# US 2019/0169983 A1 · Subsea isolation sleeve system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0169983 A1 - Document ID: US20190169983A1 - Status: Published application - Kind: A1 - Application number: 15/833,013 - Filed: 2017-12-06 - Published: 2019-06-06 - Earliest claimed: 2017-12-06 - Assignees: OneSubsea IP UK Limited - Applicants: OneSubsea IP UK Limited - Inventors: Joshua Pollak; Claudio Santilli - Web page: https://patentgrep.com/patent/US20190169983A1 ## CPC - E21B 47/117: Detecting leaks, e.g. from tubing, by pressure testing - E21B 17/042: Threaded - E21B 33/035: specially adapted for underwater installations (E21B33/043, E21B33/064, E21B33/076 take precedence) - E21B 47/001: for underwater installation - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract A technique facilitates pressure testing of a seal positioned between a wellhead and a subsea tree system. The technique utilizes an isolation sleeve which may comprise a mandrel having an internal mandrel passage as well as a lower seal and an upper seal positioned along an exterior of the mandrel. The isolation sleeve also may comprise a retention member mounted along the exterior of the mandrel. The retention member, e.g. a retention nut, may be rotatably mounted about the exterior of the mandrel and may comprise external threads or other mechanism for securing the isolation sleeve to the subsea tree system. In some embodiments, the upper end of the isolation sleeve may be constructed in a uniform manner for insertion into a universal profile of the subsea tree system. ## Claims ### Claim 1 A system for use in a subsea operation, comprising: a wellhead having an internal wellhead passage; a subsea tree system having an internal passage, the subsea tree system being sealably coupled with the wellhead via a seal; and an isolation sleeve extending from the internal passage of the subsea tree system into the internal wellhead passage to facilitate pressure testing of the seal, the isolation sleeve comprising: a mandrel formed as a single, continuous structure having an internal mandrel passage; a lower seal position along an exterior of the mandrel for sealing engagement with the wellhead; an upper seal positioned along the exterior of the mandrel for sealing engagement with the subsea tree system; and a retention nut mounted along the exterior of the mandrel between the upper seal and the lower seal, the retention nut being threadably engaged with the subsea tree system along the internal passage. ### Claim 2 (depends on 1) The system as recited in claim 1, wherein the subsea tree system comprises a Christmas tree, the retention nut being threadably engaged with the Christmas tree. ### Claim 3 (depends on 1) The system as recited in claim 1, wherein the subsea tree system comprises a tubing head spool, the retention nut being threadably engaged with the tubing head spool. ### Claim 4 (depends on 1) The system as recited in claim 1, wherein the lower seal has a larger diameter than the upper seal. ### Claim 5 (depends on 1) The system as recited in claim 1, wherein the upper seal has a larger diameter than the lower seal. ### Claim 6 (depends on 1) The system as recited in claim 1, wherein the retention nut is slid onto the mandrel along the exterior of the mandrel and contained by at least one of an upper mandrel abutment and a lower mandrel abutment. ### Claim 7 (depends on 6) The system as recited in claim 6, wherein the upper mandrel abutment comprises a split ring. ### Claim 8 (depends on 6) The system as recited in claim 6, wherein the lower mandrel abutment comprises a split ring. ### Claim 9 (depends on 1) The system as recited in claim 1, wherein the lower seal and the upper seal are secured in place along the mandrel via a lower seal retainer and an upper seal retainer, respectively. ### Claim 10 A method, comprising: providing a subsea tree system with an internal passage having a universal profile arranged to interchangeably receive a plurality of different types of isolation sleeves; forming the universal profile with a universal seal region and a universal retention member region; selecting an isolation sleeve having a universal upper end and a lower end constructed for engagement with a designated wellhead of a plurality of different types of wellheads having wellhead passages of different configurations; and sealably retaining the universal upper end within the universal profile. ### Claim 11 (depends on 10) The method as recited in claim 10, wherein selecting the desired isolation sleeve comprises selecting an isolation sleeve having a lower seal of lesser diameter than an upper seal. ### Claim 12 (depends on 10) The method as recited in claim 10, wherein selecting the desired isolation sleeve comprises selecting an isolation sleeve having an upper seal of lesser diameter than a lower seal. ### Claim 13 (depends on 10) The method as recited in claim 10, wherein sealably retaining comprises rotating a retention nut, mounted along a mandrel of the isolation sleeve, to threadably engage the universal retention member region of the universal profile. ### Claim 14 (depends on 10) The method as recited in claim 10, wherein providing comprises providing a subsea Christmas tree with the universal profile. ### Claim 15 (depends on 10) The method as recited in claim 10, wherein providing comprises providing a tubing head spool with the universal profile. ### Claim 16 A system, comprising: an isolation sleeve for subsea pressure testing, the isolation sleeve comprising: a mandrel having an internal mandrel passage; a lower seal position along an exterior of the mandrel; an upper seal positioned along the exterior of the mandrel; and a retention member positioned along the exterior of the mandrel and slidable along the exterior of the mandrel, the retention member being constructed for secure engagement with a subsea tree system. ### Claim 17 (depends on 16) The system as recited in claim 16, wherein the retention member is rotatably positioned adjacent an abutment along the mandrel, the retention member having external threads oriented for threaded engagement with a subsea tree system. ### Claim 18 (depends on 17) The system as recited in claim 17, wherein the retention member comprises a retention mechanism to resist unthreading of the retention member after being threadably engaged with the subsea tree system. ### Claim 19 (depends on 16) The system as recited in claim 16, wherein the lower seal has a larger diameter than the upper seal. ### Claim 20 (depends on 16) The system as recited in claim 16, wherein the upper seal has a larger diameter than the lower seal.