# US 2008/0185152 A1 · Pressure control with compliant guide > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0185152 A1 - Document ID: US20080185152A1 - Status: Published application - Kind: A1 - Application number: 11/671,696 - Filed: 2007-02-06 - Published: 2008-08-07 - Earliest claimed: 2007-02-06 - Assignees: Schlumberger Technology Corporation - Inventors: Andrea Sbordone; Eric Smedstad; Rene Schuurman; Alan Johnston; Axel Destremau; Yves Le Moign - Web page: https://patentgrep.com/patent/US20080185152A1 ## CPC - E21B 33/076: specially adapted for underwater installations - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract A technique for subsea intervention operations enables pressure control to be accomplished at the surface while borehole fluid control is exercised at the seabed. A compliant guide extends between a subsea well installation and a surface location, such as a surface intervention vessel. A buffer fluid is deployed within the compliant guide to maintain the borehole fluids proximate the seabed. The buffer fluid also enables pressure control over the buffer fluid and the borehole fluid to be performed from the surface. Additionally, a flexible conveyance can be used to move intervention tools through the compliant guide. ## Claims ### Claim 1 A method of controlling pressure during a subsea intervention operation, comprising: filling a spoolable compliant guide with a buffer fluid; connecting the spoolable compliant guide between a surface vessel and a wellhead of a subsea well; deploying a dynamic seal proximate a lower end of the spoolable compliant guide; adjusting pressure of the buffer fluid until the dynamic seal is effective in isolating the buffer fluid from a borehole fluid in the subsea well; and opening the subsea well for an intervention operation. ### Claim 2 (depends on 1) The method as recited in claim 1, wherein connecting comprises connecting the spoolable compliant guide to subsea blowout preventer. ### Claim 3 (depends on 1) The method as recited in claim 1, wherein deploying comprises deploying the dynamic seal between the wellhead and the lower end of the spoolable compliant guide. ### Claim 4 (depends on 1) The method as recited in claim 1, wherein deploying comprises deploying the dynamic seal through the spoolable compliant guide with a tool string. ### Claim 5 (depends on 1) The method as recited in claim 1, wherein filling comprises filling the spoolable compliant guide with seawater. ### Claim 6 (depends on 1) The method as recited in claim 1, wherein adjusting comprises adjusting the pressure of the buffer fluid at a surface location on the surface vessel. ### Claim 7 (depends on 1) The method as recited in claim 1, further comprising deploying a tool string conveyance through the dynamic seal. ### Claim 8 (depends on 7) The method as recited in claim 7, further comprising performing an intervention operation; removing the tool string from the subsea well; and closing the well. ### Claim 9 (depends on 1) The method as recited in claim 1, wherein connecting comprises connecting the spoolable compliant guide to the wellhead through a subsea lubricator and subsea blowout preventer stack. ### Claim 10 A method, comprising: deploying a compliant guide between a subsea well installation and a surface vessel; maintaining borehole fluids at the seabed with a buffer fluid disposed in the compliant guide; and adjusting the pressure of the buffer fluid at the surface vessel. ### Claim 11 (depends on 10) The method as recited in claim 10, further comprising performing a well intervention operation beneath the subsea well installation in a subsea well. ### Claim 12 (depends on 11) The method as recited in claim 11, wherein performing comprises delivering a tool string into the subsea well via a conveyance routed through the compliant guide. ### Claim 13 (depends on 12) The method as recited in claim 12, wherein delivering comprises delivering the tool string via a cable-type conveyance. ### Claim 14 (depends on 12) The method as recited in claim 12, further comprising forming a seal with the conveyance proximate a lower end of the compliant guide. ### Claim 15 (depends on 10) The method as recited in claim 10, further comprising introducing seawater into the compliant guide to serve as the buffer fluid. ### Claim 16 (depends on 10) The method as recited in claim 10, wherein deploying the compliant guide comprises deploying a spoolable compliant guide. ### Claim 17 A system, comprising: a compliant guide disposed between a surface location and a subsea installation deployed on the seabed; a buffer fluid within the compliant guide to maintain borehole fluids at the seabed; and a pressure control located at the surface to control the pressure of the buffer fluid. ### Claim 18 (depends on 17) The system as recited in claim 17, further comprising a dynamic seal positioned proximate a lower end of the compliant guide between the borehole fluids and the buffer fluid. ### Claim 19 (depends on 18) The system as recited in claim 18, further comprising an upper dynamic seal positioned proximate an upper end of the compliant guide. ### Claim 20 (depends on 17) The system as recited in claim 17, wherein the compliant guide comprises a spoolable compliant guide. ### Claim 21 (depends on 17) The system as recited in claim 17, wherein the subsea installation comprises a lubricator positioned above a blowout preventer. ### Claim 22 (depends on 18) The system as recited in claim 18, further comprising a tool string coupled to a cable-type conveyance that extends through the compliant guide. ### Claim 23 A method, comprising: performing an intervention operation in a subsea well with a well tool coupled to a conveyance; forming a seal around the conveyance with a dynamic seal located proximate a subsea installation; and maintaining borehole fluids below the dynamic seal via a buffer fluid contained in a spoolable compliant guide. ### Claim 24 (depends on 23) The method as recited in claim 23, further comprising controlling the pressure of the buffer fluid from a surface location. ### Claim 25 (depends on 23) The method as recited in claim 23, wherein forming comprises forming a seal around a cable-type conveyance. ### Claim 26 (depends on 23) The method as recited in claim 23, wherein maintaining comprises using seawater as the buffer fluid. ### Claim 27 (depends on 23) The method as recited in claim 23, further comprising coupling the spoolable compliant guide to a surface vessel.