BRENT FIELD DECOMMISSIONING PROGRAMME
The Brent oil and gas field, a 50:50 joint venture between Shell (operator) and Esso Exploration and Production UK (Esso) lies 186kms north-east of the Shetland Islands in the North Sea.
Why is Shell decommissioning the Brent Field?
At the time of its discovery the expected lifespan of the Brent Field was 25 years. Through continuous improvement and significant investment in the 1990s, we have extended the life of the Field well beyond original expectations. After over 40 years of service to the UK, the Brent Field is now reaching the stage where almost all the economically recoverable reserves of oil and gas have been extracted, and in line with UK legislation, the Brent Field will now be decommissioned.
The decision to decommission Brent is a natural step in the life cycle of the field.
Brent Delta stopped production in 2011 and Brent Alpha and Bravo ceased in November 2014. Production from the field currently continues through Brent Charlie.
What is the Brent Field Decommissioning Programmes document?
Decommissioning in the UK Continental Shelf follows a mature and tightly defined regulatory process that is stipulated in the UK’s Petroleum Act 1998.
As the operator of the Brent Field, Shell must submit Decommissioning Programmes to The Department for Business, Energy and Industrial Strategy (BEIS), for review, followed by public consultation, as part of the extensive approval process.
In accordance with legislation, we have submitted two Decommissioning Programmes (DP) in a single document. One DP covers the Brent installations and wells, and the other covers the Brent Field Pipelines. Our DP documents includes the recommendations for closing down and making safe the four platforms, the wells and the subsea infrastructure.
The Decommissioning Programmes were subject to public consultation between 8 February and 10 April 2017, and a simultaneous consultation with other government departments, and statutory consultees was carried out.
The DP documents are supported by a suite of detailed Technical Documents (TDs) for each aspect of the programme; an Environmental Statement (ES); a Comparative Assessment (CA) process; and a Stakeholder Engagement Report.
What is in the Brent Field Decommissioning Programmes document?
Shell has been preparing for, and executing, the following decommissioning activities:
- Plugging and making safe the 146 wells across the Brent Field;
- Removing to shore, and recycling the platform’s topsides;
- Cutting the upper portion of the Brent Alpha steel jacket, and removing to shore for recycling.
- Removing the oil –known as ‘attic oil’ – trapped at the top of some of the subsea storage cells; and
- Recovering oil and gas debris from the seabed across the Brent Field;
- After completing the comparative assessment process of feasible decommissioning options, and as a result of careful and considered evaluation, the recommendations being proposed include leaving in place the Gravity Base Structures (GBS), Brent Alpha jacket footings, the drill cuttings and GBS cell contents.
A range of options have been considered for the 30 pipelines, including: leaving in place pipelines already in stable trenches or under stable rock; complete removal (reverse reel or cutting and lifting); leaving in place with a new covering of rock; and leaving in place after trenching and burying.
Where the Decommissioning Programmes recommend leaving major installations in place in the North Sea, under the OSPAR Decision 98/3, the UK Government must consult with other countries that are signatories to the OSPAR Convention. The OSPAR convention is an agreement between 15 European countries and the EU to protect the marine environment in the North-East Atlantic.
OSPAR recognises that there are difficulties associated with removing major installations, such as concrete Gravity Base Structures and large steel jackets. In these instances, operators may make a case for exemption – or derogation – from the general rule of complete removal from the sea, but they must demonstrate that there are significant reasons why an alternative option is preferable to reuse, recycling or final disposal on land.
Shell and Esso are confident the proposals set out in the DP document are safe, technically achievable, financially and socially responsible, and environmentally sound. These recommendations are the result of 10 years of review and planning, including extensive research involving engineering studies, independent experts’ input, consultations and scientific assessments.
Under current legislation, Shell and Esso will retain ownership of and responsibility for any remaining facilities after decommissioning.