# US 9,038,731 B2 · Workover riser compensator system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,038,731 B2 - Document ID: US9038731B2 - Status: Granted - Kind: B2 - Application number: 14/246,831 - Filed: 2014-04-07 - Published: 2014-11-20 - Granted: 2015-05-26 - Earliest claimed: 2006-07-06 - Assignees: Enovate Systems Limited - Applicants: Enovate Systems Limited - Inventors: Jeffrey Edwards - Web page: https://patentgrep.com/patent/US9038731B2 ## CPC - E21B 41/0007: {for underwater installations (E21B41/005, E21B41/04, E21B41/06, E21B41/08, E21B41/10 take precedence)} - E21B 17/085: {Riser connections (connectors for wellhead E21B33/038)} - E21B 19/006: {including heave compensators} - E21B 33/038: Connectors used on well heads, e.g. for connecting blow-out preventer and riser - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract A tensioning apparatus for applying a substantially constant tension to a workover riser (12) includes a first portion (40) adapted to be coupled to a workover riser, a second portion (44) adapted to be coupled to a marine riser (14) and tensioning means (46) for providing relative movement between the first portion and the second portion to, in use, tension the workover riser. ## Claims ### Claim 1 A latch device for separating a workover riser from a sub sea isolation system in the event of over-tensioning of the workover riser, the latch device comprising: a first latch portion adapted to be connected to the sub sea isolation system; a second latch portion adapted to be connected to the workover riser, the second latch portion being moveable relative to the first portion from an operating configuration to a released configuration; a latch releasably connecting the first portion to the sub sea isolation system, the latch being movable between an engaged position in which the latch is engaged with the sub sea isolation system and a disengaged position in which the latch is disengaged from the subsea isolation system; wherein, in use, when the tension in the workover riser exceeds a pre-determined value, relative movement of the second latch portion with respect to the first latch portion from the operating configuration to a displaced configuration permits the latch to move from the engaged position to the disengaged position, releasing the latch device from the sub sea isolation system such that the workover riser is separated from the sub sea isolation system wherein the second portion moves relative to the first portion at a pre-determined tension which is selected, in use, to ensure that riser tensioning device will raise the workover riser clear of a plurality of subsea isolation system BOP rams, permitting unobstructed closure of the rams. ### Claim 2 (depends on 1) The latch device of claim 1, wherein the latch device is adapted to receive a sub sea isolation system control. ### Claim 3 (depends on 2) The latch device of claim 2, wherein the sub sea isolation system control is a control line. ### Claim 4 (depends on 3) The latch device of claim 3, wherein the latch device includes a control passage adapted to provide communication between the control line and the sub sea isolation system. ### Claim 5 (depends on 4) The latch device of claim 4, wherein a first section of the control passage is defined by the first latch portion, and a second section of the control passage is defined by the second latch portion. ### Claim 6 (depends on 4) The latch device of claim 4, wherein when the second latch portion moves relative to the first latch portion, the control passage is broken, causing, in use, the sub sea isolation system to close. ### Claim 7 (depends on 4) The latch device of claim 4, wherein the control passage is a hydraulic line. ### Claim 8 (depends on 4) The latch device of claim 4, wherein the control passage is a hydraulic conduit providing, in use, fluid communication between the sub sea isolation system hydraulic control line and the sub sea isolation system. ### Claim 9 (depends on 1) The latch device of claim 1, wherein in use, when the workover riser separates from the sub sea isolation system, a workover riser retainer valve closes. ### Claim 10 (depends on 1) The latch device of claim 1, wherein the latch device further includes a guide that compensates for the pressure end load force applied to the workover riser by well pressure. ### Claim 11 A latch device for separating a workover riser from a sub sea isolation system in the event of over-tensioning of the workover riser, the latch device comprising: a first latch portion adapted to be connected to the sub sea isolation system; a second latch portion adapted to be connected to the workover riser, the second latch portion being moveable relative to the first portion from an operating configuration to a released configuration; a latch releasably connecting the first portion to the sub sea isolation system, the latch being movable between an engaged position in which the latch is engaged with the sub sea isolation system and a disengaged position in which the latch is disengaged from the subsea isolation system; wherein, in use, when the tension in the workover riser exceeds a pre-determined value, relative movement of the second latch portion with respect to the first latch portion from the operating configuration to a displaced configuration permits the latch to move from the engaged position to the disengaged position, releasing the latch device from the sub sea isolation system such that the workover riser is separated from the sub sea isolation system, wherein the latch device further includes a piston and a piston chamber, the piston being adapted to reciprocate within the piston chamber to compensate for the pressure end load force applied to the workover riser by well pressure. ### Claim 12 (depends on 11) The latch device of claim 11, wherein the piston chamber is adapted to receive a fluid. ### Claim 13 (depends on 12) The latch device of claim 12, wherein the piston chamber is adapted to receive fluid, in use, from the workover riser. ### Claim 14 (depends on 12) The latch device of claim 12, wherein the piston chamber is adapted to receive a fluid at well pressure. ### Claim 15 (depends on 12) The latch device of claim 12, wherein in use, the introduction of fluid into the piston chamber results in an increase in pressure in the piston chamber. ### Claim 16 (depends on 15) The latch device of claim 15, wherein an increase in piston chamber pressure acts on the piston. ### Claim 17 (depends on 16) The latch device of claim 16, wherein the pressure applied to the piston is, in turn, applied by the piston, in use, to the workover riser as a counter force, the counter force opposing the end load force. ### Claim 18 (depends on 17) The latch device of claim 17, wherein the counter force applied, in use, by the piston to the workover riser is proportional to the end load force. ### Claim 19 (depends on 11) The latch device of claim 11, wherein the area of the compensation piston is between 75-95% of the area of the latch.