UNITED STATES GOVERNMENT MEMORANDUM

To: Public Information (MS 5030)

Plans Section, Office of Field 

Operations (MS 5231)

Public Information copy of Exploration Plan

Control # - N-09583

Type - Initial Exploration Plan

Lease(s) - OCS-G33854 Block - 823 Green Canyon Area

OCS-G33858 Block - 867 Green Canyon Area

Operator - Apache Deepwater LLC

GC 823 Wells A, B and C, GC 867 Wells A through D

SEMISUBMERSIBLE

Attached is a copy of the subject plan for public comments on issues that 

should be addressed in an Environmental Assessment.

It has been deemed submitted as of this date and is under review for approval.

Chiquita Hill

Plan Coordinator

Description -

Rig Type -

Subject:

From:

October 6, 2011
PUBLIC INFORMATION 

June, 2011

Amended August 18, 2011 

JOINT INITIAL EXPLORATION PLAN 

Lease Number(s): OCS-G 33854 & OCS-G 33858 

Area/Block: Green Canyon Blocks 823 and 867

Prospect Name: Parmer

Offshore: Louisiana

Submitted by: Apache Deepwater LLC

2000 W. Sam Houston Pkwy S

Suite 1600

Houston, TX 77042

Terri Young

(713) 296-7456

Terri.young@apachecorp.com

Estimated start-up: October 15, 2011 

Authorized Representative: Copies Being Submitted: 

Cindy Bailey Proprietary: 1 Copy & CD 

J. Connor Consulting, Inc. Public Info: 1 Copy & CD 

16225 Park Ten Place, Suite 700 

Houston, Texas 77084 For 

BOEMRE: 

(281) 578-3388 Plan No. 

Cindy.bailey@jccteam.com Assigned to: 
Green Canyon Blocks 823 and 867 (Control Number N-9583) Record of Changes 

Date Section 

Page 

Page Revision 

07/21/11 

 

 

Appendix H Addition Wellbore schematic 

Appendix H Addition Directional Survey 

Appendix H Exhibit B Confirmed Location G is equivalent to WCD Well GC 867 D 

Appendix H CDs Submitted .mer and .nod CDs in digital format 

08/01/11 Appendix F Attachment F-1 Generated Wastes Discharges Table 

Appendix L Attachment L-1 Transported Wastes to Shore Table 

08/18/11 Appendix H All 

Add Mariner Energy’s Company Number, Amend WCD 

Barrels per BOEMRE request, and Revise Spill Response 

Discussion 
Apache Deepwater LLC 

JOINT INITIAL EXPLORATION PLAN 

LEASES OCS-G 33854 and OCS-G 33858 

APPENDIX A Plan Contents 

APPENDIX B General Information

APPENDIX C Geological, Geophysical Information

APPENDIX D H2S Information 

APPENDIX E Biological, Physical and Socioeconomic Information

APPENDIX F Wastes and Discharge Information 

APPENDIX G Air Emissions Information

APPENDIX H Oil Spills Information

APPENDIX I Environmental Monitoring Information 

APPENDIX J Lease Stipulations Information 

APPENDIX K Environmental Mitigation Measures Information 

APPENDIX L Support Vessels and Aircraft Information 

APPENDIX M Onshore Support Facilities Information 

APPENDIX N Coastal Zone Management Act (CZMA) Information 

APPENDIX O Environmental Impact Analysis

APPENDIX P Administrative Information 
LIST OF ATTACHMENTS 

A-1 OCS Plan Information Form 

A-2 Well Location Plat 

A-3 Bathymetry Map 

A-4 Pay.Gov Receipt 

C-1 Structure Contour Maps 

C-2 3-D Seismic Lines 

C-3 Geological Structure Cross Sections 

C-4 Shallow Hazard Assessment 

C-5 Stratigraphic Column 

E-1 Bathymetry and Seafloor Features Map 

F-1 Projected Generated Wastes 

H-1 OSRP Certification Letter 

H-2 Nodal Analysis Data 

L-1 Solid and Liquid Waste Transportation 

L-2 Vicinity Map 

N-1 Coastal Zone Management Consistency Certification
Apache Deepwater LLC Page A-1 

 Joint Initial Exploration Plan June, 2011 

Green Canyon Blocks 823 and 867 (OCS-G 33854 & OCS-G 33858)

APPENDIX A 

PLAN CONTENTS 

(A) PLAN INFORMATION FORM

Under this Exploration Plan, Apache Deepwater LLC (Apache Deepwater) proposes to drill and 

complete seven wells. The wells will be drilled with a semisubmersible MODU. Water depth in 

these blocks ranges between 3,646 feet to 6,397 feet. See attached OCS Plan Information Form 

– Form BOEMRE-137, included as Attachment A-1. 

(B) LOCATION: 

Included as Attachment A-2 is a Well Location Map depicting the proposed surface and bottom 

location for each well. 

Also included as Attachment A-3 is a Bathymetry Map showing the water depths across the 

lease block. The maximum radius of anchor spread of the associated drilling unit at each 

proposed well location is included as Attachment E-1. 

(C) SAFETY AND POLLUTION PREVENTION FEATURES

A description of the drilling unit is included on the OCS Plan Information Form. Rig 

specifications will be made part of each Application for Permit to Drill. 

Apache Deepwater will drill these wells with a semisubmersible drilling rig, which is equipped 

with a subsea BOP. Once a rig is contracted, BOP information and schematics will be included 

as a part of the Application for Permit to Drill. 

Safety features on the drilling unit will include well control, pollution prevention, and blowout 

prevention equipment as described in Title 30 CFR Part 250, Subparts C, D, E, and F; and as 

further clarified by BOEMRE Notices to Lessees, and current policy making invoked by the 

BOEMRE, Environmental Protection Agency and the U.S. Coast Guard. Appropriate life rafts, 

life jackets, ring buoys, etc., will be maintained on the facility at all times. 

Pollution prevention measures include installation of curbs, gutters, drip pans, and drains on 

drilling deck areas to collect all contaminants and debris. 
Apache Deepwater LLC Page A-2 

 Joint Initial Exploration Plan June, 2011 

Green Canyon Blocks 823 and 867 (OCS-G 33854 & OCS-G 33858)

(D) STORAGE TANKS AND/OR PRODUCTION VESSELS

Type of 

Storage Tank 

Type of 

Facility 

Tank Capacity 

(bbls) 

Number 

of Tanks 

Total 

Capacity 

(bbls) 

Fluid 

Gravity 

(SG) 

Fuel Oil (Marine 

Diesel) 

 Semisubmersible 3331 2 6662 .848 

Fuel Oil Day Semisubmersible 214.8 1 214.8 .848 

Emergency Generator Semisubmersible 23.8 1 23.8 .848 

Lube Oil Services Semisubmersible 1026.7 1 1026.7 .93 

Dirty Lube Oil Semisubmersible 33.4 1 33.4 .93 

Dirty Bilge Semisubmersible 45.9 1 45.9 .848 

(E) ADDITIONAL MEASURES 

Apache Deepwater does not propose additional safety, pollution prevention, or early spill 

detection measures beyond those required by 30 CFR 250. 

(F) Cost Recovery Fee 

Included as Attachment A-4 is a pay.gov receipt in the amount of $24,094 to cover operations 

proposed in this plan.
U.S. Department of the Interior OMB Control Number: 1010-0151 

Minerals Management Service OMB Approval Expires: July 31, 2008

OCS PLAN INFORMATION FORM 

 BOEMRE Form BOEMRE-137 (July 2005 – Supersedes all previous editions of form BOEMRE-137, which may not be 

used.) 

ATTACHMENT A-1

GENERAL INFORMATION 

Type of OCS Plan: X Exploration Plan (EP) Development Operations Coordination Document (DOCD) 

Company Name: Apache Deepwater LLC BOEMRE Operator Number:03165 

Address: 2000 West Sam Houston Pkwy South Contact Person: Cindy Bailey 

 Suite 2000 Phone Number: (281) 578-3388 

 Houston, Texas 77042 Email Address: cindy.bailey@jccteam.com 

Lease(s):G33854, 

G33858 Area: Green Canyon Block(s): 823 & 867 Project Name (If Applicable): Parmer 

Objective(s): Oil Gas Sulphur Salt Onshore Base: Fourchon Distance to Closest Land (Miles): 130 

Description of Proposed Activities (Mark all that apply) 

 Exploration drilling Development drilling 

 Well completion Installation of production platform 

 Well test flaring (for more than 48 hours) Installation of production facilities 

 Installation of caisson or platform as well protection structure Installation of satellite structure 

 Installation of subsea wellheads and/or manifolds Commence production 

 Installation of lease term pipelines Other (Specify and describe) 

Have you submitted or do you plan to submit a Conservation Information Document to accompany this plan? Yes x No 

Do you propose to use new or unusual technology to conduct your activities? Yes x No 

Do you propose any facility that will serve as a host facility for deepwater subsea development? Yes x No 

Do you propose any activities that may disturb an BOEMRE-designated high-probability archaeological area? Yes x No 

Have all of the surface locations of your proposed activities been previously reviewed and approved by BOEMRE? Yes x No 

Tentative Schedule of Proposed Activities 

Proposed Activity Start 

Date 

End 

Date No. of Days 

Drill, complete and TA GC 823 Well A 10-15-11 12-7-11 53 

Drill, complete and TA GC 823 Well B 12-08-11 01-30-12 53 

Drill, complete and TA GC 823 Well C 11-01-12 12-24-12 53 

Drill, complete and TA GC 867 Well A 12-25-12 02-16-13 53 

Drill, complete and TA GC 867 Well B 02-17-13 04-11-13 53 

Drill, complete and TA GC 867 Well C 11-01-13 12-24-13 53 

Drill, complete and TA GC 867 Well D 12-25-13 02-16-14 53 

Description of Drilling Rig Description of Production Platform 

 Jackup Drillship Caisson Tension leg platform 

 Gorilla Jackup Platform rig Well protector Compliant tower 

 Semisubmersible Submersible Fixed platform Guyed tower 

 DP Semisubmersible Other (Attach Description) Subsea manifold Floating production system 

 Drilling Rig Name (If Known): Spar Other (Attach description) 

Description of Lease Term Pipelines 

From (Facility/Area/Block) To (Facility/Area/Block) Diameter (inches) Length (Feet) 

 
OCS PLAN INFORMATION FORM (CONTINUED) 

Include one copy of this page for each proposed well/structure 

Proposed Well/Structure Location 

Well or Structure Name/Number (If renaming well or structure, reference previous name): A Subsea Completion 

Anchor Radius (if applicable) in feet: 10,000 Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. OCS G33854 

Area Name Green Canyon 

Block No. 823 

Blockline 

Departures 

(in feet) 

N/S Departure: 960’ FSL 

E/W Departure: 7,160’ FWL 

Lambert X-Y 

coordinates 

X: 2,478, 200 

Y: 9,853,440 

Latitude/ 

Longitude 

Latitude: 27.1304443 

Longitude: -90.4238109 

 TVD (Feet): MD (Feet): Water Depth (Feet):4,129’ 

Anchor Locations for Drilling Rig or Construction Barge (If anchor radius supplied above, not necessary) 

Anchor Name 

or No. Area Block X Coordinate Y Coordinate Length of Anchor 

Chain on Seafloor

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us 

to inform you that BOEMRE collects this information as part of an Apache Deepwater LLC’s Exploration Plan or 

Development Operations Coordination Document submitted for BOEMRE approval. We use the information to facilitate 

our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of Information Act and 

30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to respond to, a collection of 

information unless it displays a currently valid Office of Management and Budget Control Number. The use of this form is 

voluntary. The public reporting burden for this form is included in the burden for preparing Exploration Plans and 

Development Operations Coordination Documents. We estimate that burden to average 580 hours per response, including 

the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the form. Direct 

comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, 

Mail Stop 4230, Minerals Management Service, 1849 C Street, N.W., Washington, DC 20240. 
OCS PLAN INFORMATION FORM (CONTINUED) 

Include one copy of this page for each proposed well/structure 

Proposed Well/Structure Location 

Well or Structure Name/Number (If renaming well or structure, reference previous name): B Subsea Completion 

Anchor Radius (if applicable) in feet: 10,000 Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. OCS G33854 

Area Name Green Canyon 

Block No. 823 

Blockline 

Departures 

(in feet) 

N/S Departure: 1,884’ FSL 

E/W Departure: 6,538’ FWL 

Lambert X-Y 

coordinates 

X: 2,477,578 

Y: 9,854,364 

Latitude/ 

Longitude 

Latitude: 27.1330196 

Longitude: -90.4256638 

 TVD (Feet): MD (Feet): Water Depth (Feet): 4,072’ 

Anchor Locations for Drilling Rig or Construction Barge (If anchor radius supplied above, not necessary) 

Anchor Name 

or No. Area Block X Coordinate Y Coordinate Length of Anchor 

Chain on Seafloor

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us 

to inform you that BOEMRE collects this information as part of an Apache Deepwater LLC’s Exploration Plan or 

Development Operations Coordination Document submitted for BOEMRE approval. We use the information to facilitate 

our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of Information Act and 

30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to respond to, a collection of 

information unless it displays a currently valid Office of Management and Budget Control Number. The use of this form is 

voluntary. The public reporting burden for this form is included in the burden for preparing Exploration Plans and 

Development Operations Coordination Documents. We estimate that burden to average 580 hours per response, including 

the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the form. Direct 

comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, 

Mail Stop 4230, Minerals Management Service, 1849 C Street, N.W., Washington, DC 20240. 
OCS PLAN INFORMATION FORM (CONTINUED) 

Include one copy of this page for each proposed well/structure 

Proposed Well/Structure Location 

Well or Structure Name/Number (If renaming well or structure, reference previous name): C Subsea Completion 

Anchor Radius (if applicable) in feet: 10,000 Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. OCS G 33858 

Area Name Green Canyon 

Block No. 867 

Blockline 

Departures 

(in feet) 

N/S Departure: 2,990’ FNL 

E/W Departure: 5,933’ FWL 

Lambert X-Y 

coordinates 

X: 2,476,973 

Y: 9,849,490 

Latitude/ 

Longitude 

Latitude:27.1196541 

Longitude: -90.4278294 

 TVD (Feet): MD (Feet): Water Depth (Feet):4,158’ 

Anchor Locations for Drilling Rig or Construction Barge (If anchor radius supplied above, not necessary) 

Anchor Name 

or No. Area Block X Coordinate Y Coordinate Length of Anchor 

Chain on Seafloor

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us 

to inform you that BOEMRE collects this information as part of an Apache Deepwater LLC’s Exploration Plan or 

Development Operations Coordination Document submitted for BOEMRE approval. We use the information to facilitate 

our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of Information Act and 

30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to respond to, a collection of 

information unless it displays a currently valid Office of Management and Budget Control Number. The use of this form is 

voluntary. The public reporting burden for this form is included in the burden for preparing Exploration Plans and 

Development Operations Coordination Documents. We estimate that burden to average 580 hours per response, including 

the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the form. Direct 

comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, 

Mail Stop 4230, Minerals Management Service, 1849 C Street, N.W., Washington, DC 20240. 
OCS PLAN INFORMATION FORM (CONTINUED) 

Include one copy of this page for each proposed well/structure 

Proposed Well/Structure Location 

Well or Structure Name/Number (If renaming well or structure, reference previous name): A Subsea Completion 

Anchor Radius (if applicable) in feet: 10,000 Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. OCS G 33858 

Area Name Green Canyon 

Block No. 867 

Blockline 

Departures 

(in feet) 

N/S Departure: 27’ FNL 

E/W Departure: 5,888’ FWL 

Lambert X-Y 

coordinates 

X: 2,476,928 

Y: 9,852,453 

Latitude/ 

Longitude 

Latitude: 27.1278025 

Longitude: -90.4277813 

 TVD (Feet): MD (Feet): Water Depth (Feet): 4,106’ 

Anchor Locations for Drilling Rig or Construction Barge (If anchor radius supplied above, not necessary) 

Anchor Name 

or No. Area Block X Coordinate Y Coordinate Length of Anchor 

Chain on Seafloor

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us 

to inform you that BOEMRE collects this information as part of an Apache Deepwater LLC’s Exploration Plan or 

Development Operations Coordination Document submitted for BOEMRE approval. We use the information to facilitate 

our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of Information Act and 

30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to respond to, a collection of 

information unless it displays a currently valid Office of Management and Budget Control Number. The use of this form is 

voluntary. The public reporting burden for this form is included in the burden for preparing Exploration Plans and 

Development Operations Coordination Documents. We estimate that burden to average 580 hours per response, including 

the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the form. Direct 

comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, 

Mail Stop 4230, Minerals Management Service, 1849 C Street, N.W., Washington, DC 20240. 
OCS PLAN INFORMATION FORM (CONTINUED) 

Include one copy of this page for each proposed well/structure 

Proposed Well/Structure Location 

Well or Structure Name/Number (If renaming well or structure, reference previous name): B Subsea Completion 

Anchor Radius (if applicable) in feet: 10,000 Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. OCS G 33858 

Area Name Green Canyon 

Block No. 867 

Blockline 

Departures 

(in feet) 

N/S Departure: 1,480’ FNL 

E/W Departure: 2,110’ FWL 

Lambert X-Y 

coordinates 

X: 2,473,150 

Y: 9,851,000 

Latitude/ 

Longitude 

Latitude: 27.1240202 

Longitude: -90.4394800 

 TVD (Feet) MD (Feet): Water Depth (Feet): 4,267’ 

Anchor Locations for Drilling Rig or Construction Barge (If anchor radius supplied above, not necessary) 

Anchor Name 

or No. Area Block X Coordinate Y Coordinate Length of Anchor 

Chain on Seafloor

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us 

to inform you that BOEMRE collects this information as part of an Apache Deepwater LLC’s Exploration Plan or 

Development Operations Coordination Document submitted for BOEMRE approval. We use the information to facilitate 

our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of Information Act and 

30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to respond to, a collection of 

information unless it displays a currently valid Office of Management and Budget Control Number. The use of this form is 

voluntary. The public reporting burden for this form is included in the burden for preparing Exploration Plans and 

Development Operations Coordination Documents. We estimate that burden to average 580 hours per response, including 

the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the form. Direct 

comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, 

Mail Stop 4230, Minerals Management Service, 1849 C Street, N.W., Washington, DC 20240. 
OCS PLAN INFORMATION FORM (CONTINUED) 

Include one copy of this page for each proposed well/structure 

Proposed Well/Structure Location 

Well or Structure Name/Number (If renaming well or structure, reference previous name): C Subsea Completion 

Anchor Radius (if applicable) in feet: 10,000 Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. OCS G 33858 

Area Name Green Canyon 

Block No. 867 

Blockline 

Departures 

(in feet) 

N/S Departure: 2,530’ FNL 

E/W Departure: 3,420’ FWL 

Lambert X-Y 

coordinates 

X: 2,474,460 

Y: 9,849,950 

Latitude/ 

Longitude 

Latitude: 27.1210600 

Longitude: -90.4355211 

 TVD (Feet): MD (Feet): Water Depth (Feet): 4,250’ 

Anchor Locations for Drilling Rig or Construction Barge (If anchor radius supplied above, not necessary) 

Anchor Name 

or No. Area Block X Coordinate Y Coordinate Length of Anchor 

Chain on Seafloor

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us 

to inform you that BOEMRE collects this information as part of an Apache Deepwater LLC’s Exploration Plan or 

Development Operations Coordination Document submitted for BOEMRE approval. We use the information to facilitate 

our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of Information Act and 

30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to respond to, a collection of 

information unless it displays a currently valid Office of Management and Budget Control Number. The use of this form is 

voluntary. The public reporting burden for this form is included in the burden for preparing Exploration Plans and 

Development Operations Coordination Documents. We estimate that burden to average 580 hours per response, including 

the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the form. Direct 

comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, 

Mail Stop 4230, Minerals Management Service, 1849 C Street, N.W., Washington, DC 20240. 
OCS PLAN INFORMATION FORM (CONTINUED) 

Include one copy of this page for each proposed well/structure 

Proposed Well/Structure Location 

Well or Structure Name/Number (If renaming well or structure, reference previous name): D Subsea Completion 

Anchor Radius (if applicable) in feet: 10,000 Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. OCS G 33854 

Area Name Green Canyon 

Block No. 823 

Blockline 

Departures 

(in feet) 

N/S Departure: 3,752 FSL 

E/W Departure: 2,110’ FWL 

Lambert X-Y 

coordinates 

X: 2,473,150 

Y: 9,856,232 

Latitude/ 

Longitude 

Latitude: 27.1384041 

Longitude: -90.4391521 

 TVD (Feet): MD (Feet): Water Depth (Feet): 3,944’ 

Anchor Locations for Drilling Rig or Construction Barge (If anchor radius supplied above, not necessary) 

Anchor Name 

or No. Area Block X Coordinate Y Coordinate Length of Anchor 

Chain on Seafloor

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us 

to inform you that BOEMRE collects this information as part of an Apache Deepwater LLC’s Exploration Plan or 

Development Operations Coordination Document submitted for BOEMRE approval. We use the information to facilitate 

our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of Information Act and 

30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to respond to, a collection of 

information unless it displays a currently valid Office of Management and Budget Control Number. The use of this form is 

voluntary. The public reporting burden for this form is included in the burden for preparing Exploration Plans and 

Development Operations Coordination Documents. We estimate that burden to average 580 hours per response, including 

the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the form. Direct 

comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, 

Mail Stop 4230, Minerals Management Service, 1849 C Street, N.W., Washington, DC 20240. 
X = 2,471,040’ X = 2,471,040’

Y = 9,868,320’

Y = 9,852,480’

Y = 9,836,640’

X = 2,486,880’ X = 2,486,880’

866 867

822 823

BP 2

“Parmer” Prospect

(Green Canyon 823/867)

OCS-G 33854/33858

Surface

Location Map

0 2,000’

1” = 2,000’

05/20/11

Apache Loc. GC 823 A

Surface Location

Apache Loc. GC 867 C

Surface Location

Apache Loc. GC 823 B

Surface Location

Apache Loc. GC 867 D

Surface Location

Apache Loc. GC 867 A

Surface Location

Apache Loc. GC 823 C

Surface Location

Apache Loc. GC 867 B

Surface Location

960’ FSL & 7,160’ FWL of GC 823

X = 2,478,200’

Y = 9,853,440’

Lat. = 27.1304443

Long. = -90.4238109

2,530’ FNL & 3,420’ FWL of GC 867

X = 2,474,460’

Y = 9,849,950’

Lat. = 27.1210600

Long. = -90.4355211

1,884’ FSL & 6,538’ FWL of GC 823

X = 2,477,578’

Y = 9,854,364’

Lat. = 27.1330196

Long. = -90.4256638

3,752’ FSL & 2,110’ FWL of GC 823 

X = 2,473,150’

Y = 9,856,232’

Lat. = 27.1384041

Long. = -90.4391521 

27’ FNL & 5,888’ FWL of GC 867

X = 2,476,928’

Y = 9,852,453’

Lat. = 27.1278025

Long. = -90.4277813

27’ FNL & 5,888’ FWL of GC 867

2,990’ FNL & 5,933’ FWL of GC 867

X = 2,476,973’

Y = 9,849,490’

Lat. = 27.1196541

Long. = -90.4278294

1,480’ FNL & 2,110’ FWL of GC 867

X = 2,473,150’

Y = 9,851,000’

Lat. = 27.1240202

Long. = -90.4394800

APA

 GC 823 A

APA

GC 823 B

APA

GC 867 D

APA

GC 867 A

APA

GC 867 B

APA

GC 867 C

APA

GC 823 C

SL

SL

SL

SL

SL

SL

SL

2,110’ FWL

3,420’ FWL

5,933’ FWL

1,480’ FNL

2,530’ FNL

2,110’ FWL

6,538’ FWL

7,160’ FWL

960’

FSL BP 1

2,990’ FNL

3,752’ FSL

1,884’

FSL
X = 2,471,040’ X = 2,471,040’

Y = 9,868,320’

Y = 9,852,480’

Y = 9,836,640’

X = 2,486,880’ X = 2,486,880’

866 867

822 823

BP

2

BP

1

APA

GC 867 D

APA

GC 867 B

APA

GC 867 C

SL

SL

SL

-4,300’

-4,300’

-4,200’

-4,200’

-4,100’

-4,000’

-4,200’

-3,800’

-3,700’

-4,300’

-4,100’

-4,000’

-3,900’

-3,900’

-3,800’

-3,800’

-4,400’

-4,400’

-4,400’

-4,400’

-4,500’

-5,000’

-4,900’

-4,800’

-4,700’

-4,600’

-5,500’

-5,600’

-5,700’

-5,800’

-5,900’

-5,400’

-5,300’

-5,200’

-5,100’

“Parmer” Prospect

(Green Canyon 823/867)

OCS-G 33854/33858

Bathymetry

Map

0 2,000’

1” = 2,000’

05/20/11

C.I. = 100’

APA

 GC 823 A

APA

GC 823 B

APA

GC 823 C

SL

SL

SL

APA

GC 867 A

SL
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Apache Deepwater LLC Page B-1 

 Joint Initial Exploration Plan June, 2011 

Green Canyon Blocks 823 and 867 (OCS-G 33854 and OCS-G 33858)

APPENDIX B 

GENERAL INFORMATION 

(A) APPLICATIONS AND PERMITS 

Listed in the table below are additional permits/applications to be filed before operations can 

commence under this EP: 

Application/Permit Issuing Agency Status 

Application(s) for Permit to 

Drill 

BOEMRE To be submitted 

(B) DRILLING FLUIDS 

Type of Drilling Fluid Estimated Volume of Drilling Fluid to be 

Used per Well 

Water-based – 

Barite, Sodium Chloride Brine, Salt, Xantham 

Gum, Poly Plus, Lime, Poly Pac UL, Caustic 

Soda, Defoam X, 

Greencide 25g 

37,763 bbls.

Oil-based (diesel, minerals, oil) 0 bbls 

Synthetic-based (internal olefin, ester) 

Barite, Suremul, Surewet, Rheflat, Rhethik, 

Ecotrol RD, Rheduce, Rhebuild, Lime, 

Calcium Chloride, Vg Plus, Vg Supreme, 

Calcium Carbonate, G-Seal, Nut Plug, Vinseal 

6,026 bbls 

(C) NEW OR UNUSUAL TECHNOLOGY 

Apache Deepwater does not propose to use any new or unusual technology to carry out the 

proposed exploration activities. 

(D) BONDING STATEMENT 

The bond requirements for the activities and facilities proposed in this EP are satisfied by a 

$3,000,000.00 areawide development bond, furnished and maintained according to 30 CFR 256, 

subpart I; NTL No. 2000-G16, "Guidelines for General Lease Surety Bonds;" and additional 

security under 30 CFR 256.53(d) and National NTL No. 2008-N07, “Supplemental Bond 

Procedures.” 
Apache Deepwater LLC Page B-2 

 Joint Initial Exploration Plan June, 2011 

Green Canyon Blocks 823 and 867 (OCS-G 33854 and OCS-G 33858)

(E) OIL SPILL FINANCIAL RESPONSIBILITY (OSFR) 

Apache Deepwater LLC, BOEMRE company number 03165, will demonstrate oil spill financial 

responsibility for the facilities proposed in this EP according to 30 CFR Part 253; and NTL No. 

2008-N05, "Guidelines for Oil Spill Financial Responsibility for Covered Facilities". 

(F) DEEPWATER WELL CONTROL STATEMENT 

Apache Deepwater LLC, BOEMRE company number 03165, has the financial capability to drill 

a relief well and conduct other emergency well control operations. 

(G) BLOWOUT SCENARIO 

Estimated maximum flow rate, Green Canyon Block 867 Well Location D: 

The estimated maximum flow rate would occur in the objective section, if a kick were taken and 

the well blew out. The maximum Worst Case Discharge (WCD) modeled for this scenario is 

146,302 BOPD. 

Maximum duration of blowout (days) 

The duration of the blowout will be a function of the well bridging over, the ability of surface 

intervention to shut or contain the well or, as a last resort, drilling a relief well to kill the 

blowout. The expected maximum time frames for uncontrolled flow in each of the different 

operational outcomes would be as follows: 

• Bridging Over In 2 Days, 

• Surface Intervention 15 Days 

• A Relief Well 41 Days. 

Maximum discharge volume 

The following table is a linear estimate of the maximum discharge volume for each of the 

aforementioned operational outcomes. 

Operational 

Outcome 

Maximum 

Discharge Rate 

(bbl/day) 

Discharge 

Duration 

(days) 

Maximum 

Discharge 

Volume (bbl) 

Bridging Over 146,302 2 292,604 

Surface 

Intervention 

146,302 15 2,194,530 

Relief Well 146,302 41 5,998,382 

Potential of wellbore to bridge over during a blowout 

There is significant potential for the wellbore to bridge over during the WCD blowout. Bridging 

is likely to occur due to the extreme drawdown calculated between the formation and the 

openhole sections. A Merlin reservoir simulation model was used to investigate the well 

conditions during the WCD blowout scenario. The estimated reservoir pressure is 8,284 psi. The 
Apache Deepwater LLC Page B-3 

 Joint Initial Exploration Plan June, 2011 

Green Canyon Blocks 823 and 867 (OCS-G 33854 and OCS-G 33858)

reservoir model estimated bottomhole flowing pressures, based upon reservoir properties and 

flow rates. The calculated drawdown is modeled to be between 574 – 1,275 psi. 

In our experience in the deepwater GOM, we strive to limit the estimated total drawdown on a 

producing interval to reduce the risk of wellbore collapse and sand/fines migration into a well. 

We limit the drawdown to less than 1,000 psi by reducing the rates the wells produce and by 

completing each well with a cased hole, frac-pack completion. 

There is a strong likelihood of wellbore bridging over: 

• Drawdown is estimated to be greater than 1,000 psi, 

• Blowout occurs in an open hole section of the well, with no benefit of casing or a 

frac-pack completion, 

• If any water zones are exposed this will accelerate wellbore collapse and bridging. 

• Wellbore collapse and bridge over under the conditions cited is estimated not to 

exceed 2 days. 

Surface intervention to stop blowout 

In the event of a blowout and the blowout prevention equipment is still intact, the subsea BOP 

will be used for successful shut-in of the well. The well would then be killed and re-entered to 

either abandon or return to normal operations. Surface intervention would be the first line of 

defense after a blowout occurs. The specific intervention technique chosen will depend on actual 

conditions and ability to access the existing well. 

In the event that the subsea BOP is inoperable, the surface intervention would employ the Marine 

Well Containment Company (MWCC) and/or the Helix Well Containment Group (HWCG) 

containment systems to achieve successful containment of the well. The system will be 

employed, while simultaneously initiating relief well planning and operations. Specifics will be 

submitted with the Well Containment Plan. 

Typically blowouts can be controlled with surface intervention, with a good likelihood of success 

and in a relatively short time frame, as long as, the subsea casing, wellhead and BOP’s are not 

damaged beyond use. The intervention technique chosen will depend on actual conditions and 

ability to access the existing well. There can be simple solutions such as rig up and bullhead kill 

mud or to more complex solutions, but the solution will depend on wellbore conditions. 

Surface intervention time estimate 

The assumption is that the well has an uncontrolled blowout and the MODU has sunk with 

displacement from the wellhead. Additionally, it assumes that debris removal will be required to 

gain access to the subsea BOP system. The ROV has been deployed and was unsuccessful in 

shutting in the well, using the existing subsea BOP control panel. The scenario employs one of 

the aforementioned containment system’s capping BOP. The following table describes the 

estimated time required in order to shut in and secure the well using the containment system. 
Apache Deepwater LLC Page B-4 

 Joint Initial Exploration Plan June, 2011 

Green Canyon Blocks 823 and 867 (OCS-G 33854 and OCS-G 33858)

Operation Duration 

(hours) 

Cumulative Time Since 

Event 

(days) 

Assess wellbore conditions for surface 

intervention requirements. Conduct 

notifications to the regulatory agencies 

and primary contractors. 

48 2 

Site Preparation which includes 

mobilizing and deployment of the 

IWOCS system and Dispersant 

system. 

120 5 

Debris removal including mobilization 

of ROV boat and construction support 

vessel and execution of debris removal 

plan. 

168 7 

Well capping operations which include 

mobilization, deployment, installation 

and shut-in of the well with the well 

containment capping stack. 

360 15 

Note: These operations are occurring concurrently during operational phase. 

Relief Well

It is preferred to drill relief wells from an open water location, rather than a platform location. 

Open water locations provide the best option on designing a simpler intercept well and allow a 

greater choice on rig availability. There are not any platforms in the vicinity, therefore it is not 

feasible to consider as a relief well location. 

Relief well location and drilling strategy 

The surface location for the relief wells would be a function of current, wind direction and 

wellbore vertical access. The Location D relief well surface location would be approximately 

2,500’ southwest of the well at Location D. 

The well will be drilled as Build Turn and Hold trajectory design to a Target : 45.87° Inc, 

15095.42ft MD, 13961.23ft TVD, 2800.13ft VS to set the well up 100’ away from the blowout 

well and 1000’ above the 13-5/8” casing shoe. The well will then be drilled to intersect the well. 

Once intersected the well kill pumping operations will be initiated to kill the blowout. The 

typical relief well Trajectory Design for each location will be very similar to the Location D 

relief well as follows. 
Apache Deepwater LLC Page B-5 

 Joint Initial Exploration Plan June, 2011 

Green Canyon Blocks 823 and 867 (OCS-G 33854 and OCS-G 33858)

Location D Relief Well Trajectory Design 

Relief well rig availability 

There are currently eighteen floating rigs in the US GoM suitable for drilling relief wells at 

Green Canyon 823/867. The five rigs listed below currently have certified BOP systems and are 

not engaged in well operations. 

Rig Name Contractor 

Rated 

Water 

Depth 

MODU Type Rig Status 

Ensco 8501 Ensco 8,500 Semisubmersible Standby 

Ocean 

Monarch 

Diamond 

Offshore 

10,000 Semisubmersible Standby 

West Sirius Seadrill 10,000 Semisubmersible Standby 
Apache Deepwater LLC Page B-6 

 Joint Initial Exploration Plan June, 2011 

Green Canyon Blocks 823 and 867 (OCS-G 33854 and OCS-G 33858)

Maersk 

Developer 

Maersk 10,000 Semisubmersible Standby 

Danny 

Adkins 

Noble 12,000 Semisubmersible Standby 

Relief Rig package constraints 

The proposed rigs for relief well operations have suitable drilling packages with sufficient 

capabilities to work in the subject water depths of 3,944’ and drill to the required depth of 

20000’ TVD or greater. The BOP systems have met the BOEMRE certification requirements and 

will be re-inspected in transit, prior to drilling a relief well to the required true vertical depth. 

Relief well rig contract and mobilization timing 

Given the current availability of suitable rigs in the GoM, a contract could be finalized in 24-48 

hours, after undertaking the decision to begin relief well operations. Backup tubulars and 

wellhead systems are maintained in stock for each well. Mobilization of equipment and services 

to the rig could be completed in 72 hours, concurrent with contract execution. The estimated 

time to move the rig from the current location to the relief well location is 32 hours 

(approximately 106 miles). 

Duration of relief well 

Description Hours Cumulative Days 

Well Control Assessment 48 2.0 

Contract & Mobilize Rig & Spud Equipment 

through 16” Surface Liner. 104 6.3 

Set anchors and pin 36” Structural Casing 72 9.3 

Spud and drill to the top of the zone of interest 

and set casing. 521 31 

Mag-Range relief well into intersecting position. 120 36 

R/U pumping equipment and kill well. 48 41 

R/D Pumping Equipment, PA Wellbore, Pull 

Riser, Pull anchors and Demobilize 251 51 

The above time demonstrates the worst case timing for all well locations. Specific timing for 

each well is within 1.5 day of each other. 
Apache Deepwater LLC Page B-7 

 Joint Initial Exploration Plan June, 2011 

Green Canyon Blocks 823 and 867 (OCS-G 33854 and OCS-G 33858)

Blowout Prevention and Intervention

Summary of prevention measures 

Apache has maintained a safe track record of prudent operations in the GoM deepwater 

environment. It will continue to implement its safe operating practices to enhance its operating 

risk reduction program. In addition to the safe operating practices, the following measures will 

be implemented into well design, drilling and completion operations. 

• BOP Certification, BOP Drills, Pit Drill’s and all other required BOEMRE testing 

requirements, 

• Current Well Control Certification for all Drilling and Completion Rig Site 

Supervisors, 

• Taking Slow Pump Rate measurements during all openhole operations and critical 

cased hole operations, 

• Updating Kill Sheets during each tour and posting the same on the rig floor, 

• Maintain a current BOP to RKB spaceout Chart, 

• Monitoring wellbore fill-ups and displacements during trips, by the Well Site 

Supervisor, 

• Maintain the necessary circulating swages, TIW Valves and IBOP on the rig floor at 

all times during operations and function test these valves during each tour. 

The utilization of Pre-Job Safety meetings will continue to be implemented prior to each 

operation with all of the rig crews. These are intended to create a behavior based safety program 

and promote an atmosphere within the Apache and rig crew interface, such that a “Stop the Job” 

mentality is promoted across the rig contractors crew, empowering every crew member to 

question the safety of each operation. 

Early well control intervention 

In the event of a blowout situation, due to failed BOP equipment and uncontrolled flow at the 

seafloor or at surface, assuming all other surface controlled actuation measures have failed or are 

inaccessible, an ROV will fly into position at the BOP subsea actuation panel and actuate the 

shear ram or other appropriate valves, pipe rams and/or annular elements to establish 

containment. 

If the riser system and rig have been compromised, then debris removal will be initiated to obtain 

clear access to the BOP. A Capping Stack will be employed to achieve successful containment of 

the well. Once containment is established and wellbore pressure testing and assessment is 

completed by Apache and Well Control Specialist, well kill operations can be initiated through 

the existing wellbore. 

Well control engineering services 

Apache will have service agreements in place with Wild Well Control and Boots and Coots 

International Well Control prior to commencement of well operations. In the event of a blowout 
Apache Deepwater LLC Page B-8 

 Joint Initial Exploration Plan June, 2011 

Green Canyon Blocks 823 and 867 (OCS-G 33854 and OCS-G 33858)

situation, these companies will be contacted to assist in the detailed design and implementation 

of well control and/or relief well operations. 

Additional prevention & mitigation techniques 

Pursuant to wellbore cementing and zonal isolation techniques, all cementing operations will be 

modeled and designed under the guidelines set forth in API Recommended Practice 65 Part 1 & 

2. Operations will be dictated by the rules and requirements set forth in Federal Regulations, 

under the wellbore cementing requirements. 

RP 53 Recommended Practices for Blowout Prevention Equipment Systems for Drilling Wells 

and Recommended Practice 16Q for Marine Drilling Risers will be used as the guidelines for 

installation, testing and maintenance of the surface and subsea Marine Risers and BOP systems. 

The purpose of these recommended practices is to provide information that can serve as a guide 

for installation and testing of blowout prevention systems Apache has contracted for floating 

marine drilling rigs. 

The goal of using these recommended practices is to assist Apache operations in promoting 

personnel safety, public safety, integrity of the drilling equipment and preservation of the 

environment for floating marine drilling operations. These recommended practices help to 

facilitate the broad availability of proven, sound engineering and operating practices. 

These practices are considered acceptable for accomplishing BOP and Marine Riser associated 

operations. However, equivalent alternative installations and practices may be utilized to 

accomplish the same objectives. Apache when using these recommended practices or other 

alternatives will insure that operations comply with requirements of Federal Regulations. 
Apache Deepwater LLC Page C-1 

 Joint Initial Exploration Plan June, 2011 

Green Canyon Blocks 823 and 867 (OCS-G 33854 and OCS-G 33858)

APPENDIX C 

GEOLOGICAL AND GEOPHYSICAL INFORMATION 

(A) GEOLOGICAL DESCRIPTION 

Proprietary Information

(B) STRUCTURE CONTOUR MAPS 

Proprietary Information 

(C) INTERPRETED 3-D SEISMIC LINES 

Proprietary Information

(D) GEOLOGICAL STRUCTURE CROSS-SECTIONS

Proprietary Information 

(E) SHALLOW HAZARDS REPORT 

A shallow hazards survey was conducted over Green Canyon Blocks 823 and 867 by Geoscience 

Earth & Marine Services, Inc. 

Three copies of the shallow hazard report are being submitted to the BOEMRE under separate 

cover. 

(F) SHALLOW HAZARDS ASSESSMENT 

Utilizing the 3D seismic exploration data, a shallow hazards assessment was prepared for the 

proposed surface locations, and is included as Attachment C-4. 

(G) HIGH-RESOLUTION SEISMIC LINES 

Proprietary Information 

 (H) STRATIGRAPHIC COLUMN

Proprietary Information 

(I) TIME VS DEPTH TABLES

Proprietary Information 
10615 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-A 

May 20, 2011 Project No. 0411-1924

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 GC 823-A

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 1,916 ft below the mudline (bml) at the proposed Wellsite GC 823-A. The 

following discussion is based on findings provided within the main body of the geohazard report for Blocks 

823 and 867 (GEMS Report No. 0411-1924). The surface location for proposed Wellsite GC 823-A is in 

the southwestern quadrant of GC 823. Apache provided the following coordinates:

Proposed Wellsite GC 823-A

Spheroid & Datum: Clarke 1866, NAD27

Projection: UTM Zone 15 North Line Reference Block Calls

X: 2,478,200 ft Latitude: 27.1304443128059 o N Inline 6781 960 ft FSL

Y: 9,853,440 ft Longitude: 90.4238109104625° W Crossline 34082 7,160 ft FWL

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 A-1 through GC 823 A-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 zoned beyond the limits of the anchor radius is also included, NTL 2009-G40 

(MMS, 2009a).

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 A-1: Bathymetry Map

Map GC 823A-2: Seafloor Rendering

Map GC 823A-3: Seafloor Amplitude Rendering

Map GC 823A-4: Geologic Features Map

Figure GC 823A-1: Inline 6781 and Crossline 34082 Showing Conditions Beneath

Proposed Wellsite GC 823-A 

Figure GC 823 A-2:Tophole Prognosis Chart, Proposed Wellsite GC 823-A, 

Green Canyon Block 823
Project No. 0411-1924

 -2- Proposed Well GC 823-A 

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, 2008a, 2008b, and 2009a). The proposed wellsite will be required to follow NTL 2008-G06 

with respect to pre- and post-spud ROV visual inspection surveys (MMS, 2008c). 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 spectrum 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 ~0.669 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 GC 823-A

Man-Made Features

There are existing wells in GC 823 and in surrounding blocks. The closest well to Proposed Wellsite 

GC 823-A is the BP Exploration Inc., GC 823 -001 well approximately 775 ft to the north-northeast (Maps 

GC 823-A-1 through GC 823-A-4). The closest touchdown point for an anchor chain will likely be 2,000 ft 

from the proposed wellsite; therefore, the existing site should not be impacted by the proposed mooring 

pattern.

0

0.2

0.4

0.6

0.8

1

1.2

0 10 20 30 40 50 60 70 80 90 100

Power (amp2)

Frequency (hrz)

POWER SPECTRUM

GC 823-A
Project No. 0411-1924

 -3- Proposed Well GC 823-A 

Other wells near the Proposed Wellsite GC 823-A are the BP Exploration Inc., GC 823-002 well and GC 

866-001 wells. These wells are approximately 7,900 ft east-northeast and 10,925 ft west-southwest, 

respectively, of the proposed site and lie within the proposed mooring pattern. 

Proposed Wellsite GC 823-A 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, 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 Seafloor Conditions

The water depth at the proposed location is -4,129 ft (Map GC 823-A-1). The seafloor at the proposed 

location is slightly irregular and dips to the east-northeast at about 4.5 ̊. The proposed wellsite is located 

within a valley between two ridges. The valley occurs along the eastern margin of an extensive 

topographic high. The topographic high is the seafloor expression of a shallow salt diapir. 

Water depths within the potential anchor mooring area range from about -3,660 ft along a ridge line to the 

north to approximately -4,700 ft on the upper part of the Sigsbee Escarpment to the south (Map GC 823-A1).

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 north and 

southwest of the proposed location. The upper part of the Sigsbee Escarpment to the south will be marked 

by an increase in slope to 10° to 20°. 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-A-3) shows normal or 

ambient amplitude along the seabed, with no indication of any hard-bottom or fluid expulsion events within 

2,000 ft of the proposed GC 823-A location. Based on the renderings and seismic profiles deepwater 

benthic communities are not expected within 2,000 ft of the proposed GC 823-A wellsite. 

Patches of high-amplitude seafloor returns occur approximately 8,000 ft to the southwest of the location. 

The patches are associated with seafloor faults. In addition, the base of a mud mound exists approximately 

9,900 ft to the northwest (Maps GC 823-A-1 through GC 823-A-4). These features 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 420 ft to the north. Except for the faults 8,000 ft to the southwest, no high-amplitude returns 

occur along the seabed escarpments; therefore, prolific hydrocarbon seepage or carbonate hardgrounds are 

unlikely. 

Stratigraphy

Inline 6781 and Crossline 34082 are the closest 3-D lines to proposed Wellsite GC 823-A (Figure GC 823-

A-1). The Tophole Prognosis Chart (Figure GC 823-A-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. 

The 3-D data volume was used to define the sedimentary section to a depth of approximately 1,916 ft 

(Figures GC 823-A-1 and GC 823-A-2). The section was divided into four units or sequences (Figure 
Project No. 0411-1924

 -4- Proposed Well GC 823-A 

GC 823-A-1). The sequences represent variations in depositional environments and possible changes in 

soil strength and composition. 

The surficial unit, Unit 1 (Seafloor to Horizon 20), to approximately 134 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 gradually increase in strength and decrease in 

water 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 397 ft (Figure GC 823-A2).

Unit 3 (Horizon 35 to Horizon 40) consists of bedded mud-rich turbidites. The top of Unit 3, Horizon 35,

is at about 397 ft bml. The unit is approximately 394 ft thick beneath GC 823-A.

Unit 4 is a sequence bounded by Horizon 40 and the top of salt (Figures GC 823-A-1 and GC 823-A-2). 

The upper portion of the sequence consists of bedded turbidites and thin mass-transport deposits. The

sediments will be alternating clay and silt layers with thin sand or silty sand layers. The unit thins along 

the flank of the salt structure and reflection continuity is lost. The lower portion of Unit 4 (1,510 ft to 

1,916 ft, bml) is a chaotic interval affected by shallow salt emplacement and will likely consist of a mixture 

of silts, clays, and sand. Unit 4 occurs between 791 ft and 1,916 ft bml, and is 1,125 ft thick. 

The top of salt is predicted to be 1,916 ft bml (~6,045 ft bsl). The salt surface dips to the northeast at 

approximately 40°.

Faults

Three faults will be intersected by the well bore beneath the proposed Wellsite GC 823-A (Figure GC 823-

A-1). The borehole will intersect the shallowest fault near the base of Unit 2, at approximately 385 ft bml. 

The remaining deeper faults will be intersected between Horizon 40 and Top of Salt (Unit 4), at depths of 

about 974 ft and 1,689 ft bml. 

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 134 ft bml at proposed Wellsite GC 823-A (Figure GC 823-A-2). The entire unit is 

263 ft thick. At this location, Unit 2 is an unlikely zone for overpressured sand layers. 

The existing GC 823-001 well is approximately 775 ft to the northeast of the proposed GC 823-A 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 lowamplitude interval of discontinuous to chaotic reflections (Figure GC 823-A-2). 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 may not have been observed until drilling was at the 1,715 ft level.

Because of the proximity of the GC 823-001 well, the lower portion of Unit 4 has been given a high 

potential for shallow water flow (Figure GC 823-A-2). The upper portion of the unit is given a moderate 

potential for water flow considering the source of the flow in GC 823-001 may have originated higher than 

when observed during drilling. Sands within the unit are likely to be isolated and faulted. Like GC 823-

001 any flow will be short-lived and of low severity. 

Shallow Gas 

The well path will not penetrate any high-amplitude events between the seafloor and the top of salt

(Figure GC 823-A-2). There is a negligible to low potential for shallow gas in this section.
Project No. 0411-1924

 -5- Proposed Well GC 823-A 

Closing

The seafloor and near-surface conditions at Proposed Wellsite GC 823-A, Green Canyon Block 823 (OCSG-33854), appear suitable for exploration drilling operations. The existing wellsites and the potential areas 

of deepwater benthic communities will need to be avoided by anchors supporting a drilling vessel at the 

proposed location. Overpressured sand layers are possible within Unit 4.

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, 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, 

2011.

Bureau of Ocean Energy Management, Regulation, and Enforcement, 2011b, Pre-Seabed Disturbance Survey 

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

Coffeen, J. A., 1978, Seismic exploration fundamentals: Tulsa, the Petroleum Publishing 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 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 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 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.
Project No. 0411-1924

 -6- Proposed Well GC 823-A 

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, 2008d, 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 resource surveys and reports: U. S. Department of the Interior, 

Minerals Management Service, Gulf of Mexico, NTL 2008-G20.

Minerals Management Service, 2009a, 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.

Minerals Management Service, 2009b, 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.
6781.0

33800.0

6781.0

34000.0

6781.0

34200.0

6781.0

34400.0

Line:

Trace:

15000 20000 25000 30000 35000 40000

1.400

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

Horizontal

Distance (ft):

6600.0

34082.0

6800.0

34082.0

7000.0

34082.0

Line:

Trace:

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

Horizontal

Distance (ft):

Project No. 0411-1924 Filename: 111924_fig_GC823-A-1.cdr

Figure GC 823-A-1. Inline 6781 and Crossline 34082 Showing Conditions Beneath Proposed Wellsite GC 823-A

15034.839

14132.748

13230.658

12328.568

11426.478

10524.387

9622.297

8720.207

7818.116

6916.026

6013.936

5111.845

4209.755

3307.665

2405.574

1503.484

601.394

-300.697

-1202.787

-2104.877

-3006.968

-3909.058

-4811.148

-5713.239

-6615.329

-7517.419

-8419.510

-9321.600

-10223.690

-11125.781

-12027.871

-12929.961

-13832.052

-15034.839

RELATIVE AMPLITUDE

TWO-WAY TIME TRAVEL (SEC) TWO-WAY TIME TRAVEL (SEC)

GC

823

GC

867

Northwest Southeast

Inline 6781

SALT

SALT

GC

823

GC

867

Southwest Northeast

SEAFLOOR

HORIZON 20

HORIZON 35

HORIZON 40

TOP OF SALT

UNIT 1

UNIT 2

UNIT 3

UNIT 4

SEAFLOOR

HORIZON 20

HORIZON 35

HORIZON 40

TOP OF SALT

UNIT 1

UNIT 2

UNIT 3

UNIT 4

Crossline 34082

Proposed 

Wellsite GC 823-A

Proposed 

Wellsite GC 823-A

GC

866

GC

824
6781.0

34000.0

6781.0

34200.0

25000 30000

Line:

Trace:

1.400

1.500

1.600

1.700

1.800

1.900

2.000

2.100

2.200

2.300

2.400

2.500

Horizontal

Distance (ft):

Shallow Water Flow and Gas Potential

HIGH

0 1 2 3

0 = NEGLIGIBLE

1 = LOW

2 = MODERATE

3 = HIGH

NEGLIGIBLE

Figure GC 823-A-2. Tophole Prognosis Chart, Proposed Wellsite A, Green Canyon Block 823

Project No. 0411-1924 Filename: 111924_fig_GC823-A-2.cdr

3-D Seismic Section Through

Proposed Wellsite A

X = 2,478,200 FT; Y = 9,853,440 FT

 Crossline 34082 at Inline 6781

NW SE

Inline 6781

GC

823

PROPOSED WELLSITE A

TWO-WAY TRAVEL TIME (SEC)

GC

867

SEAFLOOR

Water 

Flow Gas

Unit 1

HORIZON 20

HORIZON 40

FAULT

TOP OF SALT

Unit 2 Unit 4

1.685

1.736

INTERFACE

1.975

2.280

2.353

-4,129

-4,263

-4,920

-5,818

-6,045

134

791

1,689

1,916

134

394

1,125

Seafloor Slopes at 4.5° East-Northeast

Lithology/Stratigraphy

WATER

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

FAULT 2.039 -5,103 974

FAULT 1.829 -4,515 385

HORIZON 35 1.833 -4,527 397 263

2.221 -5,639 1,510

Very 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.

Turbidites. Alternating layers of clay and silt with thin

sands.

Fault near top of unit.

Chaotic sequence created by salt movement.

Fault near base of unit.

Negligible potential for overpressured sands.

Negligible potential for shallow gas.

Negligible potential for overpressured sands.

Negligible potential for shallow gas.

Low potential for overpressured sands.

Low potential for shallow gas.

Water Flow reported in Unit 4 at GC 823-001 well, 

775 ft to Northeast.

Moderate potential for overpressured sands.

Low potential for shallow gas.

Top of salt slopes 40° to Northeast.

.

High potential for overpressured sands.

Low potential for shallow gas.

Faults are possible zones of loss circulation.

SALT

TROUGH PEAK

RELATIVE AMPLITUDE
10615 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-B 

May 20, 2011 Project No. 0411-1924

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 GC 823-B

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 2,010 ft below the mudline (bml) at the Proposed Exploration Wellsite GC 823-B. 

The following discussion is based on findings provided within the main body of the geohazard report for 

Block 823 (GEMS Report No. 0411-1924). The surface location for Proposed Wellsite GC 823-B is in the 

southwestern quadrant of GC 823. Apache provided the following coordinates:

Proposed Wellsite GC 823-B

Spheroid & Datum: Clarke 1866, NAD27

Projection: UTM Zone 15 North Line Reference Block Calls

X: 2,477,578 ft Latitude: 27.1330196394346o N Inline 6784 1,884 ft FSL

Y: 9,854,364 ft Longitude: 90.4256637928309° W Crossline 34109 6,538 ft FWL

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-B-1 through GC 823-B-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 zoned beyond the limits of the anchor radius is also included, NTL 2009-G40 

(MMS, 2009a).

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-B-1: Bathymetry Map

Map GC 823-B-2: Seafloor Rendering

Map GC 823-B-3: Seafloor Amplitude Rendering

Map GC 823-B-4: Geologic Features Map

Figure GC 823- B-1:Inline 6784 and Crossline 34109 Showing Conditions Beneath 

Proposed Wellsite GC 823-B 

Figure GC 823-B-2:Tophole Prognosis Chart, Proposed Wellsite GC 823-B, Green Canyon 823
Project No. 0411-1924

- 2 - Proposed Well GC 823-B

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, 

2008a, 2008b, and 2009a). The proposed wellsite will be required to follow NTL 2008-G06 with respect to 

pre- and post-spud ROV visual inspection surveys (MMS, 2008c). Pursuant to the recently released PreSeabed Disturbance Survey Mitigation issued by BOEMRE, the 2005-G07 NTL (MMS, 2005) does not apply 

to GC 823 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 spectrum 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 ~0.699 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 GC 823-B

Man-Made Features

There are existing wells in GC 823 and in surrounding blocks. The closest well to Proposed Wellsite 

GC 823-B is the BP Exploration Inc., GC 823-001 well approximately 820 ft to the east-southeast (Maps 

GC 823-B-1 through GC 823-B-4). The closest touchdown point for an anchor chain will probably be 2,000 

ft from the proposed wellsite; therefore, the existing site should not be impacted by the proposed mooring 

pattern. 

0

0.2

0.4

0.6

0.8

1

1.2

0 10 20 30 40 50 60 70 80 90 100

Power (amp2)

Frequency (hrz)

POWER SPECTRUM

GC 823-B
Project No. 0411-1924

- 3 - Proposed Well GC 823-B

Other wells near the Proposed Wellsite GC 823-B are the BP Exploration Inc., GC 823-002 and GC 866-001 

wells. These wells are approximately 8,400 ft east and 10,700 ft southwest, respectively, of the proposed site 

and lie within the proposed mooring pattern.

Proposed Wellsite GC 823-B 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 Seafloor Conditions

The water depth at the proposed location is -4,072 ft (Map GC 823-B-1). The seafloor at the proposed 

location is slightly irregular and dips to the east at about 2.8 ̊. The proposed wellsite occurs in a valley 

between two ridges (Map GC 823-B-2). This area is along the eastern margin of a large topographic high 

created by a salt diapir.

Water depths within the potential anchor mooring area range from about -3,660 ft along a ridge line to the 

north to approximately -4,500 ft on the upper part of the Sigsbee Escarpment to the south (Map GC 823-B1).

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 north 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 20°. 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-B-3) shows normal or 

ambient amplitude along the seabed, with no indication of any hard-bottom or fluid expulsion events within 

2,000 ft of the proposed GC 823-B location. Based on the renderings and seismic profiles deepwater benthic 

communities are not expected within 2,000 ft of the proposed GC 823-B wellsite. 

Patches of high-amplitude seafloor returns occur approximately 9,300 ft to the southwest of the location. The 

patches are associated with seafloor faults. In addition, the base of a mud mound exists approximately 9,400 

ft to the northwest (Maps GC 823-B-1 through GC 823-B-4). These features 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 fault occurs

approximately 275 ft to the south-southwest. Except for the faults 9,300 ft to the southwest, no highamplitude returns occur along the seabed escarpments; therefore, prolific hydrocarbon seepage or carbonate 

hardgrounds are unlikely. 

Stratigraphy

Inline 6784 and Crossline 34109 are the closest 3-D lines to proposed Wellsite GC 823-B (Figure GC 823-B1). The Tophole Prognosis Chart (Figure GC 823-B-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 2,010 ft 

(Figure GC 823-B-2). The section was divided into four units or sequences (Figure GC 823-B-1). The 

sequences represent variations in depositional environments and possible changes in soil strength and 

composition. 
Project No. 0411-1924

- 4 - Proposed Well GC 823-B

The surficial unit, Unit 1 (Seafloor to Horizon 20), to approximately 135 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 gradually increase in strength and decrease in 

water 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 518 ft (Figure GC 823-B-2).

Unit 3 (Horizon 35 to Horizon 40) consists of mud-rich turbidites. The top of Unit 3, Horizon 35, is at about 

518 ft bml. The sequence is approximately 312 ft thick at proposed location GC 823-B.

Unit 4 is a sequence bounded by Horizon 40 and the top of salt (Figures GC 823-B-1 and GC 823-B-2). The 

upper portion of the sequence consists of bedded turbidites and thin mass-transport deposits. The sediments 

will be alternating clay and silt layers with thin sand or silty sand layers. The unit thins along the flank of 

the salt structure and reflection continuity is lost. The lower portion of Unit 4 (1,367 ft to 2,010 ft, bml) is a 

chaotic interval affected by shallow salt emplacement and will likely consist of a mixture of silt, clay, and 

sand. Unit 4 occurs between 830 ft and 2,010 ft bml, and is 1,180 ft thick. 

The top of salt is predicted to be 2,010 ft bml (~6,082 ft bsl). The salt surface dips to the east-northeast at 

approximately 41°.

Faults

Two faults will be intersected by the well bore beneath proposed Wellsite GC 823-B (Figures GC 823-B-1

and GC 823-B-2). The borehole will intersect the shallowest fault at approximately 466 ft bml, near the base 

of Unit 2. The remaining fault will be intersected between Horizon 40 and Top of Salt (Unit 4), at a depth of 

about 1,160 ft bml. 

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 135 ft bml at proposed Wellsite GC 823-B (Figure GC 823-B-2). The entire unit is 

383 ft thick. At this location, Unit 2 is an unlikely zone for overpressured sand layers. 

The existing GC 823-001 well is approximately 820 ft to the east-southeast of the proposed GC 823-B

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 lowamplitude interval of discontinuous to chaotic reflections (Figure GC 823-B-2). 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 

may not have been observed until drilling was at the 1,715 ft level.

Because of the proximity of the GC 823-001 well, the lower portion of Unit 4 has been given a high potential 

for shallow water flow (Figure GC 823-B-2). The upper portion of the unit is given a moderate potential for 

water flow considering the source of the flow in GC 823-001 may have originated higher than when 

observed during drilling. Sands within the unit are likely to be isolated and faulted. Like GC 823-001 any 

flow will be short-lived and of low severity.

Shallow Gas 

The well path will not penetrate any high-amplitude events between the seafloor and the top of salt (Figure 

GC 823-B-2). There is a negligible to low potential for shallow gas in this section.

Closing

The seafloor and near-surface conditions at proposed Wellsite GC 823-B, Green Canyon Block 823 (OCSG-33854), appear suitable for exploration drilling operations. The existing wellsites and the areas of 
Project No. 0411-1924

- 5 - Proposed Well GC 823-B

potential deepwater benthic communities will need to be avoided by anchors supporting a drilling vessel at 

the proposed location. Overpressured sand layers are possible within Unit 4.

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, 2011.

Bureau of Ocean Energy Management, Regulation, and Enforcement, 2011b, Pre-Seabed Disturbance Survey 

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

Coffeen, J. A., 1978, Seismic exploration fundamentals: Tulsa, the Petroleum Publishing 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 

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 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 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, 2008d, 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 resource surveys and reports: U. S. Department of the Interior, 

Minerals Management Service, Gulf of Mexico, NTL 2008-G20.

Minerals Management Service, 2009a, 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.
Project No. 0411-1924

- 6 - Proposed Well GC 823-B

Minerals Management Service, 2009b, Notice to lessees and operators of federal oil and gas leases and pipeline right-ofway 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.