Rigs used to extract gas from under the Irish Sea will be decommissioned.

Spirit Energy has submitted multi-million-pound plans for the unmanned installations in Morecambe Bay, which have been in operation for more than 30 years.

The project will include the removal and recycling of a combined 22,000 tons of platform infrastructure, plugging and abandoning 12 wells, permanently isolating the facilities from the gas reservoir a kilometre below the seabed.

The DP3 and DP4 platforms in the East Irish Sea used to produce gas as part of Spirit Energy’s complex of eight installations in Morecambe Bay.

As the field has matured, the reserves the platforms previously tapped into have been produced by the larger, manned South Morecambe platform nearby.

Over the next three years, the installations will be prepared for full removal and then taken back to shore, with the aim of reusing or recycling more than 95 per cent of the steel, equipment and other materials on the platforms.

Mark Fotheringham, capital projects and decommissioning director at Spirit Energy, said: “With those reserves now being produced via the South Morecambe platform, it’s the right time for us to decommission those installations.

“The combined Morecambe Bay fields produce enough gas to heat more than a million UK homes, and will continue to do so while we work on removing this infrastructure in a safe and environmentally responsible way over the coming years.”

The DP3 and DP4 installations first produced gas in 1985 when the South Morecambe field came online.

The project to decommission the two platforms follows similar plans for the nearby Bains field, which produced gas via subsea infrastructure connected back to the main South Morecambe platform.

Spirit Energy has now launched a month-long public consultation about the process of decommissioning DP3 and DP4 installations, before the final plans will be submitted to the Department for Business, Energy and Industrial Strategy for approval.