# US 12,006,776 B2 · Installation of subsea risers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,006,776 B2 - Document ID: US12006776B2 - Status: Granted - Kind: B2 - Application number: 17/604,291 - Filed: 2020-04-15 - Published: 2022-06-23 - Granted: 2024-06-11 - Earliest claimed: 2019-04-16 - Assignees: Subsea 7 do Brasil Servicos Ltda - Applicants: Subsea 7 do Brasil Servicos Ltda - Inventors: Andre Ramiro Amorim; Davi Couto Neves Junior; Alberto Lima Dos Santos; Mauricio Suarez de Oliveira - Web page: https://patentgrep.com/patent/US12006776B2 ## CPC - E21B 17/012: {with buoyancy elements (E21B17/015 takes precedence)} - B63B 35/03: Pipe-laying vessels (laying pipes under water F16L1/12) - E21B 17/015: {Non-vertical risers, e.g. articulated or catenary-type} - E21B 19/004: {supporting a riser from a drilling or production platform} - E21B 43/0107: {Connecting of flow lines to offshore structures (E21B43/013 takes precedence)} - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - B63B: SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING (arrangements of vessel ventilation, heating, cooling, or air-conditioning B63J2/00; floating substructures as supports of dredgers or soil-shifting machines E02F9/06) ## Abstract A method of installing a wave-configuration subsea riser of unbonded flexible pipe comprises lowering the riser progressively into the sea from an installation vessel while suspending an elongate clump weight in a catenary shape that comprises first and 5 second limbs extending upwardly from a conjoining bottom portion. An upper end of the first limb, at a distal end of the clump weight, is attached to the riser and an upper end of the second limb, at a proximal end of the clump weight, is suspended from a winch or crane of the vessel. While lowering the riser from the vessel, the weight load applied to the riser by the clump weight is controlled by adjusting the relative lengths of the first 0 and second limbs of the clump weight. ## Claims ### Claim 1 A method of installing a wave-configuration subsea riser, the method comprising: suspending the riser from an installation vessel; suspending an elongate clump weight in a catenary shape comprising first and second limbs extending upwardly from a conjoining bottom portion, with an upper end of the first limb, at a distal end of the clump weight, being attached to the riser and an upper end of the second limb, at a proximal end of the clump weight, being suspended from a winch or crane of the installation vessel; and while lowering the riser progressively into the sea from the installation vessel, controlling a weight load applied by the clump weight to the riser by adjusting relative lengths of the first and second limbs of the clump weight; the method further comprising attaching buoyancy modules to a hogbend portion of the riser aboard the installation vessel. ### Claim 2 (depends on 1) The method of claim 1, comprising using the winch or crane to adjust the relative lengths of the first and second limbs. ### Claim 3 (depends on 1) The method of claim 1, comprising adjusting the relative lengths of the first and second limbs by adjusting relative lowering speeds of the riser and of the upper end of the second limb. ### Claim 4 (depends on 1) The method of claim 1, comprising bending the clump weight along its length around a curve that defines the bottom portion. ### Claim 5 (depends on 4) The method of claim 4, comprising bending the clump weight by articulation between links of the clump weight. ### Claim 6 (depends on 1) The method of claim 1, comprising attaching the distal end of the clump weight to the riser. ### Claim 7 (depends on 6) The method of claim 6, comprising attaching the distal end of the clump weight to the riser via a collar of the riser. ### Claim 8 (depends on 1) The method of claim 1, further comprising submerging the hogbend portion, carrying the buoyancy modules, under tension in the riser applied to the riser by the first limb of the clump weight. ### Claim 9 (depends on 8) The method of claim 8, comprising reducing tension in the riser by shortening the first limb of the clump weight, allowing buoyant upthrust of the submerged buoyancy modules along the hogbend portion to form a hogbend in the riser. ### Claim 10 (depends on 1) The method of claim 1, comprising attaching the distal end of the clump weight to the riser beneath the buoyancy modules that are attached to the hogbend portion of the riser. ### Claim 11 (depends on 1) The method of claim 1, comprising laying the riser on the seabed continuously while varying the weight load applied to the riser by the clump weight. ### Claim 12 (depends on 1) The method of claim 1, comprising adjusting the relative lengths of the first and second limbs by adjusting relative levels of the distal and proximal ends of the clump weight. ### Claim 13 (depends on 1) The method of claim 1, wherein the installation vessel supports the full weight load of the clump weight before, during and after attachment of the clump weight to the riser. ### Claim 14 (depends on 13) The method of claim 13, wherein the clump weight is lowered from and recovered to the installation vessel using the winch or crane of the installation vessel. ### Claim 15 (depends on 1) The method of claim 1, further comprising detaching the clump weight from the riser and recovering the clump weight to the installation vessel.