The Norwegian division of PSL Energy Services will provide seabed excavation services for Norsk Hydro's Ormen Lange project. The development includes laying of pipelines between the Ormen Lange field, 120-km north-west of Kristiansand, and the island of Gossen. The route traverses Storegga, a subsea landslide area featuring an irregular and steeply sloping seabed surface, with the water depth plunging rapidly from 250 m to 1,200 m.

Prior to pipeline and umbilical laying, the route must be prepared to avoid unacceptable free-spans of pipe between the seabed features. This entails cutting corridors through seabed undulations in numerous locations.

PSL will excavate three of these corridors under a NKr50 million contract, using the new DP3-class deepwater intervention vesselIsland Frontier, owned by Island Offshore. The vessel incorporates its own module-handling tower, designed for deployment and recovery of subsea equipment. The tower also has a fully active heave compensation system for loads up to 70 tonnes; for the Ormen Lange exercise, a drill-string deployment capability will be added.

Excavation will be conducted using deepwater subsea jetting and dispersal techniques such as the Jet Prop and Clay Cutter systems. These tools are lowered to the seabed on drillpipe and are powered by 10,000 hp water pumps on the vessel's deck. PSL will also provide survey equipment, which will allow the vessel to provide 3D seabed charts to an accuracy of a few centimeters.

2/10/05