Abstract: A subsea installation for the production of hydrocarbons includes a flowline and a group of heating cables extending along the flowline. A star end termination effecting short-circuit connection between the heating cables of the group is located at a subsea location remote from the flowline. For example, a subsea structure or fluid conduit in fluid communication with the flowline, such as a PLET or a spool, can be interposed between the termination and the flowline. The termination may be a module that is connectable electrically to the heating cables via flying leads and connector hubs.

Abstract: A subsea installation for the production of hydrocarbons includes a flowline and a group of heating cables extending along the flowline. A star end termination effecting short-circuit connection between the heating cables of the group is located at a subsea location remote from the flowline. For example, a subsea structure or fluid conduit in fluid communication with the flowline, such as a PLET or a spool, can be interposed between the termination and the flowline. The termination may be a module that is connectable electrically to the heating cables via flying leads and connector hubs.

Abstract: A subsea buoy comprises a rigid watertight external shell extending continuously around a supporting internal structure that is sealed and fully enclosed by the shell. The shell is formed integrally and simultaneously with the internal structure by the same additive manufacturing process. The internal structure comprises cavities disposed between structural members, such as struts of a lattice or webs of a matrix. The structural members and cavities can be in a hierarchical or fractal array comprising a relatively narrow outer tier adjoining the shell and at least one relatively wide inner tier within the outer tier.

Abstract: 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.

Abstract: 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.

Abstract: A method of filling a chamber with buoyant macrospheres places a mass of the spheres into a mould cavity. In the mould cavity, packing of the spheres is optimized to form an optimally-packed mass, followed by fixing the spheres in the optimally-packed mass to form a block. The block is then transferred from the mould cavity into the chamber while the spheres of the block remain fixed in the optimally-packed mass. This method enables the production of a buoyant element comprising an envelope defining an internal chamber that contains a mass of buoyant macrospheres each with an external diameter of at least 5 mm, packed with a packing factor of at least 50%.

Abstract: A method of providing buoyancy to a subsea structure such as a pipeline bundle comprises 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.

Abstract: A subsea pipeline coated with a thermally insulating coating has a radially outer surface shaped to define external hold-back formations. In a J-lay operation, the weight load of a pipeline catenary is held back using a complementary bushing or clamp of an installation vessel engaged with the hold-back formations. The weight load is transferred from the catenary to the bushing or clamp by shear forces acting through the coating. The coating extends continuously along the pipe and is interposed between the hold-back formations and the underlying pipe. The hold-back formations may be integral with the coating.

Abstract: A method of filling a chamber with buoyant macrospheres places a mass of the spheres into a mould cavity. In the mould cavity, packing of the spheres is optimized to form an optimally-packed mass, followed by fixing the spheres in the optimally-packed mass to form a block. The block is then transferred from the mould cavity into the chamber while the spheres of the block remain fixed in the optimally-packed mass. This method enables the production of a buoyant element comprising an envelope defining an internal chamber that contains a mass of buoyant macrospheres each with an external diameter of at least 5 mm, packed with a packing factor of at least 50%.

Abstract: 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.

Abstract: A subsea pipeline coated with a thermally insulating coating has a radially outer surface shaped to define external hold-back formations. In a J-lay operation, the weight load of a pipeline catenary is held back using a complementary bushing or clamp of an installation vessel engaged with the hold-back formations. The weight load is transferred from the catenary to the bushing or clamp by shear forces acting through the coating. The coating extends continuously along the pipe and is interposed between the hold-back formations and the underlying pipe. The hold-back formations may be integral with the coating.