J. Ray Mcdermott, S.a.

Subsea 7 Limited

Yun Ding

Daniel Karunakaran

Jack Darryl Payne

Frederico Nicoletti De Fraga

Chunqun Ji

Chunfa Wu

William Lawrence Soester

Bobby P Cline

A subsea riser support buoy is disclosed having a riser support member and a jumper support member that extend generally parallel to each other and that define a lengthwise direction extending between them across the buoy. Pontoons extend lengthwise beyond the riser support member and the jumper support member to provide attachment points for connecting tethers to the buoy. In this way, the attachment points are spaced more widely than lengthwise extremities of the riser support member and the jumper support member, beneficially altering the dynamic behavior of the buoy and especially its pitch characteristics.

Relating to buoyancy-supported risers

A semi-submersible structure. The hull includes four columns that are supported by two pontoons. The columns support the topsides and the topsides structural framing serves as horizontal framing between the columns. A truss frame is attached to the columns. The truss frame preferably includes heave plates. The truss frame extends downward below the pontoons a sufficient distance in the water such that it minimizes motions caused by environmental forces. The hull section and the truss space frame are constructed separately and assembled together at the offshore site where the structure is used for drilling and/or production.

Truss semi-submersible offshore floating structure

A method of mating of a buoyant hull with a truss structure while at the installation site of the completed offshore structure. The buoyant hull is moored in place. The truss structure is placed in the water, self upends, and maneuvered near the buoyant hull. The buoyant hull and truss structure are rigged with lines to allow the truss structure to be pulled into engagement with the buoyant hull. The truss structure is lowered to a predetermined depth below the water surface but above the sea floor and the weight is transferred to the lines from the buoyant hull. The truss structure is aligned with the buoyant hull and lines from the buoyant hull are used to pull the truss structure into engagement with the buoyant hull. The truss structure and buoyant hull are rigidly attached together as is customary using grouting and welding.

Mating of buoyant hull structure with truss structure

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Sugar Land, TX, United States of America

Yun Ding