|Production at one of the UK's largest-producing North Sea oil fields is expected to resume within 24 hours.
Production at Nexen's Buzzard field, about 100km north east of Aberdeen, was halted after an alarm was initiated on Monday evening.
A Nexen spokeswoman said "a release of steam caused a shutdown of the facility".
All 371 staff were accounted for and there were no reported injuries, she added.
Buzzard, which produces about 200,000 barrels of oil a day, underwent a prolonged closure last autumn.
The field was shut in early September for maintenance work and did not resume production until early November. Full capacity was not reached until the end of the month.
Buzzard, run by Nexen and with BG Group a 21.7% shareholder, is one of the biggest North Sea fields to be developed in the last 10 years.
The field holds enough crude to potentially deliver about 10% of the UK's annual forecast oil demand.