Oil major Shell has launched a 60-day public consultation on its plans for decommissioning the Brent field facilities in the North Sea.
The huge engineering project will see the first significant use of Allseas' Pioneering Spirit heavy lift vessel, which will lift out the four Brent platform topsides, each weighing in excess of 24,000-tonne.
The move puts out to consultation a proposal to leave in place the field's three large gravity-based structures and the lower section of a steel jacket, installed on the field in the 1970s, 115mi northeast of the Shetland Islands.
The topsides, debris on the seabed and remaining oil within the concrete storage cells on the gravity based structures, would be removed. Sediment in the structures and drill cuttings would be left in place. A range of options has been set out for the Brent pipelines.
The decommissioning proposal has been submitted to the Department for Business, Energy and Industrial Strategy (BEIS).
Following the consultation, the plan will also need to go to the OSPAR Commission, a body established under the OSPAR Convention to protect the marine environment of the North-East Atlantic. Under OSPAR rules, all structures should be removed, but some - depending on age and weight - can apply for a derogation order. There have been calls for this stance to be challenged, with some suggesting removing facilities could be more detrimental than leaving them in place. Read more: Up against Ospar. The Insite Program.
Since production started on the Brent field in 1976, some 3 billion boe has been produced. Production from Brent Delta ceased in 2011, and from Brent Alpha and Brent Bravo in November 2014. Production from the field will continue, via Brent Charlie, for several years to come.
Brent Delta's topsides are due to be lifted out by the Pioneering Spirit this summer, followed by the other three topsides in future years. Read more about the decommissioning program.
“After an extensive and in-depth study period, the submission of Shell’s Brent decommissioning program marks another important milestone in the history of the Brent oil and gas field,” said Duncan Manning, Brent Decommissioning Asset Manager.
“Shell has undertaken thorough analysis, extensive scientific research and detailed consultation with over 180 stakeholder organizations over the past 10 years. Working within the tightly defined regulatory process, we believe that our recommendations are safe, technically achievable, environmentally sound and financially responsible. Shell encourages all those with an interest in the decommissioning of the Brent field to review, reflect on and respond to this consultation document.”
Work to prepare for Brent decommissioning started in 2006. More than 300 expert studies have been completed and the results analyzed and verified by a group of independent scientists. Shell has also engaged with around 400 stakeholders, including non-government organizations, academics and key interest groups, including but not limited to the Scottish Fishermen’s Federation.
Image: Shell's Brent Bravo platform.