geohazard assessment, Guadalupe Prospect, blocks 554 

and 555, Mississippi Canyon Area, Gulf of Mexico, Project No. 0712-2117b. 

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, 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.