### Tolbert, Michael

From: Tolbert, Michael

Sent: Tuesday, February 22, 2011 1:56 PM

To: 'sylvia.bellone@shell.com'

Cc: Peuler, Elizabeth; Hill, Chiquita ; Wetzel, Nick; Saucier, Michael

Subject: Supplemental Exploration Plan S-7445 for Lease OCS-G 7493 (GB 427)

Importance: High 

### Page 1 of 1

2/22/2011 This email is to notify you that the following Suppleme ntal Exploration Plan received October 28, 2010, amended November 19 and 30, December 3 and 9, 2010, and January 6, 21, 27, and February 18, 2011, has been deemed submitted in accordance with 30 CFR 25 0.231(a) and 232(d) as of February 22, 2011:

Control Number - S-7445 Type - Supplemental Exploration Plan Operator – Shell Offshore Inc. Lease(s) - OCS-G 7493 (Block 427, Garden Banks Area)
A ctivities Proposed – Add Wells O, P, and Q



## Michael Tolbert Petroleum Engineer Office of Field Operations, Plans Section
Phone: (504) 736-2867
email: Michael.Tolbert@boemre.govShell 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 Email sylvia.bellone@shell.com

February 17, 2011

Regional Supervisor Office of Field Operations Bureau of Ocean Energy Management Regulation & Enforcement
1201 Elmwood Park Boulevard New Orleans, LA 70123-2394

Attn: Plans Group

MS 5321

SUBJECT: Amended Supplemental Exploration Plan 

### OCS-G 7493, Garden Banks Block 427
Garden Banks 471 Unit
O ffshore, Louisiana
S-07445

Shell submitted subject Supplemental Exploration Pl an on October 28, 2010. At this time we are reques ting an amendment to the plan to include the information contained in the attachments to this letter. The amendments include an update to our worst case disc harge number, a change in our proposed anchor pattern, and an update to our proposed schedule. T hese amendments do not change the analysis and conclusions in the previously submitted EIA. All a dditional information in our original supplemental plan remains as previously submitted.

The NTL 2010-06 Worst Case Blowout requirements for our Regional Oil Spill Response Plan highest exploration well, were previously submitted October 26, 2010 with our Supplemental Exploration Plan fo r Mississippi Canyon Blocks 391, 392 and 348, Plan Co ntrol No. R-05066.

Should you require any additional information, plea se contact me as indicated above.



### Kind regards

Sylvia A. BelloneU. S. Department of the Interior OMB Control Number: 1010-0051 

### Minerals Management Service OMB Approval Expires: 12/31/2011 

### OCS PLAN INFORMATION FORM

General Information

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

Company Name: Shell Offshore Inc. MMS Operator Num ber: 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 7493 Area: Garden Banks Block(s): 4 27 Project Name (If Applicable): NA

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

Description of Proposed Activities (Mark all that a pply)



### 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 protect ion structure Installation of satellite structure

Installation of subsea wellheads and/or manifolds Commence production

Installation of lease term pipelines Other (Specif y and describe)

Have you submitted or do you plan to submit a Conse rvation 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 ho st facility for deepwater subsea development? Yes X No

Do you propose any activities that may disturb an M MS-designated high-probability archaeological area? X Yes No

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

Tentative Schedule of Proposed Activities

Proposed Activity Start Date End Date No. of Days

Preset anchors 3/7/11 4/7/11 30

Drill O 4/7/11 9/14/11 160

Drill P 4/7/12 9/14/12 160

Drill Q 4/7/13 9/14/13 160

Description of Drilling Rig Description of Production Platform

Jackup Drillship Caisson Tension leg platform

Gorilla Jackup Platform rig Well protector Comp liant tower

X Semisubmersible Submersible Fixed platform Guy ed tower

DP Semisubmersible Other (Attach Description) Su bsea manifold Floating production system

Drilling Rig Name (If Known): Noble Jim Thompson Spar Other (Attach Description)

Description of Lease Term Pipelines

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

N/A



### MMS MMS Form MMS-137 (December 2008 – Supersedes all prev ious editions of form MMS=137 which may not be used .) Page 1 of 4

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): O Subsea Completion

Anchor Radius (if applicable) in feet: Rectangle as defined by the following four points: NW corner X=1826637 Y=10009880; NE corner X=1840946Y=10009880; SE corner X=1840946 Y=9996040 and SW
corner X=1826637 Y=9996040 X Yes No

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 7493

Area Name Garden Banks

Block No. 427

Blockline Departures (in feet) N/S Departure: 5965' FNL

E/W Departure: 1400' FEL

Lambert X-Y
coordinates X: 1,836,040

Y: 10,004,915

Latitude/ Longitude Latitude
27.56962046 Longitude
-92.39596682 TVD (Feet): MD (Feet): Water Depth (Feet): 2721’



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

Anchor Name
or No. Area Block X Coordinate Y C oordinate 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 colle cts this information as part of an applicant’s Exploration Plan or Development Operations Co ordination 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 es timate that burden to average 580 hours per response, including the time for reviewing instru ctions, gathering and maintaining data, and completing and reviewing the form. Direct commen ts regarding the burden estimate or any other aspect of this form to the Information Co llection Clearance Officer , Mail Stop 4230, Minerals Management Service, 1849 C St reet, N.W., Wash ington, DC 20240.

MMS Form MMS-137 (December 2008 – Supersedes all previous editions of form MMS=137 which may not be used.)

Page 2 of 4 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): P Subsea Completion

Anchor Radius (if applicable) in feet: 4802’ Anchor Radi us (if applicable) in feet: Rectangle as defined by the following four points: NW corner X= 1826637 Y=10009880; NE corner X=1840946Y=10009880; SE
corner X=1840946 Y=9996040 and SW corner X=1826637 Y=9996040 X Yes No

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 7493

Area Name Garden Banks

Block No. 427

Blockline Departures (in feet) N/S Departure: 5470' FNL

E/W Departure: 1920' FEL

Lambert X-Y
coordinates X: 1,835,520

Y: 10,005,410

Latitude/ Longitude Latitude
27.57098950 Longitude
-92.39756494 TVD (Feet): MD (Feet): Water Depth (Feet): 2721’



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

Anchor Name
or No. Area Block X Coordinate Y C oordinate 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 colle cts this information as part of an applicant’s Exploration Plan or Development Operations Co ordination 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 es timate that burden to average 580 hours per response, including the time for reviewing instru ctions, gathering and maintaining data, and completing and reviewing the form. Direct commen ts regarding the burden estimate or any other aspect of this form to the Information Co llection Clearance Officer , Mail Stop 4230, Minerals Management Service, 1849 C St reet, N.W., Wash ington, DC 20240.

MMS Form MMS-137 (December 2008 – Supersedes all previous editions of form MMS=137 which may not be used.)

Page 3 of 4 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): Q Subsea Completion

Anchor Radius (if applicable) in feet: Rectangle as defined by the following four points: NW corner X=1826637 Y=10009880; NE corner X=1840946Y=10009880; SE corner X=1840946 Y=9996040 and SW
corner X=1826637 Y=9996040 X Yes No

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 7493

Area Name Garden Banks

Block No. 427

Blockline Departures (in feet) N/S Departure: 6470' FNL

E/W Departure: 880' FEL

Lambert X-Y
coordinates X: 1,836,560

Y: 10,004,410

Latitude/ Longitude Latitude
27.56822388 Longitude
-92.39436890 TVD (Feet): MD (Feet): Water Depth (Feet): 2721’



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

Anchor Name
or No. Area Block X Coordinate Y C oordinate 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 colle cts this information as part of an applicant’s Exploration Plan or Development Operations Co ordination 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 es timate that burden to average 580 hours per response, including the time for reviewing instru ctions, gathering and maintaining data, and completing and reviewing the form. Direct commen ts regarding the burden estimate or any other aspect of this form to the Information Co llection Clearance Officer , Mail Stop 4230, Minerals Management Service, 1849 C St reet, N.W., Wash ington, DC 20240.

MMS Form MMS-137 (December 2008 – Supersedes all previous editions of form MMS=137 which may not be used.)

Page 4 of 4 PUBLIC INFORMATION

### (2j) Blowout scenario

Summary

This Section was prepared by Shell Offshore Inc. (S hell) pursuant to the guidance provided in the Bureau of Ocean Energy Management, Regulation and E nforcement’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 appro ach to a loss of well control event (blowout), including prevention, intervention /containment, an d 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 maintainin g staff competence with the goal of safe and environmentally sound well construction. Shell cont inues 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 No tice to Lessees.

Shell is a founding member of the Marine Well Conta inment Corporation (MWCC) and will have access to an integrated subsea well control and con tainment system that can be rapidly deployed through the MWCC. The MWCC is a non-profit organiz ation that owns, manages, and provides fully trained crews to provide operational guidance of the subsea containment system during a response. The near term containment response capabi lity will be addressed in Shell’s NTL10 submission at the time an Application to Drill (APD ) is submitted and will include lessons learned from the Macondo response. Shell is investing in R& D to improve containment systems. Also, Shell is a member of Clean Caribbean America (CCA), Marine Spill Response Corporation (MSRC), Clean Gulf Associates (CGA), and Oil Spill Response (OSR) to provide the resources necessary to respond to a spill as outlined in our Regional Oil Spill Response Plan.

The Worst Case Discharge (WCD) blowout scenario for this EP is calculated for the GB 427 O location and based on the guidelines outlined in NT L No. 2010-N06 along with subsequent Frequently Asked Questions (FAQ). The WCD for GB 42 7 O falls below the WCD exploratory scenario (MC 391) included in our Regional OSRP. In the unlikely event of a spill, Shell’s Regional OSRP (October 2010) is designed to contain and resp ond to a spill that meets or exceeds this WCD. The WCD does not take into account potential flow m itigating factors such as well bridging, obstructions in wellbore, reservoir barriers, or ea rly intervention.

Uncontrolled blowout (volume first day) 184,000 bb l Uncontrolled blowout rate (first 30-days average da ily rate) 166,000 bopd Duration of flow (days) based on relief well 109 da ys Total volume of spill (bbls) for 109 days 14.4 MMBO

Table 1 Worst Case Discharge Summary

### Shell is submitting a Supplemental Exploration Plan for GB 427 (OCS-G 7493) to appraise its recent Cardamom discovery. While the Cardamom disco very comprises multiple reservoirs, this Supplemental EP and NTL-06 documentation pertain to appraising one reservoir – the U sand. Three wells, each with unique surface and U sand bo ttom hole locations, are described in the Supplemental EP. The WCD forecast in this document pertains to the well location that, in the event of loss of well control, discharges the large st volume before containment.

The GB 427-2 will be the first well drilled with a surface location in GB Block 427; however, 17 exploratory and development wells drilled by Shell have targeted objectives in GB Block 427. Consequently, the fundamental geology of the block is well understood.

For this appraisal, Shell plans to submit in Q4 201 0 an APD for drilling a new blue water well. Given success, the well will be secured for later c ompletion in ~Q2 2012.

Subsurface Description:

Omitted from public information copies

Blowout Scenario

1) Purpose

Pursuant to 30 CFR 250.213(g), 250.219, 250.250, an d 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 firstly enhance the ability to prevent a blowout and secondly to re spond and manage a blowout scenario if it were
to occur. These calculations are based on best tech nical estimates of subsurface parameters that are derived from the offset wells and seismic. These pa rameters 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 probabilisti c 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

The GB 427-2 well is drilled to the U sand, as outl ined in the Geological and Geophysical Information Section of the approved Supplemental EP and described above, using a subsea wellhead system, conductor, surface and intermediat e casing program, and using a MODU rig with a marine riser and subsea blowout prevente r (BOP). A hydrocarbon influx and a
well control event are modeled to occur from the U Sand during a trip out of the hole. The
simulated blowout modeled results in unrestricted f low from the well at the seafloor, which represents the WCD (no restrictions in wellbore, fa ilure/loss of the subsea BOP, and a blowout to the seabed).

### b) Estimated flow rate of the potential blowout

Category Initial EP Type of Activity Drilling Facility Location (area/block) GB-427 Facility Designation MODU Distance to Nearest Shoreline (miles) 130 miles Uncontrolled blowout (volume first day) 184,000 bb l Uncontrolled blowout rate (first 30-days average da ily rate) 166,000 bopd

Table 2 Estimated Flow Rates of a Potential Blowout

c) Total volume and maximum duration of the potent ial blowout

Duration of flow (days) 109 days total duration (14 days to contract/mob rig 95 days to drill relief well)

Total volume of spill (bbls) 14.4 MMBO
Note: based on MBAL Material
balance reservoir model *

* Note: The U sand model was constructed using obse rvations from analogue fields in the area which indicate that moderate aquifer support i s likely. Model and model outputs can be provided to the BOEMRE in electronic form upon requ est.

Table 3 Estimated Duration and Volume of a Potentia l Blowout

d) Assumptions and calculations used in determinin g the worst case discharge

Information omitted from public information copies.

The NTL 2010-06 Worst Case Blowout requirements for our Regional Oil Spill Response Plan highest exploration well, were previously submitted October 26, 2010 with our Supplemental Exploration Plan for Mississippi Canyon Blocks 391, 392 and 348, Plan Control No. R-5066.

### (3f) Shallow Hazards Assessment

SITE SPECIFIC COMMENTS

History

Shell’s Auger TLP is centered in GB426 at X = 1,820 ,750 Y= 9,996,240. The anchors for the TLP
extend into blocks 426 and 427. Two of the lateral mooring anchors are within the requested anchor pattern radius. None of the Auger Platform wells have surface locations in block 427. Shell now seeks approval to use the anchored vessel Noble Jim Thompson or similar rig within a rectangle with coordinates of: NW corner X=1826637 Y=10009880; NE corner X=1840946Y=10009880; SE corner X=1840946 Y=9996040 and SW corner X=1826637 Y=9996040 with a 1000’ buffer to perform its planne d operations on proposed locations O, P, and Q. Within this area there are two Auger Lateral moo ring system lines:

C1A-L1 is located at X = 1,826,623 Y = 10,003,220 C1A-L2 is located at X = 1,829,722 Y = 9,997,196

Flowlines flank the Auger dome on all sides. Exist ing pipelines surround and cross the proposed
radius. Shell will maintain a buffer of at least 5 00’ when setting anchors. Shell will not set ancho rs at the intersection of the pipelines.

To assess the proposed anchor radius and surroundin g area, Shell used the following data:

- Fugro-McClelland Anchoring Report Proposed Tension Leg Platform and M/V George Richardson for GB 426, 427, 470 and 471 dated Febru ary 22, 1990

- Fugro’s Archeological Assessment Garden Banks Block 427 Report 2410-1061 dated May 2010 (based on Fugro report No. 0201-0526)

- Chance’s Hazard Study of GB 426, 427, 470, and 471 dated September 1985,

- C& C Technologies Engineering and Hazard Study for 10” x 6” Pipeline Route in GB 341 to 426, Report No. 3566-3662 dated March 2003

- C& C Technologies Engineering and Hazard Study for 12” x 8” Pipeline Route in GB 341 to 426, Report No. 3567-3663 dated June 2003

- Shell’s high resolution 3-D surveys

Well Locations Information

The proposed locations will use a 4,802’ (plus 1000 ’ buffer) radius. The rig center will be X = 1,836,144 Y = 10,004,512

The well centers are: Proposed Location O: X = 1836040 Y = 10004915 Proposed Location P: X = 1835520 Y = 10005410 Proposed Location Q: X = 1836560 Y = 10004410

Based on a high-resolution geophysical survey consi sting of frequency enhanced 3-D seismic, Enhanced Surface Renderings, and Enhanced Surface R enderings with amplitudes applied, deeptow data, Archeological Assessment, side scan sona r, and Subbottom profiler data, the planned anchoring operations for GB 427 are suitable for th e planned activities.

David Garner Vernessa Bradford Staff Geological Engineer Shallow Hazards Interp reter

### 6 Biological, Physical, and Socioeconomic Informati on

(6a) Chemosynthetic Communities Report

ANCHOR CLEARANCE AND CHEMOSYNTHETIC

ORGANISMS COMMENTS



## History

Shell located the Auger TLP in GB426. The anchors f or the TLP extend into blocks 426 and 427. None of the Auger Platform wells have a surface loc ation in block 427. Shell now seeks approval to use the anchored vessel Noble Jim Thompson in Garde n Banks Block 427 within a rectangle with coordinates of: NW corner X=1826637 Y=10009880; NE corner X=1840946Y=10009880; SE
corner X=1840946 Y=9996040 and SW corner X=1826637 Y=9996040 with a 1000’ buffer as required by NTL 2009-G40 to perform the planned operations on propo sed locations O, P, and Q.

To assess the proposed archeological status, well l ocations, anchor radius and surrounding area, Shell used the following data: - Fugro-McClelland Anchoring Report Proposed Tensi on Leg Platform and M/V George Richardson for GB 426, 427, 470 and 471 dated Febr uary 22, 1990 - Fugro’s Archeological Assessment Garden Banks Bl ock 427 Report 2410-1061 dated May 2010 (based on Fugro report No. 0201-0526) - Chance’s Hazard Study of GB 426, 427, 470, and 4 71 dated September 1985, - C& C Technologies Engineering and Hazard Study f or 10” x 6” Pipeline Route in GB 341 to 426, Report No. 3566-3662 dated March 2003 - C& C Technologies Engineering and Hazard Study f or 12” x 8” Pipeline Route in GB 341 to 426, Report No. 3567-3663 dated June 2003 - Shell’s high resolution 3-D surveys

Flowlines flank the Auger dome on all sides.

Chemosynthetic Community Statement Per NTL No. 2009-G40, Deepwater Benthic Communities , Attachment A

ASSOCIATED ANCHORS – NO ANCHOR DISTURBANCES WITHIN 250 FEET OF
CHEMOSYNTHETIC COMMUNITIES

For the three proposed locations O, P, Q and the as sociated anchor radius:

Shell will observe the following separation distanc es from high-density deepwater benthic communities:

1. At least 2,000 feet from each proposed muds and cuttings discharge location;
2. At least 250 feet from the location of all other proposed seafloor disturbances (including those caused by anchors, anchor chains, wire ropes, seafl oor template installation, and pipeline construction). Seafloor disturbances include all “t emporary” disturbances caused during mooring operations (e.g., anchor deployment, setting, and r etrieval) as well as those caused by anchoring activities conducted prior to a MODU arriving on lo cation (e.g., pre-installation of suction piles and cables; where seafloor impacts are much greater while the cables are located on the seafloor prior to being pulled taut and attached to the MODU ).
`

### Anchor Pattern Analysis

The proposed rectangular “radius” has the following coordinates: NW corner X=1826637 Y=10009880; NE corner X=1840946 Y=10009880; SE corn er X=1840946 Y=9996040 and SW
corner X=1826637 Y=9996040.

The center of the rig will be X = 1,836,144 Y = 10, 004,512.

The proposed well centers are:

Proposed Location O: X = 1836040 Y = 10004915 Proposed Location P: X = 1835520 Y = 10005410 Proposed Location Q: X = 1836560 Y = 10004410

The seafloor east of the diapir is relatively smoot h. The proposed locations are east of the base of the Auger diaper in GB427. There are four amplitude s and fluid expulsion features on its crest. From left to right, their center coordinates are:

1 X = 1828115.61 Y = 10001005.83
2 X = 1829096.38 Y = 10001119.85
3 X = 1830134.70 Y = 10002291.81
4 X = 1830808.04 Y = 10002577.53

Shell has designated a 250’ avoidance zone around e ach fluid expulsion feature. Outside these avoidance zones, the subsurface has a dark reflecti vity, interpreted as authigenic. The Auger dome
has numerous seafloor faults that radiate from its crest. The faults also curve around the perimeter of the dome. These faults are usually small displacements affecting the shallow sediments and the seafloor. Vertical displa cement of the subsurface reflectors was generally less than 10 feet and seafloor displacement is less than 5 feet. Because of these conditions, the placement of the suction anchors will be optimized. The suction anchors will be located to minimize penetration of shallow seafloor faults on the eastern side of the dome.

Shell will set the anchors using ROV to survey the area before installation.

The Auger Lateral Mooring System has two lines with in the proposed area. The coordinates are: Auger Lateral Line 3: X = 1826896.33 Y = 10003502.3 0 Auger Lateral Line 4: X = 1830117.92 Y = 9997246.92

Shell will observe an anchor/suction buffer of 500’ from these lines.

Archeological Assessment Per the archeological report, there are items of mo dern drilling debris such as drill pipe on the
seafloor. One item is an unidentified contact measu ring 25’ long by 25’ wide. This contact is a mud mat associated with former construction, shipping, or fishing activities. Its location is approximately X = 1822600; Y = 9995240. Previously drilled GB 471 Well # 1 is located at X = 1823472; Y = 9994628. The mud mat and the well are outside the proposed radius.
There are no landforms or identified features that might be high probability prehistoric sites, such a s natural levees or point bar deposits. The regional probability for historic shipwrecks in this area is
low.

### Within the study area, a modern day shipwreck, the shrimp boat Saint Mary sunk in 1990. Its coordinates are X = 1821348; Y = 10000919. The boat has a 750’ avoidance radius around it. A 500’ avoidance buffer has been place along each exi sting pipeline.

Slope Stability

Shell conducted a detailed study on the Auger Dome to assess the surface stability for anchoring. A determination of sediment run out in case of slope failure was calculated. The anchor placement
took this sediment run out into consideration. A sl ope stability factor of safety of 1.3 or greater is deemed stable. Per Shell’s assessment, the sediment on the dome meets this requirement.

Shell used the following methods to do the assessme nt: 3-D seismic data for seafloor bathymetric profiles upslope from proposed manifold locations, towards salt dome high Deep geotechnical borings at Auger for generalized soil conditions (s tratigraphy and mechanical properties).

Slope Conclusions and Recommendations

• Based on infinite slope results with Auger soil d ata, the study profiles are in the “stable” range (i.e., FoS ~ 1.3-1.5 at zones of maximum slope). • Based on debris flow simulations of possible “sea floor failure zones,” Proposed Location O is ~200’ outside of the maximum run-out predicted w ith Auger soil data, while Proposed Locations P and Q are ~400’ to 750’ inside the maxi mum predicted runout, respectively. • Collective results indicate that risk to proposed manifold locations is low to moderate (increasing to the south). • Moving the proposed manifold locations to 500’ ou tside the maximum predicted run-out
carries minimal risk.

Overview NTL Numbers 2009-G40, 2009-G39, 2008-G20 and 2008-G 05: Shell evaluated the seafloor and archeological data on GB Blocks 426, 427, 471, and 472. T he anchor will be designed to minimize impact on areas of potential fluid expulsion and se afloor faults. 

### Per BOEMRE regulations, Shell’s anchors will remain at least 250’ from potential fl uid expulsion features and amplitudes.

Based on a high-resolution geophysical survey consi sting of frequency enhanced 3-D seismic, Enhanced Surface Renderings, and Enhanced Surface R enderings with amplitudes applied, deeptow data, Archeological Assessment, side scan sonar , and Subbottom profiler data, the planned anchoring operations for GB 427 is suitable for the planned activities.

Vernessa Bradford
Shallow Hazards CoordinatorSupplemental Exploration Plan 

### OCS-G 7493, Garden Banks Block 427
Garden Banks 471 Unit
O ffshore, Louisiana

8 AIR EMISSIONS INFORMATION

(8a) Emissions Worksheet and Screening Questions



### Screening Questions for EP’s Yes No

Is any calculated Complex Total (CT) Emission amoun t (in tons) associated with your proposed exploration activities more than 90% of the amounts calculated using the following formulas: CT

= 3400D 2/3 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 ea st of 87.5° W longitude? 

## x Do you expect to encounter H 2 S at concentrations greater than 20 parts per milli on (ppm)? 

## x
Do you propose to flare or vent natura l gas for more than 48 continuous hours From any proposed well? 

## x
Do you propose to burn produced hydrocarbon liquids ? 

## x

(8b) If you answer no to all of the above screening questions from the appropri ate table, provide:

(1) Summary information regarding the peak year emissi ons 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 for ms or use the format below. You do not need
to include the entire set of worksheets.

Air Pollutant Plan
Emission 1

Amounts (tons) Calculated

Exemption 2

Amounts (tons) Calculated

Complex Total
Emission
Amounts 3
(tons)

PM 17.36 4329 17.36
SO

x 98.91 4329 98.91
NOx 742.18 4329 742.18
VOC 23.44 4329 23.44
CO 161.89 87251.82 161.89

1 For activities proposed in your EP or DOCD, list t he projected emissions calculated from the workshee ts. 2 List the exemption amounts for your proposed activ ities calculated by using the formulas in 30 CFR 25 0.303(d). 3 List the complex total emissions associated with y our proposed activities calculated from the workshe ets



### (2) Contact: Sylvia Bellone, (504) 728-7215, Sylvia.Bellone@ she ll.com

(1) Worksheets

Because the answers to all the questions set forth above is “no”, further worksheets are not required.Supplemental Exploration Plan 

### OCS-G 7493, Garden Banks Block 427
Garden Banks 471 Unit
O ffshore, Louisiana



### 9 OIL SPILLS INFORMATION

(9a) Oil Spill Response Planning

(i) All the proposed activities and facilities in this EP will be covered by the Regional OSRP filed by Sh ell Offshore Inc (0689) in accordance with 30 CFR 250. An update to the Regional OSRP was filed with the BOEMRE October 26, 2010 and is pending approval. An OSRP Certification in accordance with 30 CFR 254.2 was submitted and accepted by the BOEMRE on D ecember 3, 2010.

(ii) Spill Response Sites:

Primary Response Equipment Locations Preplanned Staging Location(s)

Fourchon, LA; Cameron, LA; Houma, LA; Lake

Charles, LA Lake Charles, LA ; Cameron, LA ; Fourchon ; LA

(iii) The names of the oil spill removal organizati ons (OSRO’s) under contract include Clean Gulf Asso ciates (CGA), Marine Spill Response Company (MSRC), Clean Caribbean America (CCA), and OSRL/EARL.

(iv) Worst Case Scenario Determination

Category Regional OSRP EP
Type of Activity 1 Drilling Rig Drilling Rig
Facility Location (area/block) MC 391 GB 427
Facility Designation 2 C O
Distance to Nearest Shoreline (miles) 72 137

Volume 3
Storage tanks (total) Flowlines (on facility) Pipelines Uncontrolled blowout (volume per day)

Total Volume N/A

N/A

N/A
405,000 BOPD
405,000 Bbls N/A

N/A

N/A
184,000* BOPD
184,000 Bbls
Type of Oil(s) - (crude oil, condensate, diesel) Cr ude oil Crude oil
API Gravity(s) 4 37.5o 24o

*24 hour rate (166,000 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 m ust be taken from the appropriate section of your r egional OSRP. For EP’s, the worst-case scenario volume must be de termined by using the daily worst-case discharge vo lume 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 “Ty pe of Oil(s)” above. Estimate for EP’s.

Since Shell Offshore Inc has the capability to resp ond to the appropriate worst-case spill scenario in cluded in its regional OSRP, submitted October 26, 2010, and since the wor st-case scenario determined for our SEP does not re place the appropriate worst-case scenario in our regional OSR P, I hereby certify that Shell Offshore Inc has the capability to respond, to the maximum extent practicable, to a wo rst-case discharge, or a substantial threat of such a discharge, resulting from the activities proposed in our SEP.(9b) Oil Spill Response Discussion

A. Volume of the Worst Case Discharge

Please refer to Section 2j of this EP

B. Trajectory Analysis

Trajectories of a spill and the probability of it i mpacting a land segment have been projected utilizi ng information in the BOEMRE Oil Spill Risk Analysis M odel (OSRAM) for the Central and Western Gulf of Mexico available on the BOEMRE website using 30 day impact. Offshore areas along the trajectory betwee n the source and land segment contact could be impact ed. The land segment contact probabilities are show n in
Table 9.C.1.

Area/Block OCS-G Launch
Area Land Segment Contact %

Exploratory
GB 427 20 Kleberg, TX Nueces, TX Aransas, TX Calhoun, TX Matagorda, TX Brazoria, TX Galveston, TX Jefferson, TX Cameron, LA Vermillion, LA Iberia, LA Terrebonne, LA Plaquemines, LA 1%
1%
1%
1%
3%
2%
6%
4%
9%
3%
1%
2%
1%

Table 9.C.1 Probability of Land Segment Impact
C. Resource Identification

The locations identified in Table 9.C.1 are the hig hest probable land segments to be impacted using th e BOEMRE Oil Spill Risk Analysis Model (OSRAM). The e nvironmental sensitivities are identified using the appropriate National Oceanic and Atmospheric Admini stration (NOAA) Environmental Sensitivity Index (ESI) maps for the given land segment. ESI maps pro vide a concise summary of coastal resources that ar e at risk if an oil spill occurs nearby. Examples of at- risk resources include biological resources (such a s birds and shellfish beds), sensitive shorelines (such as mars hes 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 objective s: reducing the environmental consequences of the spil l and the cleanup efforts. Additionally, ESI maps c an be used by planners to identify vulnerable locations, establish protection priorities, and identify clean up strategies.

The following is a list of resources of special eco nomic or environmental importance that potentially could be impacted by the Cardamom WCD scenario.

Onshore/Nearshore: Cameron Parish is identified as the most probable impacted Parish within the Gulf of Mexico for the Exploratory WCD. Cameron Parish is located in the southwest corner of Louisiana and ha s a total area of 1,932 square miles of which, 1,313 sq uare miles of it is land and 619 square miles is wa ter. Cameron Parish includes four National Wildlife Refu ges including the Cameron Prairie National Wildlife Refuge, East Cove National Wildlife Refuge, Sabine National Wildlife Refuge and part of the Lacassine National Wildlife Refuge.

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 man aged species; conclusions regarding the effects on the E FH; and proposed mitigation, if applicable.Significant pre-planning of joint response efforts was undertaken in response to provisions of the Nat ional

Contingency Plan (NCP). Area Contingency Plans (ACP s) were developed to provide a well coordinated response to oil discharges and other hazardous rele ases. The One Gulf Plan is specific to the Gulf of Mexico to advance the unity of policy and effort in each of t he Gulf Coast ACPs. Strategies used for the respons e to an oil spill regarding protection of identified resour ces are detailed in the One Gulf Plan and relevant Gulf Coast
ACPs.

D. Worst Case Discharge Response

Shell will make every effort to respond to the Card amom WCD as effectively as possible. Applied Science Associates (ASA) conducted a deepwa ter blowout simulation to better determine subsurfa ce and surface evaporation and dispersion rates. Below is a table outlining the estimated applicable evap oration and dispersion quantities:

Garden Banks 427 Calculations
(BBLS)

i. 30 Day Average WCD = 166,000 bbls

ii. Subsurface dispersion – 25% (Water Depth = ~2,700) -41,500 bbls

iii. REMAINING WCD AFTER SUBSURFACE DISPERSION 124,500 bbls

iv. Surface dispersion and evaporation – 25% -31,200 bbls

TOTAL REMAINING ~93,300 bbls

Table 9.D.1 Oil Remaining After Subsurface and Surf ace Dispersion

Shell has contracted OSROs to provide equipment, pe rsonnel, materials and support vessels as well as temporary storage equipment to be considered in ord er to respond to a WCD spill. Under adverse weather conditions, major response vessels and Transrec ski mmers are still effective and safe in sea states of 6-8 ft. If sea conditions prohibit safe mechanical recovery ef forts, then natural dispersion and airborne chemica l dispersant application (visibility & wind condition s permitting) may be the only safe and viable recov ery 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 Equ ipment

Upon notification of the spill, Shell would request a full mobilization of contracted resources, inclu ding, but not limited to: MWCCs IRCS, skimming vessels, oil storage vessels, dispersant aircraft, subsea disper sant, insitu burn teams, shoreline protection, wildlife pro tection, and containment equipment. Following is a list of the contracted resources including de-rated recover y capacity, personnel, and estimated response times (procurement, load out, travel time to the site, an d deployment). The Incident Commander or designee m ay contact other regional or global response resources and 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 MWCC, will have access to the IRCS that can be rapidly deployed through the MWCC. The IRCS is designed to contain oil flow in the unlikel y event of an underwater well blowout, and is designe d, constructed, tested, and available for rapid res ponse.Shell’s specific containment response for Cardamom will be addressed in Shell’s NTL10 submission at th e

time the APD is submitted.

Mechanical Recovery (skimming): Response strategies include skimming utilizing ava ilable 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 capabili ty of approximately 865,000 barrels/day. Temporary storage associated with the identified skimming and temporary storage equipment equals approximately 836,000 barrels.

De-rated Recovery Rate (bopd) Storage (bbls)
Offshore Recovery 476,000 273,400

Offshore Storage 211,500

Nearshore Recovery 106,000 17,000

Total 583,000 502,000

Table 9.D.3 Mechanical Recovery Combined De-Rated C apability

Table 9.D.4 Offshore On-Water Recovery Activation List Table 9.D.5 Offshore On-Water Storage Activation Li st Table 9.D.6 Nearshore On-Water Recovery Activation List

Oil Storage: The strategy for transferring, storing and disposi ng of oil collected in these recovery zones is to utilize two 150,000-160,000 ton (dead weight) tanke rs mobilized by Shell (or any other tanker immediat ely 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 ev ent.

Table 9.D.7 Arial Surveillance Activation List

Aerial Dispersant: Depending on proximity to shore and water depth, d ispersants 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 7,700 to 9,600 barrel s of oil per day. Additionally, 3 to 4 sorties from the BE90 King Air and 3 to 4 sorties from the Hercules C-13 0A within the first 12 hour operating day of the respo nse could disperse 4,600 to 6,100 barrels of oil pe r day. For continuing dispersant operations, the CCA’s Aerial Dispersant Delivery System (ADDS) would be mobilize d. The ADDS has a dispersant spray capability of 5,000 gallons per sortie.

Table 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 b oom arm spray systems. Vessels can apply dispersant within the first 12-24 hours of the response and co ntinually as directed.

Table 9.D.9 Offshore Boat Spray Dispersant Activat ion 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 th e surface. Additional data collection, laboratory tests and fi eld tests will help in facilitating the optimal app lication rate and effectiveness numbers. For planning purposes, T he system has the potential to disperse approximate ly 24,500 to 34,000 barrels of oil per day.

Table 9.D.10 Subsea Dispersant Package Activation ListIn-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 p rovided by the primary OSRO contractors. If appropr iate 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 aerially -deployed oil ignition system. At least one support /safety boat would be present during active burning operati ons to provide logistics, safety and monitoring sup port. Depending upon a number of factors, up to 4 burns p er 12-hour day could be completed per ISB fire team

.

Most fire boom systems can be used for approximatel y 8-12 burns before being replaced. Fire intensity and weather will be the main determining factors for ac tual burns per system. Although the actual amount o f oil that will be removed per burn is dependent on many factors, recent data suggests that a typical burn m ight eliminate approximately 600 barrels. For planning p urposes and based on the above assumptions, a singl e task force of four fire teams with the appropriate weath er and safety conditions could complete four burns per day and remove up to ~10,000 bbls/day. In-situ burning nearshore and along shorelines may be a possible op tion based on several conditions and with appropriate ap provals, as outlined in Section 19, In-situ Burn Pl an (OSRP). In-situ burning along certain types of shor elines may be used to minimize physical damage wher e access is limited or if it is determined that mecha nical/manual removal may cause a substantial negati ve impact on the environment. All safety considerations will be evaluated. In addition, Shell will assess the si tuation and
can make notification within 48 hours of the initia l spill to begin ramping up fire boom production th rough 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 res ponse workers; and risk of secondary fires.

Table 9.D.11 In-Situ Burn Equipment Activation Lis t

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 so rbent boom on vegetated areas. Strategies would be based upon surveillance and real time trajectories provid ed by The Response Group that depict areas of poten tial impact given actual sea and weather conditions. Str ategies from the New Orleans, Louisiana Area Contin gency Plan, The Response Group and Unified Command would be consulted to ensure that environmental and speci al economic resources would be correctly identified an d prioritized to ensure optimal protection. The Res ponse Group shoreline response guides depict the protecti on response modes applicable for oil spill clean-up operations. Each response mode is schematically rep resented to show optimum deployment and operation o f the equipment in areas of environmental concern. Su pervisory personnel have the option to modify the deployment and operation of equipment allowing a mo re effective response to site-specific circumstance s.

Table 9.D.12 Shoreline Protection and Wildlife Sup port List

Wildlife Protection: If wildlife is threatened due to a spill, the cont racted OSRO’s have resources available to Shell, which can be utilized to protect and/or reha bilitate wildlife. The resources under contract for the protection and rehabilitation of affected wildlife are in the following table:

Table 9.D.12 Shoreline Protection and Wildlife Sup port List1 Table 9.D.12 Shoreline Protection and Wildlife Support List

Figure 9.C.1 Environmental Sensitivity Index Map Legend2 Figure 9.C.2 Texas Point ESI Map3 Figure 9.C.3 Smith Bayou ESI Map4 . Figure 9.C.4 Johnsons ESI Map5 Figure 9.C.5 Peveto Beach ESI Map6 Figure 9.C.6 Holly Beach ESI Map7 Figure 9.C.7 Cameron ESI Map8 Figure 9.C.8 Grand Bayou ESI Map9 Figure 9.C.9 Creole ESI Map10 Figure 9.C.10 Hackberry Beach ESI Map11 

### Table 9.D.4 Offshore On-Water Recovery Activation List12 

### Table 9.D.4 Offshore On-Water Recove ry Activation List (continued)13 

### Table 9.D.4 Offshore On-Water Recove ry Activation List (continued)14 

### Table 9.D.4 Offshore On-Water Recove ry Activation List (continued)15 

### Table 9.D.5 Offshore On-Water Storage Activation List16 

### Table 9.D.6 Nearshore On-Water Recovery Activation List17 

### Table 9.D.6 Nearshore On-Water Rec overy Activation List (continued)18 

### Table 9.D.6 Nearshore On-Water Rec overy Activation List (continued)19 

### Table 9.D.6 Nearshore On-Water Rec overy Activation List (continued)20 

### Table 9.D.6 Nearshore On-Water Rec overy Activation List (continued)21 

### Table 9.D.7 Aerial Surveillance Activation List22 

### Table 9.D.8 Offshore Aerial Di spersant Activation List23 

### Table 9.D.9 Offshore Boat Spray Dispersant Activation List24 

### Table 9.D.10 Subsea Dispersant Package Activation List25 

### Table 9.D.11 In-Situ Burn E quipment Activation List26 

### Table 9.D.11 In-Situ Burn Equipmen t Activation List (continued)27 

### Table 9.D.12 Shoreline Protecti on and Wildlife Support List

### 18. Environmental Impact Analysis (EIA)

The updated worst case discharge number of 184,000 BOPD, change in proposed anchor pattern, and update to the proposed schedule addressed in this a mended Exploration Plan do not change the conclusions reached in the EIA submitted as part of the Exploration Plan on October 28, 2010.