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Ensign Installation

Decommissioning Programme

Ensign Installation Decommissioning Programme Page 2 of 30

DOCUMENT CONTROL

Document ID: SPT-DCM-SNS0104-REP-0004

Document Classification: PUBLIC

Document Ownership: Decommissioning

Date of Document: 30/08/18 Signature Date

Prepared by: S. Axon 02 Oct 2019

Reviewed by: S. Mackenzie 02 Oct 2019

Approved by: M. Fotheringham M. Fotheringham 02 Oct 2019

REVISION RECORD

Revision No. Date of Revision Reason for Issue

A1 15/03/19 Combined DP issued for Review and Comment

A2 24/04/19 Issued to OPRED for Review and Comment

A3 08/10/19 Issued for Statutory Consultation

DISTRIBUTION LIST

Company No. of copies

Offshore Petroleum Regulator for Environment and Decommissioning 1 electronic

GMG, NFFO, NIFPO, SFF 1 electronic

Hull Central Library 1 hardcopy

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TABLE OF CONTENTS INST P/L

1. Executive Summary 7

1.1 Decommissioning Programme 7

1.2 Requirement for Decommissioning Programme 7

1.3 Introduction 7

1.4 Overview of Installation Being Decommissioned 8

1.5 Summary of Proposed Decommissioning Programme 8

1.6 Field Location in UKCS 10

1.7 Industrial Implications 13

2. Description of Items to be decommissioned 14

2.1 Installation: Surface Facilities 14

2.2 Wells 16

2.3 Inventory Estimates 16

3. Removal and Disposal Methods 16

3.1 Topsides 17

3.2 Jacket 19

3.3 Wells 21

3.4 Waste Streams 22

4. Environmental Impact Assessment 23

4.1 Potential Environmental Impacts and their Management 23

5. Interested Party Consultations 26

5.1 Informal Consultations 26

6. Programme Management 27

6.1 Project Management and Verification 27

6.2 Post-Decommissioning Debris Clearance and Verification 27

6.3 Schedule 27

6.4 Costs 27

6.5 Close Out 28

6.6 Post-Decommissioning Liability, Monitoring and Evaluation 28

7. Supporting Documents 29

Appendix A PUBLIC NOTICE & CONSULTEE CORRESPONDENCE 30

Appendix A.1 Public Notices 30

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Ensign Installation Decommissioning Programme Page 4 of 30

FIGURES AND TABLES

Figure 1.6.1: Field Location in UKCS............................................................................................ 10 Figure 1.6.2: Ensign Prior to Decommissioning ............................................................................ 11 Figure 1.6.3: Overview of Ensign Approaches .............................................................................. 12 Figure 2.1.1: Overview of Ensign decommissioning proposals ..................................................... 15 Figure 2.3.1: Pie chart of estimated installation inventory ............................................................. 16 Figure 3.1.1: Ensign Looking North .............................................................................................. 17 Figure 3.1.2: Ensign Looking West ............................................................................................... 18 Figure 3.2.1: Elevations on West & East Jacket Faces ................................................................. 20 Figure 3.2.2: Elevations on North and South Jacket Faces .......................................................... 21 Figure 6.3.1: Gantt Chart of Project Plan ...................................................................................... 27 Table 1.4.1: Installations Being Decommissioned........................................................................... 8 Table 1.4.2: Installation Section 29 Notice Holders Details ............................................................. 8 Table 1.5.1: Summary of Decommissioning Programme ................................................................ 8 Table 1.6.1: Adjacent Facilities ..................................................................................................... 12 Table 2.1.1: Surface Facilities Information .................................................................................... 14 Table 2.2.1: Well Information ........................................................................................................ 16 Table 3.1.1: Cleaning of topsides for removal ............................................................................... 18 Table 3.1.2: Topside Removal Methods ....................................................................................... 19 Table 3.2.1: Jacket Decommissioning Methods ............................................................................ 19 Table 3.3.1: Well Decommissioning ............................................................................................. 21 Table 3.4.1: Waste Stream Management Method......................................................................... 22 Table 3.4.2: Inventory Disposition ................................................................................................ 22 Table 3.4.3: Re-use, Recycle & Disposal Aspirations for Recovered Material .............................. 22 Table 4.1.1: Environmental Impact Management [2] ..................................................................... 23 Table 5.1.1: Summary of Stakeholder Comments ........................................................................ 26

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TERMS AND ABBREVIATIONS

ABBREVIATION EXPLANATION

CPUK Conoco Phillips UK Limited

CSV Construction Support Vessel

DCA Decommissioning Operations (Master Application Template)

DSV Diving Support Vessel

Ensign Installation comprising small topsides and jacket held in location using 4x piles

ESDV Emergency Shutdown Valve

GMG Global Marine Group

HSE Health and Safety Executive

Installation Installation as defined by the Section 29 Notice, comprising topsides and jacket

“ Inch; 25.4 millimetres

JNCC Joint Nature Conservation Committee

JUWB Jack Up Work Barge

km Kilometre

LAT Lowest Astronomical Tide

LOGGS Lincolnshire Offshore Gas Gathering System

m Metre(s)

MAT, SAT Master Application Template, Supplementary Application Template

MCV Monohull Crane Vessel

MSV Multipurpose Support Vessel

N,S,E,W, ESE North, South, East, West, East-South-East

n/a Not Applicable

NFFO National Federation of Fishermen's Organisations

NIFPO Northern Ireland Fish Producers Organisation

NORM Naturally Occurring Radioactive Material

NPAI Not Permanently Attended Installation

NUI Normally Unattended Installation

OPEP Oil Pollution Emergency Plan

OPRED Offshore Petroleum Regulator for Environment and Decommissioning

OSPAR Oslo-Paris Convention

Piggybacked Smaller pipeline is adjacent and clamped to a larger pipeline throughout its length

Pipeline Pipeline or umbilical

PL Pipeline Identification numbers

PLA Pipeline Operations as defined in MAT Operation Types

Platform Installation, typically comprising topsides and jacket

PON Petroleum Operations Notice

ROVSV Remotely Operated Vehicle Support Vessel

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ABBREVIATION EXPLANATION

SFF Scottish Fishermen’s Federation

SLV Shear Leg Vessel

Spirit Energy Spirit Energy North Sea Limited

SSCV Semi-Submersible Crane Vessel

UK United Kingdom

UKCS United Kingdom Continental Shelf

WGS84 World Geodetic System 1984

Ensign Installation Decommissioning Programme Page 7 of 30

1. EXECUTIVE SUMMARY

1.1 Decommissioning Programme

This document contains one Decommissioning Programme for the set of notices under Section 29 of the Petroleum Act 1998. The Decommissioning Programme is concerned with:

• The Ensign installation, comprising a steel jacket and topsides.

Although decommissioning of the Ensign installations and pipelines is being treated in this document as a standalone project, Spirit Energy will also continue to explore cost saving synergies with other projects.

A separate Decommissioning Programme will be prepared for the Ensign pipelines.

1.2 Requirement for Decommissioning Programme

Installations: In accordance with the Petroleum Act 1998, Spirit Energy North Sea Limited (as operator of the Ensign field, and on behalf of the Section 29 notice holders (Table 1.4.2), is applying to the Offshore Petroleum Regulator for Environment and Decommissioning (OPRED) to obtain approval for decommissioning the installations detailed in Section 2 of this document.

In conjunction with public, stakeholder and regulatory consultation, this Decommissioning Programme is submitted in compliance with national and international regulations and