Claims
- 1. An offshore fluid transfer system which includes a fluid-passing seafloor structure such as one connected to a seafloor well or pipeline, a compliantly anchored floating structure such as a vessel, at least one mooring line that is anchored to the seafloor and that holds said floating structure in the vicinity of said seafloor structure and at an initial position in a calm environment, and a fluid-carrying conduit structure that extends up from said seafloor structure to said floating structure, wherein:
said conduit structure includes a rigid seafloor riser support that extends a plurality of meters above the seafloor and that has lower and upper portions lying respectively at the seafloor and a plurality of meters above the seafloor, and said conduit structure includes a conduit that extends largely upward along said seafloor riser support to said upper portion of said seafloor riser support, and that includes a flexible portion that extends in a double catenary curve from said upper portion of said seafloor riser support to said floating structure in said calm environment.
- 2. The system described in claim 1 wherein:
said sea has a predetermined sea depth above the seafloor at the bottom of said seafloor riser support, and said seafloor riser support comprises a rigid structure that extends above the seafloor by at least 10% of said predetermined sea depth.
- 3. The system described in claim 2 wherein:
said seafloor riser support extends above the seafloor by at least 20% of said predetermined sea depth.
- 4. The system described in claim 1 wherein:
said conduit includes a rigid pipe of a length of a plurality of meters that extends along at least part of the height of said riser support, and said conduit flexible portion extends from said rigid pipe and from said seafloor riser support to said floating structure.
- 5. The system described in claim 4 wherein:
said conduit structure includes a curved rigid pipe section with an inner end connected to an upper end of said rigid pipe and an outer end connected to said flexible conduit portion, said pipe section inner end extending at an upward incline away from rigid pipe and said pipe section outer end extending at a downward incline away from said pipe section inner end.
- 6. The system described in claim 1 wherein:
said seafloor riser support upper portion forms a convexly rounded hose-supporting top surface, and said conduit flexible portion includes a part that extends around said top surface and that can lift off said top surface.
- 7. The system described in claim 1 including:
at least one pile that is driven into the seafloor and that fixes said rigid seafloor riser support to the seafloor.
- 8. An offshore fluid transfer system that lies in a sea of predetermined depth for transferring fluid between a fluid-carrying seafloor structure that lies at the seafloor and a floating structure that floats at the sea surface and that is compliantly anchored to remain in the vicinity of the seafloor structure, the system including a conduit comprising a flexible conduit member that extends along much of the sea depth, said conduit having upper and lower ends coupled respectively to said floating structure and to said seafloor structure, comprising:
a rigid frame having a lower end fixed to the seafloor and an upper portion extending above the seafloor by at least 10% of said sea depth; and wherein
said conduit has a lower portion mounted on said frame, said conduit extends along said frame to said frame upper portion, and said conduit has a portion that includes said flexible conduit member that extends from said frame upper portion to said floating structure.
- 9. The system described in claim 8 wherein:
said conduit includes a rigid pipe mounted on said frame and extending a plurality of meters along said frame, said rigid pipe having an upper end connected to said flexible conduit member.
- 10. The system described in claim 8 wherein:
said flexible conduit member extends in a double catenary curve from said upper portion of said rigid frame to said floating structure, with a lower portion of said flexible conduit member that extends from said upper portion of said rigid frame, extending at a downward incline away from said upper portion of said rigid frame.
- 11. The system described in claim 8 wherein:
said rigid frame has a convex upper surface with a radius of curvature of a plurality of meters, and said flexible conduit member has a lower portion that lies on said convex upper surface.
- 12. The system described in claim 8 wherein:
said rigid frame extends at an incline of more than 100 to the vertical and to the horizontal as viewed along a lateral direction; and including
a plurality of rigid pipe members spaced in said lateral direction along said frame, one of said rigid pipe member comprising at least a portion of said conduit lower portion; a plurality of flexible conduit elements, including said flexible conduit member, having lower ends extending from said pipe members and having upper ends coupled to said floating structure.
- 13. The system described in claim 8 wherein:
said rigid frame extends above the seafloor by at least 20% of said sea depth.
- 14. An offshore fluid transfer system that lies in a sea of predetermined depth for transferring fluid between a fluid-carrying seafloor structure that lies at the seafloor and a floating structure that floats at the sea surface and that is compliantly anchored to remain in the vicinity of the seafloor structure, the system including a conduit comprising a flexible conduit member that extends along much of the sea depth, said conduit having upper and lower ends coupled respectively to said floating structure and to said seafloor structure, comprising:
a rigid frame having a lower end fixed to the seafloor and an upper portion extending above the seafloor; and wherein
said frame has an upper surface and said flexible conduit member has a lower portion that rests on said upper surface and that is free to lift off and fall back onto said upper surface.
- 15. The system described in claim 14 wherein:
said upper surface has a portion of a length of over one meter that faces primarily upwardly.
- 16. The system described in claim 14 wherein:
said upper surface is convex with a radius of curvature of more than one meter.
CROSS-REFERENCE TO RELATED APPLICATION
[0001] Applicant claims priority from U.S. provisional application No. 60/352,751 filed Jan. 30, 2002.
Provisional Applications (1)
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Number |
Date |
Country |
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60352751 |
Jan 2002 |
US |