Shell wants to abandon steel and concrete structures as large as the Empire State Building when it decommissions one of the biggest oil and gas fields in the North Sea.
Regulations demand all traces of oil and gas production are removed although exemptions are allowed if removal is deemed too difficult or environmentally damaging.
Shell plans to submit its proposals for approval from the UK’s Department for Energy and Climate Change by the end of this year.
The decommissioning project is being headed by Duncan Manning, who responded to criticism there could be risks to shipping and fisheries by suggesting these could be reduced by measures to warn vessels away from the area.
Environmental groups have also raised concerns over multiple “cells”, each the size of Nelson’s Column, which would be left once the top of the rigs have been removed.
WWF Scotland Director Lang Banks said: “The industry pushed the boundaries of science and engineering to access North Sea oil and gas. 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.”