Flexible riser system
AssigneeBechtel Corporation
InventorKeith Shotbolt
Life of this patent
Estimating the term…
Abstract
A flexible riser 10 has a lower connector 11 which is moved laterally over the seabed by a pull-in sled 7 under a mid-water support buoy 3 to connect it to a connection point 17 on subsea equipment 1. The riser 10 is attached at a point part way along its length to buoy 3. This is done at one side of the buoy prior to construction vessel 13 laying the riser over the buoy and connecting the upper connector 24 to a production vessel 2 positioned over the subsea equipment. Attachment is done by guiding the riser pipe into a channel 36, a projection 20 on the riser engaging the channel against lowering of the pipe. A upper connector of the riser may include a single pivotal arm and a single offset guide post to maintain its orientation while it is being pulled into engagement with a mating part on the production vessel.
Claims23
A method of installing a flexible riser system in water to bring flexible risers from seabed equipment to a production vessel at the sea surface, including
- (a) providing a support to one lateral side of a line running vertically from the production vessel and at a level intermediate the seabed and the sea surface,
- (b) lowering at least one flexible pipe from the sea surface in a region laterally further from said line than said support to at least contact the seabed,
- (c) bringing said pipe to the support at a lateral side portion thereof remote from the said line,
- (d) attaching said pipe and said support together whereby to sustain on said support at least the weight of the pipe below said support,
- and thereafter
- (e) laying an upper portion of the pipe over the support towards said line to form a catenary upper leg of a riser.
In a flexible riser system comprising
- (a) a production vessel at the sea surface
- (b) underwater equipment at the seabed
- (c) a support for at least one riser at a level between the seabed and the sea surface, the support having a first and second lateral side
- (d) at least one flexible riser joining the equipment to the vessel said at least one riser lying over said support to form a catenary upper leg of the riser from said support to the vessel at the first lateral side of the support and hanging therefrom at the second lateral side thereof t define a catenary lower leg of the riser;
- the improvement comprising
- (e) means at said second lateral side of the support for engaging said riser for preventing downward movement of said riser a said side whereby to transfer at least the weight of said lower leg to said support.
Dependencies are inferred from the claim text.