Brent Facilities Decommissioning · • The Brent field is currently producing some 26000 bpd oil, 183000 bpd of produced water and 260 MMSCFD gas. • The platforms are occupied

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Shell Exploration and Production Europe

Brent Facilities Decommissioning

Project Overview

(Shell is operator of the Brent Field for and on behalf of Shell U.K. Limited and Esso Exploration and Production UK Limited .)

16 &18 January 2007 Stakeholder Engagements, Aberdeen & London 2

Context

• The project is at a very early stage.

• Feasibility studies are still being put together.

• The scope is still being defined.

• The strategy is still to be finalised.

• We are seeking input and listening.

• This is an opportunity to influence direction.


Where is the Brent Field ?


Overview of Brent Field…

~160 wells4 topsides1 steel jacket3 GBS~36 pipelines2 subsea locations


Brent Field History…

• License partners – Shell 50% , Esso 50% (1965 Agreement)

• Discovered 1971, 1.96 billion bbls oil and 5.69 trillion cu.ft gas produced (to 1.1.06)

• First production from Brent Bravo in 1976

• Continuous innovation in reservoir management

– Oil recovery with pressure maintenance

– Gas export

– LTFD project (£1.3 bln, 3 platforms) – reservoir depressurisation

– Penguins field development – longest subsea tie-back @ 65kms

– Enhanced Voidage project – increased depressurisation by water production

– Low Pressure Operation project – LP compression


Brent Alpha – a steel jacket substructure platform… On 5th May 1976 the 13,000 ton Brent `A' jacket was

towed from the construction yard of RedpathDorman Long (North Sea)Ltd., Methil, Fife, Scotland.

Supported on two barges in a catamaran arrangement, the 500 foot high jacket was towed about three miles offshore. Here it was released from the barges and taken in tow under it`s own buoyancy for the journey to Shell/Esso`s Brent oilfield 112 miles northeast of Sheland.

The first three half modules were installed in the deck of Brent `A' during February 1977.

Topsides installed weight is about 16,000te

The platform currently exports all its well production over to the Brent B platform for processing.

The Western Leg and Northern Leg gas pipelines come up onto the platform topsides where they are co-mingledbefore going back down to the seabed where they join the FLAGS pipeline to St Fergus.


Brent C – a concrete GBS platform...

The Shell/Esso Brent `C' gravity base storage platform has a total concrete weight of 282,000 tons and was constructed at the Sir Robert McAlpine & Sons yard, west coast of Scotland site at ArdynePoint. The base caisson contains 36 storage cells capable of holding 660,000 barrels of oil.

On 4th February 1978 the 6,400 ton deck substructure for the production platform left the Penn and Bauduin yard at Dordrecht for Stavanger in Norway. There it was mated with the submerged Brent `C' substructure.

Some 20 lifts were scheduled to place modules and facilities in position before the platform was due for tow-out to the North Sea at the beginning of June 1978.

Topsides installed weight is about 30,000te.


Brent B & D – concrete GBS platforms...

Brent ‘B’ and ‘D’ platforms are of the sameCondeep design.

The deck substructures were mated with the concrete substructures in Norway before being towed to the field for final installation.

The 348,000 ton concrete and steel ‘B’platform, was towed by five tugs with a combined horsepower of 70,000. Even with a towing draught of 260 feet the structure towers 420 feet above the water, the height of a 30 storey building.

Additional modules were added to the ‘B’production platform by the derrick barge Hercules - June 1976.

Topsides weights are about 24,000 te.


End of Field Life...

Status

• The Brent field is currently producing some 26000 bpd oil, 183000 bpd of produced water and 260 MMSCFD gas.

• The platforms are occupied by approx 500 people working in shifts at any one time.

• New developments continue to be pursued ie

– Installation of gaslift facilities and 65km pipeline to Penguins subsea field,

– And drilling of the Barnacle well from Brent ‘D’ platform.

Planning

• A team of SUBSURFACE specialists are developing the final field development plan which will be agreed with DTI and will identify Cessation of Production dates for each platform.

• After CoP is agreed with the DTI, a Decommissioning Programme will be submitted covering all Brent facilities i.e all platforms and subsea facilities.

• Well abandonment will start end 2007, ahead of CoP, as there are a large number of non-producing wells already and activity is covered by different regulations (not OSPAR).

• Decommissioning will occur over many years.


Early Stages of Decommissioning Studies


Decommissioning Studies

• What are the issues ?

• What is feasible, what is not feasible ?

• Are risks manageable ?

• How do we minimise impact on the environment ?

• Have we identified all the options ? ?

• How should we compare options ?


Some Topsides Removal Options

Heavy liftPiece small

Reverse float over Single lift


Some Jacket Removal Options

Reverse installation

buoyancySingle lift

Heavy lift


Gravity Base Storage

• GBS refloat risks and feasibility issues

– Reaction of GBS to breaking loose from seabed.

– Structural integrity of GBS under refloat conditions

– Weather during transit

– Landing and Dismantling the GBS

• GBS cell contents

– Determine the contents and inventory

– Access via shaft pipework (10”)

– Sampling

– Remediation methodology – to what degree is sufficient


Drill Cuttings

• Drill cuttings survey 1997 & 2005

• New survey planned end 2006….(now 2007)

• Focus on chemical analysis, volumetrics, coverage under jacket and on cells


Brent Pipelines

• There are a large number of pipelines connecting the Brent platforms to each other;

– Gas

– Oil

– Water

– Mixed oil,gas and water

• There are also pipelines connecting Brent platforms to gas and oil gathering systems some of which need to retain their functionality;

– Gas export to St Fergus

– Oil export (via Cormorant Alpha) to Sullom Voe terminal

• Also...

– operational pipelines to Penguins subsea field

– Redundant pipelines to Brent South subsea field, the Brent Spar and Flare.


Brent Pipelines

Background

• Technical challenge of removal

• Condition of concrete coatings

• Impact on environment and other sea users

Options

• Complete removal

• Lines trenched and buried

• Lines on the seabed.

• Reconfiguration of pipelines for oil and gas transport by others


Waste Disposal

Background

• Understand and quantify the waste inventory

• Options available under current (and future) legislation

• Impact on the environment

Challenges

• Capacity and availability of existing waste disposal routes

• Transfrontier shipment of waste - in an EU perspective ?

• OSPAR 2008 and subsequent reviews

Brent Decommissioning will be a long term project….

• …how best to develop agreed plans and commitments in a developing regulatory environment ?


In summary….

• Early days ….still a long road ahead.

• Actively working to promote openness and transparency in our processes.

• We are keen to look for opportunities to extend the technical envelope and apply innovative solutions.

• The scale of Brent Decommissioning may create resource and regulatory challenges. We will work with industry, regulators and stakeholders to address these.

• The project has full management involvement, within Shell and Esso, as befits a billion pound project.


Shell Exploration & Production

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Brent Facilities DecommissioningRegulatory Framework & Option Selection Process

January 2007


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Regulatory Framework

Decommissioning Regulation

• International

– IMO Guidelines.

• Regional

– OSPAR 98/3.

• UK

– Petroleum Act 1998 enabling Act requires submission of detailed Programme for approval.

– DTI Guidelines (2006)provides framework.


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Installations

• OSPAR 98/3 Presumption of Total Removal

• Waste Hierarchy Re-Use/ Recycle/ Dispose

• Right to derogate for certain categories by comparative assessment:

– GBS

– Steel Jacket > 10,000 tonne Footings

– Damage


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Regulatory Framework - Experience

Installation Status

• Small/Med Experience: Leman – Odin – Froy

• Some larger ‘Unique’: Spar – Maureen – Hutton tlp

• Ekofisk: First Concrete Tank Derogation accepted Execution Ongoing –15 platforms to be removed (<10,000tn)

• Frigg: Concrete GBS derogation accepted - 4 concrete platforms. 3 steel jackets to be removed (<10,000tn)

• BP NW Hutton: First steel derogation (>10,000tn)– approval to leave lower section


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- NW Hutton Steel Jacket DerogationUK Sector

- Frigg Area 4 Concrete DerogationNorwegian/UK Sector(3 Steel Installations Removed)

- Ekofisk Concrete Tank DerogationNorwegian Sector(15 Steel Installations Fully Removed)


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Historic Cuttings Piles

• OSPAR Recommendation 2006

• UK/Norway issue

• Proactive UKOOA R&D programme in conjunction OLF

• Options

– natural attenuation/ cover/ re-inject?/ return to shore & landfill

• Key is good characterisation – need to survey and understand behaviour

– hydrocarbon leaching and persistence key parameters


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Pipelines

• DTI Guidance/ Approval

• Case by Case

• Comparative Assessment – balance env/safety/cost/feasibility

• Criteria – cleanliness/ stability/ burial/ other users


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Pipeline Status

• Varied but limited outcomes

– Some left;

– Some lifted where reel-able or short lengths

– Trenched or buried more obvious leave candidates

• Consider as Future Assets?


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Wells

• Not part of Decommissioning Programmes

• Approved separately

• National Guidance by UKOOA accepted by regulators as best practice


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Comparative Assessment – A Balanced Judgement

TECHNICAL

Feasibility

Complexity

SOCIAL

Sea Users

Community

ECONOMIC

Cost/Benefit

Uncertainty

SAFETY

Risk Assessment

Implementation

ENVIRONMENTAL

Air

Sea

Land

Reputation

TECHNICAL

Feasibility

Complexity

SOCIAL

Sea Users

Community

ECONOMIC

Cost/Benefit

Uncertainty

SAFETY

Risk Assessment

Implementation

ENVIRONMENTAL

Air

Sea

Land

Reputation

Regulatory Framework – Option Selection


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Option Selection Process

Technical Development and Stakeholder Engagement in Parallel

I R G I R G

DTI Approval

Current Status Recommend Option Plan Approved

Ongoing Stakeholder Engagement

Challenge & Assurance on Robustness of Technical Basis

Regular Engagement opportunity to listen/share.Identify Issues

Inform decisions

OPEN

TRANSPARENT

INCLUSIVE

INTEGRATED


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Independent Review Group

IRG…an Independent group of experts

• Role appreciated by stakeholders on previous projects

• Independent review of technical scope and conclusions, to provide assurance to technical basis of decisions

• Individuals invited to participate by Prof John Shepherd (Chair)–

– Independent experts – international reputations in key fields of scientific and technical activity

• Retain “freedom to publish” findings

Documents

Brent Facilities Decommissioning · • The Brent field is currently producing some 26000 bpd oil, 183000 bpd of produced water and 260 MMSCFD gas. • The platforms are occupied