Abstract: Disclosed is a riser including a plurality of pipelines. In one example there are three such pipelines extending from the seabed toward the surface and having an upper end supported at a depth below the sea surface. In one embodiment, a first of the pipelines acts as a central structural core, and the other pipelines are arranged around the first pipeline. In another embodiment, three pipelines are arranged around a structural core. In each case, the first of the pipelines can be a fluid injection line, and the other pipelines are production lines. Also disclosed is a riser having buoyancy along at least a part of its length. The buoyancy results in the riser having a generally circular cross-section, the circumference of which is non-contiguous. Methods of installing such risers are also described.

Abstract: Disclosed is a method of fabricating and installing a riser tower structure, preferably in a welding chamber, and a welding chamber suitable for the method. The method includes fabricating sections of the riser tower structure at a site remote from the site of installation; transporting the sections of the riser tower structure to within the vicinity of the installation site; and assembling together the sections of the riser tower structure in the vicinity of the installation site. The welding chamber includes a plurality of guide means, each providing a guide for one of the elongate elements of the riser tower structure, and floats on the sea surface when in use.

Abstract: Disclosed is a riser including a plurality of pipelines. In one example there are three such pipelines extending from the seabed toward the surface and having an upper end supported at a depth below the sea surface. In one embodiment, a first of the pipelines acts as a central structural core, and the other pipelines are arranged around the first pipeline. In another embodiment, three pipelines are arranged around a structural core. In each case, the first of the pipelines can be a fluid injection line, and the other pipelines are production lines. Also disclosed is a riser having buoyancy along at least a part of its length. The buoyancy results in the riser having a generally circular cross-section, the circumference of which is non-contiguous. Methods of installing such risers are also described.

Abstract: Disclosed is a riser tower structure including a plurality of elongate objects. The riser tower structure is provided with blocks, preferably of buoyant material, along at least part of its length. The blocks provide the riser tower with a substantially circular cross-sectional profile, wherein one or more strakes are provided on the outside of the blocks. The strakes in a main embodiment are helical. Also disclosed is a corresponding method of constructing such a riser tower structure.

Abstract: Disclosed is a riser comprising a plurality of pipelines. In one example there are three such pipelines, extending from the seabed toward the surface and having an upper end supported at a depth below the sea surface, wherein, in one embodiment a first of said pipelines acts as a central structural core, the other pipelines being arranged around said first pipeline. In another embodiment three pipelines are arranged around a structural core. In each case, the first of said pipelines may be a fluid injection line, said other pipelines being production lines. Also disclosed is a riser having buoyancy along at least a part of its length, said buoyancy resulting in said riser having a generally circular cross-section, the circumference of which being non-contiguous. Methods of installing such risers are also are also described.

Abstract: Disclosed is a riser tower structure including a plurality of elongate objects. The riser tower structure is provided with blocks preferably of buoyant material, along at least part of its length. The blocks provide the riser tower with a substantially circular cross-sectional profile, wherein one or more strakes are provided on the outside of the blocks. the strakes in a main embodiment are helical. Also disclosed is a corresponding method of constructing such a riser tower structure.

Abstract: Disclosed is a method of fabricating and installing a riser tower structure, preferably in a welding chamber, and a welding chamber suitable for the method. The method includes fabricating sections of the riser tower structure at a site remote from the site of installation; transporting the sections of the riser tower structure to within the vicinity of the installation site; and assembling together the sections of the riser tower structure in the vicinity of the installation site. The welding chamber includes a plurality of guide means, each providing a guide for one of the elongate elements of the riser tower structure, and floats on the sea surface when in use.

Abstract: A device for winding up or unwinding elongated flexible articles comprising two bearings (1) forming a winch, supported on a substantially horizontal surface (7), and means (17) for moving all the bearings (1) towards and away from one another perpendicular to the unwinding direction so that the bearing (1) may be brought to bearing relationship with a drum (9) thereby enabling a rotation of said drum, and means (14, 16) adapted to be moved to supporting contact with a drum (9) and for lifting and lowering said drum relative said bearings. The supporting contact means comprise slings (14) connected to said lifting and lowering means (16).