Installation of Two Permanent Deep Penetrating Anchors at the Gjøa Field in the North Sea
Two fullsize 75ton Deep Penetrating Anchors™ were fabricated at the Western Shipyard in Klaipeda, Lithuania and delivered at the Central Coastal Base in Ågotnes near Bergen, Norway in late July 2009. These anchors are part of a qualification program for the DPA concept for installation at the Gjøa field in the North SeaWest of Bergen off the coast of Norway. These anchors are 13m in length with four meters wide fins. Maximum pullout capacity is approximately 700tons and will be used by the mobile drilling rig unit (MODU) TransOcean Searcher for completing the wells at the Gjøa field. The anchors are designed to take larger loads than what will be realized by the present MODU, which may be operating on the field in the future where 84mm chain is manditory with MBL in excess of 700tons.
The anchors were sucessfully installed at the Gjøa field in mid August 2009 using the anchor handling vessel M/S Island Vanguard (photo below right) with less than two degrees tilt and anchor tip penetration in excess of 30m. Water depth was 360m. Maximum velocity when they hit the seabed was approximately 27m/sec (nearly 100kmh) dropped from a height of 75m above the sea floor. The sucessful installation and qualification of these anchors at the Gjøa field have subsequently resulted in an anchor solution that can now be offered to the oil and gass industry as a vialble alternative to present day solutions for anchoring of FPSOs and similar structures in soft seabed sediments. The Deep Penetrating Anchor™ was qualified by DNV in the last quarter of 2009.