Retrieving a subsea tree plug

Abstract

A method for riserless intervention of a subsea well includes: lowering a pressure control assembly (PCA) from a vessel to a subsea production tree; fastening the PCA to the tree; deploying a plug running tool (PRT) into the PCA, wherein the PRT comprises a latch, an anchor, and a stroker; engaging the latch with a plug of the tree; engaging the anchor with the PCA; and operating the stroker to pull the latch and the plug from the tree.

1  A method for riserless intervention of a subsea well, comprising:
 lowering a pressure control assembly (PCA) from a vessel to a subsea production tree; 
 fastening the PCA to the tree; 
 deploying a plug running tool (PRT) into the PCA, wherein the PRT comprises a latch, an anchor, and a stroker; 
 engaging the latch with a plug of the tree; 
 engaging the anchor with the PCA; and 
 operating the stroker to pull the latch and the plug from the tree. 
 
     
     
         2 . The method of  claim 1 , wherein:
 the PRT further comprises a jar, and   the method further comprises operating the jar as the stroker pulls the latch and the plug, thereby jarring the latch and the plug.   
     
     
         3 . The method of  claim 2 , wherein:
 the jar is a vibratory jar, and   the latch and the plug are repeatedly jarred at a frequency greater than or equal to one cycle per second.   
     
     
         4 . The method of  claim 1 , further comprising:
 retrieving the PRT and plug to the vessel;   deploying a second PRT carrying a tree saver into the PCA; and   connecting the tree saver to the tree using the second PRT.   
     
     
         5 . The method of  claim 1 , wherein:
 the PRT is deployed from the vessel using a workstring,   the PRT carries a workstring module during deployment, and the PRT is deployed by:
 fastening the workstring module to the PCA; and 
 engaging a seal of the workstring module with the workstring. 
   
     
     
         6 . The method of  claim 5 , further comprising:
 washing the plug and PRT within the workstring module and PCA with a hydrates inhibitor;   releasing the workstring module from the PCA; and   retrieving the workstring module, the washed PRT, and the washed plug to the vessel.   
     
     
         7 . The method of  claim 5 , further comprising, before operation of the PRT:
 slacking the workstring; and   moving the vessel a safe distance from the tree.   
     
     
         8 . The method of  claim 5 , further comprising:
 releasing the workstring module from the PCA;   retrieving the workstring module, the PRT, and the plug to the vessel;   deploying an intervention bottomhole assembly (BHA) from the vessel using a second workstring, the BHA carrying a second workstring module;   fastening the second workstring module to the PCA;   engaging a seal of the second workstring module with the second workstring; and   deploying the BHA into the wellbore.   
     
     
         9 . A plug running tool (PRT) for riserless intervention of a subsea well, comprising:
 a cablehead for connection to a wireline;   a hydraulically operated anchor connected to the cablehead;   a hydraulically operated stroker comprising a housing and a shaft, the housing connected to the anchor;   an electric pump connected to the cablehead for operating the stroker and the anchor; and   a latch connected to the shaft and comprising a gripper and an actuator operable to lock and release the gripper,   wherein the PRT is tubular.   
     
     
         10 . The PRT of  claim 9 , further comprising a jar comprising a housing connected to the shaft and a knocker connected to the latch. 
     
     
         11 . The PRT of  claim 10 , wherein:
 the jar further comprises a valve and a hammer, and   the valve is operable to reciprocate the hammer in response to hydraulic fluid pumped through the jar.   
     
     
         12 . A system for riserless intervention of a subsea well, comprising:
 the PRT of  claim 9 ; and   a wireline module, comprising:
 a bore formed therethrough; 
 an adapter having a connector for fastening the wireline module to a pressure control assembly (PCA) and a seal face for engaging the PCA; 
 a tool catcher connected to the adapter and operable to receive the cablehead; 
 a frame connected to the adapter; 
 a stuffing box connected to the tool catcher and comprising a seal and an actuator operable to engage and disengage the seal with/from the wireline; and 
 a grease injector connected to the stuffing box and operable to lubricate the wireline; 
 a grease pump connected to the frame and in fluid communication with the grease injector; 
 a grease reservoir connected to the frame and in fluid communication with the grease pump. 
   
     
     
         13 . The system of  claim 12 , wherein the wireline module further comprises:
 a fluid sub connected to the tool catcher and having a port in communication with the bore; and   an isolation valve connected to the fluid sub and operable to close the bore.   
     
     
         14 . The system of  claim 12 , wherein the wireline module further comprises:
 a control relay connected to the frame and operable to interface with a control pod of the PCA; and   a manifold connected to the frame and operable to interface with a manifold of the PCA.   
     
     
         15 . The system of  claim 12 , further comprising:
 the PCA, comprising:
 a bore formed therethrough; 
 a production tree adapter having a connector for fastening the PCA to a subsea production tree and a seal sleeve for engaging an internal profile of the tree; 
 a frame connected to the adapter; 
 a fluid sub connected to the adapter and having a port in communication with the bore; 
 an isolation valve connected to the fluid sub and operable to close the bore; 
 a blow out preventer (BOP) connected to the isolation valve and operable to shear the wireline and close the bore; 
 an accumulator for storing pressurized hydraulic fluid to operate the BOP; 
 a tool housing connected to the BOP; 
 a control pod receptacle connected to the frame for receiving a control pod; and 
 a manifold connected to the frame for receiving a fluid conduit from a vessel.