After years in the planning, Shell is now ready to press ahead with one of the most challenging decommissioning projects the world has ever seen – dismantling the enormous platforms in its Brent oil field in the North Sea.
The oil field – from which the benchmark Brent crude price takes its name – has produced about 2 billion barrels of oil and 5.7 trillion cubic feet of gas since production began in 1976. That equates to more than 10 per cent of all North Sea oil and gas production.
But 99.5 per cent of Brent’s commercially extractable reserves have now been recovered, and three of its four platforms have already ceased production.
Shell has drawn up plans for decommissioning the platforms in the Brent field, which is 115 miles north-east of Lerwick in the Shetland Islands, and has 1,ooo offshore workers on the project.
It wants to start with the Brent Delta platform, and has submitted proposals to the Department of Energy & Climate Change, which will open them to consultation for 30 days from 16 February.
“The Brent field has been a prolific national asset for many years,” said Alistair Hope, Shell’s Brent decommissioning project director.
“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,” he added
The proposal for the Brent Delta platform recommends that the 23,500 tonne “topside” of the platform is removed in one piece by a specialised heavy-lifting vessel that Shell has moored in Rotterdam.
The company says the “single-lift” technique will substantially reduce the risk, cost and environmental impact of the operation, and is in the process of strengthening the topside to prepare for it.
Shell said that it would submit a second round of decommissioning proposals, covering the remaining infrastructure in the Brent field, when it was confident that it had come up with proposals that were “safe, technically viable, environmentally sound and financially responsible”.
These will cover the topsides of the other three platforms, together with the legs of all four, as well as 140 wells and 28 pipelines.
Although some limited decommissioning has taken place in the North Sea, this would be by far the biggest project that has ever been undertaken.
It heralds a period of intense decommissioning as large swathes of infrastructure retire from service and need to be cleaned up after decades of production.
A report from the industry association Oil & Gas UK calculates that 475 installations, 10,000km of pipelines, 15 onshore terminals and 5,000 wells will eventually need to be decommissioned, at a cost of about £40bn between now and 2040.
British sea power: field facts
*Shell initially named its fields after waterbirds: Brent is from the Brent goose, and was discovered in 1971 after Auk but before Cormorant, Dunlin and Eider.
*It started to produce oil in 1976, a year after the first North Sea oil began flowing from BP’s Forties field.
*At its peak in 1982, the field was producing enough to meet the energy needs of half the UK for a year.
*Brent Delta was the second platform built after Brent Bravo in 1975. There are also Brent Charlie and Brent Alpha, as well as a floating storage facility, Brent Spar, which after a row over decommissioning in the 1990s, ended up in the foundations of a ferry quay in Norway.