Fmc Corporation

Fmc Technologies, Inc.

John A Fitzgerald

Harold Brian Skeels

Marcus Alan Smedley

Christopher E Cunninham

Expandable and contractible buoyancy modules are assembled to the risers of a deepwater exploration spar or other offshore structure to provide an upwardly directed buoyancy force to offset at least a portion of the weight of the riser. The buoyancy modules have a fabricated pressure tight expandable and contractible envelope composed of rubber or rubber-like material which is mounted onto a tubular member having a central passage for receiving the riser to be supported. The tubular member projects beyond the respective upper and lower ends of the envelope and defines upper and lower riser joint connectors and buoyancy module travel stops which secure the buoyancy module to the riser and provide for force transmission from the buoyancy module to selected locations along the length of the riser or to the upper end of the riser. The envelope is provided with at least one access port through which an inflation medium such as a gas or an uncured polymer can be added to control inflation of the envelope and through with liquid ballast is added or removed for ballast control.

Collapsible buoyancy device for risers on offshore structures

A subsea system is provided for producing a number of subsea wells which may be arranged in groups. Each of the groups of subsea wellheads is connected to deliver production flow to a subsea manifold and each subsea manifold is connected to deliver production flow to a production riser. A plurality of production risers each being connected to receive production flow from one of said subsea manifolds extend from the subsea manifolds for groups of wells. A deep draft floating spar is located generally above the subsea wellheads with mooring lines and has a production platform located above the sea surface and has buoyancy and ballast chambers to control floatation. The spar structure defines a riser bore receiving the production risers extending from the subsea wellheads to the production platform. The spar is also capable of being shifted laterally by its mooring lines for positioning above a selected well to thus permit well intervention activities as needed. The subsea wells are each provided with wellheads having a removable cap to permit ROV actuated cap removal and replacement as needed to permit well intervention.

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New Orleans, LA, United States of America

John A Fitzgerald