Statfjord oil clean-up done, StatoilHydro says

OSLO (Reuters) - The clean-up of an oil spill at the Statfjord field in the North Sea has been completed, all workers have returned to the platform, and preparations are under way to restart production, operator StatoilHydro said on Sunday.

The leak on Saturday shut down output of about 138,000 barrels per day at Statfjord and two linked fields and triggered evacuation of the Statfjord A platform, but the spill was stopped by Saturday afternoon and clean-up vessels deployed.

About 20 cubic metres of crude -- equal to 126 barrels -- were skimmed from the sea, the Norwegian company's spokesman Ola Morten Aanestad said. "The clean-up was concluded yesterday ... There was no more oil to be seen so the operation was ended."

StatoilHydro had said on Saturday that 1,200 cubic metres of oily water -- equal to about 7,550 barrels -- were pumped to sea and that most of that volume was water.

"Everyone returned to the installation yesterday and the situation was normalized," Aanestad said.

"They are preparing for start-up of production," he said, but added that investigation of the cause of the leak continues and it was too early to say when production could resume.

The company said in a statement on Saturday that production at Statfjord A, one of three Statfjord platforms, would probably be shut down for several days.

The leak caused a shutdown of about 19,000 barrels per day at Statfjord A and 119,000 bpd of production from the nearby Snorre A platform and the Vigdis field because volumes from those installations were being processed at Statfjord.

But the Vigdis output of about 44,000 bpd normally goes to StatoilHydro's Gullfaks field and can probably be re-routed there soon, the company said.

"That is expected to happen on Monday at the latest, so that should be out of the equation soon," Aanestad said.

Discovered in 1974 and on stream since 1979, the Statfjord field straddling the Norwegian-UK boundary line was once the biggest oilfield in the North Sea.

Production has fallen from a 1987 peak of 850,000 barrels to about 150,000-160,000 barrels per day from three platforms.

Oil is also produced from satellite fields tied to Statfjord, bringing total output to around 470,000-480,000 bpd.

The spill was the second at Statfjord in the past five and a half months. In mid-December, about 27,700 barrels of oil were spilled during a tanker loading operation at Statfjord A.

The Petroleum Safety Authority said it would launch an investigation into Saturday's leak.

(Reporting by John Acher; editing by Elaine Hardcastle)