The company said it mobilized an emergency response team to respond to evacuation alarms at the facility north of Stavanger. All 445 employees near the incident were able to return to their work obligations about two hours after the alarms went off. No injuries were reported.
"The part of the facility affected has been depressurized and closed down," the company said in a statement Wednesday. "Statoil will investigate the incident thoroughly to ascertain its immediate and underlying causes."
The Karsto processing facility receives natural gas from the Norwegian and North Seas before sending it on to European consumers.
Norway is the largest oil producer and the third-largest natural gas producer in Europe. It supplied members of the European Union with about 21 percent of their gas needs last year, just behind Russia.
There was no comment on the incident from Norwegian state-owned gas transit company Gassco, which operates the Karsto facility. Statoil is the technical service provider.