6784.0 33800.0 6784.0 34000.0 6784.0 34200.0 6784.0 34400.0 Line: T race: 15000 20000 25000 30000 35000 40000 1.500 1.600 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 Horizontal Distance (ft):

6600.0 34109.0 6800.0 34109.0 Line: T race: 15000 20000 25000 30000 35000 40000 1.600 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 Horizontal Distance (ft): Project No. 041 1-1924 Filename: 1 1 1924_fig_GC823-B-1.cdr



### Figure GC 823-B-1. Inline 6784 and Crossline 34109 Showing Conditions Beneath Proposed W ellsite GC 823-B 15034.839 14132.748 13230.658 12328.568 1 1426.478 10524.387 9622.297 8720.207 7818.1 16 6916.026 6013.936 51 1 1.845 4209.755 3307.665 2405.574 1503.484 601.394 -300.697 -1202.787 -2104.877 -3006.968 -3909.058 -481 1.148 -5713.239 -6615.329 -7517.419 -8419.510 -9321.600 -10223.690 -1 1 125.781 -12027.871 -12929.961 -13832.052 -15034.839RELATIVEAMPLITUDETWO-WAYTIMETRAVEL(SEC)TWO-WAYTIMETRAVEL(SEC) GC 823 GC 867 Northwest Southeast

Inline 6784 SAL T

SAL T GC 823 GC 867 Southwest Northeast SEAFLOOR HORIZON 20 HORIZON 35 HORIZON 40 T OP OF SAL T UNIT 1 UNIT 2

UNIT 3 UNIT 4

SEAFLOOR HORIZON 20 HORIZON 35

HORIZON 40

T OP OF SAL T UNIT 1

UNIT 2

UNIT 3

UNIT 4

Crossline 34109 Proposed W ellsite GC 823-B Proposed W ellsite GC 823-B

GC 866 GC 8246800.0 34109.0 Line: T race: 25000 30000 1.600 1.700 1.800 1.900 2.000 2.100 2.200 2.300 2.400 2.500 2.600 2.700 Horizontal Distance (ft): Shallow W ater Flow and Gas Potential HIGH 0 1 2 3 0 = NEGLIGIBLE 1 = LOW 2 = MODERA

TE 3 = HIGH NEGLIGIBLE



### Figure GC 823-B-2. T

ophole Prognosis Chart, Proposed W ellsite B, Green Canyon Block 823 Filename: 1 1 1924_fig_GC832-B-2.cdr Project No. 041 1-1924 3-D Seismic Section Through Proposed W ellsite B X = 2,477,578 FT; Y

= 9,854,364 FT Crossline 34109 at Inline 6784 SW NE

Crossline 34109

GC 867 PROPOSED WELLSITE BTWO-WAYTRAVELTIME (SEC) GC 823

SEAFLOOR W ater Flow GasUnit 1 HORIZON 20

HORIZON 40

T OP OF SAL TUnit 2Unit 4 1.661

1.713

INTERF ACE 1.966

2.360 -4,072

-4,207

-4,902

-6,082 135

830

2,010 135

312

1,180 Seafloor Slopes at 2.8° East.

Lithology/Stratigraphy W A TER FLOW AND GAS POTENTIAL Horizon Horizon TWT (sec, bsl) Depth

(ft, bsl) Depth (ft, bml)Units Unit

(Interval) Thickness (ft)Unit 3 Potential Drilling Constraints

F AUL T 2.080 -5,232 1,160 F AUL T 1.835 -4,538 466 HORIZON 35 1.854 -4,590 518 383

2.150 -5,439 1,367 V ery soft, pelagic drape at seafloor . Hemipelagic silty clays and thin mass-transport deposits. Alternating layers of hemipelagic silty clays with chaotic mass-transport deposits. Fault at very base of unit. Mud-rich turbidites.

T urbidites. Alternating layers of clay and silt with thin sands. Fault within top half of unit.

Chaotic sequence created by salt movement. Negligible potential for overpressured sands. Negligible potential for shallow gas. Negligible potential for overpressured sands. Negligible potential for shallow gas. Faults are possible zones of loss circulation. Low potential for overpressured sands. Low potential for shallow gas. W ater flow reported in Unit 4 at GC 823-001, 820 ft to East-Southeast. Moderate potential for overpressured sands. Low potential for shallow gas. High potential for overpressured sands. Low potential for shallow gas. Faults are possible zones of loss circulation.

T op of salt slopes 41 ° to East-Northeast SAL T

TROUGH PEAK

RELA TIVE AMPLITUDE10615 SHADOW WOOD DRIVE SUITE 200 HOUSTON, TEXAS 77043 Phone: (713) 468 - 1410

Fax: (713) 468 - 1438 E - mail: gems@gemsinc.com

- 1 - Proposed Well GC 823 - C May 20 , 2011 Project No. 0411 - 1 92 4 Apache Deepwater, LLC 2000 W. Sam Houston Pkwy. South , Suite 1600 Houston, Texas 77042 - 3622 Attention: Mr. John A. Worthen 

### Site Clearance Letter Proposed Wellsite G C 823 - C

Block 823 (OCS - G - 33854 ) Green Canyon Area Gulf of Mexico Apache Deepwater, LLC ( Apache ) plans to drill an exploration well in Block 823 , of the Green Canyon Area ( GC ), Gulf of Mexico. This letter addresses specific seafloor and subsurface geologic conditions to a depth of approximately 893 ft below the mudline ( bml ) at the Proposed Explorati on Wellsite GC 823 - C . The following discussion is based on findings provided within the main body of the geohazard report for Block s 823 and 867 ( GEMS Report No. 0411 - 1924) . The surface location for Proposed Wellsite GC 823 - C is in the northwestern quadr ant of GC 867 . Apache provided the following coordinates: Proposed Wellsite G C 823 - C Spheroid & Datum: Clarke 1866, NAD27 Projection: UTM Zone 1 5 North Line Reference Block Calls ( SL in GC 867 ) X : 2 , 476 , 973 ft Latitude: 27. 1196541357444 o N Inline 6823 2 ,9 90 ft F N L Y: 9 , 849 , 490 ft Longitude: 9 0 . 4278294471442 ° W Crossline 34007 5 , 93 3 ft F W L Apache will drill this well using a moored vessel. An exact anchor pattern for the proposed well location is undetermined at this time. Maps GC 823 - C - 1 through GC 823 - C - 4 show an anchor radius representing a typical maximum length of chain and anchor on bottom is displayed at 10,000 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, 2 009 a ). 

### Attachments The maps and 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 GC 823 - C - 1: Bathymetry Map Map GC 823 - C - 2: Seafloor Rendering Map GC 823 - C - 3: Seafloor Amplitude Rendering Map GC 823 - C - 4: Geologic Features Map Figure GC 823 - C - 1: Inline 6823 and Crossline 34007 Showing Condit ions Beneath Proposed Wellsite GC 823 - C Figure GC 823 - C - 2: Tophole Prognosis Chart, Proposed Wellsite GC 823 - C , G reen Canyon Block 823Project No. 04 11 - 1924

- 2 - Proposed Well GC 823 - C 

### NTL Requirements The following report complies with the Bureau of Ocean Energy Management, Regulation, and Enforcement (BOEMRE; formerly the MMS) Notice to Lessees (NTLs) 2008 - G04, 2008 - G05 and 2009 - G40 ( MMS, 200 8a, 2008b, and 200 9 a ). The proposed wellsite will be required to follow NTL 2008 - G06 with respect to pre - and post - spud ROV visual inspection surveys (MMS, 2008 c ). Pursuant to the recently released Pre - Seabed Disturbance Survey Mitigation issued by BOEMRE, the 2005 - G07 NTL (MMS, 2005) does not apply to GC 823/867 in terms of high - probability (MMS, 2008d) , but an archaeological assessment of the data must be performed prior to any bottom disturbing activities (BOEMRE, 2011b) . According to NTL 2008 - G05 (MMS, 2008b), 3 - D seismic reflection data may be used for shallow hazard assessments. A power spectrum analysis was conducted from the 3 - D seismic data cube provided by Apache to illustrate the data parameters. The power spectru m curve (below) was generated within a 500 - ft radius of the intersection of the inline and crossline at the proposed wellsite location, over a time interval from the seafloor to ~0.326 second below mudline, i.e., the salt/sediment interface. 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.

Power Spectrum Analysis Curve, Proposed Wellsite G C 823 - C 

### Man - Made Features There are exist ing wells in G C 823, GC 867, and in surrounding blocks. The closest well to Proposed Wellsite GC 823 - C, with a surface location in GC 867, is the BP Exploration Inc. , GC 823 - 001 well approximately 4,925 ft to the north - northeast ( GC 823 - Maps C - 1 through G C 823 - C - 4). 0 0.2 0.4 0.6 0.8

1 1.2

0 10 20 30 40 50 60 70 80 90 100Power (amp2)

Frequency (hrz) POWER SPECTRUM

GC 823 - CProject No. 04 11 - 1924

- 3 - Proposed Well GC 823 - C Other wells near the surface location of the Proposed Wellsite GC 823 - C are the BP Exploration Inc. , GC 866 - 001 and GC 823 - 001 wells. These wells are approximately 9,070 ft west and 10,485 ft east northeast, respectively, of the proposed site and lie within the proposed mooring pattern. Proposed Wellsite GC 823 - C and its anchors lie within the “Military Warning Zone W - 92”. Military warning zones typically do not have any impact on exploration drilling operations or other oilfield activities. However, some permitting issues and/or notifications to appropriate military commands need to be addressed by Apache (MMS, 2009b). Restrictions would only be enforced during military operations in the area or during an emergency. 

### Water Depth and Seafloo r Conditions T he water depth at the proposed location is - 4,158 ft (Map GC 823 - C - 1). The seafloor at the proposed location is relatively smooth and dips to the south at about 5.1  ̊. The location lies on a tilted, terrace - like area south of a narrow ridge. South of the location is an arcuate valley created by a Pleistocene slump . Water depths within the potential anchor mooring area range from about - 3,660 ft along a ridge line to the north to approximately - 5,300 ft on the upper part of the Sigsbee Escarpment to the south - southeast (Map GC 823 - C - 1). The seafloor within the potential anchoring area varies from smooth and featureless to very irregular. The seafloor irregularities include narrow ridges and gullies, faults, and mounds. Seafloor gradient within the mooring pattern will average from 1° to 5°. The highest seafloor gradients in the area are associated with fault escarpments. Gradients of over 20  ̊ are associated with fault scarps that occur primarily no rth , south, and southwest of the proposed location . The upper part of the Sigsbee Escarpment to the south will be marked by an increase in slope from 10° to over 2 5 °. Near - surface soils along the Sigsbee Escarpment are likely to be highly overconsolidated and much stronger than typical slope soils. 

### Deepwater Benthic Communities The Seafloor Amplitude Rendering based on the 3 - D data volume (Map GC 823 - C - 3) shows normal or ambient amplitude along the seabed, with no indication of any hard - bot tom or fluid expulsion events within 2,000 ft of the proposed GC 823 - C location. Based on the renderings and seismic profiles d eepwater benthic communities are not expected within 2,000 ft of the proposed GC 823 - C wellsite. Patches of high - amplitude sea floor returns occur within the 10,000 ft anchor radius. The areas of high amplitude se a floor return occur to the west, southwest , and southeast of the proposed location. The y are located between 7 , 100 and 10 , 000 ft from the location. Some of the seafloo r anomalies are associated with fault scarps (Maps GC 823 - C - 1 through GC 823 - C - 4). The zones of high - amplitude seafloor have a high potential for deepwater benthic communities. Therefore, anchors must avoid these features by at least 250 ft (MMS, 2009a). A number of seafloor faults occur within the proposed mooring pattern. The closest seafloor faults occur approximately 350 ft to the north west . Most of the fault escarpments show normal or ambient amplitude returns on the rendering created from the 3 - D d ata volume. 

### Stratigraphy Inline 6823 and Crossline 34007 are the closest 3 - D lines to the proposed GC 823 - C location (Figure GC 823 - C - 1 ). The Tophole Prognosis Chart (Figure GC 823 - C - 2 ) shows the crossline 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. The 3 - D data volume was used to define the sedimentary section to a depth of approximately 893 ft (Figures GC 823 - C - 1 and GC 823 - C - 2). The section was divided into four units or sequences (Figure GC 823 - C - 1 ). The sequences represent variations in depositional environments and possible changes in soil strength and composition.Project No. 04 11 - 1924

- 4 - Proposed Well GC 823 - C The surficial unit, Unit 1 (Seafloor to Horizon 20 ), to appro ximately 149 ft bml, consists of a very soft pelagic drape underlain with hemipelagic silty clays and thin, mass - transport deposits . Very soft clays with high water content will exist at the seabed. The soils will increase in strength and decrease in wat er content with depth. Unit 2 (Horizon 20 to Horizon 35) consists of bedded hemipelagic clays and turbidites interlayered with thin chaotic mass - transport deposits. The sediments will be mud - rich; however, some thin sand seams and pockets are possible. The combined thickness of Units 1 and 2 is approximately 500 ft (Figure GC 823 - C 2 ). Unit 3 (Horizon 35 to Horizon 40) consists of mud - rich turbidites. The top of Unit 3 , Horizon 35, is at about 500 ft bml. The unit is approximately 275 ft thick beneath GC 823 - C. Unit 4 is a sequence bounded by Horizon 40 and the top of salt (Figures GC 823 - C - 1 and GC 823 - C - 2). Generally the sequence consists of bedded turbidites and thin mass - transport deposits. At this location the unit is thin and has a chaotic chara cter. The sediments will be a mixture of clay and silt layers with thin sand or silty sand seams or pockets. Unit 4 occurs between 775 ft and 893 ft bml at the proposed location. The sequence is only about 118 ft thick. The top of salt is predicted to be 893 ft bml (~5,051 ft bsl). The salt surface dips to the east at approximately 7.2°. 

### Faults A fault will be intersected by the well bore beneath proposed Wellsite GC 823 - C (Figure s GC 823 - C - 1 and GC 823 - C - 2 ). The borehole will intersect the fault a pproximately 673 ft bml, near the base of Unit 3. 

### Shallow Water Flow Unit 2 between Horizons 20 and 35 is possibly the regional “Red Unit” slope - fan sequence. However, the top of the unit is only 149 ft bml at proposed Wellsite C (Figure GC 823 - C - 2). The entire unit is 351 ft thick. At this location, Unit 2 is an unlikely zone for overpressured sand layers. The existing GC 823 - 001 well is approximately 4 ,925 ft to the north - northeast of the proposed GC 823 - C wellsite. A “low” severity shallow water flow occurred in the GC 823 - 001 well at 1,715 ft bml ( - 5,840 ft bsl). Based on the reported depth the flow occurred in the lower portion of Unit 4 within a generally low amplitude interval of discontinuous to cha otic reflections. In addition, the interval is bounded by faults that extend from salt to the seafloor. The shallow water flow may have originated from an isolated sand pocket or layer within the chaotic interval. An alternative explanation is the flow originated in the shallower interval at the top of the unit consisting of bedded, moderate - amplitude turbidites. The flow was not observed until drilling was at the 1,715 ft level. Unit 4 at proposed GC 823 - C wellsite is very thin (118 ft thick) as well a s the entire sedimentary section above salt (893 ft). The section has been eroded as well as extensively faulted. At this location there is a low - potential for overpressured sand layers within Unit 4 or the shallower sequences. 

### Shallow Gas The well pat h will not penetrate any high - amplitude events between the seafloor and the top of salt (Figure GC 823 - C - 2). 

### Closing The seafloor and near - surface conditions at Proposed Wellsite GC 823 - C , Green Canyon Block 823 (OCS G - 33854), appear suitable for explo ration drilling operations. The existing wellsites and the potential benthic communities will need to be avoided by anchors supporting a drilling vessel at the proposed location. One fault will be encountered at depth.Project No. 04 11 - 1924

- 5 - Proposed Well GC 823 - C Sincerely, GEOSCIENCE EARTH & MARINE SERVICES, INC. ®
Thomas W. Neurauter Ph. D. Daniel Lanier Senior Marine Geologist Vice - President/Marine Geologist Attachments ( 4 Maps, 2 Figures) Distribution: Mr . John Worthen , Apache Deepwater, LLC , Houston, TX. ( 6 ) References: Bureau of Ocean Energy Management and Enforcement, 2011a , ASCII Data Files, published on the BOEMRE Gulf of Mexico Region Homepage, <http://www.gomr.mms.gov/homepg/pubinfo/freeasci/freedesc.html>, accessed May , 20 11 . Bureau of Ocean Energy Management, Regulation, an d Enforcement , 20 11b, Pre - Seabed Disturbance Survey Mitigation < http://www.gomr.boemre.gov/homepg/regulate/environ/archaeological/Conditional - Archaeological Mitigation.pdf >. Coffeen, J. A., 1978, Seismic exploration fundamentals: Tulsa, the Petroleum Publi shing Co., p. 125. 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 r eports: 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 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. Effective Date May 1, 2008. Minerals Management Ser vice, 2008 b , 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, 200 8 c , 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 Me xico, NTL 2008 - G06. Minerals Management Service, 2008 d , 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), Gulf of Mexico OCS region (GOMR), Revisions to the list of OCS lease blocks requiring archaeological resourc e surveys and reports: U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2008 - G20. Minerals Management Service, 20 09a , Notice to lessees and operators of federal oil and gas leases in the outer continental shelf, Gulf of M exico OCS region, Deepwater benthic communities: U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 200 9 - G 4 0. Minerals Management Service, 2009b, Notice to lessees and operators of federal oil and gas leases and pipeline rig ht of

- 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.