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

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 15055TWO-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 1,948 -6,595 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 and shallow gas. Mass-transport deposits (MTD) interlayered by silty- 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 0.543 1,456 -6,103 2.432 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 Filename: 122117b_ill_MC554-A-3.ppt** **Green circle represents 2,000 ft radius** **and outer** **dashed purple** (A)ExpulsionfeaturesFaultsGridNorthBuried raftedblocksMC 554 MC 555BACKSCATTERBuried slumpBuriedslumpExpulsionfeaturesBuried raftedblocks(C)MC554-AFaultsGridNorthMC 554 MC 5551,000 ftSEAFLOOR RENDERING**Potential for Benthic Communities radius** **and outer** **dashed purple** **circle represents 11,500 ft maximum anchor radius.** **1,000 ft buffer beyond maximum anchor radius** (A)MC554-A1,000 ft**Illustration MC554-A-3 .** (B)MC554-AExpulsionfeaturesFaults1,000 ftBuried raftedblocksGridNorthSIDE-SCAN SONAR MOSAICMC 554 MC 555Buried slump**High reflectivity on backscatter data (A), hard returns and irregular rocky topography on sonar data (B), are indicators** **of carbonate hard grounds at expulsion sites. The rendered multibeam bathymetry (C), show some of the expulsion** **features (mounds and depressions) within the mooring radius. The presence of hard grounds are conducive for the** **growth and support of potential benthic communities. The mound-like features associated with buried rafted blocks** **lack hard returns. This validates that the features are not 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 (Amp2)

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**

**r adius around proposed**  **wellsite** ExxonMobil #1 MC 555

MC 599**Two-way travel time (secs) Horizontal**  **Distance (ft)** Proposed Wellsite MC555-B ExxonMobil #1

**MC 599**

**MC 555**

Arbitrary Line A-A` **5,000 ft** NE SW **Seafloor**

**H orizon 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 **High Low**  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/Seismic**  **Water-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.**