Installing subsea risers
AssigneeSubsea 7 Limited
InventorLewis Alexander Harper
Life of this patent
Estimating the term…
Abstract
A subsea riser is installed by lowering at least one riser conduit to the seabed when piggybacked to an elongate support that comprises at least one flowline. The elongate support may be a pipeline bundle, which may be attached to one or more towheads in a towable bundle unit. The riser conduit may be in fluid communication with the flowline. At the seabed, a free end portion of the riser conduit is detached from the elongate support by releasing subsea-releasable fastenings. Then, with the elongate support and a root end of the riser remaining at the seabed, the detached free end portion of the riser conduit is lifted away from the elongate support to a riser support, such as a platform, an FPSO (floating production, storage and offloading vessel), or a buoy.
Claims24
A method of installing a subsea riser, the method comprising:
- lowering at least one riser conduit to a seabed location when piggybacked to an elongate support that comprises at least one flowline;
- effecting fluid communication between the at least one riser conduit and the at least one flowline through a root end of the at least one riser conduit;
- at the seabed location, detaching a free end of the at least one riser conduit from the elongate support;
- and
- while leaving the elongate support and the root end of the at least one riser conduit at the seabed location, lifting the detached free end of the at least one riser conduit away from the elongate support to a riser support that is positioned at or near to the surface of the sea.
An assembly for use in constructing a subsea riser, the assembly comprising:
- at least one riser conduit that extends from a coupled root end to an uncoupled free end;
- subsea-releasable attachments;
- an elongate support that comprises at least one flowline;
- and
- a hinge structure at a root end of the at least one flowline that effects fluid communication between the root end of the at least one riser conduit and the root end of the at least one flowline, and that is arranged to move when pivoting the at least one riser conduit away from the elongate support;
- wherein the at least one riser conduit is held by the subsea-releasable attachments in piggybacked relation along the elongate support.
Dependencies are inferred from the claim text.