Scan Update segment 13698, 13699 ROW OCS-G28760

United States Department of the Interior BUREAU OF SAFETY AND ENVIRONMENTAL ENFORCEMENT

Gulf of Mexico OCS Region 1201 Elmwood Park Boulevard New Orleans, LA 70123-2394

In Reply Refer To: GE 1035A

Mr. Dominick Faraci Anadarko Petroleum Corporation 1201 Lake Robbins Drive The Woodlands, TX 77380

Dear Mr. Faraci:

November 7, 2017

Reference is made to Anadarko Petroleum Corporation's (Anadarko) plan of corrective action dated October 17, 2017 to upgrade Cathodic Protection for Subsea Umbilical Terminal Assembly for Umbilical Segment No. 13699 associated with Pipeline Segment No. 13698.

Specifically, Anadarko proposes to install a small anode sled (8' X 8' X 12') approximately 20 feet away from the SUTA and connecting the anode sled to the SUTA with tie back cables.

PSN 13698 and 13699 are described as follows:

PSN Diameter

(inch) Length (feet) Service Origin Termination

Subsea SLED Platform A 13698 06 25,819 Bulk Gas East Break East Break

Block 690 Block 602

13699 04 26,985 Umbilical Platform A East Break Block 602

Subsea Well No. 1 East Break Block 690

Pursuant to 30 CFR 250.1008(g), your application is hereby approved.

Please be reminded that, in accordance with 30 CFR 250.1008(g), you shall submit a written notification to this office within 30 days from the date the corrective action is completed. The notification should include the date of the completion of the project and an indication that the remedial action was performed in accordance with the proposed plan.

(for)

Sincerely,

BIMAL SHRESTHA Bryan A. Domangue Acting Regional Supervisor Regional Field Operations

Digitally signed by BIMAL SHRESTHA Date: 2017.11.07 09:50:17 -06'00'

A N A D A R K O P E T R O L E U M C O R P O R A T I O N 1201 LAKE ROBBINS DRIVE • THE WOODLANDS, TEXAS 77380

P.O. Box 1330 • HOUSTON, TEXAS 77251-1330

Petroleum Corporation

October 16, 2017

Regional Supervisor, Field Operations Pipeline Section (GE 1035A) Bureau of Safety and Environmental Enforcement 1201 Elmwood Park Blvd New Orleans, LA 70123-2394

RE: ***Plan of Corrective Action*** PSN 13699; Main Control Umbilical from Hansen Spar (EB 602; OCS-G 14205) to SUTA (EB 646; OCS-G 20725)

Dear Ladies and Gentlemen:

Anadarko US Offshore LLC as the designated operator of PSN 13699 is filing this plan of corrective action to upgrade the cathodic protection of the Subsea Umbilical Termination Unit (SUTA). Additional cathodic protection for the SUTA will be provided by installing a small anode sled (8' X 8' X 12') approximately 20 feet away from the SUTA and connecting the anode sled to the SUTA with tie back cables. Please see the enclosed drawing that shows the location of the SUTA and the anode sled.

The existing SUTA has marine coatings and anodes that were installed on the structure and mudmat. Cathodic protection readings were taken recently and found to be lower than desired. Cathodic protection is proposed to be added utilizing 4 Al-Zn anodes with a net weight of 725 lbs, which will yield a cathodic protection life in excess of 20 years. Please see enclosed calculation.

Anadarko plans to install the anode sled on or about November 1, 2017 if all approvals are received; therefore, your expedited approval is appreciated.

Further, the operator of PSN 13699 should be Anadarko Petroleum Corporation, not Anadarko US Offshore LLC to match the operator of the associated pipeline, PSN 13698. Please make this change in your records.

If you have any questions or need additional information, please contact the undersigned or our regulatory consultant, Wanda Parker, at 972-516-1177 or by email at wanda.barker^jwibenterprises.com.

Very truly yours,

Dominick Faraci Facilities Regulatory Manager Dominick.Faraci(a)anadarko.com

Rashlri.Kissoon 10/10/2017 2:55:41 PM — File Path: G:\WGK\US-Houston\Projec1s\108969 EB 646 NO 12\Drafting\Drawings by WGK\108969 - Nansen EB 646 #12 Layout Set.dwg (NG-EB646-FA0600-WGS-E04-00004-00)

EB646

" 5 5

EXISTING STFL -

EXISTING EFL -

EXISTING STFL -

-EXISTING EFL

EXISTING NAVAJO SUTA LOCATION

1,157,497.00 9,917,385.00

(REF. 1 &2)

EXSITING 3.0" CD • ! SHACKLETON/DP-1 |NFIELD UMBII ICAI

(SEG. #16158)

\ \

\

TIE-BACK CABLE-[351] (20') (NOTE 5)

PROPOSED NAVAJO ANODE POD LOCATION

1,157,509.11 9,917,371.44 \

\

\ \

\

\

\

KEY MAP

NOTES

1. ALL UNITS ARE IN FEET UNLESS OTHERWISE NOTED.

2. STRUCTURES SHOWN ARE FOR ILLUSTRATIVE PURPOSES ONLY. ACTUAL STRUCTURES TO BE DETERMINED.

3. ANODE POD SHALL BE LAID IN A 5•x5, TARGET BOX.

4. ALL FLYING LEADS ARE SHOWN FOR GRAPHICAL PURPOSES ONLY. AS LAID LOCATIONS ARE UNKNOWN.

5. FLYING LEAD LENGTHS IN [ ] ARE LENGTHS ORDERED. LENGTHS IN ( ) ARE LENGTHS ILLUSTRATED.

LEGEND

TIE-BACK CABLE

PROPOSED TARGET BOX

EXISTING FLOWLINE

EXISTING UMBILICAL

EXISTING FLYING LEADS

NOMENCLATURE

EFL: STFL: SUTA:

ELECTRICAL FLYING LEAD STEEL TUBE FLYING LEAD SUBSEA UMBILICAL TERMINATION ASSEMBLY

GEODETIC DATA

CLARK 1866

CENTRAL MERIDIAN:

GRID UNITS: US SURVEY FEET

UMBILICAL TERMINATION ASSEMBLY. SUBSEA, KERR MCGEE NAVAJO. REV. 02 (By: Knaerner Oilfield Pofducts Inc.)

REFERENCE TITLE

2028-50-P-DW-002

REFERENCE No.

ISSUED FOR USE

ISSUED FOR REVIEW

DESCRIPTION

PROJECT ENGINEERING MANAGER

R. SEVERSON

SCALE AT'D'-SIZE

DATE

10/5/17

DATE

10/5/17

DATE

10/5/17

NANSEN EB 646 #12

NAVAJO ANODE POD APPROACH

Petroleum Corporation WOOD GROUP

NG-NS-FA0600-WGS-E04-00004-00

NG-EB646-FA0600-WGS-E04-00004-00

1.1 Cathodic Protection System

The existing coating system for the Navajo SUTA consists of a 3-Layer marine epoxy coating that

has been in use for approximately 15 years. The SUTA CP system will be augmented with an Al-

Zn-ln anode array herein referred to an Anode Pod to provide an additional 20 years of CP.

A summary of the design calculations are as follows:

Navajo SUTA Design Calculations Summary

Design Life (years) 20

Coated Surface Area of SUTA in Seawater (ft2) 300

Un-Coated Surface Area of SUTA in Seawater (ft2) 50

Coated Surface Area of SUTA in Sediments (ft2) 34

Un-Coated Surface Area of SUTA in Sediments (ft2) 150 Initial Coating Breakdown (after 15 years in operation) (%) 0.14 Mean Coating Breakdown (%) 0.22 Final Coating Breakdown (%) 0.30

Initial Current Density (mA/ft2) 16.72

Maintenance Current Density (mA/ft2) 8.36

Final Current Density (mA/ft2) 12.08

Sediments Current Density (mA/ft2) 1.86 Anode Capacity in Seawater (A-hr/lb) 907 Anode Potential (-V vs Ag/AgCI) 1.050 Driving Voltage (V) 0.250 Seawater resistivity (ohm-cm) 30.0 Total Initial Current Required for SUTA (A) 2.739 Total Mean Current Required for SUTA (A) 1.894 Total Final Current Required for SUTA (A) 2.983 Design Safety Value (%) 50 Anode Mass Required for SUTA (lb) 406.4 Anode Mass Recommended for SUTA (lb) 2900 Anode Pod Utilization 90%

The design life for the cathodic protection system is 20 years. The calculated anode design life is

given as follows:

M*U*v

~ I Where;

T = Time (yrs)

M = Total net anode mass (lb)

U = Utilization factor (U=0.90 for platform anodes)

v = Electrochemical efficiency = 2000 amp-hr/kg (907 amp-hr/lb)

I = Current demand (amp)

Navajo SUTA: M = 4 anodes x 725 lbs = 2900 lbs

I = 1.894 A, based on average current demand

T= 142.73 years