Multi-vessel process to install and recover subsea equipment packages
AssigneeSafe Marine Transfer, LLC
InventorsJames E. Chitwood, Art J. Schroeder, Jr., Jason C. Mailand, Timothy T. Krasin
Life of this patent
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Abstract
According to one or more embodiments disclosed herein is a method of transporting equipment between sea-surface and seafloor by providing a structure with a subsea equipment package mounted thereon. The structure is used for installation and recovery in a subsea environment by changing the buoyancy of the structure or ballasting the structure to effect a controlled sinking motion.
Claims28
A process for lowering a subsea equipment package to the seafloor, the process comprising:
- towing the subsea equipment package to sea, via one or more vessels, on a sea surface;
- attaching a plurality of vessels via cable and weighted line to corresponding landing points of the subsea equipment package;
- paying out an amount of the cables from the plurality of vessels;
- tensioning the cables forming a catenary shape in the weighted line;
- adjusting a length of the weighted catenary cable such that a vertical buoyant force of the subsea equipment package will be overcome by the weight of the weighted line causing the subsea equipment package to sink while maintaining the catenary shape;
- controlling a position of the subsea equipment package as the subsea equipment package is lowered toward a sea floor;
- landing the subsea equipment package directly on the sea floor.
A process for lowering a subsea equipment package to the seafloor, the process comprising:
- towing the subsea equipment package to sea, via one or more vessels, on a sea surface;
- attaching a plurality of vessels via cable and weighted line to corresponding landing points of the subsea equipment package;
- paying out an amount of the cables from the plurality of vessels to increase the overall system compliance to vessel motion;
- tensioning the cables forming a catenary shape in the weighted line;
- decreasing buoyancy of the subsea equipment package to lower the subsea equipment package to below the sea surface;
- controlling the vessel position, spacing, thrust, and catenary shape on the subsea equipment package to maintain system compliance as the subsea equipment package is lowered toward the sea floor;
- positioning the subsea equipment package on the sea floor.
A process for lowering a positively buoyant subsea equipment package to the seafloor, the process comprising:
- towing the subsea equipment package to sea, via one or more vessels, on a sea surface;
- attaching a plurality of vessels via cables and weighted line to corresponding landing points of the positively buoyant subsea equipment package;
- paying out an amount of a linear, or non-linear, weighted line from the plurality of vessels to overcome the residual subsea equipment package buoyancy and increase the overall system compliance to vessel motions;
- adjusting buoyancy or ballast of the subsea equipment package to partial sink the subsea equipment package;
- controlling a vessel position, spacing, thrust, and cable tension on the subsea equipment package to maintain system compliance as the subsea equipment package is lowered toward the sea floor;
- completely landing the subsea equipment package on the sea floor.
Dependencies are inferred from the claim text.