The Skarv floating production storage and offloading (FPSO) vessel is the key feature of the new Skarv field in the Norwegian Sea, located in the Haltenbanken area. The field includes 16 wells across 5 subsea templates, with reserves of 16.8 million Sm3 of oil and 48.3 billion Sm3 of gas. The vessel is moored using 15 suction anchors, placed in 3 clusters of 5. Due to the complex geological history, soil conditions vary across the site, with hard glaciomarine sediments and till overlain by soft marine clay. The suction anchor design approach was robust, with a limited number of geometries to allow flexibility during the installation phase. Finite element modelling of each anchor's holding capacity, as well as careful prediction of the required installation under-pressures, allowed the anchor geometries to be grouped in this way. The successful installation of the suction anchors was completed early 2011 to allow the hook-up of the FPSO as planned, with production due to start in 2012. This paper describes details of the anchor design and installation process, and outlines how this anchor type can be used successfully in challenging soil conditions.
The Skarv field development is located in the Norwegian Sea close to the Arctic Circle, 210km off the coast of Norway. The development consists of one large floating production, storage and offloading (FPSO) vessel and five subsea templates (see Figure 1). The water depth at the FPSO location is about 360m, and it is due to start production in 2012. Reserves are around 17 million Sm3 of oil and condensate, and 48 billion Sm3 of rich gas. The vessel is 300m long and 50m wide, with a capacity of 15 million Sm3 of gas and 80 000 barrels of oil per day.