Patent ID: 7537416
Filing Date: 2009-05-26
Classification: B63B,E21B

Abstract:
1. A floating offshore platform containing a plurality of substantially vertical and rigid risers extending upward from the floor of a body of water, said platform comprising: (a) a buoyant and ballastable hull containing a passageway; (b) a buoyant and ballastable riser support structure located inside said passageway and comprising a plurality of tubes, wherein each of said risers (1) passes through one of said tubes such that each tube contains a single riser and (2) is attached to the inside of said tube at a location below the surface of said body of water and below the center of buoyancy of said buoyant and ballastable riser support structure and wherein said buoyant and ballastable riser support structure is devoid of vertical tethers and flexible moorings; and (c) means in each of said tubes for attaching said riser to the inside of said tube, wherein said support structure is free to move in the axial direction inside of said passageway independent of the axial movement of said hull.