Top 5 questions about Brent

The Brent field is situated in the North Sea 116 miles offshore, north-east of Lerwick, Scotland. It consists of four large platforms; Alpha, Bravo, Charlie and Delta. After 40 years of producing oil and gas, the field is now being taken out of service, or ‘decommissioned’.

Decommissioning Brent is a complex, major engineering project, because of its size, age, the type of infrastructure, and the harsh environment of the North Sea. Our recommendation for Brent is to remove the topsides of the four platforms to shore for recycling, leaving the legs in the sea.

Our recommendations are the result of 10 years of research, involving more than 300 scientific and technical studies. We established an independent group of scientific experts to review the findings and ensure all feasible decommissioning options were investigated thoroughly. We submitted our recommendations to the UK Government following extensive stakeholder engagement involving over 180 different organisations, and only when we were confident that they were safe, technically achievable, environmentally sound and socially and economically responsible.

Read more about our stakeholder engagement

Once the topsides have been removed, the concrete legs (called gravity base structures) which are part of Bravo, Charlie and Delta would be left in place. Studies predict that the legs would degrade slowly over hundreds of years as the seawater penetrates the concrete and the reinforcing steel bars within begin to corrode. According to independent analysis, this slow process of degradation and corrosion would have no measurable impact on the environment. Small pieces of concrete could separate from the legs and fall to the seabed or on top of the cells over time.

Read more about our recommendations for gravity base structures

Our recommendations are the result of 10 years of research and independent verification. While removing the legs may feel like the right thing to do, the risk to people and the environment is not justified given the small impact of leaving them in place.

We know the sediment contained in the base of the concrete storage cells on Bravo, Charlie and Delta contains no significant non-biodegradable compounds. It is a sticky mixture of about 50% water, 25% sand and grit, and 25% oil particles attached to the sand and grit. It does not flow and is difficult to move. Independent laboratories have scrutinized the samples.

Read more about our recommendations for the Brent field cell contents

We studied two options for removing the sediment; to remove and inject it into subsea wells, and one to pump it into tankers and take it to shore.  Both would be technically difficult and present significant safety risks to people working on them, on balance with only a minor benefit in terms of reducing the legacy environmental impact.