Gas on a North Sea oil platform exposed workers to a risk of an explosion, the Health and Safety Executive has said.
Several gas detectors on EnQuest’s Heather Alpha – about 245 miles north east of Aberdeen – were triggered on 1 March.
The uncombusted flammable gas came from a flare system which was supposed to be lit.
The resulting shutdown led to an accumulation of gas on the platform, setting off more detectors.
The HSE said it exposed the 131 workers on board to a risk of fire and explosion. It served EnQuest with an improvement notice.
An EnQuest spokeswoman said: “During routine operations, the flare extinguished which resulted in a limited amount of gas accumulating, externally, around the north face of the platform.
“The safety systems activated automatically, as designed, and production was shut down immediately.
“The safety of our people remains our first priority and we have taken steps to prevent re-occurrence.
“We are working closely with the HSE to learn from the incident and are on target to comply with the terms of the notice.”