Energy giant Shell has announced plans to decommission the North Sea Brent oil and gas field, with a public consultation scheduled to start on 16 February.
The oil exploration firm has already outlined plans for tearing down the Brent Delta platform, in operation since the 1970s.
The ambitious engineering project will see Shell removing the 23,500-tonne topside of the platform in one piece by a heavy-lift vessel, to be brought to Teesside, UK, for disassembly.
“The Brent field has been a prolific national asset for many years, creating and sustaining thousands of jobs and contributing billions of pounds to the UK government,” said Alistair Hope, Brent Decommissioning Project Director at Shell.
“The engineering and planning skills which led to the discovery and subsequent successful production of oil and gas over four decades are essential during decommissioning, which is the natural next stage of the field’s life.”
Work is already under way to strengthen the topside of Brent Delta to withstand the lift without breaking up. Shell said the technique would reduce environmental impact of the operation as well as keep costs down. More than 97 per cent of the material is expected to be reused or recycled by specialised company Able UK.
Brent Delta’s legs, as well as topsides and legs of the three other platforms in the field, together with its 140 wells and 28 pipelines, will be removed in the second phase of the decommissioning programme after Shell proves the procedure is safe.
The Brent field, located in the East Shetland basin some 186km north-east of Lerwick, used to be one of the region’s most productive oil fields and one of the most complex.
Its four platforms, Brent Alpha, Bravo, Charlie and Delta, have produced around 10 per cent of the UK North Sea oil and gas output, generating more than £20bn of tax revenue since production began in 1976.
Oil extraction at Brent Delta stopped in 2011 and Brent Alpha and Bravo closed down in November 2014. The only remaining active platform in the region operated by Shell is Brent Charlie.
The discovery of the field in 1971 not only helped turn the UK into an energy exporter, addressing a shortage of energy supply, but also encouraged technology and engineering innovations. The UK’s longest subsea pipeline was built at the time, connecting the field with land. In the 1990s engineers carried out the world’s largest oilfield depressurisation to extend the life of the field.
"The industry pushed the boundaries of science and engineering to access North Sea oil and gas,” WWF Scotland director Lang Banks commented.
"Having made massive profits over the last few decades, it's only right that it should push those limits once again to clean up their potentially hazardous legacy and protect the marine environment
"Given the enormous size of the rigs and the iconic nature of the Brent field, this decommissioning will be watched closely and should therefore be aiming to set the highest possible benchmarks for the rest of the industry to follow.
"If done right, then it could open the door for Scotland to lead a new multi-billion pound, global decommissioning industry."
Shell said it had carried out more than 300 studies and consulted more than 400 stakeholders from about 180 organisations to find the best way to close down the field.
The decommissioning programme has been formally approved by the Department of Energy and Climate Change (DECC).