Acergy France Sas

Blaise Seguin

Vincent Loentgen

Brice Viellard

Marcel Marco Landwehr

Benoit Vigot

Emmanuel Guilloir

Emilie Brunet

Marcel Landwehr

A method of providing buoyancy to a subsea structure such as a pipeline bundle includes attaching to the structure a rigid elongate buoyancy tube that defines a floodable envelope. The envelope is arranged to contain a mass of buoyant macrospheres. Multiple openings penetrate a tubular wall of the buoyancy tube, in fluid communication with a void that extends between the macrospheres inside the tube. The void floods via the openings when the buoyancy tube is submerged, whereupon the macrospheres apply buoyant upthrust to the surrounding buoyancy tube and hence to the subsea structure to which the tube is rigidly attached.

Subsea buoyancy systems

A buoyant element for conferring buoyancy on a subsea structure or apparatus has a floodable envelope that contains a mass of buoyant spheres and a void extending between the spheres. Openings penetrate the envelope, in fluid communication with the void. One or more one destruction devices are arranged to destroy at least one of the spheres within the envelope in use. After the envelope has been submerged and flooded to fill the void between the spheres with water, the destruction devices are imploded to create shockwaves that expand the void by sympathetic implosion of the spheres. Additional water is admitted into the envelope through the openings to fill the expanding void, thereby ballasting the buoyant element.

Controlling the buoyancy of a mass of buoyant spheres

A subsea riser system with a gas-lift facility has a production riser having a riser conduit and at least one lift gas injection port communicating with the riser conduit. An umbilical is arranged to supply lift gas to the lift gas injection port. A heating unit is positioned to act on a downstream end region of the umbilical adjacent to the lift gas injection port. A method of providing lift gas to a subsea riser system includes the steps of conveying lift gas toward a production riser and, before injecting the lift gas into the production riser, heating the lift gas locally adjacent to the production riser.

Production riser with a gas lift facility

A coated or sleeved pipe for a hybrid riser tower is disclosed. The pipe has at least one stop formation that is integral with or attached to an external coating or sleeve of the pipe. The stop formation is arranged to restrain movement along the pipe of a structure attached to the pipe, such as a guide frame.

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Paris, France

Blaise Seguin