Proposals for retiring oil installations in the North Sea have been published for consultation by Shell. The oil company wants to leave the legs of four rigs along with their contents at the Brent field site.
Shell has four installations in the area, north-east of Shetland. At their peak, they delivered 500,000 barrels of oil a day but almost all of the resources that can be recovered economically have been extracted.
The proposals from the Anglo-Dutch multinational include securing 154 wells, removing the tops from all four platforms, recovering debris on the seabed and extracting the oil trapped in underwater storage cells. It also hopes to leave the concrete structures, including the legs supporting the platforms and their contents, in the seabed.
According to Shell, these were constructed nearly 50 years ago and were not designed to be removed. The safety risks of removing them outweighs the environmental benefits, it claimed.
But campaign group Greenpeace accused Shell of trying to wriggle out of decommissioning rules agreed under the OSPAR Convention on marine protection. These state that oil and gas installations should be brought ashore for decommissioning unless there are compelling reasons not to do so. The campaign group backs the recommendation to leave in place the concrete legs, but wants the removal of oil residues inside them.
Doug Parr, Greenpeace chief scientist, said decisions on decommissioning the rigs could set a precedent for other oil fields that are due to be retired. Shell estimates there are 470 oil and gas installations in the North Sea due to be decommissioned over the next 30 years. ‘At some point the cells will break down, so they should be rendered safe,’ Parr said.
