Shell Oil Comapny

Anders G Ekvall

David A Huete

Early B Denison

Bobby E Cox

Lee K Brasted

Stephen W Balint

A deepwater riser assembly is disclosed for a riser connecting subsea equipment to a surface wellhead. A buoyancy can assembly provides an open ended buoyancy can tube which surrounds the upper end of the riser and an upper seal which effectively closes the annulus between the riser and the buoyancy can tube. A load transfer connection in the buoyancy can assembly then connects the riser to buoyancy can tube. A pressure charging system communicates with the annulus between the riser and the buoyancy can tube below the upper seal. Injecting gas into this annulus then provides support to the riser.

Deepwater riser system

A bumper system is disclosed for docking an auxiliary drilling vessel to a compliant platform through first and second pads having vertically extending, complementary outboard faces presented from the respective structures in vertically slidable abutment. A biasing system pushes the vessel and platform into abutment across the first and second pads and the system allows the vessel to dock to the structure in a manner such that vertical loading is not substantially transmitted between the vessel and the structure across the sliding engagement.

Bumper docking between offshore drilling vessels and compliant platforms

An improved method for conducting offshore well operations is disclosed in which a compliant platform is installed adjacent a selected well site and an auxiliary vessel is temporarily docked to the compliant platform to provide for support for the well operations which will be produced through the compliant platform. In the practice of the improved method, the compliant platform is isolated from vertical loads upon the auxiliary vessel docked thereto during the performance of well operations conducted for the compliant platform by the offshore auxiliary vessel. Another aspect of the present invention is an improved system for restraining an offshore drilling vessel temporarily to a compliant platform which uses a slide-connection for isolating the compliant platform from vertical loads upon the offshore drilling vessel during the well operations.

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Houston, TX, United States of America

Anders G Ekvall