After producing 200 million barrels of oil from beneath the North Sea over 17 years, the 110,000-tonne Maureen Alpha platform was removed from the bed, in late June, and refloated in a 60-hour operation, to be returned to land. The 241-m-tall steel gravity structure had been "uniquely" engineered to allow possible reuse, according to the owner, though chances of finding a buyer with the same needs seem remote.

UNIQUE Design allowed for refloating. (Photo courtesy of Niki Photography Limited)

At the deep sea site 260 kilometers from Scotland, where the platform was built, workers with Norwegian recovery contractor Aker Offshore Partner A/S, Oslo, injected water under the bearing pads of three huge storage cylinders, which support the structure, to unstick them from the bottom. At the same time, they deballasted the cylinders by pumping in nitrogen to expel sea water, causing the structure to float with a 55-m draft.

"She came up smooth as a nut," says Lynnda Robson, spokeswoman for field operator Phillips Petroleum Co. U.K. Ltd., Aberdeen. A fraction of the expected water pressure was needed to loosen the structure, she adds. After being towed to a deep fjord near Bergen, Norway, for cleaning and examination, the platform will await a buyer or disposal. A decision is due this year. Aker's contract includes an option to cut up the platform for reuse or scrapping, says spokesman Torbjørn Andersen.

Associated equipment, including a 142-m-high vertical column, used to load tankers, is also being removed from the sea. The 2.3-km-long pipeline connecting it to the platform will remain, having been cleaned by the operator. Aker's $10 million contract, not including demolition, represents just under 5% of money spent in studies and surveys by the operator in preparing for the refloat since 1993, says Robson.

Towed out in November 1982, the platform includes a 119-m-high, tripod gravity base with 75-m-high steel, 25.6-m-dia storage cylinders attached to each leg. Its retrieval was in line with the U.K.'s May 2000 decommissioning guidelines, confirms Dept. of Trade and Industry.