Vapour from a spill oil tank in one of the shafts on Statoil's Gullfaks A platform in the North Sea activated a gas detector on Friday. This in turn initiated a gas leak alert, and the crew of 180 were sent to the lifeboats.
The tank was opened at 0830 for routine inspection. Statoil is now ventilating the shaft where the vapour was observed.
Production was shut down, but was scheduled to resume again on Friday.