Importance

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Abstract

A single point spar buoy mooring apparatus adapted to freely float in vertical position and readily attachable to a vessel, said apparatus including an outer rotatable cylinder and a superstructure supported therefrom, an inner nonrotatable cylinder coaxially within the outer cylinder and connected by mooring lines to anchors on the sea floor, a riser system including multiple riser lines extending from subsea wells through the inner cylinder to the top thereof, fluid transfer lines extending from the superstructure to the vessel, each riser line being connected to an associated transfer line and a turntable rotatable on the superstructure and connected with each riser line, said turntable being locked and held against rotation relative to said superstructure whereby turning of the vessel about the axis of the apparatus imparts a twist to said plurality of riser lines, said turntable being unlockable relative to the superstructure and rotatable to return the turntable to a reference position relative to the superstructure for untwisting said multiple risers without movement of the vessel about the axis of the spar buoy apparatus. A spar buoy apparatus and method permitting rotation of a vessel about the axis of the apparatus while preserving individual well fluid paths from multiple subsea wells.

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First Claim