WR51 Proposed Location D 4 

### Gas Hazards. No amplitude anomalies suggestive of gassy sediments are penetrated at the proposed well site. There is a negligible risk fo r gas hazards at the pro posed well location D

. The nearest interpreted gassy sediments are about 1,360 ft NE in U nit 2

. Shallow - Water - Flow (SWF ). A negligible risk for severe SWF is assessed. There is a possible contribution of salt movement to overpressure pore fluids. However, it is not a strong driver of overpressure in thin shallow sediments that overlie the salt. Suitability for Temporary Occupation for Drilling. Proposed WR51 Location D is suitable for temporary occupation for drilling provided that the conditions and constraints that have been identified are considered and planned for in the final well design.WR51 Proposed Location D 5 

### We appreciate the opportunity to work with you on this project and look forward to continuing as your geohazards and marine geoscience consultants. Please call us at 713

- 532

- 2624 if you have any questions or if we can offer further assistance.

Sincerely,
AOA GEOPHYSICS INC.

Brenda I. Monsalve Geophysicist - Marine Geohazards Specialist

Dan McConnell, P.G. Manager - Marine G eohazards

Attachments:

• Description of 3

- D Seismic Data including Amplitude and Power Spectrum Figure and Wavelet Figure

• Figure Appendix C

- 51 D- 1: Tophole Prognosis Chart Location D , Block 5 1 , Walker Ridge Area

• Figure Appendix C - 51D- 2: 3- D Seismic Record, Line 31 695 , Location D , Block 5 1 , Walker Ridge Area

• Figure Appendix C - 51 D- 3: 3

- D Seismic Record, Crossline 31 49 , Location D , Block 51 , Walker Ridge Area

• Water Depth & Seafloor Features Showing Potential Anchor Touchdown for Proposed Well D , Walker Ridge ( WR ) 51 , and Vicinity, Gulf of Mexico, Anchor Chart D (1:12,000)WR51 Proposed Location D Description of 3

- D Seismic Data 

### Description of 3 - D Seismic Data Sets: The 3

- D seismic sur veys that have been provided to AOA Geophysics Inc., by Anadarko , are of good quality to interpret the shallow section. The 3

- D seismic data volume called VTS Walker Ridge I ( wr ph1_3d ) are interpreted around the proposed well sites and are used for most of the surface and all of the subsurface interpretation. These data are thirty

- two
- bit format. The 3

- D seismic data parameters for VTS Walker Ridge I are described in the table below:

3 - D Seismic Data **VTS Walker Ridge I (wrph1_3d) Spacing, Increment, and**  **O rientation**  Spacing Increment Orientation Inlines 41.0143 ft (12.5 m) 5 EW Traces 65.6161 ft (20 m) 1 N S **Frequency Content in Tophole Section**  Spectral analysis shows significant (0.45 to 0.65 on a normalized scale of 0 to 1) 50 Hz frequency content i n the data at each of the proposed well locations. **Reprocessed for Shallow Section?**  Yes, spectral whitening **Processed sample interval** Acquired at 2 ms - Processed at 4 ms **Acquisition Parameters** • Acquisition Contractor CGG Veritas

• Vessel Polar Princess/Polar Search

• Date Available 1998

• Source Airgun

• Streamer length 7,200 meters

• Shotpoint Interval 37. 5 meters

• CMP Xline 40 m

• Record Length 12.5 seconds

• Nominal Fold 48 **Processin g Parameters**  • Reformat

• Anti- alias filter (Minimum Phase, Out – 90 Hz)

• Resample to 4 ms

• Adjustment for differences in recording systems

• Trace edits

• Merge navigation with seismic

• Spherical divergence correction (V2T)

• Mute - First break suppression

• Gap deconvolution based on waterbottom

- Operator Length: 240 ms

- Predictive Gap: 24 ms

- 15 trace average

• Mutiple attenuation, Radon transform algorithm

• DMO velocity analysis (2 km grid)

• Bin offset regularization (Utilizing 2 km grid)

• 3D dip moveout correction on common offsets, (V(Z))

• Bin fold normalization

• Interpolation to 12.5 x 20 m bins on each common offset

• One pass phase shift migration of each offset (V(Z))

• Migration velocity analysis (Moves Velocity Analysis) 0.5 km grid

• 3D normal moveout correction (Moves Velocity Field)

• Offset weighting - based on waterbottom

• Mute - based on waterbottom

• Common mid

- point stack 12.5 x 20 m bins

• Inverse migration of MOVES stack, (V(Z))

• One pass migration with velocity model generated from inversion of mo ves velocities (GLINVEL)

• Datum correction to sea level +10 ms **Quality of Primary 3 -**  **D Data with respect to NTL Guidelines and**  **Comments** • The 32 bit data were loaded as 16 bit format for interpretation and these data show good quality.

• The data show signifi cant energy in the 50 Hz range.WR51 Proposed Location D Description of 3

- D Seismic Data • Assuming a shallow section velocity of ~5500 ft/sec at 50 Hz the limit of separability between reflectors is approximately 27.5 ft.

• There are no indications of over migration artifacts in the shallow section.

• The seabed re flector is continuous at faults and is characterized by a wavelet of stable form.

• The data are good at imaging gas.

• Faults are well imaged in the data.

### 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 90 100 110 120 130 140 A m p l i t u d e

Frequency (Hz) 

## Reprocessed Amplitude Spectrum Well WR51_D

WR51_D



### 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 90 100 110 120 130 140 P o w e r

Frequency (Hz) 

## Reprocessed Power Spectrum Well WR51_D

WR51_D

WR52D Amp and Power Spectra Report No. 4064-ANA-GOMWaveletReport No. 4064-ANA-GOM

- 0.6 - 0.4 - 0.2 0 0.2 0.4 0.6 0.8 1



### - 0.05

- 0.04

- 0.03

- 0.02

- 0.01 0 0.01 0.02 0.03 0.04 0.05 Original: 33 ft Reprocessed:27.5ft



## 0.024 sec

0.021 sec Wavelet

N o r m a l i
z e d

A m p l i t u d
e



## Time (sec)3100.0 3200.0

Trace: WR51_C

WR51_D 1027 ft

2.400

2.500

2.600

2.700

2.800 

### WR51_A WR51_A Inferred Lithology and Comments

E W Event and Unit Designations Depths BML (ft) BSS

(ft)



### TOPHOLE PROGNOSIS CHART

LOCATION D BLOCK 51, WALKER RIDGE AREA Thickness (ft) TWT BSS (s)

thole51D.cdr Hazardous Shallow Gas Risk Shallow

Water Flow Risk

TWT: Two-Way Travel Time BML: Below Mudline BSS: Below Sea Surface 3-D Seismic Record at Proposed Location D Walker Ridge Block 51 X = 2,103,179 FT, Y = 9,767,041 FT ~1000 ft LINE 31695

0 5837 2.401

280 6117 2.475

389 6226 2.504

733 6570 2.595

2264 8101 3.000 SEAFLOOR

1 280 NEGLIGIBLE NEGLIGIBLE

HOR. 1

2 109 NEGLIGIBLE NEGLIGIBLE

Topsalt

3 344 NEGLIGIBLE NEGLIGIBLE

salt 1531 NEGLIGIBLE NEGLIGIBLE 453 Seafloor slopes less than 1 degree to the east Marine clays with mass transport deposits
Mostly clay-prone sediments with possible mass transport deposits

Most clay-prone deposits with possible sand Reflectors show a chaotic feature in the unit due to the vertical and lateral salt movement. Faults may cross the wellbore in the unit, but do not have clear seismic expression.Report No. 4064-ANA-GOM-WR51DFigure Appendix C-51D-1 Slope at top of salt is 2.8o to the southwest

All depths and thicknesses are approximate and are based on drilling report of WR08#1 provided by Anadarko WR 08#1 is located 6,448 ft NE from A possible salt stringer was found 140 ft above top of salt in WR08#1 well.

Possible inclusions and rafted sediments31695.0 2700.0 31695.0 2800.0 31695.0 2900.0 31695.0 3000.0 31695.0 3100.0 31695.0 3200.0 31695.0 3300.0 31695.0 3400.0 31695.0 3500.0 Line: Trace: 10000 15000 20000 25000 30000 35000 40000 Offset: WR51_C WR51_D

2.400

2.500

2.600

2.700

2.800

2.900

3.000Report No. 4064-ANA-GOM-WR51DFigure Appendix C-51D-2



### 3-D Seismic Record, Line 31695, Location D, Block 51, Walker Ridge AreaTwo-Way Travel Time (s) 

### Unit 1

Unit 2 Seafloor

H1

Topsalt 5000 ft WR51 WR52 

### W E

Salt Possible gassy sediments Pos

R e l a t i v e

A m p l i t u d e
Neg30800.0 3149.0 31300.0 3149.0 31800.0 3149.0 32300.0 3149.0 32800.0 3149.0 Line: Trace: 10000 15000 20000 25000 30000 35000 40000 Offset: WR51_D

2.300

2.400

2.500

2.600

2.700

2.800

2.900Report No. 4064-ANA-GOM-WR51DFigure Appendix C-51D-3



### 3-D Seismic Record, Crossline 3149, Location D, Block 51, Walker Ridge Area 

### Unit 1

Unit 2 Seafloor

H1

Topsalt

Salt WR51 WR07 

### S N

Pos

R e l a t i v e

A m p l i t u d e
Neg