In the morning hours of December 11, a dual vessel float-over operation of the Aasta Hansteen topside was completed off Norway, Boskalis said.
The Aasta Hansteen FPSO spar is a gas production and storage platform that will be operated by Statoil on the Aasta Hansteen field approximately 300 kilometers off the coast of Norway.
The spar consists of a lower part, referred to as the hull or substructure, and the topsides on top of the spar hull.
The spar hull was transported horizontally by Boskalis from the yard in South Korea to a fjord near Stavanger in Norway. This cylindrical buoy with a diameter of 50 meters, a length of 198 meters and a weight of 46,000 tons was transported by the Dockwise Vanguard earlier this year.
Subsequently, Boskalis transported the 24,300-ton topside which was also built in Korea. This operation was carried out with the White Marlin, the newest vessel in the Dockwise fleet.
The third and final phase was the installation of the topside on top of the spar hull. Once the White Marlin arrived in Norway, the topside was transferred onto two S-class vessels.
After accurately positioning these two vessels on either side of the White Marlin, they started un-ballasting whilst the White Marlin ballasted down and maneuvered out from underneath. The result was a sort of catamaran structure with the topside linking the two hulls.
Over the past weekend, the catamaran structure with the topside was towed out to the vertical spar hull. Once everything was in position above the substructure, the mating operation between the hull and topside was completed.
Video Courtesy: Boskalis