Oil giant Shell has successfully removed a World War II mine which had threatened a major North Sea gas pipeline.
The unexploded device was discovered on the sea-bed 62 miles off the coast of St Fergus in Aberdeenshire in 1993.
At the time the mine was inspected by Royal Navy experts who advised pipeline operators Shell to leave it there.
However, the firm joined forces with specialised bomb disposal contractor Ramora UK to develop new equipment to remove it. Almost 20 years on, the ordnance was finally lifted from the seabed and disposed off during a controlled explosion at about 5.30am on Sunday.
Shell’s Glen Cayley said the operation had been a “technical challenge”.
“We did a lot of preparation including detailed risk assessment, to ensure this operation was as safe as possible – for this important gas pipeline to theUK, for the local environment and of course of all of the people involved,” he said.
“It was a technical challenge, but we and our contractors have a lot of experience working in these conditions offshore in the North Sea, and I know that the team rehearsed and carried this out with close attention to detail to ensure a safe outcome.”
The British-made mine lay beneath a pipeline responsible for 5% of the UK’s daily gas supply.
It was not visible when the line – known as FLAGS (Far North Liquids and Associated Gas System) and used to transport liquids and associated gas from a number of platforms, including the four Brents – was completed in 1978 and commissioned in May 1982.
Shell and Portsmouth-based Ramora eventually decided to attach an inflatable bag to the mine to bring it safely to the surface.
Ramora UK managing director David Welch said: “We have developed a suite of equipment which can be deployed by a subsea remotely operated vehicle permitting connection of an automated lifting bag system, thereby allowing transfer of ordnance to the surface suspended beneath the lifting bag.
“The unexploded ordnance is then towed to the disposal position and returned to the seabed under control for final disposal.
“The entire operation was designed to eliminate interaction with personnel, such as divers, thereby greatly improving levels of safety.”