Kvaerner Oil & Gas A.s.

Morten Bye

Leiv Gunnar Wanvik

Terje Karp

A surface vessel is anchored almost geostationarily by a turret rotatable relative to the vessel about a vertical axis and having mooring cables extending to the seabed. A well is drilled from a drilling section in the vessel at a distance from the axis of rotation of the turret. The drilling is performed using a drill string through a riser extending from the seabed to the drilling section, which riser can be broken and shut off between the seabed and the vessel. By manipulating (hauling in and slackening) the mooring cables, the vessel is held in position so that the derrick is kept almost geostationary relative to the well during drilling operations. The system includes a surface vessel, a turret rotatable relative to the vessel about a vertical axis and which can be anchored to the seabed by a plurality of mooring cables, and a riser extending from the seabed to the vessel through which the well can be drilled with a drill string from a derrick in a drilling section on board the vessel. The turret and the drilling section are arranged so as to be spaced apart in the longitudinal direction of the vessel. The riser is arranged in a circular sector around the turret which is free of mooring cables and possible production risers. The turret includes elements for manipulating (hauling in/slackening) the mooring cables. The riser is capable of breaking and being shut off between the seabed and the vessel.

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Moss, Norway

Morten Bye