UNITED STATES GOVERNMENT MEMORANDUM

To: Public Information (MS 5030)

Plans Section, Office of Field 

Operations (MS 5231)

Public Information copy of Exploration Plan

Control # - R-05177

Type - Revised Exploration Plan

Lease(s) - OCS-G31943 Block - 95 Walker Ridge Area

Operator - Shell Offshore Inc.

Subsea Wells A, B, C, D, and E

DRILLSHIP

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.

Michelle Griffitt

Plan Coordinator

Description -

Rig Type -

Subject:

From:

July 28, 2011
Shell Offshore Inc

P. O. Box 61933

New Orleans, LA 70161-1933

United States of America

Tel +1 504 728 7215

Fax +1 504 728 6747

Telex http://www.shell.com/eandp-en

Email sylvia.bellone@shell.com

April 27, 2011 PUBLIC INFORMATION

Ms. Liz Peuler, Section Chief 

Bureau of Ocean Energy Management, 

Regulation and Enforcement 

1201 Elmwood Park Boulevard 

New Orleans, LA 70123-2394 

 

Attn: Plans Group MS 5231 

SUBJECT: Revision to Exploration Plan N-9410 – Walker Ridge Block 95 

 OCS-G 31943, Offshore Louisiana 

 

Gentlemen: 

 

In compliance with 30 CFR 250.103 and NTLs 2008-G04, 2009-G27 and 2010-N06, giving Exploration 

Plan guidelines, Shell Offshore Inc (SOI) requests your approval of this Revised Exploration Plan 

requesting approval to drill Well Locations A, B, C, D & E. 

The NTL 2010-06 Worst Case Blowout requirements for our Regional Oil Spill Response Plan’s highest 

exploration well was previously submitted October 26, 2010. The WCD in this Plan does not exceed that 

total. 

This Plan consists of a series of attachments describing our intended operations. The attachments we 

desire to be exempted from disclosure under the Freedom of Information Act are marked “Confidential” 

and excluded from the Public Information Copies of this submittal. 

Should you require additional information, please contact me as indicated above. 

Sincerely, 

Sylvia A. Bellone 
SHELL OFFSHORE INC. 

REVISED EXPLORATION 

PLAN N-9410 

for 

WALKER RIDGE BLOCK 95 

OCS-G 31943

PUBLIC INFORMATION 

PREPARED BY: 

Sylvia A. Bellone 

Sr. Regulatory Specialist 

504.728.7215 

Sylvia.bellone@shell.com

 
REVISONS TO Plan R-5177 

Request Section of What Changed Date of 

Date Plan Response

5/12/11 Section 1 A Info about dry hole tree 

 Description, Objectives & Schedule 

 Section 1, Plan Information BHL 5/13/11 

 From “A” (2 of 6) 

Section 6A 

Chemosynthetic Communities Reference to Plan N-9410 

 Section 14E Corrected OCS Number 

 Vicinity Map 

6/7/11 Section 6A 

 Chemosynthetic Communities Provided ESR maps 6/21/11 

 Provided revised ESR maps 6/28/11 

 

7/12/11 Section 9 Oil Spill Info and Revised OSRP comparison 7/13/11 

 9 iv Regional OSRP numbers and filing dates 
REVISED EXPLORATION PLAN (R-5177) 

WALKER RIDGE Area 

BLOCK 95 

Table of Contents

1. Plan Contents 

2. General Information 

3. Geological and Geophysical 

4. Hydrogen Sulfide - H2S 

5. Mineral Resource Conservation 

6. Biological, Physical and Socioeconomic Information 

7. Waste and Discharge Information 

8. Air Emission Information 

9. Oil Spill Information 

10. Environmental Monitoring 

11. Lease Stipulations 

12. Environmental Mitigation Measures 

13. Related Facilities and Operations Information 

14. Support Vessels and Aircraft 

15. Onshore Support Facilities Information 

16. Sulphur Operations 

17. Coastal Zone Management Act Information 

18. Environmental Impact Analysis 

19. Administrative Information 

 

 

 
SECTION 1: PLAN CONTENTS

A. DESCRIPTION, OBJECTIVES & SCHEDULE

This Revised Exploration Plan (EP/Plan) with appendices, including an Environmental Impact Analysis (EIA) found 

in Section 18, describes the drilling activities Shell Offshore Inc. (Shell) plans to conduct with respect to Lease 

OCS-G 31943 located in Walker Ridge block 95. Wells A through E were approved in Plan N-9410 September 22, 

2009. The wells were never drilled. This Revised Plan will provide updated information for this activity. 

Shell’s Plan, as detailed in its EP, is to use a drillship, the M/V Noble Globetrotter or equivalent (the “Rig”). The 

initial drilling activities are planned to commence on or about January 1, 2012 depending on rig arrival. The 

drilling is expected to take approximately 198 days for the first well and approximately 165 days for the other 

wells. The timeframe to complete the initial drilling activities is an estimate based on the best available 

information regarding downhole conditions likely to be encountered while drilling each well and not intended to be 

a limitation. The timeframe for drilling the first well will further define the timing for further development of the 

prospect. Once the well(s) are drilled, a dry hole tree will be installed. Shell will complete and commence 

production under a separate DOCD. 

The Rig is a DP drillship and is equipped with state-of-the-art drilling and well control equipment. The Rig will 

comply with the requirements in the Interim Final Rules. The drilling activities will be supported by the support 

vessels and aircraft as well as onshore support facilities as listed in Sections 14 and 15 of the EP. Shell has 

employed or contracted with trained personnel to carry out its exploration activities. Shell is committed to local 

hire, local contracting and local purchasing to the maximum extent possible. Shell personnel and contractors are 

experienced at operating in the Gulf of Mexico and are well versed in all Federal and State laws regulating 

operations. Shell’s employees and contractors share Shell’s deep commitment to operating in a safe and 

environmentally responsible manner. 

Shell, through its parent and affiliate corporations, has extensive experience safely exploring for oil and gas in the 

Gulf of Mexico. Shell will draw upon this experience in organizing and carrying out its planned WR 95 drilling 

program. Shell believes that the best way to manage blowouts is to prevent them from happening. Significant 

effort goes into the design and execution of wells and into building and maintaining staff competence. In the 

unlikely event of a spill, Shell’s Regional OSRP (October 2010) is designed to contain and respond to a spill that 

meets or exceeds the WCD detailed in section 9 of this EP. The WCD does not take into account potential flow 

mitigating factors such as well bridging, obstructions in wellbore, reservoir barriers, or early intervention. We 

continue to invest in Research and Development (R&D) to improve safety and reliability of our well systems. All 

operations will be conducted in accordance with applicable federal and state laws, regulations, and lease and 

permit requirements. Shell will have trained personnel and monitoring programs in place to ensure such 

compliance. 

B. LOCATION

 See attached Maps. 

 
C. RIG SAFETY AND POLLUTION FEATURES: 

The rig (Noble Globe Trotter or similar) will comply with all of the regulations of the American Bureau of Shipping 

(ABS), International Maritime Organization (IMO) and the United States Coast Guard (USCG). All drilling 

operations will be conducted under the provisions of 30 CFR, Part 250, Subpart D, and other applicable regulations 

and notices, including those regarding the avoidance of potential drilling hazards and safety and pollution 

prevention control. Such measures as inflow detection and well control, monitoring for loss of circulation and 

seepage loss, and casing design will be our primary safety measures. Primary pollution prevention measures are 

contaminated and non-contaminated drain system, mud drain system, and oily water processing. 

DRAIN SYSTEM POLLUTION FEATURES 

Drains are provided on the Rig in all spaces and on all decks where water or oil can accumulate. The drains are 

divided into two categories, non-contaminated and contaminated. All deck drains are fitted with a removable 

strainer plate to prevent debris entering the system. 

Deck Drainage from rainfall, Rig washing, deck washing, and runoff from curbs and gutters, including drip pans 

and work areas, are discharged depending on if it comes in contact with the contaminated or non-contaminated 

areas of the Rig. 

1) Non-contaminated Drains 

Non-contaminated drains are designated as drains that under normal circumstances do not contain 

hydrocarbons, and can be discharged directly overboard. These are mostly located around the main deck and 

outboard in places where it is unlikely that hydrocarbons will be found. 

Drains within 50 feet of a designated chemical storage area which uses the weather deck as a primary 

containment means shall be designated “normally plugged.” An adequate number of drains around the rig shall 

be designated as “normally open” to allow run-off of rain water. Normally open drains shall have a plug located 

in a conspicuous area near the drain which can be easily installed in the event of a spill. 

The rig’s drain plug program consist at a minimum of a weekly check of all deck drains leading to the sea to 

verify that their status is as designated If normally open they shall verify that the drain is open and that the 

plug is available in the area. If normally closed they shall verify that the plug is securely installed in the drain. 

In the event a leak or spill is observed, the event shall be contained (drain plug installation and / or spill kit 

deployment as appropriate) and reported immediately. 

Rig personnel shall ensure that the perimeter kick-plates on weather decks are maintained and drain plugs are 

in place as needed to ensure a proper seal. 

2) Contaminated Drains 

Contaminated drains are designated as drains that contain hydrocarbons and cannot be discharged overboard. 

When oil-based mud is used for drilling it will be collected in portable tanks and sent to shore for processing. 

3) Mud Drain System 

 None 

 
4) Oily Water Processing 

Oily water is collected in an oily water tank. It must be separated and not pumped overboard until oil 

content is < 15 ppm. The separated oil is pumped to a dirty oil tank and has to be sent ashore for disposal. 

On board the MODU an oil record log has to be kept according to instructions included in the log. Any and 

all pollution pans are subjected to a sheen test before being pumped out. If the water passes the sheen test 

then it is pumped over board. If it does not pass the sheen test then the water/oil mixture is pumped to a 

dirty oil tank and sent to shore for disposal. All waste oil that is sent in to be disposed of is recorded in the 

MODU’s oil log book. 

All discharges will be in accordance with applicable NPDES permits. See Section 18, EIA. 

5) Lower Hull Bilge System 

• The main bilge system is designed to drain the pontoons. There are Goulds electrically driven, self 

priming centrifugal pumps - one for each main pump room. The aux pumps can be pump out with the 

bilge pump but has to be line up manually from the main pump room. 

• Bilge water is pumped overboard after a sheen test has been completed. 

• The pontoon bilge pumps are operable from the Bridge, and have audible and visual bilge alarms set for 

high and low levels. 

• Portable submersible pumps are carried onboard the rig to service all column void spaces and are also 

used for emergency bilge pump in the event of the main pump room flooding. 

• Alternate means of pumping the bilges in each pontoon pump room include the use of: 

• The ballast system emergency bilge valve which is operated from the control panel. 

• Portable submersible pumps 

• Emergency bilge suction line connected directly to the ballast manifold. (Main Pump rooms only) 

The Bilge pumps are manual/automatic type pumps. They are equipped with sensors that give a high and a 

high high alarm. They are set to a point at which the water gets to a certain point they will automatically 

turn on to pump water out in order to keep flooding under control. The pumps are also capable of being put 

in manual mode in which they can be turned on by hand. 

6) Emergency Bilge System 

Main ballast pumps may also be used for emergency bilge pumping directly from the pump rooms via 

remotely actuated direct bilge suction valves on the ballast system. These valves will operate in a fully 

flooded compartment. The ballast pumps can be supplied from the emergency switchboard. 

7) Oily Water Drain/Separation System

 Oily water/engine room bilge water is collected in an oily water tank. It must be separated and not pumped 

overboard until oil content is < 15 ppm. The separated oil is pumped to a dirty oil tank and has to be sent 

ashore for disposal. On board all drilling Units, an oil record log has to be kept according to instructions 

included in the log. The rig floor has two skimmer tanks and each is subjected to a sheen test before 

pumping overboard to ensure environmental safety. All three anchor winch windlasses have skimmer tanks 

and are subjected to sheen tests before discharge as well. 

8) Drain, Effluent and Waste Systems 

• The Rig’s drainage system is designed in line with our environmental and single point discharge policies. 

Drains are either hazardous, i.e. from a hazardous area as depicted on the Area Classification drawings, 

or non-hazardous drains from nonhazardous areas. 

• To prevent migration of hazardous materials and flammable gas from hazardous to non-hazardous 

areas, the drainage systems are segregated. 

• The Rig drainage systems tie into oily water separators that take out elements in the drainage that 

could harm the environment. This is part of Noble’s initiative to be good stewards of the environment. 

The oily water separators divide the drainage system into these sections: 

 
9) Rig Floor Drainage 

The Rig floor has been outfitted with a Facet International MAS 34-3 separator. The separator has 

coalescent plates that remove the solids from the drainage, and the remaining drainage goes to a skimmer 

tank. From the skimmer tank it is drained to one of the column dirty oil tank systems where it is then sent 

through 2 separators and cleaned further to reduce oil content to less than 15 ppm. 

10) Columns #3 & 4 

The drains on the decks and machinery spaces are separated at mid ship and directed to either the #3 or 

#4 columns. The separators in these columns go through three cycles of circulation and remove oil to less 

than 15ppm, then discharge the clean product to sea. 

11) Main Engine Rooms 

• The engine rooms have their own drainage and handling system. The engine rooms are outfitted with a 

dirty oil tank and the drainage in the tank is processed through the separator, the waste from the 

separator goes back to the dirty oil tank and the clean water (less than 15ppm) goes overboard. 

• The locations and models of the separators are as follows: 

• Column #3 – Westfalia WSD-18 

• Column #4 – Westfalia WSD-18 

• Drill Floor – Facet International MAS 34-3 

12) Helideck Drains 

The helideck has a dedicated drainage system around its perimeter to drain heli-fuel from a helicopter incident. 

The fuel can be diverted to the designated heli fuel recovery tank which is located under the Helideck structure. 

Operating configurations are as follows: 

3⁄4 The overboard piping valves and hydrocarbons take on valves are closed and locked. To unlock 

overboard or take on valves a permit has to be filled out. 

3⁄4 The oily water collection tank overflow valve is closed. 

3⁄4 The drill floor drains are lined-up to the drill floor skimmer tank. The Skimmer tanks have a high 

alarm which sounds by means of an air horn. Before tanks are pumped out a sheen test is 

performed. Water is pump out the skimmer tanks down the shunt line. Oil containment side is 

pumped out into 550 gal tote tanks. 

3⁄4 The BOP test area drains are normally lined-up to drain overboard. 

3⁄4 The oily water separator continuously circulates the oily water collection tank. Waste oil is 

discharged into the waste oil tank and oily water is re-circulated back into the oily water collection 

tank. Clean water is pumped overboard, which is controlled/monitored by the oil content detector, 

set at 15 ppm. 

3⁄4 The solids control system is capable of being isolated for cuttings collection. 

3⁄4 The bilge system is normally pumped directly overboard after a sheen test has been performed. 

3⁄4 The engine dirty oil sump can be drained down in Port column oily water separator which 

discharges water overboard from the water side and oil being pumped out into a 550 gal tote tank 

oil containment side. There is a high audible alarm on the ballast control panel. 

 
D. Storage Tanks: 

Type of Storage Tank Type of Tank Number of Total Fluid 

Facility Capacity 

(bbls) 

Tanks Capacity 

(bbls) 

Gravity (API) 

Fuel oil MODU 2652 1 2652 No. 2 diesel 

Fuel oil MODU 1,743 1 1743 No. 2 diesel 

Fuel oil MODU 5767 1 5767 No. 2 diesel 

Fuel oil MODU 4399 1 4399 No. 2 diesel 

Fuel oil MODU 2652 1 2652 No. 2 diesel 

Fuel oil MODU 3250 1 3250 No. 2 diesel 

Fuel oil MODU 4399 1 4399 No. 2 diesel 

Fuel oil MODU 2618 1 2618 No. 2 diesel 

Fuel oil MODU 115 4 460 No. 2 diesel 

Fuel oil MODU 129 4 516 No. 2 diesel 

E. Pollution Prevention Measures 

Pursuant to NTL No. 2008-G04 the proposed operations covered by this EP do not require Shell to specifically 

address the discharges of oils and greases from the Rig during rainfall or routine operations. Nevertheless, Shell 

has provided this information as part of its response in 1(c) above. 

F. Additional Measures

 

3⁄4 HSE (health safety and environment) are the primary topics in pre-tour and pre-job safety meetings. 

The discussion around no harm to people or environment is a key mindset. All personnel are 

reminded daily to inspect work areas for safety issues as well as potential pollution issues. 

3⁄4 All tools that come to and from the Rig have their pollution pans inspected, cleaned and confirmation 

of plugs installed prior to leaving dock and prior to loading on the boat. 

3⁄4 Preventive Maintenance of Rig equipment includes visual inspection of hydraulic lines and reservoirs 

on routine scheduled basis. 

3⁄4 All pollution pans on Rig are inspected daily. 

3⁄4 Containment dikes are installed around all oil containment, drum storage areas, fuel vents, and fuel 

storage tanks. 

3⁄4 All used oil and fuel is collected and sent in for recycling. 

3⁄4 Every drain on the Rig is assigned a number on a checklist. The checklist is used daily to verify drain 

plugs are installed. 

3⁄4 All trash containers are checked and emptied daily. The trash containers are kept covered. Trash is 

disposed of in a compactor and shipped in via boat. 

3⁄4 The Rig is involved in a recycling program for cardboard, plastic, paper, glass, and aluminum. 

3⁄4 Fuel hoses and SBM are changed on annual basis. 

3⁄4 TODO spill prevention fittings are installed on all liquid take on hoses. 

3⁄4 Waste paint thinner is recycled on board with a solvent still to reduce hazard of shipping and storage. 

3⁄4 All equipment on board utilizes Envirorite hydraulic fluid as opposed to hydraulic oil. 

3⁄4 Shell has obtained ISO14001 certification. 

3⁄4 Shell uses low sulfur fuel 
U. S. Department of the Interior OMB Control Number: 1010-0049 

Minerals Management Service OMB Approval Expires: August 31, 2006 

OCS PLAN INFORMATION FORM 

General Information 

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

Company Name: Shell Offshore Inc. MMS Operator Number: 0689 

Address: P. O. Box 61933 Contact Person: Sylvia Bellone 

New Orleans, LA 70161-1933 Phone Number: (504) 728-7215 

 E-Mail Address: sylvia.bellone@shell.com

Lease(s): OCS-G 31943 Area: Walker Ridge Block(s): 95 Project Name (If Applicable): NA 

Objective(s): X Oil Gas Sulphur Salt Onshore Base: Fourchon & 

Boothville 

Distance to Closest Land (Miles): 

156 

Description of Proposed Activities (Mark all that apply)

X 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 MMS-designated high-probability archaeological area? Yes X No 

Have all of the surface locations of your proposed activities been previously reviewed and approved by MMS?* X Yes* No 

Tentative Schedule of Proposed Activities 

Proposed Activity Start Date End Date No. of Days 

Drill Well A 1/1/2012 7/17/2012 198 

Drill Well B 1/1/2013 6/15/2013 165 

Drill Well C 1/1/2014 6/15/2014 165 

Drill Well D 1/1/2015 6/15/2015 165 

Drill Well E 1/1/2016 6/14/2016 165 

*The SLs for these wells were reviewed and approved in Plan N-9410 

Description of Drilling Rig Description of Production Platform 

 Jackup X 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): Noble Globe Trotter or similar Spar Other (Attach Description) 

Description of Lease Term Pipelines 

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

N/A 

 

MMS Form MMS-137 (August 2003) Page 1 of 6 PUBLIC INFORMATION 

 
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: NA X Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. OCS-G 31943 

Area Name Walker Ridge 

Block No. 95 

Blockline 

Departures 

(in feet)

N/S Departure: 7122’ FNL 

 E/W Departure: 5625’ FEL 

Lambert X-Y 

coordinates 

X: 2101095 

 Y: 9750318 

Latitude/ 

Longitude

Latitude 26.86322929 

Longitude -91.58656019 

TVD (Feet): MD (Feet): Water Depth (Feet): 5848’ 

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 

 

 

 

 

 

 

 

 

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

to inform you that MMS collects this information as part of an applicant’s Exploration Plan or Development Operations 

Coordination Document submitted for MMS 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.

MMS Form MMS-137 (August 2003) Page 2 of 6 PUBLIC INFORMATION
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: NA X Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. OCS-G 31943 

Area Name Walker Ridge 

Block No. 95 

Blockline 

Departures 

(in feet)

N/S Departure: 7531’ FNL 

 E/W Departure: 4079’ FEL 

Lambert X-Y 

coordinates 

X: 2102641 

 Y: 9749909 

Latitude/ 

Longitude

Latitude 26.86205653 

Longitude -91.58183200 

TVD (Feet): MD (Feet): Water Depth (Feet): 5833’ 

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 

 

 

 

 

 

 

 

 

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

to inform you that MMS collects this information as part of an applicant’s Exploration Plan or Development Operations 

Coordination Document submitted for MMS 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.

MMS Form MMS-137 (August 2003) Page 3 of 6 PUBLIC INFORMATION
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: NA X Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. OCS-G 31943 

Area Name Walker Ridge 

Block No. 95 

Blockline 

Departures 

(in feet)

N/S Departure: 3717’ FNL 

 E/W Departure: 1035’ FEL 

Lambert X-Y 

coordinates 

X: 2105685 

 Y: 9753723 

Latitude/ 

Longitude

Latitude 26.87245572 

Longitude -91.57236315 

TVD (Feet): MD (Feet): Water Depth (Feet): 5841’ 

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 

 

 

 

 

 

 

 

 

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

to inform you that MMS collects this information as part of an applicant’s Exploration Plan or Development Operations 

Coordination Document submitted for MMS 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.

MMS Form MMS-137 (August 2003) Page 4 of 6 PUBLIC INFORMAITON

 
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: NA X Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. OCS-G 31943 

Area Name Walker Ridge 

Block No. 95 

Blockline 

Departures 

(in feet)

N/S Departure: 7805’ FNL 

 E/W Departure: 5427’ FEL 

Lambert X-Y 

coordinates 

X: 2101293 

 Y: 9749635 

Latitude/ 

Longitude

Latitude 26.861344111 

Longitude –91.585976207 

TVD (Feet): MD (Feet): Water Depth (Feet): 5949’ 

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 

 

 

 

 

 

 

 

 

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

to inform you that MMS collects this information as part of an applicant’s Exploration Plan or Development Operations 

Coordination Document submitted for MMS 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.

MMS Form MMS-137 (August 2003) Page 5 of 6 PUBLIC INFORMATION

 
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): E Subsea Completion 

Anchor Radius (if applicable) in feet: NA X Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. OCS-G 31943 

Area Name Walker Ridge 

Block No. 95 

Blockline 

Departures 

(in feet)

N/S Departure: 8278’ FNL 

 E/W Departure: 4144’ FEL 

Lambert X-Y 

coordinates 

X: 2102576 

 Y: 9749162 

Latitude/ 

Longitude

Latitude 26.86000335 

Longitude –91.58205701 

TVD (Feet): MD (Feet): Water Depth (Feet): 5843’ 

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 

 

 

 

 

 

 

 

 

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

to inform you that MMS collects this information as part of an applicant’s Exploration Plan or Development Operations 

Coordination Document submitted for MMS 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.

MMS Form MMS-137 (August 2003) Page 6 of 6 PUBLIC INFORMAITON

 

SECTION 2: GENERAL INFORMATION

A. Application and Permits

There are no individual or site-specific permits other than general NPDES Permit and rig move notification that 

need to be obtained. 

B. Drilling Fluids 

 See Table 7A 

C. Production

Information regarding production is not included in this EP as such information is only necessary in the case 

of DOCDs. 

D. Oil Characteristics 

Information regarding oil characteristics is not included in this EP as such information is only necessary in the 

case of DOCDs. 

E. New Or Unusual Technology

Shell is not proposing to use new or unusual technology as defined in 30 CFR 250.200 to carry out the proposed 

activities in this EP. 

F. Bonding

The bond requirement for the activities proposed in this SEP are satisfied by an area-wide bond furnished and 

maintained according to 30 CFR Part 256, subpart I; NTL No. 2000-G16, Guideline for General Lease Surety 

Bonds;” and National NTL No. 2003-N06, “Supplemental Bond Procures.” 

G. Oil Spill Financial Responsibility (OSFR)

Shell Offshore Inc (SOI), BOEMRE Operator Number 0689, has demonstrated oil spill financial responsibility for 

the facilities proposed in the EP according to 30 CFR Part 253, and NTL No. 2008-N05, “Guidelines for Oil Spill 

Financial Responsibility for Covered Facilities.” 

H. Deepwater well control statement

Shell Offshore Inc (SOI), BOEMRE Operator Number 0689, has the financial capability to drill a relief well and 

conduct other emergency well control operations. 

I. Suspension of Production

Information regarding Suspension of Production is not included in this EP as such information is only 

necessary in the case of DOCDs. 

 
J. Blowout scenario

Summary 

This Section 2j was prepared by Shell Offshore Inc. (Shell) pursuant to the guidance provided in the Bureau 

of Ocean Energy Management, Regulation and Enforcement’s (BOEMRE) Notice to Lessees (NTL) No. 2010-

N06 with respect to blowout and worst case discharge scenario descriptions. 

Shell focuses on an integrated, three-pronged approach to a blowout, including prevention, intervention 

/containment, and recovery. Shell believes that the best way to manage blowouts is to prevent them from 

happening. Significant effort goes into the design and execution of wells and into building and maintaining 

staff competence. Shell continues to invest independently in Research and Development (R&D) to improve 

safety and reliability of our well systems. Shell intends to comply with all applicable laws, regulations, rules 

and Notices to Lessees. 

Shell is investing in R&D to improve containment systems. As outlined in Shell’s Oil Spill Response Plan 

(OSRP), and detailed in EP Section 9a (ii), Shell has contracts with Oil Spill Removal Organizations (ORSOs) to 

provide the resources necessary to respond to this Worst Case Discharge (WCD) scenario. 

The WCD blowout scenario for Yucatan North is calculated for the WR-95 C location penetration of the Wilcox 

Formation and based on the guidelines outlined in NTL No. 2010-N06 along with subsequent Frequently 

Asked Questions (FAQ). Shell has submitted MC-391 C as the new worst-case scenario to the BOEMRE for 

inclusion in our Regional OSRP. In the unlikely event of a spill, Shell’s Regional OSRP (October 2010) is 

designed to contain and respond to a spill that exceeds this WCD. This WCD does not take into account 

potential flow mitigating factors such as well bridging, obstructions in wellbore, reservoir barriers, and early 

intervention including containment capabilities. 

Uncontrolled blowout (volume first day) 99,000 bbls. 

Uncontrolled blowout rate (first 30-days average daily rate) 79,000 bopd 

Duration of flow (days) based on relief well 211 days 

Total volume of spill (bbls) for 211 days 15 MMBO 

Table 1. Yucatan North Worst Case Discharge Summary 

The green-field exploration prospect Yucatan North is located approximately 135 nautical miles southsouthwest of the nearest Louisiana shoreline in the Gulf of Mexico (GOM), in water depths of approximately 

5800 feet (ft) across the prospect. The structural component of the target is defined by a three-way 

culmination against base-salt/salt weld that is approximately 2 miles long by 3 miles wide, with the crest of 

the objective near 28,000 ft subsea (SS). In early 2009, Anadarko announced their discovery (Shenandoah 

WR52#1BP2 OCS G-25232) in the Wilcox Formation in Walker Ridge OCS block 52 approximately 5 miles to 

the northeast of Yucatan North. The Shenandoah and Yucatan North prospects share a common structural 

saddle at the Wilcox Formation stratigraphic level. Shell obtained all the well data collected from the 

Shenandoah wellbore, and our WCD calculations for Yucatan North presented in this document incorporate 

this offset well data. The only objective interval with predicted flow potential is the Wilcox Formation 

reservoir of Eocene-Paleogene age. 

1) Purpose 

Pursuant to 30 CFR 250.213(g), 250.219, 250.250, and NTL No. 2010-N06, this document provides a blowout 

scenario description, further information regarding any potential oil spill, the assumptions and calculations 

used to determine the WCD and the measures taken to 1) enhance the ability to prevent a blowout and 2) 

respond and manage a blowout scenario if it were to occur. These calculations are based on best technical 

estimates of subsurface parameters that are derived from the offset Shenandoah well data, additional 

regional Wilcox Formation offset well data, and seismic data. These parameters are better than or consistent 

with the estimates used by Shell to justify the investment. Therefore, these assumed parameters were used 

to calculate the WCD. They do not reflect probabilistic estimates. 

 
2) Background 

This attachment has been developed to document the additional information requirements for Exploration 

Plans as requested by NTL No. 2010-N06 in response to the explosion and sinking of the Mobile Offshore 

Drilling Unit (MODU) Deepwater Horizon and the resulting subsea well blowout and recovery operations of 

the exploration well at the MC-252 Macondo location. 

3) Information Requirements 

a) Blowout scenario 

All five locations in the approved Yucatan North EP were assessed for WCD. The WR-95 well from the 

approved C location represents the highest flow potential. The C well penetrates the Wilcox 

Formation reservoir as outlined in the Geological and Geophysical Information Section of the 

Supplemental EP using a subsea wellhead system, conductor, surface and intermediate casing 

program, and using a DP drillship with a marine riser and subsea blowout preventer (BOP). A 

hydrocarbon influx and a well control event are modeled to occur from the Wilcox Formation 

reservoir. The simulated blowout modeled results in unrestricted flow from the well at the seafloor, 

which represents the WCD (no restrictions in wellbore, failure/loss of the subsea BOP, and a blowout 

to the seabed). 

b) Estimated flow rate of the potential blowout 

Category EP 

Type of Activity Drilling 

Facility Location (area/block) WR-95 

Facility Designation MODU 

Distance to Nearest Shoreline (Nautical miles) 135 

Uncontrolled blowout (volume first day) 99,000 bbl 

Uncontrolled blowout rate (first 30-days average daily rate) 79,000 bopd 

Table 2. Estimated Flow Rates of a Potential Blowout 

c) Total volume and maximum duration of the potential blowout 

Duration of flow (days) 211 days total duration to drill relief well 

(14 rig mob, 4 transit, 151 spud to base Wilcox Fm., 42 ranging). 

Total volume of spill (bbls) 15 MMBO based on 211 days flowing. 

Note: From CMG numerical simulation model 

Table 3. Estimated Duration and Volume of a Potential Blowout 

There is usually a decline in the discharge rate as time proceeds, which is illustrated by the 

differences between the first 24-hour volume and 30-day average rate. The total volume calculated 

until a well is killed in a potential blowout further demonstrates this decline. At very short times, e.g. 

during the first 24 hours, the pressure profile in the reservoir changes from the moment when a well 

first starts flowing to a pseudo-steady state pressure profile with time, and as a result the rate 

declines. At somewhat longer time scales, effects such as reservoir voidage and the impact of 

boundaries can cause the rate to drop continuously with production. Simulation and material balance 

models can include these effects and form the basis of the NTL No. 2010-N06 calculations for 24-

hour and 30-day rates as well as maximum duration volumes. 

 
d) Assumptions and calculations used in determining the worst case discharge (Proprietary): 

 Omitted from Public Information Copies 

e) Potential for the well to bridge over 

Mechanical failure/collapse of the borehole in a blowout scenario is influenced by several factors 

including in-situ stress, rock strength and fluid velocities at the sandface. Based on the nodal analysis 

and reservoir simulation models outlined above, a seabed blowout would create a high drawdown at 

the sand face. Given the substantial fluid velocities inherent in the worst case discharge, and the 

scenario as defined where the formation is not supported by a cased and cemented wellbore, it is 

possible that the borehole may fail/collapse/bridge over within the span of a few days, significantly 

reducing the outflow rates. However, this WCD scenario does not include any bridging. 

f) Likelihood for intervention to stop the blowout. 

Safety of operations is our top priority. Maintaining well control at all times to prevent a blowout is 

the key focus of our operations. Our safe drilling record is based on our robust standards, 

conservative well design, prudent operations practices, competency of personnel, and strong HSE 

focus. Collectively, these constitute a robust system making blowouts extremely rare events. 

Intervention Devices: Notwithstanding these facts, the main scenario for recovery from a blowout 

event is via intervention with the BOP attached to the well. There are built in redundancies in the 

BOP system to allow activation of selected components with the intent to seal off the well bore. As a 

minimum, the Shell contracted rig fleet in the GOM will have redundancies meeting the Interim Final 

Drilling Safety Rule with respect to Remotely Operated Vehicle (ROV) hot stab capabilities, a 

deadman system, and an autoshear system. 

Additionally the Noble Globetrotter (dynamically positioned Drillship) will consist of 2 – 10K annulars, 

4 – 15K drill pipe rams, 1 – 15K casing shear, and 1 – 15K CVX shear ram. The Globetrotter is also 

equipped with a deadman system and an autoshear system. 

Containment: The experience of gaining control over the Macondo well has resulted in a better 

understanding of the necessary equipment and systems for well containment. As a result, industry 

and government are better equipped and prepared today to contain an oil well blowout in deepwater 

(See page 17 of the Decision Memorandum dated October 1, 2010). Shell is further analyzing these 

advances and incorporating them into its comprehensive approach to help prevent and, if needed, 

control another deepwater control incident. 

Pursuant to NTL No. 2010-N10 Shell will provide additional information regarding our containment 

capabilities in a subsequent filing. 

g) Availability of a rig to drill a relief well and rig package constraints 

Blowout intervention can be conducted from an ROV equipped vessel, the existing drilling rig or from 

another drilling rig. Shell has an active portfolio of well operations in the GOM which will be 

supported by a total of four to six MODU rigs in 2011 – 2015 timeframe. The dynamically positioned 

rigs under contract, the Noble Danny Adkins, Globetrotter, and the Bully 1, will be the preferred rigs 

for blowout intervention work. However, moored rigs can also be used in some scenarios. 

Additionally, in the event of a blowout, there is the distinct possibility that other non-contracted rigs 

in the GOM could be utilized whether for increased expediency or better suitability. All efforts will be 

made at the time to secure the appropriate rig. Shell’s current contracted rigs capable of operating at 

Yucatan North water depths and reservoir depths without constraints are in the following table: 

 
Rig Name Rig Type

Noble Danny Adkins

dynamically positioned

semisubmersible

Bully #1*

dynamically positioned

Drillship

Noble

Globetrotter*

dynamically positioned

Drillship

Deepwater Nautilus moored semisubmersible

Noble Jim

Thompson moored semisubmersible

Table 4. Shell Contracted Rigs Capable at Yucatan North. 

Above are current as of April 2011. Future modifications may change the rig’s capability. 

Rig capabilities need to be assessed on a work scope specific basis. 

*Bully 1 estimated arrival January 2012. Globetrotter estimated arrival Dec. 2011 

h) Time taken to contract a rig, move it onsite, and drill a relief well 

Relief well operations will immediately take priority and displace any activity from Shell’s contracted 

rig fleet. Table 4 lists the Shell contracted rigs capable of operating at Yucatan North. It is expected 

to take an average of 14 days to safely secure the well that the rig is working on up to the point the 

rig departs location, and an additional 4 days transit to mobilize to the relief well site depending on 

distance to the site. The relief well will take approximately 151 days to drill down to the last casing 

string above the blowout zone, plus approximately 42 days for precision ranging activity to intersect 

the blowout well bore. Total time to mobilize and drill a relief well would be 211 days for the 

Yucatan North wells. 

If a moored rig is chosen to conduct the relief well operations, anchor handlers would be prioritized 

to prepare mooring on the relief well site while the rig is being mobilized. This mooring activity is not 

expected to delay initiation of relief well drilling operations. Shell has three deepwater anchor 

handlers, the Laney, Dino, and Ross Chouest, on long term contract to support its moored rigs. 

It is not possible to drill relief wells from any existing platforms as there are none in the region. 

i) Measures proposed to enhance ability to prevent blowout and to reduce likelihood of a 

blowout. 

Shell believes that the best way to manage blowouts is to prevent them from happening. Detailed 

below are the measures employed by Shell with the goal of no harm to people or the environment. 

The Macondo incident has highlighted the importance of these practices. The lessons learned from 

the investigation are, and will continue to be, incorporated into our operations. 

Standards: Shell’s well design and operations adhere to internal corporate standards, the Code of 

Federal Regulations, and industry standards. A robust management of change process is in place to 

handle un-defined or exception situations. Ingrained in the Shell standards for well control is the 

philosophy of multiple barriers in the well design and operations on the well. 

Risk Management: Shell believes that prevention of major incidents is best managed through the 

systematic identification and mitigation process (Safety Case). All Shell contracted rigs in the GOM 

have been operating with a Safety Case and will continue to do so. A Safety Case requires both the 

owner and contractors to systematically identify the risks in drilling operations and align plans to 

mitigate those risks; an alignment which is critical before drilling begins. 
Well Design Workflow: The Well Delivery Process (WDP) is a rigorous internal assurance process 

with defined decision gates. The WDP leverages functional experts (internal and external) to examine 

the well design at the conceptual and detailed design stages for robustness before making a 

recommendation to the management review board. Shell’s involvement in global deepwater drilling, 

starting in the GOM in the mid-1980’s, provides a significant depth and breadth of internal drilling 

and operational expertise. Third party vendors and rig contractors are involved in all stages of the 

planning, providing their specific expertise. A Drill the Well On Paper (DWOP) exercise is conducted 

with rig personnel and vendors involved in execution of the well. This forum communicates the well 

plan, and solicits input as to the safety of the plan and procedures proposed. 

Well and rig equipment qualification, certification, and quality assurance: All rigs will meet 

all applicable rules, regulations, and Notice to Lessees. Shell works closely with rig contractors to 

ensure proper upkeep of all rig equipment, which meets or exceeds the strictest of Shell, industry, or 

regulatory requirements. Well tangibles are governed by our internal quality assurance/control 

standards and industry standards. 

MWD/LWD/PWD Tools: Shell intends to use these tools at Yucatan North. The MWD/LWD/PWD 

tools are run on the drill string so that data on subsurface zones can be collected as the well 

advances in real time instead of waiting until the drill string is pulled to run wireline logs. Data from 

the tools are monitored and interpreted real time against prognosis to provide early warning of 

abnormal pressures to allow measures to be taken to progress the well safely. 

Mud Logger: Mud-logging personnel continually monitor returning drilling fluids for indications of

hydrocarbons, utilizing both a hot wire and a gas chromatograph. An abrupt increase in gas or oil 

carried in the returning fluid can be an indication of an impending kick. The mud logger also monitors 

drill cuttings returned to the surface in the drilling fluid for changes in lithology that can be an 

indicator that the well has penetrated or is about to penetrate a hydrocarbon-bearing interval. Mud 

logging instruments also monitor penetration rate to provide an early indication of drilling breaks that 

show the bit penetrating a zone that could contain hydrocarbons. The mud logging personnel are in 

close communication with both the offshore drilling foremen and onshore Shell representative(s) to 

report any observed anomalies so appropriate action can be taken. 

Remote Monitoring: The Real Time Operating Center has been used by Shell to complement and 

support traditional rig-site monitoring since 2003. Well site operations are monitored 24/7 virtually by 

onshore teams consisting of geoscientists, petrophysicists, well engineers, and monitoring specialists. 

The same real time well control indicators monitored by the rig personnel are watched by the 

monitoring specialist for an added layer of redundancy. 

Competency and Behavior: A structured training program for Well Engineers and Foremen is 

practiced, which includes internal professional examinations to verify competency. Other industry 

training in well control, such as by International Association of Drilling Contractors (IADC) and 

International Well Control Forum (IWCF) are also mandated. Progressions have elements of 

competency and Shell continues to have comprehensive internal training programs. The best systems 

and processes can be defeated by lack of knowledge and/or improper values. We believe that a 

combination of HSE tools (e.g. stop work, pre-job analysis, behavior based safety, DWOPs, audits), 

management HSE involvement and enforcement (e.g. compliance to life saving rules) have created a 

strong safety culture in our operations. 

j) Measures to conduct effective and early intervention in the event of a blowout. 

The response to a blowout is contained in our Well Control Contingency Plan (WCCP) which is a 

specific requirement of our internal well control standards. The WCCP in turn is part of the wider 

emergency response framework within Shell that addresses the overall organization response to an 

emergency situation. Resources are dedicated to these systems and drills are run frequently to test 

preparedness (security, medical, oil spill, and hurricane). This same framework is activated and 

tested during hurricane evacuations, thereby maintaining a fresh and responsive team. 

 
The WCCP specifically addresses implementing actions at the emergency site that will ensure 

personnel safety, organizing personnel and their roles in the response, defining information 

requirements, establishing protocols to mobilize specialists, pre-selecting sources, and developing 

mobilization plans for personnel, material and services for well control procedures. The plan 

references individual activity checklists, a roster of equipment and services, initial information 

gathering forms, a generic description of relief well drilling, strategy and guidelines, intervention 

techniques and equipment, site safety management, exclusion zones, and re-boarding. 

As set forth in 3f of this document, Shell is currently analyzing recent advances in containment 

technology and equipment and will incorporate them as they become available. 

k) Arrangements for drilling a relief well 

The size of the Shell contracted rig fleet in the GOM from 2010-2015 ensures that there is adequate 

well equipment (e.g. casing and wellhead) available for relief wells. Rigs and personnel will also be 

readily available within Shell, diverted from their active roles elsewhere. Resources from other 

operators can also be leveraged should the need arise. Generally, relief well plans will mirror the 

blowout well, incorporating any learning on well design based on root cause analysis of the blowout. 

A generic relief well description is outlined in the WCCP. 

l) Assumptions and calculations used in approved or proposed OSRP 

Shell has submitted MC-391 C (Appomattox) as the new exploratory worst-case scenario to the 

BOEMRE on 10-26-10 (plan code S7444) for inclusion in our Regional OSRP. 

Shell has designed a response program (Regional OSRP October 2010) based upon a regional 

capability of responding to a range of spill volumes, from small operational spills up to and including 

the WCD from an exploration well blowout. Shell’s program is developed to fully satisfy federal oil 

spill planning regulations. The Regional OSRP presents specific information on the response program 

that includes a description of personnel and equipment mobilization, the incident management team 

organization, and the strategies and tactics used to implement effective and sustained spill 

containment and recovery operations. 

 
SECTION 3: Geological & Geophysical Information

A. Geological description

Omitted from PI copies.

B. Structure contour maps.

Omitted from PI copies.

C. Interpreted 2D and/or 3D Seismic line(s)

Omitted from PI copies.

D. Geological Structure Cross-section(s)

Omitted from PI copies.

E. Shallow Hazards Report – Geologic & Stratigraphic Assessment of Walker Ridge Blocks 95 & 139, 

prepared by GEMS for Shell Offshore Inc, dated February 19, 2009, project No. 1008-1564. 

F. Shallow Hazards Assessment

Proposed Wellsite A (I in the Report)

Shell, Block 95 (OCS-G-31943)

Walker Ridge Area

Gulf of Mexico

The Proposed Wellsite A location in Walker Ridge area, Block 95 appears favorable for exploration drilling 

operations relevant to the shallow geologic and stratigraphic conditions. The geohazard report (No. 1008-

1564) and this letter comply with the Minerals Management Service (MMS) Notice-to-Lessees (NTL’s) 2000-

G20, 2005-G07, and 2008-G05 (MMS, 2000, 2005, and 2008a, respectively). 

The seafloor at Proposed Wellsite A, Walker Ridge Block 95 (OCS-G-31943), appears suitable for exploration 

drilling operations. The well bore will intersect a fault plane at approximately 200 ft bml. Soil conditions are 

likely to be very similar to those encountered in the nearby WR 52-1 well a few miles north of the proposed 

location. 

The Proposed Wellsite B location in Walker Ridge area, Block 95 appears favorable for exploration drilling 

operations relevant to the shallow geologic and stratigraphic conditions. The geohazard report (No. 1008-

1564) and this letter comply with the Minerals Management Service (MMS) Notice-to-Lessees (NTL’s) 2000-

G20, 2005-G07, and 2008-G05 (MMS, 2000, 2005, and 2008a, respectively). 

The Proposed Wellsite C location in Walker Ridge area, Block 95 appears favorable for exploration drilling 

operations relevant to the shallow geologic and stratigraphic conditions. The geohazard report (No. 1008-

1564) and this letter comply with the Minerals Management Service (MMS) Notice-to-Lessees (NTL’s) 2000-

G20, 2005-G07, and 2008-G05 (MMS, 2000, 2005, and 2008a, respectively). 

The Proposed Wellsite D location in Walker Ridge area, Block 95 appears favorable for exploration drilling 

operations relevant to the shallow geologic and stratigraphic conditions. The geohazard report (No. 1008-

1564) and this letter comply with the Minerals Management Service (MMS) Notice-to-Lessees (NTL’s) 2000-

G20, 2005-G07, and 2008-G05 (MMS, 2000, 2005, and 2008a, respectively). 
The Proposed Wellsite E location in Walker Ridge area, Block 95 appears favorable for exploration drilling 

operations relevant to the shallow geologic and stratigraphic conditions. . The geohazard report (No. 1008-

1564) and this letter comply with the Minerals Management Service (MMS) Notice-to-Lessees (NTL’s) 2000-

G20, 2005-G07, and 2008-G05 (MMS, 2000, 2005, and 2008a, respectively). 

Report prepared by GEOSCIENCE EARTH & MARINE SERVICES, INC.® 

Thomas W. Neurauter Michael J. Kaluza 

Ph. D. Senior Marine Geologist President/Marine Geologist 

G. High-Resolution Seismic Lines

Omitted from PI copies.

See attached ESR. 

H & I Stratigraphic Column with Time vs depth table

Omitted from PI copies.

 




SECTION 4: Hydrogen Sulfide

A. Concentration 

 0 ppm. 

B. Classification

Based on CFR 250.490 (c), SOI requests that the Regional Supervisor, Field Operations, determine the 

zones in the proposed drilling operations in this plan to be classified as an area where the absence of H2S 

has been confirmed.

 

C. H2S Contingency Plan

In accordance with 30 CFR 250.490(f) a Contingency Plan is not required for this Lease. 

D. Modeling Report

We do not anticipate to encounter or handle H2S at concentrations greater than 500 parts per million 

(ppm) and therefore have not included modeling for H2S. 

 
SECTION 5: Minerals Resource Conservation

Information regarding Mineral Resource Conservation is not included in this EP as such information is only 

necessary in the case of DOCDs. 
SECTION 6: Biological, Physical and Socioeconomic Information

A. Chemosynthetic Communities Report

The wells proposed in this Plan were previously reviewed in Plan N-9410 for Chemosynthetic Community 

clearance and biological, physical and socioeconomic review using a semi-submersible with anchor radius. 

That Plan was approved without mitigations from the BOEMRE. This revised plan is not utilizing anchors and 

should suffice to NTL 2010-G39 and G40. 

Site Specific Assessments 

And Chemosynthetic Communities Clearance 

Proposed Wellsite A (I in the Report) 

Shell, Block 95 (OCS-G-31943) 

Walker Ridge Area 

Gulf of Mexico 

The Proposed Wellsite A location in Walker Ridge area, Block 95 appears favorable for exploration drilling 

operations relevant to the shallow geologic and stratigraphic conditions. The geohazard report (No. 1008-

1564) and this letter comply with the Minerals Management Service (MMS) Notice-to-Lessees (NTL’s) 2000-

G20, 2005-G07, and 2008-G05 (MMS, 2000, 2005, and 2008a, respectively). 

Introduction 

Shell Offshore Inc., (Shell) contracted Geoscience Earth & Marine Services, Inc®., (GEMS) to prepare a 

geohazard analysis of Blocks 95 and 139 of the Walker Ridge (WR) Area, Gulf of Mexico. The geohazard 

report, submitted to Shell in February 2009 (GEMS, 2009), discusses the seafloor and subsurface conditions 

within these and surrounding blocks based on 3-D geophysical data. Shell has designated several possible 

drilling locations within the study area. This Site Clearance Letter addresses the specific conditions at 

Proposed Wellsite WR 95-A (OCS-G-31943). The data set, maps, and interpretations used for the geohazard 

report were reviewed for this assessment of Proposed Wellsite A. The figures included with this letter were 

extracted from the 3-D data volume used for the geohazard assessment (GEMS, 2009). The Proposed 

Wellsite WR 95-A surface location is located in the northeastern quadrant of Block 95, Walker Ridge area, 

Gulf of Mexico. Shell provided the following coordinates: 

Proposed Wellsite WR 95-A is Location I in the Report

Spheroid & Datum: Clarke 

1866, NAD27 Projection: 

UTM Zone 15 North 

Line Reference Block Calls 

X: 2,101,095 ft Latitude: 

26.863229287o N 

Inline 0420 7,122 ft FNL 

Y: 9,750,318 ft Longitude: -

91.586560189o W 

Crossline 3098 5,625 ft FEL 

Attachments 

The figures accompanying this letter were extracted from the 3-D data volume. The figures (listed below) are 

centered on the proposed well location. 

Figure I-1: Tophole Prognosis Chart, Proposed Wellsite A, Walker Ridge Block 95 

Figure I-2: Inline 30420 and Crossline 3098 Showing Conditions Beneath Proposed Wellsite A, 

Walker Ridge Block 95 Project No. 1008-1564 Proposed Well WR 95-A 

Figure I-3: Power Spectrum Chart Based on 3-D Data Volume within 500-ft Radius of Proposed 

Wellsite A, Walker Ridge Block 95. 

Water Depth and Seafloor Conditions 

The water depth at the proposed location is -5,848 ft (Figure I-1). The seafloor slopes to the west at a 

gradient of 1.034° (1.8%). WR 95-A is situated above a shallow salt sheet. The overburden above the top of 

salt is only 579 ft thick (Figures I-1 and I-2). The seafloor topography in the area of WR 95-A mimics the 
rough, faulted and folded salt surface. The location lies between a series of seafloor faults. The seafloor faults 

are approximately 175 ft to the southwest and 350 ft to the east-northeast of the proposed location. 

Chemosynthetic Communities 

There is no evidence of hydrocarbon seepage within 1,500 ft of the proposed location. Therefore, the 

potential for high-density chemosynthetic communities within 1,500 ft of the proposed location is negligible. 

The Amplitude-Enhanced Surface Rendering (Map 4; GEMS, 2009) shows normal or ambient amplitudes 

along the seabed near the proposed wellsite. The Enhanced Surface Rendering and Amplitude-Enhanced 

Surface Rendering (GEMS, 2009) show few indications of seepage-related features within the 16-block area 

examined for this evaluation. Anomalous seabed amplitudes occur in the northwest quadrant of WR 50, 

approximately 6.2 miles from the proposed location. The high-amplitude response is most likely caused by 

variable sediment properties within mass-transport deposits rather than gaseous sediments. These 

anomalous seabed amplitude returns are not likely to influence anchor locations. 

Man-Made Features 

An exploration well occurs approximately 4.1 miles north-northeast of the proposed location. The well is in 

the northwest corner of WR 52. Anadarko spudded the well in June 2008. No other infrastructure, 

shipwrecks, or other man-made debris are reported in the vicinity. 

Stratigraphy 

Inline 30420 and Crossline 3098 are the closest lines to the proposed WR 95-A location (Figure I-2). The 

Tophole Prognosis Chart (Figure I-1) 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 top of salt is estimated to be approximately 579 ft below the mudline (bml) at this location. 

The relatively thin overburden is divided into two units or sequences. The sequences represent variations in 

depositional environments and possible changes in soil strength and composition. The surficial unit, Unit 1 

(Seafloor to Horizon A), to approximately 164 ft bml, will consist of mud-rich hemipelagic and thin masstransport deposits. The soils at the seabed are likely to be soft high water content silty clays. The shear 

strength of the sediments will gradually increase with depth corresponding to a decrease in water content. 

Stiff, overconsolidated sediments have been encountered in some areas along the lower continental slope. 

These areas generally have experienced erosion from strong bottom currents. No evidence of furrows or 

other erosional seabed features are identified around the proposed wellsite. Overconsolidated sediments 

within Unit 1 may occur along the steep walls of the basins west, northwest, and south of the proposed 

location. 

Horizon A is a continuous prominent reflecting horizon mapped throughout the study area. Horizon A marks 

the transition between the weakly stratified surficial unit (Unit 1) with a sequence of closely-spaced 

continuous reflection sequence of Unit 2 (Figure I-2). Unit 2 possibly represents mud-rich turbidites 

interlayered with thin mass-transport deposits. Beneath WR 95-A, Unit 2 is approximately 415ft thick (Figure 

I-1). The reflections within Unit 2 vary from parallel and continuous to discontinuous. The discontinuities 

within the section are caused by faulting and folding of the unit above the shallow salt sheet and not a 

change in depositional environment. The sediments within Unit 2 are likely alternating layers of clay and silt. 

Occasional thin sand seams are possible but no significant sand layers are likely. An increase in sediment 

shear strength will likely occur across the Horizon A interface (i.e., ~164 ft bml). The amount of increase will 

depend on the age and amount of sediment erosion in this section. Highly overconsolidated sediments could 

influence the jetting of the surface conductor. However, no problems were reported when jetting the 

conductor for the WR 52-1 well a few miles to the north. The top of salt at WR 95-A is at -6,427 ft subsea 

(579 ft bml). The salt surface dips to the east at ~2.5°. 

Faults 

Several seafloor faults occur in the area around WR 95-A (Maps 2a, 3, and 5; GEMS, 2009). The location is 

between the surface expression of two of these faults (Figures I-1 and I-2). These seafloor faults lie 

approximately 175 ft to the southwest and 350 ft to the east-northeast of the proposed location. The well 

bore is predicted to intersect the fault plane for the western fault at approximately 200 ft below the mudline. 

Movement along the fault is likely analogous to soil creep. 

 
Shallow Water Flow 

Shallow water flow has not been reported in the Walker Ridge area (MMS, 2007). The sedimentary section 

above the salt surface is only 579 ft thick and there are no indications of sand-prone sequences. The 

potential for overpressured sands is negligible. 

Shallow Gas 

The well path will not penetrate any high-amplitude events between the seafloor and top of salt (Figure I-1). 

However, a high-amplitude event occurs approximately 550 ft to the east of the location (Figure I-1). The 

horizon that correlates with event is 490 ft beneath the mudline. The amplitude event possibly represents a 

thin sand layer with some biogenic gas. At the proposed location the sand should be very thin and based on 

the reduced amplitude, does not have the concentration of biogenic gas. Therefore the potential of shallow 

gas at this level (~490 ft bml) is considered low. 

Power Spectrum 

In accordance with NTL 2008-G04 and NTL 2008-G05 (MMS 2008a,b), we have extracted the power 

spectrum diagram (Figure I-3) from the 3-D seismic data cube. The extraction was generated within a 500-ft 

radius of the intersection of the inlines and crosslines at the proposed wellsite. We converted the amplitude 

vs. frequency spectrum, generated by the SMT software, to power vs. frequency by squaring the amplitude 

values as described by J. A. Coffeen, 1978. 

Closing 

The seafloor at Proposed Wellsite A, Walker Ridge Block 95 (OCS-G-31943), appears suitable for exploration 

drilling operations. The well bore will intersect a fault plane at approximately 200 ft bml. Soil conditions are 

likely to be very similar to those encountered in the nearby WR 52-1 well a few miles north of the proposed 

location. 

Proposed Wellsite B (A in Report) 

Shell, Block 95 (OCS-G-31943) 

Walker Ridge Area 

Gulf of Mexico 

The Proposed Wellsite B location in Walker Ridge area, Block 95 appears favorable for exploration drilling 

operations relevant to the shallow geologic and stratigraphic conditions. The geohazard report (No. 1008-

1564) and this letter comply with the Minerals Management Service (MMS) Notice-to-Lessees (NTL’s) 2000-

G20, 2005-G07, and 2008-G05 (MMS, 2000, 2005, and 2008a, respectively). 

Introduction 

Shell Offshore Inc., (Shell) contracted Geoscience Earth & Marine Services, Inc®., (GEMS) to prepare a 

geohazard analysis of Blocks 95 and 139 of the Walker Ridge (WR) Area, Gulf of Mexico. The geohazard 

report discusses the seafloor and subsurface conditions within these and surrounding blocks based on 3-D 

geophysical data. Shell has designated several possible drilling locations within the study area. This Site 

Clearance Letter addresses the specific conditions at Proposed Wellsite WR 95-B (OCS-G-31943). This 

proposed location is plotted on the maps referenced in the main text of this report. The figures included with 

this letter are taken from the 3-D data volume used for the geohazard assessment of the study area. The 

Proposed Wellsite WR 95-B surface location is located in the northeastern quadrant of Block 95, Walker Ridge 

area, Gulf of Mexico. Shell provided the following coordinates: 

Proposed Wellsite WR 95-B is Location A in the Report 

Spheroid & Datum: Clarke 

1866, NAD27 Projection: 

UTM Zone 15 North 

Line Reference Block Calls 

X: 2,102,641 ft Latitude: 

26.862056527o N 

Inline 30390 7,531 ft FNL 

Y: 9,749,909 ft Longitude: -

91.581832000o W 

Crossline 3136 4,079 ft FEL 

 
Attachments 

The figures accompanying this letter were extracted from the 3-D data volume. The figures (listed below) are 

centered on the proposed well location. 

Figure A-1: Tophole Prognosis Chart, Proposed Wellsite B, Walker Ridge Block 95 

Figure A-2: Inline 30390 and Crossline 3136 Showing Conditions Beneath Proposed Wellsite B, 

Walker Ridge Block 95 

Figure A-3: Power Spectrum Chart Based on 3-D Data Volume Within 500-ft Radius of Proposed 

Wellsite B, Walker Ridge Block 95. 

Water Depth and Seafloor Conditions 

The water depth at the proposed location is -5,833 ft (Figure A-1). The seafloor slopes to the southwest at a 

gradient of 2.4° (4.2%). WR 95-B is situated above a shallow salt sheet. The overburden above the top of 

salt is only 651 ft thick (Figures A-1 and A-2). The seafloor topography mimics the rough, faulted and folded 

salt surface. Several faults affect the seafloor around the proposed location. The closest offset is 

approximately 150 ft to the east of WR 95-A. 

Chemosynthetic Communities 

There is no evidence of hydrocarbon seepage within 1,500 ft of the proposed location. Therefore, the 

potential for high-density chemosynthetic communities within 1,500 ft of the proposed location is negligible. 

The Amplitude-Enhanced Surface Rendering (Map 4) shows normal or ambient amplitudes along the seabed 

near the proposed wellsite. The Enhanced Surface Rendering and Amplitude-Enhanced Surface Rendering 

show few indications of seepage-related features within the 16-block area examined for this evaluation. 

Anomalous seabed amplitudes occur in the northwest quadrant of WR 50, approximately 6 miles from the 

proposed location. The high-amplitude response is most likely caused by variable sediment properties within 

mass-transport deposits rather than gaseous sediments. In any case, these anomalous seabed amplitude 

returns are six miles from the proposed location and not likely to influence anchor locations. 

Man-Made Features 

An exploration well occurs approximately 4 miles north-northeast of the proposed location. The well is in the 

northwest corner of WR 52. Anadarko spudded the well in June, 2008. No shipwrecks or other man-made 

debris are reported in the vicinity. 

Stratigraphy 

Inline 30390 and Crossline 3136 are the closest lines to the proposed WR 95-B location (Figure A-2). The 

Tophole Prognosis Chart (Figure A-1) 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 top of salt is estimated to be approximately 651 ft below the mudline (bml) at this location. 

The relatively thin overburden is divided into two units or sequences. The sequences represent variations in 

depositional environments and possible changes in soil strength and composition. The surficial unit, Unit 1 

(Seafloor to Horizon A), to approximately 166 ft bml, will consist of mud-rich hemipelagic and thin masstransport deposits. The soils at the seabed are likely to be soft high water content silty clays. The shear 

strength of the sediments will gradually increase with depth corresponding to a decrease in water content. 

Stiff, overconsolidated sediments have been encountered in some areas along the lower continental slope. 

These areas generally have experienced erosion from strong bottom currents. 

No evidence of furrows or other erosional seabed features are identified around the proposed wellsite. 

Overconsolidated sediments may occur along the steep walls of the basin west of the proposed location. 

Horizon A is a continuous prominent reflecting horizon mapped throughout the study area. Horizon A marks 

the transition between the weakly stratified surficial unit (Unit 1) with a sequence of closely-spaced 

continuous reflection sequence of Unit 2 (Figure A-2). Unit 2 possibly represents mud-rich turbidites 

interlayered with thin mass-transport deposits. Beneath WR 95-B, Unit 2 is approximately 485 ft thick (Figure 

A-1). The reflections within Unit 2 vary from parallel and continuous to discontinuous. The discontinuities 

within the section are caused by faulting and folding of the unit above the shallow salt sheet and not a 

change in depositional environment. The sediments within Unit 2 are likely alternating layers of clay and silt. 

Occasional thin sand seams are possible but no significant sand layers are likely. An increase in sediment 

shear strength will likely occur across the Horizon A interface (i.e., ~166 ft bml). The amount of increase will 

depend on the age of sediment in this section. The amount of increase will depend on the age and amount of 

sediment erosion in this section. Highly overconsolidated sediments could influence the jetting of the surface 

conductor. However, no problems were reported when jetting the conductor for the WR 52-1 well a few miles 

to the north. The top of salt at WR 95-B is at -6,484 ft subsea (651ft bml). The salt surface dips to the west 

at 5.2°. 
Faults 

Several seafloor faults occur in the area around WR 95-B (Maps 2a and 3). The closest faults are 150 ft to the 

east. The fault is downthrown west (Figures A-1 and A-2). The well bore at WR 95-B will intersect the fault 

plane at approximate position of Horizon A which is 166 ft bml. 

Shallow Water Flow 

Shallow water flow has not been reported in the Walker Ridge area (MMS, 2007). The sedimentary section 

above the salt surface is only 651 ft thick and there are no indications of sand-prone sequences. The 

potential for overpressured sands is negligible. 

Shallow Gas 

The well path will not penetrate any high-amplitude events between the seafloor and top of salt (Figure A-1). 

The potential for shallow gas accumulations beneath WR 95-B is negligible. 

Power Spectrum 

In accordance with NTL 2008-G04 and NTL 2008-G05 (MMS 2008a,b), we have extracted the power 

spectrum diagram (Figure A-3) from the 3-D seismic data cube. The extraction was generated within a 500-ft 

radius of the intersection of the inlines and crosslines at the proposed wellsite. We converted the amplitude 

vs. frequency spectrum, generated by the SMT software, to power vs. frequency by squaring the amplitude 

values as described by J. A. Coffeen, 1978. 

Closing 

The seafloor at Proposed Wellsite B, Walker Ridge Block 95 (OCS-G-31943), appears suitable for exploration 

drilling operations. The well bore will intersect a fault plane at approximately 166 ft bml. Soil conditions 

should be very similar to those encountered in the WR 52-1 well a few miles north of the proposed location. 

Proposed Wellsite C (E in the Report) 

Shell, Block 95 (OCS-G-31943) 

Walker Ridge Area 

Gulf of Mexico 

The Proposed Wellsite C location in Walker Ridge area, Block 95 appears favorable for exploration drilling 

operations relevant to the shallow geologic and stratigraphic conditions. The geohazard report (No. 1008-

1564) and this letter comply with the Minerals Management Service (MMS) Notice-to-Lessees (NTL’s) 2000-

G20, 2005-G07, and 2008-G05 (MMS, 2000, 2005, and 2008a, respectively). 

Introduction 

Shell Offshore Inc., (Shell) contracted Geoscience Earth & Marine Services, Inc®., (GEMS) to prepare a 

geohazard analysis of Blocks 95 and 139 of the Walker Ridge (WR) Area, Gulf of Mexico. The geohazard 

report, submitted to Shell in February, 2009 (GEMS, 2009), discusses the seafloor and subsurface conditions 

within these and surrounding blocks based on 3-D geophysical data. Shell has designated several possible 

drilling locations within the study area. This Site Clearance Letter addresses the specific conditions at 

Proposed Wellsite WR 95-C (OCS-G-31943). The data set, maps, and interpretations used for the geohazard 

report were reviewed for this assessment of Proposed Wellsite C. The figures included with this letter were 

extracted from the 3-D data volume used for the geohazard assessment (GEMS, 2009). The Proposed 

Wellsite WR 95-C surface location is located in the northeastern corner of Block 95, Walker Ridge area, Gulf 

of Mexico. Shell provided the following coordinates: 

Proposed Wellsite WR 95-C is Location E in Report

Spheroid & Datum: Clarke 

1866, NAD27 Projection: 

UTM Zone 15 North 

Line Reference Block Calls 

X: 2,105,685 ft Latitude: 

26.872455722o N 

Inline 30680 3,717 ft FNL 

Y: 9,753,723 ft Longitude: -

91.572363151o W 

Crossline 3210 1,035 ft FEL 

Attachments 
The figures accompanying this letter were extracted from the 3-D data volume. The figures (listed below) are 

centered on the proposed well location. 

Figure E-1: Tophole Prognosis Chart, Proposed Wellsite C, Walker Ridge Block 95 

Figure E-2: Inline 30680 and Crossline 3210 Showing Conditions Beneath Proposed Wellsite C, 

Walker Ridge Block 95 

Figure E-3: Power Spectrum Chart Based on 3-D Data Volume Within 500-ft Radius of Proposed 

Wellsite C, Walker Ridge Block 95. 

Water Depth and Seafloor Conditions 

The water depth at the proposed location is -5,860 ft (Figure E-1). The seafloor slopes to the southeast at a 

gradient of 0.83° (1.4%). WR 95-C is situated above a shallow salt sheet. The overburden above the top of 

salt is only 556 ft thick (Figures E-1 and E-2). The seafloor topography in the area of WR 95-C mimics the 

rough, faulted and folded salt surface. 

Chemosynthetic Communities 

There is no evidence of hydrocarbon seepage within 1,500 ft of the proposed location. Therefore, the 

potential for high-density chemosynthetic communities within 1,500 ft of the proposed location is negligible. 

The Amplitude-Enhanced Surface Rendering (Map 4; GEMS, 2009) shows normal or ambient amplitudes 

along the seabed near the proposed wellsite. The Enhanced Surface Rendering and Amplitude-Enhanced 

Surface Rendering (GEMS, 2009) show few indications of seepage-related features within the 16-block area 

examined for this evaluation. Anomalous seabed amplitudes occur in the northwest quadrant of WR 50, 

approximately 5.5 miles from the proposed location. The high-amplitude response is most likely caused by 

variable sediment properties within mass-transport deposits rather than gaseous sediments. These 

anomalous seabed amplitude returns are not likely to influence anchor locations. 

Man-Made Features 

An exploration well occurs approximately 3.3 miles north-northeast of the proposed location. The well is in 

the northwest corner of WR 52. Anadarko spudded the well in June 2008. No other infrastructure, 

shipwrecks, or other man-made debris are reported in the vicinity. 

Stratigraphy 

Inline 30680 and Crossline 3210 are the closest lines to the proposed WR 95-E location (Figure E-2). The 

Tophole Prognosis Chart (Figure E-1) 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 top of salt is estimated to be approximately 556 ft below the mudline (bml) at this location. 

The relatively thin overburden is divided into two units or sequences. The sequences represent variations in 

depositional environments and possible changes in soil strength and composition. The surficial unit, Unit 1 

(Seafloor to Horizon A), to approximately 166 ft bml, will consist of mud-rich hemipelagic and thin masstransport deposits. The soils at the seabed are likely to be soft high water content silty clays. The shear 

strength of the sediments will gradually increase with depth corresponding to a decrease in water content. 

Stiff, overconsolidated sediments have been encountered in some areas along the lower continental slope. 

These areas generally have experienced erosion from strong bottom currents. No evidence of furrows or 

other erosional seabed features are identified around the proposed wellsite. Overconsolidated sediments 

within Unit 1 may occur along the steep walls of the basins west, northwest, and south of the proposed 

location. 

Horizon A is a continuous prominent reflecting horizon mapped throughout the study area. Horizon A marks 

the transition between the weakly stratified surficial unit (Unit 1) with a sequence of closely-spaced 

continuous reflection sequence of Unit 2 (Figure E-2). Unit 2possibly represents mud-rich turbidites 

interlayered with thin mass-transport deposits. Beneath WR 95-C, Unit 2 is approximately 390 ft thick (Figure 

E-1). The reflections within Unit 2 vary from parallel and continuous to discontinuous. The discontinuities 

within the section are caused by faulting and folding of the unit above the shallow salt sheet and not a 

change in depositional environment. The sediments within Unit 2 are likely alternating layers of clay and silt. 

Occasional thin sand seams are possible but no significant sand layers are likely. An increase in sediment 

shear strength will likely occur across the Horizon A interface (i.e., ~166 ft bml). The amount of increase will 

depend on the age and amount of sediment erosion in this section. Highly overconsolidated sediments could 

influence the jetting of the surface conductor. However, no problems were reported when jetting the 

conductor for the WR 52-1 well a few miles to the north. The top of salt at WR 95-E is at -6,416 ft subsea 

(556 ft bml). The salt surface dips to the north at ~3.1°. 

 
Faults 

Several seafloor faults occur in the area around WR 95-C (Maps 2a, 3, and 5; GEMS, 2009). The seafloor is 

irregular in the area of the proposed wellsite, however, no well-defined seafloor offsets occur within ~1,000 ft 

of the location (Figures E-1 and E-2). The wellbore will no intersect any fault planes at depth. 

Shallow Water Flow 

Shallow water flow has not been reported in the Walker Ridge area (MMS, 2007). The sedimentary section 

above the salt surface is only 556 ft thick and there are no indications of sand-prone sequences. The 

potential for overpressured sands is negligible. 

Shallow Gas 

The well path will not penetrate any high-amplitude events between the seafloor and top of salt (Figure E-1). 

However, a slightly high-amplitude event occurs approximately 1,200 ft to the west of the location (Figure E1). The horizon that correlates with event is 322 ft beneath the mudline. The amplitude event possibly 

represents a thin sand layer with some biogenic gas. At the proposed location the sand should be very thin or 

non-existent. Based on the reduced amplitude, a concentration of biogenic gas is unlikely. Therefore, the 

potential of shallow gas at this level (~332 ft bml) is considered negligible. 

Power Spectrum 

In accordance with NTL 2008-G04 and NTL 2008-G05 (MMS 2008a,b), we have extracted the power 

spectrum diagram (Figure E-3) from the 3-D seismic data cube. The extraction was generated within a 500-ft 

radius of the intersection of the inlines and crosslines at the proposed wellsite. We converted the amplitude 

vs. frequency spectrum, generated by the SMT software, to power vs. frequency by squaring the amplitude 

values as described by J. A. Coffeen, 1978. 

Closing 

The seafloor at Proposed Wellsite C, Walker Ridge Block 95 (OCS-G-31943), appears suitable for exploration 

drilling operations. The well bore will not intersect any fault planes or shallow gas at depth. Soil conditions 

are likely to be very similar to those encountered in the nearby WR 52-1 well. 

Proposed Wellsite D (D in Report) 

Shell, Block 95 (OCS-G-31943) 

Walker Ridge Area 

Gulf of Mexico 

The Proposed Wellsite D location in Walker Ridge area, Block 95 appears favorable for exploration drilling 

operations relevant to the shallow geologic and stratigraphic conditions. The geohazard report (No. 1008-

1564) and this letter comply with the Minerals Management Service (MMS) Notice-to-Lessees (NTL’s) 2000-

G20, 2005-G07, and 2008-G05 (MMS, 2000, 2005, and 2008a, respectively). 

Introduction 

Shell Offshore Inc., (Shell) contracted Geoscience Earth & Marine Services, Inc®., (GEMS) to prepare a 

geohazard analysis of Blocks 95 and 139 of the Walker Ridge (WR) Area, Gulf of Mexico. The geohazard 

report discusses the seafloor and subsurface conditions within these and surrounding blocks based on 3-D 

geophysical data. Shell has designated several possible drilling locations within the study area. This Site 

Clearance Letter addresses the specific conditions at Proposed Wellsite WR 95-D (OCS-G-31943). This 

proposed location is plotted on the maps referenced in the main text of this report. The figures included with 

this letter are taken from the 3-D data volume used for the geohazard assessment of the study area. The 

Proposed Wellsite WR 95-D surface location is located in the northeastern quadrant of Block 95, Walker Ridge 

area, Gulf of Mexico. Shell provided the following coordinates: 

 
Proposed Wellsite WR 95-D 

Spheroid & Datum: Clarke 

1866, NAD27 Projection: 

UTM Zone 15 North 

Line Reference Block Calls 

X: 2,101,293 ft Latitude: 

26.861344111o N 

Inline 30370 7,805 ft FNL 

Y: 9,749,635 ft Longitude: -

91.585976207o W 

Crossline 3103 5,427 ft FEL 

Attachments 

The figures accompanying this letter were extracted from the 3-D data volumes. The figures (listed below) 

are centered on the proposed well location. 

Figure D-1: Tophole Prognosis Chart, Proposed Wellsite D, Walker Ridge Block 95 

Figure D-2: Inline 30370 and Crossline 3103 Showing Conditions Beneath Proposed Wellsite D, 

Walker Ridge Block 95 

Figure D-3: Power Spectrum Chart Based on 3-D Data Volume Within 500-ft Radius of Proposed 

Wellsite D, Walker Ridge Block 95. 

Water Depth and Seafloor Conditions 

The water depth at the proposed location is -5,949 ft (Figure D-1). The seafloor slopes to the east at a 

gradient of 3.0° (5.2%). 

WR 95-D is situated above a shallow salt sheet. The overburden above the top of salt is only 591 ft thick 

(Figures D-1 and D-2). The seafloor topography mimics the rough, faulted and folded salt surface. Several 

faults affect the seafloor around the proposed location. The closest offset is approximately 215 ft to the east 

of WR 95-D. 

Chemosynthetic Communities 

There is no evidence of hydrocarbon seepage within 1,500 ft of the proposed location. Therefore, the 

potential for high-density chemosynthetic communities within 1,500 ft of the proposed location is negligible. 

The Amplitude-Enhanced Surface Rendering (Map 4) shows normal or ambient amplitudes along the seabed 

near the proposed wellsite. 

The Enhanced Surface Rendering and Amplitude-Enhanced Surface Rendering show few indications of 

seepage-related features within the 16-block area examined for this evaluation. Anomalous seabed 

amplitudes occur in the northwest quadrant of WR 50, approximately 6 miles from the proposed location. The 

high-amplitude response is most likely caused by variable sediment properties within mass-transport deposits 

rather than gaseous sediments. In any case, these anomalous seabed amplitude returns are six miles from 

the proposed location and not likely to influence anchor locations. 

Man-Made Features 

An exploration well occurs approximately 4.3 miles north-northeast of the proposed location. The well is in 

the northwest corner of WR 52. Anadarko spudded the well in June, 2008. 

No shipwrecks or other man-made debris are reported in the vicinity. 

Stratigraphy 

Inline 30370 and Crossline 3103 are the closest lines to the proposed WR 95-D location (Figure D-2). The 

Tophole Prognosis Chart (Figure D-1) 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 top of salt is estimated to be approximately 591 ft below the mudline (bml) at this location. The relatively 

thin overburden is divided into two units or sequences. The sequences represent variations in depositional 

environments and possible changes in soil strength and composition. 

The surficial unit, Unit 1 (Seafloor to Horizon A), to approximately 158 ft bml, will consist of mud-rich 

hemipelagic and thin mass-transport deposits. The soils at the seabed are likely to be soft high water content 

silty clays. The shear strength of the sediments will gradually increase with depth corresponding to a 

decrease in water content. Stiff, overconsolidated sediments have been encountered in some areas along the 

lower continental slope. These areas generally have experienced erosion from strong bottom currents. No 

evidence of furrows or other erosional seabed features are identified around the proposed wellsite. 

Overconsolidated sediments may occur along the steep walls of the basins west and north of the proposed 

location. 
Horizon A is a continuous prominent reflecting horizon mapped throughout the study area. Horizon A marks 

the transition between the weakly stratified surficial unit (Unit 1) with a sequence of closely-spaced 

continuous reflection sequence of Unit 2 (Figure D-2). Unit 2 possibly represents mud-rich turbidites 

interlayered with thin mass-transport deposits. Beneath WR 95-D, Unit 2 is approximately 433 ft thick (Figure 

D-1). The reflections within Unit 2 vary from parallel and continuous to discontinuous. The discontinuities 

within the section are caused by faulting and folding of the unit above the shallow salt sheet and not a 

change in depositional environment. The sediments within Unit 2 are likely alternating layers of clay and silt. 

Occasional thin sand seams are possible but no significant sand layers are likely. An increase in sediment 

shear strength will likely occur across the Horizon A interface (i.e., ~158 ft bml). The amount of increase will 

depend on the age of sediment in this section. The amount of increase will depend on the age and amount of 

sediment erosion in this section. Highly overconsolidated sediments could influence the jetting of the surface 

conductor. However, no problems were reported when jetting the conductor for the WR 52-1 well a few miles 

to the north. The top of salt at WR 95-D is at -6,540 ft subsea (591 ft bml). The salt surface dips to the east 

at 3.3° 

Faults 

Several seafloor faults occur in the area around WR 95-D (Maps 2a and 3). The closest fault is 215 ft to the 

east and is downthrown away from the location. The other seafloor faults in the area are over 500 ft away 

from the WR 95-D location. Reflections at depth, in places, are discontinuous but no well-defined fault planes 

are defined beneath the proposed location. 

Shallow Water Flow 

Shallow water flow has not been reported in the Walker Ridge area (MMS, 2007c). The sedimentary section 

above the salt surface is 591 ft thick and there are no indications of sand-prone sequences. The potential for 

overpressured sands is negligible. 

Shallow Gas 

The well path will not penetrate any high-amplitude events between the seafloor and top of salt (Figure D-1). 

The potential for shallow gas accumulations beneath WR 95-D is negligible. 

Power Spectrum 

In accordance with NTL 2008-G04 and NTL 2008-G05 (MMS 2008a,b), we have extracted the power 

spectrum diagram (Figure D-3) from the 3-D seismic data cube. The extraction was generated within a 500-ft 

radius of the intersection of the inlines and crosslines at the proposed wellsite. We converted the amplitude 

vs. frequency spectrum, generated by the SMT software, to power vs. frequency by squaring the amplitude 

values as described by J. A. Coffeen, 1978. 

Closing 

The seafloor at Proposed Wellsite D, Walker Ridge Block 95 (OCS-G-31943), appears suitable for exploration 

drilling operations. No major hazards or constraints are defined by the 3-D data at the proposed location. Soil 

conditions should be very similar to those encountered in the WR 52-1 well a few miles north of the proposed 

location. 

Proposed Wellsite E (B in Report) 

Shell, Block 95 (OCS-G-31943) 

Walker Ridge Area 

Gulf of Mexico 

The Proposed Wellsite E location in Walker Ridge area, Block 95 appears favorable for exploration drilling 

operations relevant to the shallow geologic and stratigraphic conditions. . The geohazard report (No. 1008-

1564) and this letter comply with the Minerals Management Service (MMS) Notice-to-Lessees (NTL’s) 2000-

G20, 2005-G07, and 2008-G05 (MMS, 2000, 2005, and 2008a, respectively). 

Introduction 

Shell Offshore Inc., (Shell) contracted Geoscience Earth & Marine Services, Inc®., (GEMS) to prepare a 

geohazard analysis of Blocks 95 and 139 of the Walker Ridge (WR) Area, Gulf of Mexico. The geohazard 

report discusses the seafloor and subsurface conditions within these and surrounding blocks based on 3-D 

geophysical data. Shell has designated several possible drilling locations within the study area. This Site 

Clearance Letter addresses the specific conditions at Proposed Wellsite WR 95-E (OCS-G-31943). This 

proposed location is plotted on the maps referenced in the main text of this report. The figures included with 

this letter are taken from the 3-D data volume used for the geohazard assessment of the study area. The 
Proposed Wellsite WR 95-E surface location is located in the southeastern quadrant of Block 95, Walker Ridge 

area, Gulf of Mexico. Shell provided the following coordinates: 

Proposed Wellsite WR 95-E is B in the Report

Spheroid & Datum: Clarke 

1866, NAD27 Projection: 

UTM Zone 15 North 

Line Reference Block Calls 

X: 2,102,576 ft Latitude:26.8600033

49o N 

Inline 30335 7,562 ft FSL 

Y: 9,749,162 ft Longitude: -

91.582057006o W 

Crossline 3134 4,144 ft FEL 

Attachments The figures accompanying this letter were extracted from the 3-D data volume. The figures 

(listed below) are centered on the proposed well location. 

Figure B-1: Tophole Prognosis Chart, Proposed Wellsite E, Walker Ridge Block 95 Figure B-2:

Inline 30335 and Crossline 3134 Showing Conditions Beneath Proposed Wellsite E, Walker Ridge 

Block 95 

Figure B-3: Power Spectrum Chart Based on 3-D Data Volume Within 500-ft Radius of Proposed 

Wellsite E, Walker Ridge Block 95. 

Water Depth and Seafloor Conditions 

The water depth at the proposed location is -5,843 ft (Figure B-1). The seafloor slopes to the northeast at a 

gradient of 1.2° (2.1%). WR 95-E is situated above a shallow salt sheet. The overburden above the top of 

salt is only 628 ft thick (Figures B-1 and B-2). The seafloor topography mimics the rough, faulted and folded 

salt surface. The seafloor in the area of WR 95-E is irregular and hummocky. The location lies between a 

series of seafloor faults. The seafloor offsets are approximately 300 ft to the east and west of the proposed 

location. 

Chemosynthetic Communities 

There is no evidence of hydrocarbon seepage within 1,500 ft of the proposed location. Therefore, the 

potential for high-density chemosynthetic communities within 1,500 ft of the proposed location is negligible. 

The Amplitude-Enhanced Surface Rendering (Map 4) shows normal or ambient amplitudes along the seabed 

near the proposed wellsite. The Enhanced Surface Rendering and Amplitude-Enhanced Surface Rendering 

show few indications of seepage-related features within the 16-block area examined for this evaluation. 

Anomalous seabed amplitudes occur in the northwest quadrant of WR 50, approximately 6.3 miles from the 

proposed location. The high-amplitude response is most likely caused by variable sediment properties within 

mass-transport deposits rather than gaseous sediments. In any case, these anomalous seabed amplitude 

returns are six miles from the proposed location and not likely to influence anchor locations. 

Man-Made Features 

An exploration well occurs approximately 4.3 miles north-northeast of the proposed location. The well is in 

the northwest corner of WR 52. Anadarko spudded the well in June 2008. No shipwrecks or other man-made 

debris are reported in the vicinity. 

Stratigraphy 

Inline 30335 and Crossline 3134 are the closest lines to the proposed WR 95-E location (Figure B-2). The 

Tophole Prognosis Chart (Figure B-1) 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 top of salt is estimated to be approximately 628 ft below the mudline (bml) at this location. 

The relatively thin overburden is divided into two units or sequences. The sequences represent variations in 

depositional environments and possible changes in soil strength and composition. 

The surficial unit, Unit 1 (Seafloor to Horizon A), to approximately 171 ft bml, will consist of mud-rich 

hemipelagic and thin mass-transport deposits. The soils at the seabed are likely to be soft high water content 

silty clays. The shear strength of the sediments will gradually increase with depth corresponding to a 

decrease in water content. Stiff, overconsolidated sediments have been encountered in some areas along the 

lower continental slope. These areas generally have experienced erosion from strong bottom currents. No 

evidence of furrows or other erosional seabed features are identified around the proposed wellsite. 

Overconsolidated sediments may occur along the steep walls of the basins west and north of the proposed 

location. 
Horizon A is a continuous prominent reflecting horizon mapped throughout the study area. Horizon A marks 

the transition between the weakly stratified surficial unit (Unit 1) with a sequence of closely-spaced 

continuous reflection sequence of Unit 2 (Figure B-2). Unit 2 possibly represents mud-rich turbidites 

interlayered with thin mass-transport deposits. Beneath WR 95-E, Unit 2 is approximately 457 ft thick (Figure 

B-1). The reflections within Unit 2 vary from parallel and continuous to discontinuous. The discontinuities 

within the section are caused by faulting and folding of the unit above the shallow salt sheet and not a 

change in depositional environment. The sediments within Unit 2 are likely alternating layers of clay and silt. 

Occasional thin sand seams are possible but no significant sand layers are likely. An increase in sediment 

shear strength will likely occur across the Horizon A interface (i.e., ~171 ft bml). The amount of increase will 

depend on the age and amount of sediment erosion in this section. Highly overconsolidated sediments could 

influence the jetting of the surface conductor. However, no problems were reported when jetting the 

conductor for the WR 52-1 well a few miles to the north. The top of salt at WR 95-E is at -6,471 ft subsea 

(628 ft bml). The salt surface dips to the north at 3.7°. 

Faults 

Several seafloor faults occur in the area around WR 95-E (Maps 2a, 3, and 5). The location is between the 

surface expressions of two of these faults (Figures B-1 and B-2). The well is roughly equidistance from the 

seafloor offsets (~300 ft). The well bore is predicted to intersect the fault plane for the western fault at 

approximately 291 ft below the mudline. 

Shallow Water Flow 

Shallow water flow has not been reported in the Walker Ridge area (MMS, 2007). The sedimentary section 

above the salt surface is only 628 ft thick and there are no indications of sand-prone sequences. The 

potential for overpressured sands is negligible. 

Shallow Gas 

The well path will not penetrate any high-amplitude events between the seafloor and top of salt (Figure B-1). 

The potential for shallow gas accumulations beneath WR 95-E is negligible.

Power Spectrum 

In accordance with NTL 2008-G04 and NTL 2008-G05 (MMS 2008a,b), we have extracted the power 

spectrum diagram (Figure B-3) from the 3-D seismic data cube. The extraction was generated within a 500-ft 

radius of the intersection of the inlines and crosslines at the proposed wellsite. We converted the amplitude 

vs. frequency spectrum, generated by the SMT software, to power vs. frequency by squaring the amplitude 

values as described by J. A. Coffeen, 1978. 

Closing 

The seafloor at Proposed Wellsite E, Walker Ridge Block 95 (OCS-G-31943), appears suitable for exploration 

drilling operations. The well bore will intersect a fault plane at approximately 291 ft. 

Report prepared by GEOSCIENCE EARTH & MARINE SERVICES, INC.® 

Thomas W. Neurauter Michael J. Kaluza 

Ph. D. Senior Marine Geologist President/Marine Geologist 

B – F

Pursuant to NTL No. 2008-G04 the proposed operations covered by this EP do not involve operations 

impacting the following: Topographic features map, Topographic features statement (shunting), Live 

bottoms, (Pinnacle Trend) map, Live bottoms (low relief) map, potentially sensitive biological features map. 

 
G. Remotely Operated Vehicle (ROV) Monitoring Plan

In accordance with the provisions of NTL No. 2008-G06, Remotely Operated Vehicle Surveys in Deepwater, 

Walker Ridge Block 95 is located in Grid 10. Grid 10 is an area that has adequate ROV survey coverage; 

therefore we are not proposing to run the pre and post ROV survey in accordance with the NTL. 

H. Threatened and Endanger Species Information

There are 5 species of sea turtles that may be found in the Gulf of Mexico (see table). No critical habitat for 

these species has been designated in the Gulf of Mexico. 

Common Name Scientific Name T/E Status

Hawksbill Turtle Eretmochelys imbricata E 

Green Turtle Chelonia mydas T 

Kemp's Ridley Turtle Lepidochelys kempii E 

Leatherback Turtle Dermochelys coriacea E 

Loggerhead Turtle Caretta caretta T 

There are 28 species of marine mammals that may be found in the Gulf of Mexico (see table). Of the species 

listed as Endangered, only the Sperm whale is commonly found in the project area. No critical habitat for 

these species has been designated in the Gulf of Mexico. 

Common Name Scientific Name T/E Status

Atlantic Spotted Dolphin Stenella frontalis 

Blainville's Beaked Whale Mesoplodon densirostris 

Blue Whale Balaenoptera musculus E 

Bottlenose Dolphin Tursiops truncatus 

Bryde's Whale Balaenoptera edeni 

Clymene Dolphin Stenella clymene 

Cuvier's Beaked Whale Ziphius cavirostris 

Dwarf Sperm Whale Kogia simus 

False Killer Whale Pseudorca crassidens 

Fin Whale Balaenoptera physalus E 

Fraser's Dolphin Lagenodelphis hosei 

Gervais' Beaked Whale Mesoplodon europaeus 

Humpback Whale Megaptera novaeangliae E 

Killer Whale Orcinus orca 

Melon-headed Whale Peponocephala electra 

Minke Whale Balaenoptera acutorostrata 

Northern Right Whale Eubalaena glacialis 

Pantropical Spotted Dolphin Stenella attenuata 

Pygmy Killer Whale Feresa attenuata 

Pygmy Sperm Whale Kogia breviceps 

Risso's Dolphin Grampus griseus 

Rough-toothed Dolphin Steno bredanensis 

Sei Whale Balaenoptera borealis E 

Short-finned Pilot Whale Globicephala macrorhynchus 

Sowerby's Beaked Whale Mesoplodon bidens 

Sperm Whale Physeter macrocephalus E 

Spinner Dolphin (Long-snouted) Stenella longirostris 

Striped Dolphin Stenella coeruleoalba 
I. Archaeological Report

WR 95 is not in an area of high potential for historic shipwrecks. At the time of this Revised EP filing, no 

archaeological data had been acquired. Prior to performing any bottom-disturbing activities such as casing 

setting at the proposed well surface locations, a survey will be conducted covering any impacted seafloor 

using digital global positioning system DGPS or an equivalent navigation system. The area may be surveyed 

by an autonomous underwater vehicle, a deep tow survey, or an ROV survey with a marine archaeologist on 

board. Shell will submit the archaeological report to the BOEMRE as soon as it becomes available. 

Alternatively, in the case of an ROV survey, Shell will post the statements to the BOEMRE site in compliance 

with the approved Revised EP Mitigation and submit the required End of Operations Report (EOR). 

J. Air and Water Quality Information

Pursuant to NTL No. 2008-G04 the proposed operations covered by this EP do not require Shell to provide 

additional information relating to air and water quality information. For specific information relating to air 

and water quality information please refer to the EIA, Attachment 18. 

K. Socioeconomic Information

Pursuant to NTL No. 2008-G04 the proposed operations covered by this EP do not require Shell to provide 

additional information relating to air and water quality information. For specific information relating to 

socioeconomic information please refer to the EIA, Attachment 18. 

 
SECTION 7: Waste and Discharge Information

A. Discharge to GOM or Downhole

Note: Please specify if the amount reported is a total or per well amount Walker Ridge 95

Type of Waste and Composition Composition Projected Amount Discharge rate Discharge Method Answer yes or no

Will drilling occur ? If yes, you should list muds and cuttings

EXAMPLE: Cuttings wetted with ynthetic based fluid 

Cuttings generated while using synthetic 

based drilling fluid. X bbl/well X bbl/day discharge pipe No

Water-based drilling fluid barite, additives, mud 20,000 bbls / well 3,333 bbls / day

Overboard and seafloor discharge prior to 

marine riser installation No

Water-based drilling fluid barite, additives, mud 1,000 bbls / well 1,000 bbls / day discharge overboard No

Cuttings wetted with water-based fluid

cuttings coated with water based drilling 

mud 984 bbls / well 164 bbls / day Sea bed during riserless drilling No

Cuttings wetted with synthetic-based fluid 

Cuttings generated while using synthetic 

based drilling fluid. 7,347 bbls / well 40 bbls / day

Overboard discharge line to 39.4’ below the 

water level No

Synthetic based drilling fluid adhering to washed drill 

cuttings

Synthetic based drilling fluid adhering to 

washed drill cuttings 3,726 bbls / well 15 bbls / day

Overboard discharge line to 39.4’ below the 

water level No

Chemical product waste 50 bbls / well 2 bbls / day

Treated to meet NPDES limits and 

discharged overboard No

Brine brine N/A N/A N/A No

Will humans be there? If yes, expect conventional waste

EXAMPLE: Sanitary waste water X liter/person/day NA chlorinate and discharge No

Domestic waste (kitchen water, shower water) grey water 26,000 bbls/well 130 bbls / day

Grinded to less than 25 mm mesh size and 

discharge overboard No

Sanitary waste (toilet water) treated sanitary waste 6,000 bbls/well 30 bbls / day

Treated in the MSD** prior to discharge to 

meet NPDES limits No

Is there a deck? If yes, there will be Deck Drainage

Deck Drainage Wash and rainwater 3,900 bbls / well 20 bbls / day Drained overboard through deck scuppers No

Will you conduct well treatment, completion, or workover? 

well treatment fluids NA NA NA NA No

well completion fluids NA NA NA NA No

workover fluids NA NA NA NA No

Miscellaneous discharges. If yes, only fill in those associated with your activity. 

Desalinization unit discharge Rejected water from watermaker unit 74,100 bbls / well 380 bbls /day

Discharged overboard 35 feet below 

waterline No

Blowout prevent fluid Water based 400 bbls/well 50 bbls/day Disharge at seafloor No

Ballast water Uncontaminated seawater 390,000 bbls / well 2,000 bbls / day Discharged overboard Just above waterline No

Bilge water

Bilge and drainage water will be treated to 

MARPOL standards (< 15ppm oil in water). 390,000 bbls / well 2,000 bbls / day

Bilge and drainage water will be treated to 

MARPOL standards (< 15ppm oil in water). No

Excess cement at seafloor Cement slurry

246 bbls/well (assume planned 

100% excess is discharged) 246 bbls / well

Discharged at the seafloor during riserless 

drilling No

Fire water Treated seawater 11,000 bbls / well 2,000 bbls / month Drained overboard through deck scuppers No

Cooling water Treated seawater 23,295,000 bbls / well 145,000 bbls / day

Discharged overboard 40 feet below 

waterline No

Will you produce hydrocarbons? If yes fill in for produced water.

Produced water NA NA NA NA NA

Will you be covered by an individual or general NPDES permit ? GENERAL PERMIT GMG290103

NOTE: If you will not have a type of waste, enter NA in the row. 

TABLE 7A: WASTES YOU WILL GENERATE, TREAT AND DOWNHOLE DISPOSE OR DISCHARGE TO 

THE GOM

Projected 

Downhole 

Projected generated waste Projected ocean discharges Disposal
B. Landfill, inject, incinerate or recycle table

C. Modeling Report

Shell did not model the trajectory for discharges because it is not required in the GOM. 

Solid and Liquid Wastes 

transportation 

Type of Waste Composition Transport Method Name/Location of Facility Amount Disposal Method

Will drilling occur ? If yes, fill in the muds and cuttings.

EXAMPLE: Oil-based drilling fluid or mud NA NA NA NA NA

Oil-based drilling fluid or mud NA NA NA NA NA

Synthetic-based drilling fluid or mud used SBF and additives Drums on barges

Newpark Environmental Services 

(Fourchon, La.) or US Liquids of 

Louisiana (Fourchon, La.) 2,500 bbls/well Recycled

Cuttings wetted with Water-based fluid NA NA NA NA NA

Cuttings wetted with Synthetic-based fluid 

Drill cuttings from synthetic 

based interval. storage tank on supply boat.

Newpark Environmental Services 

(Fourchon, La.) or US Liquids of 

Louisiana (Fourchon, La.) 300 bbls / well disposed

Cuttings wetted with oil-based fluids NA NA NA NA NA

Will you produce hydrocarbons? If yes fill in for produced sand.

Produced sand NA NA NA NA NA

EXAMPLE: trash and debris cardboard, aluminum, barged in a storage bin shorebase z tons total recycle

Trash and debris - recyclables trash and debris storage bins on supply boat

Omega Waste Management, W. 

Patterson, LA or ARC, New Iberia, LA 60 lbs/month recylce

Non-Hazardous trash and debris - nonrecyclables trash and debris storage bins on supply boatRepublic/BFI landfill, Sorrento, LA or 

the parish landfill, Avondale, LA. 118 lbs/month landfill

Hazardous waste

paints, solvents and unused 

chemicals drums on supply boat Safety Kleen, Denton, TX 60 lbs/month recylce

Used oil & glycole

used oil, oily rags and pads, 

empty drums and cooking 

oil drums on supply boat

Omega Waste Management, W. 

Patterson, LA or ARC, New Iberia, LA 20 bbls/month recycle

Universal waste items

Batteries, lamps, glass and 

mercury-contaminated 

waste drums on supply boat Lamp Environmental, Hammond, LA 30 bbls/month disposed

NOTE: If you will not have a type of waste, enter NA in the row. 

Waste Disposal

Will you have additional wastes that are not permitted for discharge? If 

yes, fill in the appropriate rows. 

Projected generated waste
SECTION 8: AIR EMISSIONS INFORMATION

A. Emissions Worksheet and Screening Questions 

Screening Questions for EP’s Yes No 

Is any calculated Complex Total (CT) Emission amount (in tons) associated with 

your proposed exploration activities more than 90% of the amounts calculated 

using the following formulas: CT = 3400D2/3 for CO, and CT 33.3D for the 

other air pollutants (where D distance to shore in miles)?

x 

Do your emission calculations include any emission reduction measures or 

modified emission factors? x 

Are your proposed exploration activities located east of 87.5° W longitude? x 

Do you expect to encounter H2S at concentrations greater than 20 parts per million 

(ppm)? x 

Do you propose to flare or vent natural gas for more than 48 continuous hours 

From any proposed well? x 

Do you propose to burn produced hydrocarbon liquids? x 

B. If you answer no to all of the above screening questions from the appropriate table, 

provide: 

1) Summary information regarding the peak year emissions for both Plan Emissions and Complex 

Total Emissions, if applicable. This information is compiled on the summary form of the two 

sets of worksheets. You can submit either these summary forms or use the format below. You 

do not need to include the entire set of worksheets. 

Air Pollutant Plan 

Emission1 

Amounts 

(tons) 

Calculated 

Exemption2

Amounts 

(tons) 

Calculated 

Complex Total 

Emission 

Amounts3

(tons) 

PM 112.72 5194.8 NA 

SOx 64.63 5194.8 NA 

NOx 3874.22 5194.8 NA 

VOC 116.24 5194.8 NA 

CO 845.28 98528.53 NA 

1

 For activities proposed in your EP or DOCD, list the projected emissions calculated from the worksheets. 2

 List the exemption amounts for your proposed activities calculated by using the formulas in 30 CFR 250.303(d). 3

 List the complex total emissions associated with your proposed activities calculated from the worksheets 

2) Contact: Sylvia Bellone, (504) 728-7215, Sylvia.Bellone@shell.com

(1) Worksheets

Because the answers to all the questions set forth above is “no”, further worksheets are not required. 

However, Shell is providing the worksheets for your review. 

 
SECTION 9: OIL SPILLS INFORMATION

A. Oil Spill Response Planning

3⁄4 All the proposed activities and facilities in this EP will be covered by the Regional OSRP filed by 

Shell Offshore Inc (0689) in accordance with 30 CFR 250. Updated Regional OSRPs were filed 

with the BOEMRE on October 26, 2010; March 15, 2011; May 31, 2011 and July 6, 2011 and are 

pending approval. An OSRP Certification in accordance with 30 CFR 254.2 was submitted and 

accepted by the BOEMRE on July 11, 2011. 

 (ii) Spill Response Sites: 

Primary Response Equipment Locations Preplanned Staging Location(s) 

Galveston, TX ; Lake Charles, LA ; Cameron, LA ; 

Fourchon ; LA 

Galveston, TX ; Lake Charles, LA ; Cameron, 

LA ; Fourchon ; LA 

(iii) The names of the oil spill removal organizations (OSRO’s) under contract include Clean Gulf 

Associates (CGA), Marine Spill Response Company (MSRC), Clean Caribbean America (CCA), and 

OSRL/EARL. 

(iv) Worst Case Scenario Determination 

Category Regional OSRP EP 

Type of Activity1 Drilling Rig & Subsea 

Installation 

Drilling Rig & Subsea 

Installation 

Facility Location (area/block) MC 762 WR 95 

Facility Designation2 Subsea well N Subsea well C 

Distance to Nearest Shoreline (miles) 51 156 

Volume3

Storage tanks (total) 

Flowlines (on facility) 

Pipelines 

Uncontrolled blowout (volume per day) 

Total Volume 

N/A 

N/A 

N/A 

 449,000* BOPD 

449,000 Bbls 

N/A 

N/A 

N/A 

 99,000** BOPD 

99,000 Bbls 

Type of Oil(s) - (crude oil, condensate, diesel) Crude oil Crude oil 

API Gravity(s)4 27o 27o 

 *24 hour rate (359,000 BOPD 30 day average) 

**24 hour rate (79,000 BOPD 30 day average) 

Footnotes: 

1. Types of activities include pipeline, platform, caisson, subsea completion or manifold, and mobile drilling rig. 

2. E.g., Well No. 2, Platform JA, Pipeline Segment No. 6373. 

3. Your regional OSRP worst-case scenario volume must be taken from the appropriate section of your regional OSRP. For EP’s, the 

worst-case scenario volume must be determined by using the daily worst-case discharge volume determined using the guidance at 

30 CFR 254.47(b). For DOCD’s, the daily worst-case discharge volume must be determined by using the guidance at 30 CFR 

254.47 (a) and/or (b), as appropriate. 

4. Provide API gravity of all oils given under “Type of Oil(s)” above. Estimate for EP’s. 

Shell submitted the Exploration WCD scenario for MC 391 to the BOEMRE GOMR on October 26, 2010 for 

inclusion in our Regional OSRP. 

Since Shell Offshore Inc has the capability to respond to the appropriate worst-case spill scenario included in 

its regional OSRP, submitted October 26, 2010, and since the worst-case scenario determined for our EP does 

not replace the appropriate worst-case scenario in our regional OSRP, I hereby certify that Shell Offshore Inc 

has the capability to respond, to the maximum extent practicable, to a worst-case discharge, or a substantial 

threat of such a discharge, resulting from the activities proposed in our EP. 

 
B. Oil Spill Response Discussion

1) Volume of the Worst Case Discharge 

Please refer to Table above and complete discussion in Section 2J. 

 2) Trajectory Analysis 

Trajectories of a spill and the probability of it impacting a land segment have been projected 

utilizing information in the BOEMRE Oil Spill Risk Analysis Model (OSRAM) for the Central and 

Western Gulf of Mexico available on the BOEMRE website using 30 day impact. Offshore areas along 

the trajectory between the source and land segment contact could be impacted. The land segment 

contact probabilities are shown in Table 9.C.1. 

Area/Block OCS-G Launch 

Area Land Segment Contact % 

Exploratory 

WR 95 47 

Calhoun, TX - 

Matagorda, TX 1 

Brazoria, TX 1 

Galveston, TX 2 

Jefferson, TX 1 

Cameron, LA 3 

Vermilion, LA 1 

Iberia, LA - 

St. Mary, LA - 

Terrebonne, LA 1 

Lafourche, LA - 

Jefferson, LA - 

Plaquemines, LA 1 

Table 9.C.1 Probability of Land Segment Impact 

C. Resource Identification 

The locations identified in Table 9.C.1 are the highest probable land segments to be impacted using 

the BOEMRE Oil Spill Risk Analysis Model (OSRAM). The environmental sensitivities are identified 

using the appropriate National Oceanic and Atmospheric Administration (NOAA) Environmental 

Sensitivity Index (ESI) maps for the given land segment. ESI maps provide a concise summary of 

coastal resources that are at risk if an oil spill occurs nearby. Examples of at-risk resources include 

biological resources (such as birds and shellfish beds), sensitive shorelines (such as marshes and 

tidal flats), and human-use resources (such as public beaches and parks). 

 
In the event an oil spill occurs, ESI maps can help responders meet one of the main response 

objectives: reducing the environmental consequences of the spill and the cleanup efforts. 

Additionally, ESI maps can be used by planners to identify vulnerable locations, establish protection 

priorities, and identify cleanup strategies. 

The following is a list of resources of special economic or environmental importance that potentially 

could be impacted by the WR 95 WCD scenario. 

Onshore/Nearshore: Cameron Parish is identified as the most probable impacted Parish within 

the Gulf of Mexico for the Exploratory Worst Case Discharge. Cameron Parish is located in the 

southwest corner of Louisiana and has a total area of 1,932 square miles of which, 1,313 square 

miles of it is land and 619 square miles is water. Cameron Parish includes four National Wildlife 

Refuges including the Cameron Prairie National Wildlife Refuge, East Cove National Wildlife Refuge, 

Sabine National Wildlife Refuge and part of the Lacassine National Wildlife Refuge. Key ESI maps for 

Cameron Parish and the legend are shown in Figures 9.C.1through 9.C.10. 

Offshore: An offshore spill may require an Essential Fishing Habitat (EFH) Assessment. This 

assessment would include a description of the spill, analysis of the potential adverse effects on EFH 

and the managed species; conclusions regarding the effects on the EFH; and proposed mitigation, if 

applicable. 

Significant pre-planning of joint response efforts was undertaken in response to provisions of the 

National Contingency Plan (NCP). Area Contingency Plans (ACPs) were developed to provide a well 

coordinated response to oil discharges and other hazardous releases. The One Gulf Plan is specific 

to the Gulf of Mexico to advance the unity of policy and effort in each of the Gulf Coast ACPs. 

Strategies used for the response to an oil spill regarding protection of identified resources are 

detailed in the One Gulf Plan and relevant Gulf Coast ACP. 

D. Worst Case Discharge Response 

Shell will make every effort to respond to the WR 95 Worst Case Discharge as effectively as 

possible. 

Applied Science Associates (ASA) conducted a deepwater blowout simulation for The Response 

Group to better determine subsurface and surface evaporation and dispersion rates. Below is a table 

outlining the applicable evaporation and dispersion quantities: 

Walker Ridge Block 95 

Calculations 

(BBLS) 

i. 30 Day Average WCD = 79,000 bbls 

ii. Subsurface dispersion – 25% (Water Depth = ~5,800) -19,750 bbls 

iii. REMAINING WCD AFTER SUBSURFACE DISPERSION 59,250 bbls 

iv. Surface dispersion and evaporation – 25% -14,813 bbls 

TOTAL REMAINING ~44,400 bbls 

Table 9.D.1 Oil Remaining After Subsurface and Surface Dispersion 

 
Shell has contracted OSROs to provide equipment, personnel, materials and support vessels as well 

as temporary storage equipment to be considered in order to cope with a WCD spill. Under adverse 

weather conditions, major response vessels and Transrec skimmers are still effective and safe in sea 

states of 6-8 ft. If sea conditions prohibit safe mechanical recovery efforts, then natural dispersion 

and airborne chemical dispersant application (visibility & wind conditions permitting) may be the 

only safe and viable recovery option. 

MSRC OSRV 8 foot seas 

VOSS System 4 foot seas 

Expandi Boom 6 foot seas, 20 knot winds 

Dispersants Winds more than 25 knots, 

Visibility less than 3 nautical miles, or 

Ceiling less than 1,000 feet. 

Table 9.D.2 Operational Limitations of Response Equipment 

Upon notification of the spill, Shell would request a partial or full mobilization of contracted 

resources, including, but not limited to, skimming vessels, oil storage vessels, dispersant aircraft, 

subsea dispersant, shoreline protection, wildlife protection, and containment equipment. Following 

is a list of the contracted resources including de-rated recovery capacity, personnel, and estimated 

response times (procurement, load out, travel time to the site, and deployment). The Incident 

Commander or designee may contact other service companies if the Unified Command deems such 

services necessary to the response efforts. 

Subsea Control and Containment: Shell, as a founding member of the Marine Well Containment 

Company (MWCC), will have access to a fully integrated subsea well control and containment 

system that can be rapidly deployed through the MWCC. The IRCS is designed to contain oil flow in 

the unlikely event of an underwater well blowout, and is designed, constructed, tested, and 

available for rapid response. 

Shell’s specific containment response will be addressed in Shell’s NTL10 submission at the time the 

APD is submitted. 

 

 

Mechanical Recovery (skimming): Response strategies include skimming utilizing available 

OSROs Oil Spill Response Vessels (OSRVs), Oil Spill Response Barges (OSRBs), ID Boats, and Quick 

Strike OSRVs. There is a combined de-rated recovery rate capability of approximately 583,358 

barrels/day. Temporary storage associated with the identified skimming and temporary storage 

equipment equals approximately 505,724 barrels. 

 

De-rated Recovery Rate

(bopd) 

Storage 

(bbls) 

Offshore Recovery 476,365 277,000 

Offshore Storage 211,500 

Nearshore Recovery 106,993 17,224 

Total 583,358 505,724 

Table 9.D.3 Mechanical Recovery Combined De-Rated Capability 

 See attachment 9.D.4 Offshore On-Water Recovery Activation List 

See attachment 9.D.5 Offshore On-Water Storage Activation List 

 See attachment 9.D.6 Nearshore On-Water Recovery Activation List 

 
Oil Storage: The strategy for transferring, storing and disposing of oil collected in these recovery 

zones is to utilize two 150,000-160,000 ton (dead weight) tankers mobilized by Shell (or any other 

tanker immediately available). The recovered oil would be transferred to Motiva’s Norco, LA storage 

and refining facility, or would be stored at Delta Commodities, Inc. Harvey, LA facility.

Aerial Surveillance: Aircraft can be mobilized to detect, monitor, and target response to oil spills. 

Aircraft and spotters can be mobilized within hours of an event. 

 See attachment 9.D.7 Aerial Surveillance Activation List 

Aerial Dispersant: Depending on proximity to shore and water depth, dispersants may be a viable 

response option. If appropriate and approved, 4 to 5 sorties from three DC-3’s can be made within 

the first 12 hour operating day of the response. These aerial systems could disperse approximately 

7,704 to 9,630 barrels of oil per day. Additionally, 3 to 4 sorties from the BE90 King Air and 3 to 4 

sorties from the Hercules C-130A within the first 12 hour operating day of the response could 

disperse 4,600 to 6,100 barrels of oil per day. For continuing dispersant operations, the CCA’s Aerial 

Dispersant Delivery System (ADDS) would be mobilized. The ADDS has a dispersant spray capability 

of 5,000 gallons per sortie. 

 See attachment 9.D.8 Offshore Aerial Dispersant Activation List 

Vessel Dispersant: Vessel dispersant application is another available response option. If 

appropriate, vessel spray systems can be installed on offshore vessels of opportunity using inductor 

nozzles (installed on fire-water monitors), skid mounted systems, or purpose-built boom arm spray 

systems. Vessels can apply dispersant within the first 12-24 hours of the response and continually as 

directed. 

 See attachment 9.D.9 Offshore Boat Spray Dispersant Activation List 

Subsea Dispersant: Shell has contracted with Wild Well Control for a subsea dispersant package. 

Subsea dispersant application has been found to be highly effective at reducing the amount of oil 

reaching the surface. Additional data collection, laboratory tests and field tests will help in facilitating 

the optimal application rate and effectiveness numbers. For planning purposes, The system has the 

potential to disperse approximately 24,500 to 34,000 barrels of oil per day.

 See attachment 9.D.10 Subsea Dispersant Package Activation List 

In-Situ Burning: Open-water in-situ burning (ISB) also may be used as a response strategy, 

depending on the circumstances of the release. ISB services may be provided by the primary OSRO 

contractors. If appropriate conditions exist and approvals are granted, one or multiple ISB task 

forces could be deployed offshore. Task forces typically consist of two to four fire teams, each with 

two vessels capable of towing fire boom, guide boom or tow line with either a handheld or aeriallydeployed oil ignition system. At least one support/safety boat would be present during active 

burning operations to provide logistics, safety and monitoring support. Depending upon a number of 

factors, up to 4 burns per 12-hour day could be completed per ISB fire team. Most fire boom 

systems can be used for approximately 8-12 burns before being replaced. Fire intensity and weather 

will be the main determining factors for actual burns per system. Although the actual amount of oil 

that will be removed per burn is dependent on many factors, recent data suggests that a typical 

burn might eliminate approximately 750 barrels. For planning purposes and based on the above 

assumptions, a single task force of four fire teams with the appropriate weather and safety 

conditions could complete four burns per day and remove up to ~12,000 bbls/day. In-situ burning 

nearshore and along shorelines may be a possible option based on several conditions and with 

appropriate approvals, as outlined in Section 19, In-situ Burn Plan (OSRP). In-situ burning along 

certain types of shorelines may be used to minimize physical damage where access is limited or if it 

is determined that mechanical/manual removal may cause a substantial negative impact on the 

environment. All safety considerations will be evaluated. In addition, Shell will assess the situation 

and can make notification within 48 hours of the initial spill to begin ramping up fire boom 

production through contracted OSRO(s). There are potential limitations that need to be assessed 

prior to ISB operations. Some limitations include atmospheric and sea conditions; oil weathering; air 

quality impacts; safety of response workers; and risk of secondary fires. 

 See attachment 9.D.11 In-Situ Burn Equipment Activation List 
 Shoreline Protection: If the spill went unabated, shoreline impact in St. Bernard or Plaquemines 

Parish, LA would depend upon existing environmental conditions. Nearshore response may include 

the deployment of shoreline boom on beach areas, or protection and sorbent boom on vegetated 

areas. Strategies would be based upon surveillance and real time trajectories provided by The 

Response Group that depict areas of potential impact given actual sea and weather conditions. 

Strategies from the New Orleans, Louisiana Area Contingency Plan, The Response Group and Unified 

Command would be consulted to ensure that environmental and special economic resources would 

be correctly identified and prioritized to ensure optimal protection. The Response Group shoreline 

response guides depict the protection response modes applicable for oil spill clean-up operations. 

Each response mode is schematically represented to show optimum deployment and operation of 

the equipment in areas of environmental concern. Supervisory personnel have the option to modify 

the deployment and operation of equipment allowing a more effective response to site-specific 

circumstances. 

 See attachment 9.D.12 Shoreline Protection and Wildlife Support List 

Wildlife Protection: If wildlife is threatened due to a spill, the contracted OSRO’s have resources 

available to Shell, which can be utilized to protect and/or rehabilitate wildlife. The resources under 

contract for the protection and rehabilitation of affected wildlife are in the following table: 

 See attachment 9.D.12 Shoreline Protection and Wildlife Support List 

Estimated time to contain spill to the maximum extent practicable: Times to respond are 

listed in Section 9 of the EP and estimated time to contain will be scenario driven and depend on the 

physical configuration of the spill source. The physical configuration of the release will dictate 

specific capabilities of response equipment and tools. Therefore, the time to contain the spill can 

range from a few hours for BOP manipulation/activation, to a few weeks for cap and contain 

equipment, and months for relief well execution. 

New or unusual technology be employed, in regards to spill prevention, control, cleanup, 

etc.: We will use our normal well design and construction processes with multiple barrier approach 

as well as new stipulations mandated by NTL 05; response techniques will utilize new learnings from 

Macondo response to include in-situ burning and subsea dispersant application. In addition, 

mechanical recovery advancements are underway to incorporate utilization of Koseq arms outfitted 

on barges, conversion of Platform Support Vessels for Oil Spill Response, and inclusion of nighttime 

spill detection radar to improve tracking capabilities (X-Band radar, Infrared sensing, etc.). 

(9c) Modeling Report 

 

Shell did not model a potential oil or hazardous substance spill. 
Figure 9.C.1 Environmental Sensitivity Index Map Legend 
Figure 9.C.2 Texas Point ESI Map 
Figure 9.C.3 Smith Bayou ESI Map 
Figure 9.C.4 Johnsons ESI Map 
Figure 9.C.5 Peveto Beach ESI Map 
Figure 9.C.6 Holly Beach ESI Map 
Figure 9.C.7 Cameron ESI Map 
Figure 9.C.8 Grand Bayou ESI Map 
Figure 9.C.9 Creole ESI Map 
Figure 9.C.10 Hackberry Beach ESI Map 
Table 9.D.4 Offshore On-Water Recovery Activation List 
Table 9.D.4 Offshore On-Water Recovery Activation List (continued) 
Table 9.D.4 Offshore On-Water Recovery Activation List (continued) 
Table 9.D.4 Offshore On-Water Recovery Activation List (continued) 
Table 9.D.5 Offshore On-Water Storage Activation List 
Table 9.D.6 Nearshore On-Water Recovery Activation List 

31943 
Table 9.D.6 Nearshore On-Water Recovery Activation List (continued) 
Table 9.D.6 Nearshore On-Water Recovery Activation List (continued) 
Table 9.D.6 Nearshore On-Water Recovery Activation List (continued) 
Table 9.D.7 Aerial Surveillance Activation List 
Table 9.D.8 Offshore Aerial Dispersant Activation List 
Table 9.D.9 Offshore Boat Spray Dispersant Activation List 
Table 9.D.10 Subsea Dispersant Package Activation List 
Table 9.D.11 In-Situ Burn Equipment Activation List 
Table 9.D.11 In-Situ Burn Equipment Activation List (continued) 
Table 9.D.12 Shoreline Protection and Wildlife Support List 

 
SECTION 10: Environmental Monitoring Information

A. Monitoring Systems 

A rig based Acoustic Doppler Current Profiler (ADCP) is used to continuously monitor the current beneath 

the Rig. Metocean conditions such as sea states, wind speed, ocean currents, etc. will also be continuously 

monitored 

B. Incidental Takes 

No incidental takes are anticipated. Shell implements the mitigation measures and monitors for incidental 

takes of protected species according to the following notices to lessees and operators from the Minerals 

Management Service: 

 

 NTL No.2007-G03 “Marine Trash and Debris Awareness and Elimination” 

 NTL No.2007-G04 “Vessel Strike Avoidance and Injured/Dead Protected Species Reporting” 

C. Flower Garden Banks National Marine Sanctuary 

The operations proposed in this EP will not be conducted within the Protective Zones of the Flower Garden 

Banks and Stetson Bank. 
SECTION 11: Lease Stipulations Information

OCS-G 31943 is not a part of any Biological Sensitive Area, Military Warning Area, high Archeological probability area, 

or Shipping Fairway. 

Lease Stipulation No. 6, Protected Species, is addressed in the following sections of this plan: 

Section 6h, Threatened or endangered species, critical habitat, and marine mammal information 

Section 10b, Environmental Monitoring Information, Incidental takes 

Section 12b, Environmental Mitigation Measures Information, Incidental takes 

Section 18, Environmental Impact Assessment 

SECTION 12: Environmental Mitigation Measure Information

A. Impacts to Marine and coastal environments 

The proposed action will implement mitigation measures required by laws and regulations, including all applicable 

Federal & State requirements concerning air emissions, discharges to water, and solid waste disposal, as well as 

any additional permit requirements and Shell policies. Project activities will be conducted in accordance with the 

Regional Oil Spill Response Plan. The EIA attached as Section 18 to this plan discusses impacts and mitigation 

measures. 

B. Incidental Takes 

We do not anticipate any incidental takes related to the proposed operations. Shell implements the mitigation 

measures and monitors for incidental takes of protected species according to the following notices to lessees and 

operators from the Minerals Management Service: 

NTL No.2007-G03 “Marine Trash and Debris Awareness and Elimination” 

NTL No.2007-G04 “Vessel Strike Avoidance and Injured/Dead Protected Species Reporting” 

SECTION 13: Related Facilities and Operations Information

Information regarding Related Facilities and Operations Information, transportation systems, & produced liquid 

hydrocarbon transportation vessels are not included in this EP as such information is only necessary in the case of 

DOCDs. 

 
SECTION 14: Support Vessels and Aircraft Information

A. General 

Type Maximum Fuel Tank Storage 

Capacity (Bbls) 

Maximum No. In Area at Any 

Time 

Trip Frequency or 

Duration 

Crew Boats 1040 2 Twice per week 

Offshore Support Vessels 9750 3 165 days/well 

Helicopter 22 1 Once per day 

B. Diesel Oil Supply Vessels 

Size of Fuel Supply 

Vessel 

Capacity of Fuel Supply 

Vessel 

Frequency of Fuel 

Transfers 

Route Fuel Supply Vessel Will 

Take 

280 foot length 100,000 gal. 1 week Port Fourchon to MC 984 

C. Drilling Fluids Transportation 

Type of Material Quantity Being Transported Transportation Method 

Dry Bulk (Cement, Barite, 

Gel) 

12,000 sx max combined Below deck dry bulk tanks 

onboard OSV 

Synthetic-base drilling fluids 11,000 bbls max per voyage Tanks below deck onboard 

OSV 

D. Solid and Liquid Wastes Transportation 

See Table 7B. 

E. Vicinity Map – See attached. 

 
 
SECTION 15: Onshore Support Facilities Information

A. General 

Name Location Existing/New/Modified 

Boothville PHI Heliport Boothville, LA Existing 

C-Port II Fourchon, LA Existing 

The existing onshore support base for air transportation will be PHI Heliport in Boothville, LA located at 38963 

Highway 23. The existing onshore base for installation water traffic will be the C-Port II located at Port 

Fourchon Terminal located on Bayou LaFourche, south of Leesville, LA approximately three miles from the Gulf 

of Mexico. 

B. Support Base Construction or Expansion 

This Section does not apply to this EP as Shell does not plan to construct a new onshore support base or 

expand an existing one to accommodate the activities proposed in this EP. 

C. Support Base Construction or Expansion Timetable 

This Section does not apply to this EP as Shell does not plan to construct a new onshore support base or 

expand an existing one to accommodate the activities proposed in this EP. 

D. Waste Disposal 

 See Table 7B. 

SECTION 16: Sulphur Operations Information

Information regarding Sulfur Operations Information is not included in this EP as such information is only 

necessary in the case of DOCDs. 

 
SECTION 17: Coastal Zone Management Act (CZMA) Information

Concurrence with Louisiana CZM was obtained in Plan N-9410 for lease OCS-G 31943 in September 2009. 

LOUISIANA

COASTAL ZONE MANAGEMENT 

CONSISTENCY CERTIFICATION 

REVISED EXPLORATION PLAN 

Type of Plan 

 

WALKER RIDGE BLOCK 95 

OCS-G 31943

 

The proposed activities described in detail in this Plan will comply with Louisiana's State and Local Coastal 

Resources Management Act of 1978, Coastal Resources Program, and Coastal Area Management Enforceable 

Policies. 

We have considered all of Louisiana's Enforceable Policies in making this certification of consistency. 

SHELL OFFSHORE INC. (SOI)

Operator 

_____________________________________________ 

Sylvia A. Bellone 

Certifying Official 

 04/26/2011 

Date 

 
 

TEXAS

COASTAL ZONE MANAGEMENT 

CONSISTENCY CERTIFICATION 

Revised Exploration Plan

Type of Plan 

WALKER RIDGE BLOCK 95 

OCS-G 31943

The proposed activities described in detail in this Plan will comply with Texas State and Local Coastal Resources 

Management Act of 1978, Coastal Resources Program, and Coastal Area Management Enforceable Policies. 

SHELL OFFSHORE INC. (SOI)

Operator 

____________________________ 

Sylvia A. Bellone 

Certifying Official 

 04/26/2011 

Date 

 
Coastal Zone Management Consistency Information 

For the State of Texas 

In accordance with Subpart E of 15 CFR 903 “Consistency for Outer Continental Shelf (OCS) Exploration, 

Development and Production Activities” and as required by 15 CFR 930.58, Shell Offshore INC (SOI) is hereby 

providing the following information in support of the Environmental Impact Analysis submitted as Attachment 

18 of our Supplemental EP. 15 CFR 930.58 identifies necessary data and information to be furnished to the 

State agency. The information is as follows: 

(a) CONSISTENCY CERTIFICATION

A Coastal Zone Consistency Certification for activities that affect the State of Texas is provided above. 

OTHER INFORMATION

A detailed description of the proposed activities, coastal effects, and comprehensive information sufficient to 

support this Consistency Certification is presented in the above-mentioned EP. As per NTL 2008-G04, the 

following items have been identified as being required: 

• A discussion of the method of disposal of wastes and discharges is provided in Section 7 of the abovementioned EP. 

• Oil Spill Information is provided in Section 9 of the above-mentioned EP. All operations are covered 

by Shell Offshore Inc's Regional Oil Spill Response Plan, which is being updated with the BOEM. The 

Plan is available upon request. 

(2) Following is an evaluation that includes findings relating the coastal effects of the proposed activities 

and associated facilities to the relevant enforceable policies of the Texas’ Coastal Management Program

(TCMP), Title 31, Part 16, Chapter 501, Subchapter B:

(Category 2) 

Construction, Operation & Maintenance of Oil & Gas Exploration & Production 

Facilities 

No operations are proposed in or near any critical areas. The proposed activities are explorative in nature, so 

no facility construction is proposed. The proposed activities are located approximately 170 miles from the 

Texas shoreline; therefore we expect no adverse impacts to CNRAs or beach access and use rights of the 

public. All activities shall be conducted in a manner that minimizes significant impacts to coastal resources. 

No adverse effects to Texas’ coastal area are expected in association with the proposed activities. 

(Category 3) 

Discharges of Wastewater and Disposal of Waste from Oil and Gas Exploration and Production 

Activities 

No discharge of wastewater or disposal of waste from the proposed activities will occur in the Texas’ coastal 

zone, therefore no impact to Texas’ coastal waters is expected. 

(Category 4) 

Construction and Operation of Solid Waste Treatment, Storage, and Disposal 

Facilities 

No construction of solid waste facilities or expansion of existing facilities in the coastal zone are proposed in 

the attached plan, therefore, no adverse effects on any features of Texas’ coastal cone are expected. 
(Category 5) 

Prevention, Response, and Remediation of Oil Spills 

The proposed activities will be covered under an approved Regional Oil Spill Response Plan. The plan is in 

place, practiced, and updated as necessary. The best practical techniques shall be utilized to prevent the 

release of pollutants or toxic substances into the environment. All involved vessels and facilities are designed 

to be capable of prompt response and adequate removal of accidental discharges of oil. In addition, the 

proposed activities are 170 miles from the Texas shore; therefore no damages to natural resources are 

expected as the result of an unauthorized discharge of oil into coastal waters. 

(Category 6) 

Discharge of Municipal and Industrial Waste Water to Coastal Waters 

No discharges from the proposed activities will occur in coastal waters. The proposed activities are 170 miles 

from the Texas shore, therefore there will be no effect on coastal waters. 

(Category 8) 

Development in Critical Areas 

None of the proposed activities will occur in a critical area; therefore no effects to Texas’ coastal zone are 

expected. The activity will not jeopardize the continued existence of species listed as endangered or 

threatened, and will not result in likelihood of the destruction or adverse modification of a habitat determined 

to be a critical habitat under the Endangered Species Act. The activity will not cause or contribute to violation 

of any applicable surface water quality standards. The activity will not violate any requirement imposed to 

protect a marine sanctuary. 

(Category 9) 

Construction of Waterfront Facilities and Other Structures on Submerged lands 

No waterfront facilities or other structures are proposed on submerged lands in the Texas coastal zone, 

therefore the proposed activities are not expected to have any adverse impacts on submerged lands. 

(Category 10) 

Dredging and Dredged Material Disposal and Placement 

No dredging or disposal/placement of dredged material is proposed, therefore no adverse effects to coastal 

waters, submerged lands, critical areas, coastal shore areas, or Gulf beaches are expected. 

(Category 11) 

Construction in the Beach / Dune System 

The proposed activities do not include any construction projects in critical dune areas or areas adjacent to or 

on Gulf beaches, therefore, no impact to Texas’ beach or dune systems are expected. 

(Category 15) 

Alteration of Coastal Historic Areas 

The proposed activities do not include any alteration or disturbance of a coastal historic area; therefore, no 

impacts to are expected to adversely affect any historical, architectural, or archaeological site in Texas’ coastal 

zone. 

(Category 16) 

Transportation 

The proposed activities do not include any transportation construction projects within the coastal zone; 

therefore, no impacts to Texas’ coastal zone are expected. 
(Category 17) 

Emission of Air Pollutants 

The proposed activities shall be carried out in conformance with applicable air quality laws, standards, and 

regulations. Emissions from the proposed activities are not expected to have significant impacts on onshore 

air quality because of the prevailing atmospheric conditions, emission heights, emission rates, and the distance 

of these emissions from the coastline. The proposed activities will occur approximately 170 miles from the 

Texas shore and will be within the exemption limits set by BOEM, therefore, no impacts to Texas’ coastal zone 

is expected. 

(Category 18) 

Appropriations of Water 

The proposed activities do not include the impoundment or diversion of state water, therefore, no impacts to 

Texas’ coastal zone is expected. 

(Category 20) 

Marine Fishery Management 

The proposed activities are located approximately 170 miles from the Texas shore and are not expected to 

have any effect on marine fishery management or fishery migratory patterns within waters in the coastal zone 

of Texas. 

(Category 22) 

Administrative Policies 

The necessary information for applicable agencies to make an informed decision on the proposed activities has 

been provided 

In conclusion, all activities shall be consistent with Texas’ coastal management program and shall comply with 

all relevant rules and regulations. No activities are planned within any critical areas. Activities will be carried 

out avoiding unnecessary conflicts with other uses of the vicinity. 

 

 

 
SECTION 18: Environmental Impact Analysis (EIA)

See following report prepared by CSA. 

 
SECTION 19: Administrative Information

A. Exempted Information Description (Public Information Copies Only) 

The following attachments are excluded from the public information copies of typical plans: 

1b. OCS Plan Information form – Bottom hole locations & proposed total depth 

2j. Blowout Scenario – confidential information for NTL 2010 N06 calculation 

3a. Geologic Description 

3b. Structure Contour Maps 

3c. Interpreted 2D or 3D seismic line(s) 

3d. Cross Section(s) 

3e. Shallow Hazards Report 

3f. Shallow Hazards Assessment – confidential data 

3g. High-Resolution Seismic Lines & Top Hole Progs 

3h. & 3i. Stratigraphic Column with Time vs. depth table 

 

B. Bibliography 

3⁄4 Geologic & Stratigraphic Assessment of Walker Ridge Blocks 95 & 139, prepared by GEMS for Shell 

Offshore Inc, dated February 19, 2009, project No. 1008-1564.