A further 48 welds on flowlines on the Åsgard field in the Norwegian Sea are to be repaired by operator Statoil, with a further production shutdown for the B gas platform.
Weaknesses were uncovered by Statoil earlier this year in 72 pipe welds on Åsgard. After testing, it was resolved to repair 24 of these.
The decision to redo the remaining welds follows the discovery of a leak earlier this month in a gas line linking Åsgard B with the A oil production ship.
A brittle fracture was found to have occurred in a weld previously given a clean bill of health by in-house and external experts.
Åsgard B will be shut down until mid-October while the welds closest to it are repaired. A schedule for the remaining repairs is due to be drawn up within six-eight weeks.
Statoil also intends to use the production halt to review other critical systems on the gas floater.
“We’ll do the work in a way which has the smallest possible consequences for output,” says Henrik Carlsen, executive vice president for Exploration & Production Norway.
He emphasises that the improvements will not be carried out at the expense of safety and the environment.
The goal is to ensure that the shutdown does not affect gas customers in continental Europe by drawing on other Norwegian fields to cover contractual volumes unavailable from Åsgard.
Statoil has initiated efforts to secure such replacement gas supplies.
The weaknesses now revealed have prompted a review of possible welding defects on other installations. Repairs to four welds on the Statfjord north flank in the North Sea are still under consideration by Statoil.
And test production from the group’s Huldra platform, also in the North Sea, has been postponed for about 14 days.
This is because a welding method and material combination used at the top of the production tubing in three wells could involve the same weaknesses which have been identified on Åsgard.
Statoil will accordingly reassess these welds before the platform starts test production.