Decommissioning Progress Report Brent Alpha Topside...The Alpha topside is the third topside to be decommissioned and removed from the Brent Field; the Delta and Bravo topsides were

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Shell U.K. Limited

Decommissioning Progress Report

Brent Alpha Topside

Frontispiece: Brent Alpha Topside in 2006

Shell Report Number BDE-A-TOP-AA-6944-00001 November 2020

2 Decommissioning Progress Report Brent Alpha Topside


Contents

1 SUMMARY 8

1.1 Summary of Decommissioning Programme ....................................................................... 8

1.1.1 Progress Report .............................................................................................................. 8

1.1.2 Brent Alpha Decommissioning ........................................................................................... 8

1.1.3 Overview of Decommissioned Installation ............................................................................ 9

1.2 Schematic of Installation Being Decommissioned ............................................................... 12

1.3 Gantt chart / progress against approved schedule ............................................................ 13

1.4 Associated Decommissioning Approvals .......................................................................... 13

2 DECOMMISSIONING ACTIVITIES THIS PERIOD 14

2.1 Organisation of the Work ............................................................................................ 14

2.1.1 Project Management and Verification ................................................................................. 14

2.1.2 Main Contractors and Their Role ....................................................................................... 14

2.2 Description of Brent Alpha Topside ................................................................................ 15

2.2.1 Introduction ................................................................................................................... 15

2.2.2 Main Features................................................................................................................ 15

2.3 Inventory of Materials ................................................................................................. 16

2.4 Preparation of Topside for Removal ................................................................................ 19

2.4.1 Introduction ................................................................................................................... 19

2.4.2 Plug and Make Safe of Wells ........................................................................................... 19

2.4.3 Cutting of the conductors and pipework .............................................................................. 19

2.4.4 Preparation for Lift ........................................................................................................... 20

2.4.5 Cleaning of topside process facilities before removal ............................................................. 20

2.4.6 Cutting the legs .............................................................................................................. 21

2.4.7 Unmanned Period ........................................................................................................... 21

2.5 Removal and Load-In of Topside .................................................................................... 21

2.5.1 Lifting the topside ........................................................................................................... 21

2.5.2 Condition of the Brent Alpha Jacket after removal of topside ................................................... 22

2.5.3 Transportation to near shore transfer site .............................................................................. 22

2.5.4 Transfer of topside from SLV to ASP facility ........................................................................... 23

2.5.5 Lifted Weight ................................................................................................................. 24

2.6 Post-Topside Removal Activities ..................................................................................... 25

2.6.1 Information to Third-Party Users of the Area .......................................................................... 25

2.6.2 Monitoring and Maintenance ........................................................................................... 25

2.6.3 Post-topside removal debris clearance and verification ........................................................... 25

3 IMPACT ON ENVIRONMENT 26

4 IMPACT ON HSE 28

4.1 Technical Safety ........................................................................................................ 28

4.2 Occupational Safety .................................................................................................. 28

5 LESSONS LEARNED 29

6 COST 30

7 PHOTOGRAPHS 31


Table 1-1: Overview of Installation(s) to be Decommissioned .................................................................... 9

Table 1-2: Pipeline(s) Being Decommissioned ........................................................................................ 9

Table 1-3: Summary of approved Decommissioning Option ...................................................................... 9

Table 1-4: Associated Decommissioning Approvals ............................................................................... 13

Table 2-1: Decommissioning activities this period ................................................................................. 14

Table 2-2: Brent Alpha Topside, estimated inventory of materials ............................................................. 17

Table 2-3: Durations of the main phases of work .................................................................................. 24

Table 2-4: Sources of additional weight during lift ................................................................................ 24

Figure 1 Location of the Brent Field and the Brent Alpha Platform........................................................... 11

Figure 2 Brent Alpha Jacket with Topside. ........................................................................................ 12

Figure 3 The Three Main Deck Levels of the Brent Alpha Topside. ......................................................... 12

Figure 4 The Survey Area for Birds, in red, in Relation to the Location of the Brent Delta at the ASP Facility. ... 27

Figure 5 The SLV Pioneering Spirit with the Cargo Barge Iron Lady. ....................................................... 31

Figure 6 Rope Access Team Cross-Hauling a Bearing Block into Position on a Leg. .................................. 32

Figure 7 Rope Access Team Lifting a Bearing Block into Position on a Leg............................................... 33

Figure 8 Welding a Bearing Block in Place. ..................................................................................... 34

Figure 9 Bearing Block Fitted to Brent Alpha Leg. ............................................................................... 34

Figure 10 Bearing Blocks in Place above the +6.5m LAT Framing on Brent Alpha, May 2020. ................ 35

Figure 11 DSV Oceanic Working to Prepare Brent Alpha Topside. ...................................................... 35

Figure 12 Gangway from DSV Oceanic to Brent Alpha Topside. ......................................................... 36

Figure 13 Rope Access Team Working above the +6.5m LAT Framing Preparing Legs for Cutting. ............. 36

Figure 14 Rope Access Team Initiating Cut through Brent Alpha Leg, May 2020. ................................... 37

Figure 15 Castellated Cut through Brent Alpha Leg, May 2020. ......................................................... 37

Figure 16 SLV Pioneering Spirit manoeuvring underneath the Brent Alpha Topside, June 2020. .................. 38

Figure 17 SLV Pioneering Spirit manoeuvring into Position under the Brent Alpha Topside, June 2020. ........ 38

Figure 18 Extending the TLS Beams to Connect with the Bearing Blocks. ............................................... 39

Figure 19 “Horseshoe” Fitting on the TLS that locks into Bearing Block on Leg. ........................................ 39

Figure 20 The Horseshoes on the TLS Beams being Connected to the Bearing Blocks, Ready for Lift. ........... 40

Figure 21 ‘Fast lift’ of the Brent Alpha Topside, June 2020. ................................................................ 40

Figure 22 Pioneering Spirit with Alpha Topside Moving Back from the Alpha Jacket. ............................... 41

Figure 23 Pioneering Spirit with Alpha Topside Moving Back from the Alpha Jacket. ............................... 41

Figure 24 Condition Offshore of Brent Alpha Jacket after removal of the Topside. ................................... 42

Figure 25 The Brent Alpha Topside being transferred to the cargo barge Iron Lady. ................................. 42

Figure 26 The Brent Alpha Topside being towed up the River Tees on the barge Iron Lady to Quay 6 at the ASP Facility. 43

Figure 27 The Brent Alpha Topside being towed up the River Tees on the barge Iron Lady to Quay 6 at the ASP Facility. 43

Figure 28 Preparations for Skidding the Brent Alpha Topside Ashore at Quay 6, ASP. ............................. 44

Figure 29 Skid track on Link Bridge between Iron Lady and Quay 6 ASP Facility. ................................... 45

Figure 30 Final Skid Unit on Quay 6, clear of Bridge from Iron Lady. ................................................... 45

Figure 31 The Brent Alpha Topside ashore at Quay 6 ASP facility. ...................................................... 46

Figure 32 The Brent Alpha Topside ashore at Quay 6 ASP facility. ...................................................... 46


Terms and Abbreviations

Abbreviation Explanation Able Able UK Limited ABS Acrylonitrile Butadiene Styrene ACTM Additional Compressions Train Module ALARP As Low As Reasonably Practicable ASP Able Seaton Port BEIS Department for Business, Energy and Industrial Strategy Bq Becquerel, the SI unit measuring the activity of a quantity of radioactive material CoP Cessation of Production CSV Construction Support Vessel DECC Department of Energy and Climate Change DP Decommissioning Programme DSV Diving Support Vessel DyP Dynamic Positioning EIA Environmental Impact Assessment EPDM Ethylene Propylene Diene Monomer (a type of rubber) ES Environmental Statement ESDV Emergency Shut Down Valve ESHIA Environmental, Societal, Health Impact Assessment FishSAFE An electronic means of alerting vessels to the proximity of a structure in the sea FLAGS Far North Liquids and Associated Gas System GRP Glass-Reinforced Plastic HAZID Hazard Identification HSE Health, Safety and Environment HSSE Health, Safety, Security and Environment IA Impact Assessment IMDG International Maritime Dangerous Goods INCA Industry Nature Conservation Association Km Kilometre LAT Lowest Astronomical Tide LSA Low Specific Activity (scale) m Metre MAH Major Accident Hazard MBq MegaBecquerel, One Million (106) Becquerels MCA Maritime and Coastguard Agency nm Nautical Mile OGA Oil and Gas Authority OGUK Oil and Gas UK OPEP Oil Pollution Emergency Plan OPRED Offshore Petroleum Regulator for Environment and Decommissioning OSPAR Oslo Paris Convention OSRL Oil Spill Response Limited P&A Plug and Abandon Pb Lead PCB Polychlorinated Biphenyls PGDS Plate Girder Deck Structure PON Petroleum Operations Notice PS Performance Standard PTFE Polytetrafluorethylene


PVC Polyvinylchloride Ra Radium RSA Radioactive Substances Act 1993. SCE Safety Critical Element SLV Single Lift Vessel SOPEP Shipboard Oil Pollution Emergency Plan SP Social Performance Te Tonne (1,000kg) TLS Topside Lifting System UKHO United Kingdom Hydrographic Office UK HSE UK Health and Safety Executive WLGP Western Leg Gas Pipeline


References AECOM, 2016. Brent Removals and Dismantlement Impact Assessment (ESHIA), BDE-F-TRM-HX-6873-00002.

BEIS, 2018. Guidance Notes: Decommissioning of Offshore Oil and Gas Installations and Pipelines, November 2018.

DNV GL, 2017. Brent Field Decommissioning Environmental Statement, BDE-F-GEN-HE-0702-00006.

Oil and Gas UK Limited, 2012. Guidelines for Suspension and Abandonment of Wells.

OSPAR, 1998. Decision 98/3 on the Disposal of Disused Offshore Installations. Ministerial meeting of the OSPAR commission – SINTRA: 22 – 23 July 1998.

Shell, 2017. Brent Field Decommissioning Programmes, BDE-F-GEN-AA-5880-00015.

Shell, 2018. Brent Field Topsides Decommissioning Programme, BDE-F-TOP-AA-5880-00001.

Shell, 2019. Brent Field Pipelines Decommissioning Programme, BDE-F-PIP-AA-5880-00002.

Shell, 2020. Brent Alpha Jacket Decommissioning Programme, BDE-A-JKT-AA-5880-00001.


1 SUMMARY

1.1 Summary of Decommissioning Programme

1.1.1 Progress Report

In accordance with the Petroleum Act 1998 and the BEIS Guidance Notes: Decommissioning of Offshore Oil and Gas Installations and Pipelines, the owners, as Section 29 Notice holders, sought approval from the Department for Business, Energy and Industrial Strategy (BEIS1) via a Decommissioning Programme (DP) to decommission the Brent Alpha topside by removing it completely and returning it to shore for recycling and disposal. The Brent Field Topsides Decommissioning Programme (covering Brent Alpha, Brent Bravo and Brent Charlie) was approved on 6th August 2018. This document is a progress report covering the offshore programme of work to cut, lift and remove the Brent Alpha topside and deliver it to the dismantling facility at Able Seaton Port (ASP) on Teesside. It is submitted by the co-venturers Shell U.K. Limited and Esso Exploration and Production UK Limited. A final close out report will be submitted within twelve months of the completion of all the onshore operations to dismantle, recycle and dispose of the topside. The report will describe the programmes of work that were performed and explain the reasons for any variations from the planned programme. The Alpha topside is the third topside to be decommissioned and removed from the Brent Field; the Delta and Bravo topsides were lifted in May 2017 and June 2019 respectively. Delta dismantling was completed in February 2019, and Bravo dismantling is currently being finalised.

1.1.2 Brent Alpha Decommissioning

Shell started planning the complex engineering process of decommissioning the Brent Field in 2006, and Alpha formally ceased production on 1st November 2014 after nearly 40 years of production. The Alpha topside was removed on 21st of June 2020 using the single lift vessel (SLV) Pioneering Spirit (Figure 5). It was transported to the ASP facility at Teesside, which is operated by Able UK Limited (Able), where it is currently being dismantled. Tables 1.1, 1.2 and 1.3 provide a summary of the decommissioning activities for the Alpha topside. Figure 2 and Figure 3 show the topside and its major components.

1 In July 2016 the Department of Energy and Climate Change (DECC) was replaced by Department for Business, Energy and Industrial Strategy (BEIS) and further reference to DECC should be taken as BEIS. However, at that time a number of DECC regulatory responsibilities also transferred to the new Oil and Gas Authority (OGA) and where this is the case that will be notified accordingly.


1.1.3 Overview of Decommissioned Installation

Table 1-1: Overview of Installation(s) to be Decommissioned

Surface Installation(s)

Number Type Topside Weight (Te) Jacket Weight (Te)

1 Steel topside on steel jacket 16,922 tonnes when lifted N/A

Subsea Installation(s) Number of Wells

Number Type Platform Subsea

N/A N/A 28 N/A

Drill Cuttings pile(s)

Number of Piles There are no drill cuttings piles associated with this Topside-only programme.

Table 1-2: Pipeline(s) Being Decommissioned

Number of Pipeline(s) to be decommissioned N/A.

Total Km of Pipeline(s) to be decommissioned N/A

Table 1-3: Summary of approved Decommissioning Option

1. Topsides

Complete removal, onshore dismantling, reuse, recycling and disposal of the Alpha topside in compliance with the requirements of OSPAR Decision 98/3 relating to topsides. The Alpha topside was removed in one piece by a SLV, transferred to a barge at a near-shore site and back-loaded to the ASP facility at Teesside. It is planned that more than 97% of the material will be recycled, with some equipment re-used and small amounts of non-recyclable material disposed to landfill. The steel jacket which supported the topside was left with its legs protruding approximately 6.7 m above the sea. The attainment of this condition did not pre-judge the outcome of the proposals for the decommissioning of the Brent Alpha jacket, which were presented in the separate Brent Alpha Jacket Decommissioning Programme. The Brent Alpha Jacket DP was approved in July 2020, and the upper jacket was removed on 9th August 2020. During the short interval between the topside and upper jacket lifts, the jacket was guarded by a Field vessel. Notices to mariners were issued and the United Kingdom Hydrographic Office (UKHO) and Maritime and Coastguard Agency (MCA) were informed. Its changed status was entered into the FishSAFE programme of electronic warning, and for as long as the jacket extended above the sea surface the 500m radius safety zone remained in place.

2. Substructures

N/A

3. Subsea Installation(s)

N/A

4. Pipelines, Flowlines & Umbilicals

N/A


Table 1-3: Summary of approved Decommissioning Option (cont.)

5. Wells

All the Alpha wells have been plugged and abandoned in accordance with the Oil & Gas UK (OGUK) Guidelines for the Suspension and Abandonment of Wells. PON5/PON15 applications under the relevant regulations were submitted and approved.

6. Drill Cuttings

N/A

Figure 1 shows the location of the Brent Field and of Brent Alpha in relation to the other Brent platforms. The removal of the Alpha topside by the SLV and its transportation to shore had no effects on, or any implications for, any other facility either within or beyond the Brent Field.


Figure 1 Location of the Brent Field and the Brent Alpha Platform.


1.2 Schematic of Installation Being Decommissioned Figure 2 Brent Alpha Jacket with Topside.

Figure 3 The Three Main Deck Levels of the Brent Alpha Topside.


1.3 Gantt chart / progress against approved schedule

Note: Conductor preparations (for top and middle sections lifts with topside and upper jacket respectively) were completed as part of topside preparations.

1.4 Associated Decommissioning Approvals

Table 1-4: Associated Decommissioning Approvals

Platform Well Plug & Abandon (P&A)

The campaign to ‘plug and make safe’ the Alpha wells began in September 2016 and was completed in November 2018. The removal of the well inner strings to mud level was completed in March 2019.

Topside removal The Brent Field Topsides Decommissioning Programme was approved by the Offshore Petroleum Regulator for Environment and Decommissioning (OPRED) in August 2018. The Alpha topside was removed on 21st June 2020.

Pipeline Preparatory works Before the Alpha topside was removed, the oil and gas pipelines to and from Brent Alpha were depressurised and purged. The oil lines have been cleaned using mechanical pigging, flushed with seawater to ensure that they do not contain any bulk hydrocarbons, and then filled with inhibited seawater. The gas lines have been flushed to ensure that they do not contain any bulk hydrocarbons, and the majority have been left filled with inhibited seawater. The Brent Bypass Project, designed to allow the continuing export of gas through the Western Leg Gas Pipeline (WLGP) and Far North Liquids and Associated Gas System (FLAGS) export routes without ‘going over’ Brent Alpha, was completed in February 2019. All connections to oil and gas pipelines have now been severed. The proposed decommissioning of the pipelines is covered in the separate Brent Field Pipelines Decommissioning Programme.

Dismantlement Safety Case The Dismantlement Safety Case for the Brent Alpha topside was approved by the UK Health and Safety Executive (UK HSE), in October 2018.


2 DECOMMISSIONING ACTIVITIES THIS PERIOD

Table 2-1: Decommissioning activities this period

Wells P&A Completed November 2018

Brent Bypass Project Completed February 2019

Platform Down-man Completed October 2019

Topside Lift Completed June 2020

2.1 Organisation of the Work

2.1.1 Project Management and Verification

The project was managed in accordance with applicable regulatory requirements and to Shell’s Global Project Management standards. It was led by an experienced Shell Project Director with sub-project managers, project engineers and support functions including Health, Safety and Environment (HSE), Quality, and Project Services. The project was divided into a series of sub-projects and tendered to the open market as appropriate. Synergies were sought with other Shell project activities (and in principle other decommissioning activities) where they made economic and business sense.

2.1.2 Main Contractors and Their Role

The offshore removals contract for the topsides was awarded to Excalibur AS (part of the Allseas Group) in 2013, together with the Brent Delta and Bravo topsides. Allseas were tasked with completing design work and engineering to ensure the topside was suitable for the single lift, as well as providing the interface between the single lift vessel and the disposal yard. In 2016 the Brent Alpha was re-tendered and Allseas retained this work and the execution of the topsides preparations for lift were added to the scope. The total scope of the contract included the following:

• Single lift design engineering and project management.

• Platform preparations for lifting (installation of lift points, module sea-fastening, topsides strengthening and underdeck destruct to separate topside from jacket).

• Leg cutting design and execution.

• Lift of topside using Pioneering Spirit.

• Transport to barge transfer location.

• Load in from barge to onshore disposal yard.

Excalibur AS subcontracted offshore execution of the platform lift preparation scope to the PD&MS Group. Shell concluded that there was an advantage by also adopting PD&MS to execute engineering-down activities and platform modifications for down-man. This allowed a reduction in the number of interfaces between parties. The work for Shell was contracted though its existing Minor-Mods Contract with PD&MS. These scopes included:

• Installation of temporary power generation for down-man.

• Installation of solar powered Nav-Aids package.

• Removal upper conductor sections.

• Removal of umbilicals and BAR Riser from conductor BA-06.

• Installation of dead-man anchors for seawater caissons on jacket.


The contract for onshore dismantling and recycling was awarded to Able UK in 2013. The Onshore Disposal scope comprised the following:

• Provision of a suitable quayside facility and laydown area to receive the topside.

• Provision of facilities, equipment and personnel to safely dismantle the topside.

• Re-use and/or recycling of materials, with a target of at least 97%.

• Disposal of debris in accordance with statutory requirements.

2.2 Description of Brent Alpha Topside

2.2.1 Introduction

Under OSPAR Decision 98/3, topsides are defined as those parts of an entire offshore installation which are not part of the substructure and includes modular support frames and decks where their removal would not endanger the structural stability of the substructure. The topside on Alpha comprised three deck levels - the plate girder deck structure (PGDS), the Module Deck and the Drilling Deck. Together these decks housed the modules, facilities and equipment for oil and gas drilling, production and processing, and for the accommodation, safety and welfare of the platform’s personnel. Figure 3 shows the general arrangement of such facilities on the Alpha (note that the topside was not split into three deck levels for removal). A detailed description and inventory of the Brent Alpha topside is given in the Brent Topsides DP. The Alpha topside was supported by the six full-height legs of the jacket (Figure 2). All the topside modules and equipment were located on the PGDS (Figure 3).

2.2.2 Main Features

The Alpha topside housed the following modules and systems:

Accommodation and helideck. Comprised the accommodation, laundry, catering, and recreation facilities for the crew. Helicopter landing and fuelling facilities were located on the roof of this module.

Drilling derrick and support. Comprised equipment for the drilling and maintenance of oil and gas wells. The drilling derrick was skid-mounted for positioning over the well slots. Once the final conductors had been removed, the derrick was skidded to its final position and sea fastened. The out of use drilling packages are located on the upper deck levels. The pipe deck and laydown areas lie to the south of the derrick on the roofs of the pre-absorber cooler module and mud pump and sack storage modules.

As part of the well abandonment operations on Brent Alpha, it was determined that the efficiency of these operations could be increased by replacing the unreliable East Crane and removing the Additional Compressions Train Module (ACTM). In 2016, the Saipem S7000 was contracted to replace the East Crane and remove the old crane and the ACTM for onshore dismantling, recycling and disposal at the Stena Recycling Yard in Norway. The crane, excluding the superstructure and machinery house, was estimated to weigh 51 tonnes and the ACTM had an installed weight of approximately 444 tonnes. The overall lift weight recorded by the vessel was 495 tonnes.


Truss deck. The truss deck contained the valves and pipework associated with the Northern and Western Leg Gas Gathering Systems (which were taken out of use as part of the Bypass Phase 1), diesel oil transfer and storage, crude oil coolers, methanol injection, pig launcher and oil and gas export pipework. Emergency shutdown valves were fitted to risers and were positioned and protected to minimise the risk of damage arising from fire, explosion and impact. Upon disconnection of the FLAGS pipeline and riser, there were no live risers on the installation and all associated riser ESDVs were redundant. The telecommunications cabin, battery room, drains interceptor tank and safety store areas were also at this level. The equipment/areas of the truss deck that had already been taken out of use because of the BAR project include; crude oil coolers, methanol injection, pig launcher, telecommunications cabin and battery room.

Utilities module. Comprised the Interface Room, the fire pump, basic services diesel generator, essential services gas turbine generator (oil fired), instrument air, potable water systems and oil-fired water heaters. Before the removal of the topside, the gas turbine generator, potable water system and oil-fired water heaters had been taken out of use.

Oil and Gas separation module. At the time of topside removal, the east half of this module contained the redundant production separation train, to which access was controlled. The west half of the module was used for storing scaffolding, and equipment from the engineering and decommissioning departments.

Water injection module. Contained the equipment used to filter and treat raw seawater so that it could be pumped down-hole to enhance production by augmenting the natural pressure of the reservoir. The module contained seawater lift pumps, chemical injection storage and pumps, 6.6kv Switch room, transformers, laboratory, fabrication shop and a temporary rigging store. The water injection pumps, ESP switch room and transformers had been taken out of use before topside removal.

Power generation module. Contained one fire pump, a decommissioning department storage area and redundant power turbine room, all individually segregated. Prior to decommissioning, power to Alpha was supplied from Bravo. Once the power cables had been severed as part of planned decommissioning operations, power was supplied by the drill Caterpillar system which ran on diesel. In the final days before down-man, power was provided by a temporary diesel generator.

Wellhead modules. Contained wellheads, production manifolds, production headers and the wellhead shutdown hydraulic skid. The production manifolds and production headers had been taken out of use before topside removal. Wells had been plugged, lubricated and abandoned before topside removal. Trees had been removed and the well conductors remained in place.

Drainage systems. The drains on the Alpha platform were divided into those serving hazardous areas, non-hazardous areas and living quarters. They were used to manage permitted discharges to sea via the oil/water separators.

2.3 Inventory of Materials During the early stages of decommissioning, Shell prepared an inventory of the materials that it estimated would be present in or on the Alpha topside; the total mass of the topside was estimated to be approximately 15,068 tonnes (Table 2-2). This estimate did not take account of the effects of any structural preparations, such as strengthening or the fitting of load-bearing lifting points, that might be made prior to lifting. At the time of lifting Allseas determined that the Alpha topside weighed 16,922 tonnes. Section 2.5.5 describes the main reasons why the lifted weight of the topside was greater than the estmiated weight presented in the DP. On the basis of the pre-lifting inventory, Shell estimated that together, carbon steel and stainless steel accounted for approximately 84% of the mass of the topside.


Table 2-2: Brent Alpha Topside, estimated inventory of materials

Material Unit Estimated Amount Notes Disposal Method

ABS Tonnes 2 Plastic pipes

Alloy steel Tonnes 216 Pipework, pumps

Aluminium Tonnes 419 Anodes, engines

Aluminium Bronze Tonnes 1 Pumps

Americium 241 MBq 5 Smoke Detectors

Asbestos (total) Tonnes 4 Insulation, gaskets

Batteries Tonnes 28 Various battery sets

Brass Tonnes 1

Bronze Tonnes 1

Buna Tonnes 1

Butyl rubber Tonnes 2 O-ring seals

Carbon steel Tonnes 11,921 Structural steel, equipment

Cement (powder) Tonnes 2 Residual bulk material

Ceramics (all types) Tonnes 5 White ware

Chartex/fire protection Tonnes 27 Penetrations

Copper Tonnes 107 Pipes, cables, transformers

Copper nickel alloys Tonnes 67 Pipe valves, pumps

Cork Tonnes 2 Lifebuoys

Cotton Tonnes 2 Bedding

Diesel m3 <1 Bulk and day tanks

Drill cutting residues Tonnes 12 Behind shale shakers

EPDM Tonnes 23 Cables

Ethylene/Polypropylene Tonnes 72 Cables

Fire foam m³ 10 Firefighting systems

Fluorescent tubes Number 1,396 Lighting

Formica Tonnes 2 Living areas

Glass Tonnes 5 Living areas

GRP Tonnes 7 Replaced floor grids

Graphite / Charcoal Tonnes 0.1 Water Filters

Gun Metal Tonnes 1 Pumps, valves


Material Unit Estimated Amount Notes Disposal Method

Heli-fuel m3 <1 Volume for safe operations

Inconel/nimonics Tonnes 6 Generators

Insulation Tonnes 31 Structures, pipes

Iron (cast) Tonnes 3 Weights

Lead Tonnes 11 Batteries

LSA scale Tonnes 22 Pipework, vessels

Lube Oil m3 <1 Compressors, generators

Melamine Tonnes 1 Laminates

Mercury (lamps only) grams 15 Lamps

Monel Tonnes 0.1 Pumps and valves

Neoprene Tonnes 5 Various

Ni-resist Tonnes 10 Pump valves

Nylon Tonnes 10 Electrical equipment, rope

Paint Tonnes 930 Paint on structured steel

Pb-210 MBq 13 LSA scale

PCBs ppm <5 Residues in transformer form

PTFE Tonnes 0.1

Plastics Tonnes 4 Floor coverings

PVC Tonnes 32 Cable covering

Radium (Ra-226) MBq 376 LSA scale

Radium (Ra-228) MBq 261 LSA scale

Residual hydrocarbons Tonnes 7 Walls of pipes and tanks

Rubber Tonnes 20 Floor coverings

Sewage Tonnes 1 Sewage system bilges

Smoke detectors Number 384 Smoke detectors

Stainless steel Tonnes 459 Pipes and vessels

Tin Tonnes 1 Solder

Titanium Tonnes 28 Pipes and machines

Wood Tonnes 20 Accommodation

Zinc Tonnes 537 Anodes, galvanising

Approx. Total Weight Tonnes 15,068


2.4 Preparation of Topside for Removal

2.4.1 Introduction

The marine warranty surveyor DNV-GL reviewed and accepted all relevant calculations, specifications, procedures and marine spread for the programmes of work for topsides lift, transportation and load-in, such that a Certificate of Approval was provided to assure Shell’s insurers that the marine activities were ready to proceed safely. Bureau Veritas provided an independent verification of platform modifications of Safety Critical Elements (SCE) that affected the Dismantlement Safety Case, and for the removal of the topside this covered a verification of the leg cutting design. The technical requirements for which compliance was demonstrated included:

• Lloyd’s Register Class requirements for Dynamic Positioning Class 3 Standard and appropriate redundancy concept for Dynamic Positioning system.

• Robustness against Single Point Failures of Ballast, Power Management, Dynamic Positioning and Lifting System Failures.

• Application of Two Compartment Damage Stability Standard.

2.4.2 Plug and Make Safe of Wells

Before the topside was removed, all of Alpha’s 28 wells were plugged and made safe. This programme of work was performed in accordance with the OGUK Guidelines for the Suspension and Abandonment of Wells and was completed in November 2018. Following P&A, all the internal 20” and 13-3/8” casings were removed from the well conductors and recycled onshore via an existing pan-Shell UK disposal contract; this inner string removal work was completed in March 2019.

2.4.3 Cutting of the conductors and pipework

The topside was linked to the jacket by the conductors and other pipework. In preparation for the topside lift, the conductors and casings were cut at a height of approximately 6.7m above Lowest Astronomical Tide (LAT) using an internal abrasive water cutting tool deployed from the topside. The upper conductor sections were then lifted up inside the topside and secured there, so that they could be transported with the topside to the onshore recycling facility. The conductors were then cut at 84.5m below LAT using the platform rig, to prepare the middle section of the conductors for removal with the upper jacket. Other connections between the topside and the jacket were cut at various heights to permit the separation of the topside and to facilitate clearance of the legs for the installation of the lifting points. For all the risers, dead-man supports were in place on the jacket, except for the Remote Flare Riser where a new hang-off support was created on the jacket. To permit the removal of the four service/fire-water caissons with the jacket, dead-man supports were installed on the jacket spider deck.


2.4.4 Preparation for Lift

Structural preparations for the removal of the Alpha topside started in April 2018. To lift the topside, the lifting beams of the SLV had to be securely attached to the legs above the cut line, not the underside of the topside itself (as was the case for both the Bravo and Delta topsides). This connection was created by installing six pairs of large steel ‘bearing blocks’ on the six topside legs. One pair of bearing blocks was welded onto each leg at a height of about 13.6m above LAT (Figure 6 to Figure 10). The end of each of the SLV lifting beams was fitted with so-called ‘horseshoe’ clamps, that would engage with the platform and go around each of the legs. The bearing blocks were designed to fit inside these horseshoe clamps and transfer the weight of the topside to the SLV. Additional strengthening on the topside itself was achieved by installing plugs in each of the legs and then filling the legs with a grout mixture. To prevent movement during lifting and transportation, the modules on the topside PGDS were sea-fastened by welding ‘stoppers’ to the modules and PGDS structure. In order to have enough clearance for the lifting beams, and to separate the topside from the jacket structure, all connecting members (e.g. pipelines, stairs to Spider Deck) were removed underdeck. The Dismantlement Safety Case was accepted by the UK HSE in October 2018, well in advance of the 2020 lift. The whole structure was checked for loose or damaged items and components, and these were either repaired or removed.

2.4.5 Cleaning of topside process facilities before removal

Before the topside was de-manned, the topside process systems were drained, purged, and vented (and in most cases also flushed), as appropriate, to ensure no pockets of hydrocarbon liquid or gas were present before the topside was removed. Additional vents were created at selected locations in the topside process system to ensure that they were not recharged from any trapped inventories, and drained systems were left open to the atmosphere to allow free venting to occur so that gases did not build up. It was known that residual material might have accumulated in ‘dead legs’ (such as the bends of pipes) but large quantities were not expected to be present; by virtue of their location such residual materials were not likely to escape during lifting or transportation. Any potential leak sources that were created in the preparation for the removal of the topside were managed through each individual work-pack associated with each project scope. Shell provided Able with an overview of the tanks and vessels that had been cleaned. Most of the lubricating (‘lube’) oil was removed and shipped to shore for disposal before down-man in October 2019. During the topside preparation scopes, all drains within the modules were flushed, isolated and plugged. Drains within modules that would not be affected by the weather were plugged (except for the storm outlets), and drains exposed to the weather were cleaned and left open to sea. Alpha had one drain tank and historically all fluids from this tank would be exported to Bravo. When that outlet was no longer available due to the decommissioning of Bravo, the only input to the tank would be from an accidental overflow of heli-fuel. There was minimal chance of contamination because the majority of oils and chemicals had been removed from the platform, and any oils and chemicals which were needed right up to the time of down-manning had been bunded in one central area of the platform which was not exposed to weather. Any liquids present on the topside were collected in drip trays and bunds. Any chemicals/oils required for maintaining the equipment for a possible re-manning were secured in a bunded container. The remaining chemicals were containerised, and oils were transferred to tote tanks (transportable containers) before being shipped to shore for disposal.


2.4.6 Cutting the legs

In contrast to the concrete legs on Delta and Bravo, the Alpha topside legs to be cut were steel tubular sections. The leg-cutting programme was designed to create a “castellated cut” profile that allowed for the continued transfer of the weight of the topside after cutting, as well as creating sufficient lateral rigidity to prevent the topside from ‘sliding off’ the jacket. In preparation for topside removal, leg cutting started in 2019 with the cutting of the middle two legs (Leg A2 and Leg B2). To provide added integrity against winter storms, and in the remote chance that waves would hit the topside structure, the decision was made to cut the remaining four legs in 2020, just before the topside removal operation. All work in 2019 was performed using Rope-Access from the topside and cutting was undertaken using oxy-propane cutting equipment. In May 2020, the platform was re-boarded from a vessel using a motion-compensated gangway system. Access to the legs was again achieved using Rope-Access, and the remaining four legs were cut using oxy-propane cutting equipment (Figure 11 to Figure 15).

2.4.7 Unmanned Period

On completion of the preparatory phase, the platform was left unmanned for 6 months, from October 2019 to May 2020 when the structure was re-boarded for final leg cutting. Interim navigation aids were fitted to the platform to warn vessels, and an obstruction light was fitted to the top of the flare to warn aircraft. Both these aids were powered by solar-panels and batteries that were fitted on the topside before it was down-manned. The Field stand by vessel made regular observation visits. The state of the topside was monitored until the beginning of the lifting campaign to ensure that it remained in a condition suitable for lifting.

2.5 Removal and Load-In of Topside

2.5.1 Lifting the topside

The Alpha topside was lifted from the jacket as a single piece by the SLV Pioneering Spirit, in an operation that took about 1 day. Topside removal operations took place during a suitable ‘weather window’ which was defined by the maximum limits for sea state and wind speed. Before finally committing to the operation, a detailed weather forecast was obtained by the Metocean engineer based on the vessel to determine if the weather conditions would be within the design limits for the lift and a safe voyage to a predetermined safe-harbour, in the event that the voyage to Teesside could not be undertaken for technical or meteorological reasons. The SLV mobilized from Rotterdam, Netherlands on June 19th 2020 and sailed directly to the Brent Field. After completing pre-operational checks on the dynamic positioning (DyP), ballast and lift systems, the vessel was granted formal approval from Shell and the Marine Warranty Surveyor, and entered the 500m safety zone on June 21st 2020 (Figure 16 and Figure 17). The vessel was accurately positioned so that the jacket fitted into the vessel’s slot; the clearance between the vessel’s hull and the jacket was enough to allow for some movement of the vessel. The beams of the Topside Lifting System (TLS) were fully retracted to provide the maximum clearance between the SLV and the substructure when manoeuvring. Positioning was achieved by using a combination of the Pioneering Spirit’s advanced DyP system, a global reference system and a local reference system fitted on the platform substructure during the preparatory phase.


The SLV was stationed beneath the topside and 12 of the 16 large beams of the TLS (paired into 6 fork-lift units) were positioned opposite the prepared lift points on the topside’s legs (Figure 18). Each fork-lift unit was fitted with a ‘horseshoe’ (Figure 19), that fitted and locked on to one pair of bearing blocks installed on each topsides leg. The bearing blocks were kept positively in touch with the leg by a hydraulic system that compensated for the movement of the vessel. When all of the beams were in place and the horseshoes securely engaged (Figure 20), the SLV was progressively deballasted so that it took nearly all of the topside weight. The final ‘fast lift’ to take the topside clear of the top of the jacket was accomplished in less than one minute by a combination of a hydraulically-actuated upward thrust of the yokes and some fast deballasting of the SLV (Figure 21). Once clear of the legs, further deballasting took place in order to create clearance between the underside of the lifting arms and the top of the jacket to allow the SLV to move away safely. Once the SLV was clear of the jacket, the hull connection beam was closed, the X, Y and Z drives of the lifting arms were placed into sea-fastening mode ready for the voyage and the vessel was ballasted to its transit draft (Figure 22 and Figure 23).

2.5.2 Condition of the Brent Alpha Jacket after removal of topside

The jacket was left with its six legs protruding approximately 6.7m above the sea (Figure 24). The attainment of this condition did not pre-judge the outcome of the proposals for the decommissioning of the Brent Alpha Jacket, as described in the Brent Alpha Jacket DP. During the short interval between the removal of the topside and the removal of the upper jacket, the Alpha jacket was guarded by a Field vessel to warn mariners of this hazard. Notices to Mariners were issued and the UKHO and Maritime and Coastguard Agency (MCA) informed of the changed status of the platform. The new status of the Alpha structure was entered into the FishSAFE programme of electronic warning. The proposed decommissioning of the Brent Alpha jacket itself is presented in the Brent Alpha Jacket DP.

2.5.3 Transportation to near shore transfer site

The topside was carried on the SLV to the transfer location off the coast of NE England, some 388 nautical miles from the Brent Field. The SLV proceeded under her own power and this voyage took about 37 hours (Table 2-3). The vessel’s maximum speed in different sea conditions was determined by operational procedures, based on acceptable accelerations and subsequent loads in the structure. The topside was considered ‘cargo’ in this phase of the project and because it contained some hazardous materials that were subject to special permitting requirements, these materials were itemised in the vessel’s cargo manifest and all necessary permits and consents were obtained for the carriage and movement of these materials. The removal and transportation of LSA scale, for example, was in accordance with the Radioactive Substances Act (RSA) 1993. All radioactive sources, for example in instruments and gauges, were transported in accordance with the International Maritime Dangerous Goods (IMDG) Code 2011 which is mandatory under the International Convention for the Prevention of Pollution from Ships (MARPOL 73/78). Shell had worked closely with the appropriate Regulators and, through Allseas, with the local Marine/Harbour authorities, to ensure that all the contingency plans were in place before the planned lift date. Emergency response plans were in place for the removal and transportation activities including a Brent Field System Oil Pollution Emergency Plan (OPEP) incorporating a contract for specialist response services through Oil Spill Response Limited (OSRL). Once the topside had been secured on the SLV, the emergency response reverted to the vessel’s Shipboard Oil Pollution Emergency Plan (SOPEP). A bridging document was in place between Shell and Allseas to confirm all of the responsibilities and response arrangements. Well before the lift Shell, Allseas, Able, the Marine Warranty Surveyor and Harbour Master performed a detailed Marine Hazard Identification (HAZID) exercise for the transfer, tow-in and load-in of the Alpha topside. This was


informed by the knowledge that was gained from the previous transfers and load-ins of the Bravo and Delta topsides, and other similar operations that have been performed in and around Teesside over the last few years. Shell also undertook a gap analysis of the Environmental Societal and Health Impact Assessment (ESHIA) that had been prepared for the removal and dismantling of the Brent Delta topside at the ASP facility, bearing in mind the inventory of materials that would be present on the Alpha topside when it was ready to be removed. The Alpha Dismantlement Safety Case, detailing the management of the remaining offshore Major Accident Hazards (MAH), was issued and approved, along with the associated OPRED environmental permits.

2.5.4 Transfer of topside from SLV to ASP facility

There is insufficient water depth at the ASP facility for the Pioneering Spirit to moor alongside Quay 6. The Alpha topside was therefore transferred to the quay using the Allseas’ cargo barge, the Iron Lady, which is approximately 200m long and 50m wide. The Iron Lady was mobilised from Rotterdam port and was towed directly to the transfer site by tugs. Prior to sailing, the barge was fitted with load-spreading beams, sections of skid beams on top of the load-spreading beams, pre-installed skidding equipment (Push/Pull units and P1000n pads) and six specially designed and positioned Topside Support Skids that would receive and support the cut ends of the legs protruding from the topside, and transfer the load of the topside into the barge structure. The topside was transferred to the cargo barge Iron Lady at a designated nearshore transfer site which is a circular area of 2.78km diameter centred on 54o44.0’ N, 01o06.0’ W. The centre of this area is approximately 5.5 nm from the mouth of the River Tees and approximately 3 nm from the nearest coastline (The Headland at Hartlepool), and has a water depth of approximately 35m. Transfer operations were conducted during very specific weather and metocean conditions. At the transfer site, the hull connection beam was opened and the mechanical lock (sea fastening) of the TLS beams was undone. The barge was then manoeuvred into the slot using tugs and pre-rigged mooring wires from the SLV. The transfer was performed by (i) ballasting the SLV and deballasting of the cargo barge, and (ii) lowering of the topsides using the TLS system to perform the final set-down on the supports. The TLS system was used so that the topsides legs would only engage once with the Topsides Support Skids (i.e. to avoid bouncing on the structure) and the ensure a smooth transfer of weight to the barge (Figure 25). The ballasting and deballasting of the Pioneering Spirit and the barge were carefully controlled and coordinated to ensure that both vessels stayed horizontal and level. Load monitors on the TLS beams confirmed that the load had been successfully transferred. The TLS forklift units were then fully retracted to create maximum clearance for the barge to be towed out of the slot. Upon completion of this operation, the Pioneering Spirit demobilized back to Kristiansand in preparation for its next project. The barge was towed by four tugs to Quay 6 of the ASP facility (Figure 26 and Figure 27). The timing of this operation was determined by the tide because the barge required a high tide to enter the Seaton Channel and move into the dock at Quay 6. The barge was first towed to the ‘Turning Circle’ in the River Tees, where it was more sheltered from the sea whilst waiting for optimum tide conditions for the final part of the tow through the Seaton Channel to the ASP facility. At the ASP facility it was moored with its stern to the quayside and then carefully ballasted until it rested on the pre-installed grounding pad. Ballasting control was also used to ensure that the barge remained on the grounding bed during tidal changes and load transfer from the barge to the quay.


At the ASP facility, the load-in contractor Fagioli SPA fitted skid beams from the quay, across the quay wall and onto the barge. To ensure that the tracks were level, the skid beams were shimmed with timber blocks, and steel plates were installed underneath them (Figure 28 to Figure 30). These metal skid beam tracks were fitted with P1000n blocks, and the bases of the skid shoes were stainless steel. With the addition of a lubricant this combination of P1000n and stainless steel has a very low friction, allowing heavy loads to be moved with limited force. The skidding operation therefore comprised many hundreds of small movements in which the Push-Pull Units skidded the topside laterally. The push-pull hydraulic cylinder expanded by about 1m and pushed the load along the track by gripping the central guidance bar on the skid tracks. After each stroke the cylinder was retracted, locked onto the next section of skid track and the skidding process repeated. The various cylinders were grouped hydraulically to synchronise all their movements during the skidding operations, and each stroke was verified by software to control the operation. In this way, the 16,922 tonnes mass of the topside and support stools was skidded approximately 160m from the barge to its planned dismantling location on Quay 6. The skidding operation took about 48 hours and was completed on 2nd July 2020 (Figure 31 and Figure 32). Table 2-3 presents a record of the durations of each of the main phases of the topside removal programme, from the SLV entering the Field to the skidding of the topside onto Quay 6 at the ASP facility.

Table 2-3: Durations of the main phases of work

Aspect Data Measured weight of Brent Alpha topside 16,922 tonnes Time taken to position all lifting beams, after entering 500m zone 4 hours 30 mins Duration of fast lift and quick deballasting 40 seconds Total time in 500m zone 11 hours 32 mins Total time in the Brent Field 20 hours 13 mins Time taken to travel to nearshore transfer site 37 hours 38 mins Time taken to transfer topside to cargo barge 11 hours 10 mins Time taken to transport upriver on cargo barge 8 hours 40 mins Time taken to skid topside from cargo barge to Quay 6 at ASP facility 48 hours

2.5.5 Lifted Weight

The lifted weight of the Alpha topside was found to be 1,854 tonnes greater than the estimated weight presented in the DP, because the estimated topside weight was strictly for the topside itself, i.e. everything on and above the PGDS, and did not include a number of items. Some of the items not included are listed in Table 2-4, and their total mass accounts for about 94% of the additional topside mass.

Table 2-4: Sources of additional weight during lift Item Additional Weight (tonnes) Platform preparations 486 Conductors and Casings from PGDS to Cut Line 170 Caisson and risers 30 Jacket legs from PGDS to Cut Line 318 Operational Items 737 Total Identified Additional Weight 1,741

‘Platform preparations’ weight includes grout filling in legs, the new bearing blocks attached to the legs, steel reinforcement, and sea-fastening.

‘Operational weight’ incudes small items and scaffolding left in place on the topside.


2.6 Post-Topside Removal Activities

2.6.1 Information to Third-Party Users of the Area

After the removal of the topside; the Alpha jacket was entered into the FishSAFE programme of electronic warning, the UKHO and MCA were notified, and a Notice to Mariners was issued so that other users of the sea could amend their charts.

2.6.2 Monitoring and Maintenance

Following the removal of the Alpha topside, and while waiting for OPRED’s decision on the Brent Alpha Jacket DP, Shell initiated an agreed interim programme for monitoring the Alpha jacket. The variation of the Consent to Locate permit was approved by OPRED. Weekly checks were carried out by the standby vessel as agreed with OPRED.

2.6.3 Post-topside removal debris clearance and verification

The programme to remove the Alpha topside by SLV did not result in the deposition of any debris on the seabed at the Alpha platform, along the route to the transfer site, at the nearshore transfer site or on the short tow in the River Tees to Quay 6 at the ASP facility. The existing debris on the seabed within 500m of the Alpha jacket will be removed in one or more ‘campaigns’ which will be performed across the whole Brent Field once all the platforms and pipelines have been decommissioned.


3 IMPACT ON ENVIRONMENT

In accordance with the BEIS Guidance Notes for Decommissioning of Offshore Oil and Gas Installations under the Petroleum Act 1998 (as amended by the Energy Act 2008), an Environmental Impact Assessment (EIA) was carried out to support the Shell’s Brent Field Decommissioning Programmes. The findings of the EIA were reported in the Brent Field Decommissioning Environmental Statement (ES) which presents:

• A description of the Brent Field facilities, and the current environmental condition of the Brent Field, offshore transport route and onshore dismantling location.

• The results of the EIA process to identify and assess both the potential short and long-term impacts of the technically feasible decommissioning options for the Brent Field facilities after industry standard mitigation has been applied.

• The potential environmental impacts of the decommissioning programme of work proposed by Shell.

In 2016 a separate Impact Assessment (IA) – the Brent Removals and Dismantlement Impact Assessment (ESHIA) - was carried out by AECOM, which covered the following activities: the near-shore transfer of the Brent Delta topside from the SLV Pioneering Spirit to the barge Iron Lady, subsequent towing to shore at Seaton Port, Teesside, the load-in to Quay 6 of the ASP facility, and final subsequent dismantling and disposal operations to be undertaken at the ASP facility. The results of the IA for Delta are directly applicable to the similar operations that have and will be carried out on the Alpha topside. With a total weight of 16,922 tonnes, the Alpha topside is some 28% lighter than the Delta topside (23,500 tonnes) was when it was delivered to the ASP site. The IA was not undertaken to discharge any statutory requirement, in relation to any legislative or regulatory purpose, or to support the gaining of any permission or consent. Rather it was completed to satisfy Shell UK Ltd.’s mandatory requirements under their Health, Safety, Security and Environment (HSSE) and Social Performance (SP) Control Framework. The IA highlighted any areas of potential concern, and a s p e c t s where further design was required in order to provide confidence that significant effects would not result. Overall, twenty-nine actions were created as a result of the IA, and they were all closed-out before the dismantling of the Delta topside began. The potential impacts on wintering water birds from the dismantling of marine structures, and associated works such as dredging and piling at Able Seaton Port, were fully addressed in planning application H/2007/0543, and no adverse effects were identified. Nevertheless, in 2017 Shell commissioned a separate study by INCA2 to investigate whether the dismantling of the Brent Delta at ASP caused any disturbance to wintering water birds and seals using Seal Sands. Figure 4 shows the area that was surveyed for birds. The survey for seals covered the whole of Seal Sands.

2 INCA, the Industry Nature Conservation Association, have a small specialist team with extensive knowledge of the natural environment of the Tees Valley. The team is drawn from backgrounds in industry, nature conservation and regulation, giving a unique blend of skills and knowledge.


Figure 4 The Survey Area for Birds, in red, in Relation to the Location of the Brent Delta at the ASP Facility.

From September 2017 to July 2018 a total of 19 hours was spent monitoring potential disturbance to wintering water birds and 106 hours monitoring potential disturbance to seals. In neither case was any direct incidence of disturbance recorded from activities related to Brent Delta observed. The Alpha topside is being dismantled at exactly the same location as were Delta and Bravo, using similar mechanical equipment and procedures. Consequently, as was found for Delta, it is expected that there will be minimal disturbance to wintering birds and seals. In preparation for the transfer, load-in and subsequent dismantling of the Alpha topside, a gap analysis against the IA was carried out to identify any changes and assess the impact of those changes. No significant impacts were identified and in fact improvements had been made from the Delta activities including clearer identification of contamination on the topsides. There were no environmental non-compliances reported during the lift, transfer and load in of the Alpha topside.


4 IMPACT ON HSE

4.1 Technical Safety In terms of MAHs, associated SCEs, and performance standards (PS), the transition from an offshore installation in production mode through Cessation of Production (CoP), dismantlement and eventually post-dismantlement required revisions of the platform Safety Case (and subsequent Dismantlement Safety Case) to ensure that the document reflected changing installation status. Most of the revisions did not require submission to the UK HSE because they did not constitute a ‘Material Change’, as defined in the Offshore Safety Case Regulations. In terms of MAHs, the significant change during the transition from production to dismantlement was the elimination of the gross hydrocarbon inventory, which represents about 50% of the MAH profile on a production installation.

4.2 Occupational Safety The introduction by Shell of the ‘Safety’ project, which focused on a drive towards a fully integrated team approach (onshore/offshore), as well as the introduction of behavioural safety programmes, helped improve safety performance. Shell’s ‘Safety Project’ took inputs from various sources through surveys as they embarked on their safety journey. It included the notion that the right environment to decommission had to be created and that this investment in turn would encourage a positive response from the workforce. By creating the right environment and driving compliance, maintenance programmes and platform integrity, improvements were seen in safety performance and downtime was improved. This early investment put in place good foundations which were built upon and gave a strong enough base to meet the challenges which come from the human, engineering, and dynamic aspects of decommissioning, as well as those from the more obvious surroundings themselves. Shell achieved a positive change in safety culture by taking ownership offshore and driving an improved safety performance. During the project, the decision to move from reverse engineering to single lift also provided an important risk benefit. Reverse engineering requires significant offshore man-hours to deconstruct the facility in order to separate the modules for a heavy lift campaign to systematically and sequentially remove and transfer them onshore. It also involves additional flying and marine risks to support the activity, and thereby exposes personnel to offshore occupational and logistical hazards. Conversely, the single lift methodology largely eliminates the need for module segregation, greatly reduces the overall lifting offshore and considerably simplifies the offshore work scope, which in turn reduces the risk factors described above. In this context the single lift approach was considered to provide an overall risk that was as low as is reasonably practicable (ALARP). The lifting, transportation and offloading of the Alpha topside in 2020 were all achieved with no harm to people or the environment.


5 LESSONS LEARNED The removal of the Alpha topside by the Pioneering Spirit in June 2020 provided a number of important and useful lessons for Shell, Allseas and Able UK, and these are summarised below: Preparation prior to mobilisation

• Trust gained through established relationships. Benefit from having the same key personnel on the project (incorporating lessons learned from Bravo and Delta topside preparations).

• Take time to create a collaborative environment with all parties from the start of the project and maintain this with defined actions and targets.

• Re-boarding the topsides from a CSV for leg cutting worked well but gangway selection and preparation are critical.

• COVID-19 did affect the planning and preparations for all 2020 activities, but work was executed as planned.

Transfer and Tow-in

• Topsides removal using Single Lift has become an efficient offshore operation, building on the experience from an increasing number of projects.

• The project benefited from earlier engagement with Pilots and Port Authorities for the tow-in.

Load-in Activities

• Planning for barge settlement on the sediments of the grounding bed worked well.

• De-mobilisation activities at the yard are important and need planning prior to the work.


6 COST

The actual cost of the work, up to the load-in of the Alpha topside, has been provided separately to OPRED.


7 PHOTOGRAPHS

Figure 5 The SLV Pioneering Spirit with the Cargo Barge Iron Lady.


Figure 6 Rope Access Team Cross-Hauling a Bearing Block into Position on a Leg.


Figure 7 Rope Access Team Lifting a Bearing Block into Position on a Leg.


Figure 8 Welding a Bearing Block in Place.

Figure 9 Bearing Block Fitted to Brent Alpha Leg.


Figure 10 Bearing Blocks in Place above the +6.5m LAT Framing on Brent Alpha, May 2020.

Figure 11 DSV Oceanic Working to Prepare Brent Alpha Topside.


Figure 12 Gangway from DSV Oceanic to Brent Alpha Topside.

Figure 13 Rope Access Team Working above the +6.5m LAT Framing Preparing Legs for Cutting.


Figure 14 Rope Access Team Initiating Cut through Brent Alpha Leg, May 2020.

Figure 15 Castellated Cut through Brent Alpha Leg, May 2020.


Figure 16 SLV Pioneering Spirit manoeuvring underneath the Brent Alpha Topside, June 2020.

Figure 17 SLV Pioneering Spirit manoeuvring into Position under the Brent Alpha Topside, June 2020.


Figure 18 Extending the TLS Beams to Connect with the Bearing Blocks.

Figure 19 “Horseshoe” Fitting on the TLS that locks into Bearing Block on Leg.


Figure 20 The Horseshoes on the TLS Beams being Connected to the Bearing Blocks, Ready for Lift.

Figure 21 ‘Fast lift’ of the Brent Alpha Topside, June 2020.


Figure 22 Pioneering Spirit with Alpha Topside Moving Back from the Alpha Jacket.

Figure 23 Pioneering Spirit with Alpha Topside Moving Back from the Alpha Jacket.


Figure 24 Condition Offshore of Brent Alpha Jacket after removal of the Topside.

Note. The two extension casings were installed to help guide the lowering of temporary working decks for the jacket lift campaign. Figure 25 The Brent Alpha Topside being transferred to the cargo barge Iron Lady.


Figure 26 The Brent Alpha Topside being towed up the River Tees on the barge Iron Lady to Quay 6 at the ASP Facility.

Figure 27 The Brent Alpha Topside being towed up the River Tees on the barge Iron Lady to Quay 6 at the ASP Facility.


Figure 28 Preparations for Skidding the Brent Alpha Topside Ashore at Quay 6, ASP.


Figure 29 Skid track on Link Bridge between Iron Lady and Quay 6 ASP Facility.

Figure 30 Final Skid Unit on Quay 6, clear of Bridge from Iron Lady.


Figure 31 The Brent Alpha Topside ashore at Quay 6 ASP facility.

Figure 32 The Brent Alpha Topside ashore at Quay 6 ASP facility.

Documents

Decommissioning Progress Report Brent Alpha Topside...The Alpha topside is the third topside to be decommissioned and removed from the Brent Field; the Delta and Bravo topsides were