The Siri platform operated by Statoil in the Danish North Sea resumed production on the afternoon of 14 March.
An inquiry team investigating the cause of a sudden pressure rise in the living quarters on 11 March, which caused a shut-down of this installation to be extended, had finished its work on 13 March.
The team's preliminary conclusions generated seven recommendations, including three which had to be implemented before production could resume.
The latter were all related to controlling ventilation systems as well as opening and shutting flaps in the suction and evacuation ducts.
In addition, more than 80 different tests and simulations were run after the modifications had been completed to check that modifications to topside ventilation systems met the inquiry team's recommendations.
After the testing programme had been satisfactorily completed and internally documented, the green light was given to bring the platform back on stream.
The inquiry team's other recommendations will be evaluated and implemented over a rather longer period.
Work will begin as soon as materials and resources are available on repairing the damage caused to a stairwell and the control room on the platform.