Gripper assembly for a coiled tubing injector

Abstract

A gripper assembly for a coiled tubing injector is provided. The assembly comprises a gripper block coupled to a carrier at a working position using complementary mating structures. The assembly further comprises a releasable locking structure which secures the gripper block to the carrier at the working position and prevents displacement of the gripper block from the carrier during operation. In a locking position of the locking structure, at least one component of the locking structure extends between the carrier and the gripper block to contact a receiving component in the carrier or the gripper block for preventing decoupling of the gripper block from the working position. A release tool for actuating the locking structure to a released position for disengaging the gripper block from the carrier is also provided.

The embodiments of the invention for which an exclusive property or privilege is claimed are defined as follows: 
     
         1 . A gripper assembly for use in a coiled tubing injector for injecting and withdrawing a length of coiled tubing into and from a well along a moving direction, the gripper assembly comprising:
 a carrier having a mounting surface and a back surface, the carrier being driveably mounted to a gripper chain at the back surface thereof;   a gripper block having a gripping surface for receiving the coiled tubing and an attachment surface;   a sliding joint between the carrier's mounting surface and the gripper block's attachment surface and extending transverse to the moving direction, the gripper block slidable along the sliding joint for coupling the gripper block at a working position within the carrier for gripping the coiled tubing; and   one or more releasable locking pins, each locking pin having a corresponding recess, each locking pin and corresponding recess aligned between the carrier and the gripper block for extension of the locking pin to a locking position for securing the gripper block from decoupling from the working position.   
     
     
         2 . The gripper assembly of  claim 1 , wherein the sliding joint comprises complementary mating structures supported at the carrier's mounting surface and the gripper block's attachment surface. 
     
     
         3 . The gripper assembly of  claim 2 , wherein the corresponding mating structures comprise male and female sliding joints supported at the carrier's mounting surface and the gripper block's attachment surface. 
     
     
         4 . The gripper assembly of  claim 2 , wherein the corresponding mating structures comprise a first dovetail joint portion supported at the carrier's mounting surface and a second dovetail joint portion supported at the gripper block's attachment surface, the second dovetail joint portion cooperating with the first dovetail portion for coupling the gripper block at the working position. 
     
     
         5 . The gripper assembly of  claim 1 , wherein the gripper block further comprises the one or more recesses; and the carrier further comprises one or more pin bores extending into the mounting surface for holding the one or more locking pins, and wherein, in the locking position, the one or more locking pins extend into the one or more recesses, and in the released position the one or more locking pins are retracted from the one or more recesses into the mounting surface. 
     
     
         6 . The gripper assembly of  claim 1 , wherein the gripper block further comprises one or more release passages, extending from the gripping surface to a corresponding recess in the attachment surface, for enabling actuation of the locking pin from the extended, locking position to the retracted, released position. 
     
     
         7 . The gripper assembly of  claim 6 , wherein the locking pin is actuated from the extended, locking position to the retracted, released position using a release tool cooperating with the one or more release passages to displace the locking pin out of the corresponding recess and into the mounting surface. 
     
     
         8 . The gripper assembly of  claim 1 , wherein the gripper block comprises the one or more locking pins and, in the locking position, the one or more locking pins retractably extend through pin bores provided in the gripper block's attachment surface to engage the corresponding recesses to the released position. 
     
     
         9 . The gripper assembly of  claim 8 , wherein the one or more locking pins are actuated from the locking position to the released position using a release tool cooperating with the one or more pin bores to displace the one or more locking pins out of the corresponding recesses and into the one or more pin bores. 
     
     
         10 . The gripper assembly of  claim 1 , wherein each locking pin is biased to the extended locking position. 
     
     
         11 . A coiled tubing injector comprising a pair of opposing gripper chains; and a plurality of gripper assemblies of  claim 1  driven by the pair of gripper chains for running a length of coiled tubing into or from the well along the moving direction. 
     
     
         12 . A method for releasably securing a gripper block to a carrier driven by a coiled tubing injector, the method comprising:
 coupling the gripper block at a working position within the carrier by slidably engaging complementary mating structures between the gripper block and the carrier;   aligning at least one recess in one of the gripper block and the carrier with at least one locking pin extending from the other of the carrier and the gripper block;   engaging each locking pin with a corresponding recess for securing the gripper block from decoupling from the working position.   
     
     
         13 . The method of  claim 12 , wherein the coupling step further comprises:
 installing one or more of the locking pins through one or more pin bores in a mounting surface of the carrier;   sliding an attachment surface of the gripper block along the carrier's mounting surface, sliding movement actuating the one or more locking pins into a retracted, released position within the one or more pin bores and between the gripper block's attachment surface and the carrier's mounting surface, and allowing the complementary mating structures to cooperate and engage for coupling the gripper block at the working position, the coupling aligning the one or more pin bores with one or more recesses provided on the gripper block's attachment surface for engagement with the one or more recesses for securing the gripper block at the working position.   
     
     
         14 . A release tool for disengaging a gripper block secured to a carrier of a gripper assembly of  claim 1 , the tool comprising:
 a frame, the frame having a handle and a base configured to be supported in a stationary position on the gripper block;   one or more projections extending out from the base, the one or more projections configured and spaced to operatively engage with the one or more locking pins extending through the gripper block for actuating the one or more locking pins into their released position to allow the gripper block to slide out of the carrier.   
     
     
         15 . The release tool of  claim 14 , wherein the one or more projections engage with the one or more locking pins through one or more release passages extending from the gripping surface to its corresponding recess in the attachment surface. 
     
     
         16 . The release tool of  claim 15 , wherein diameter of the one or more projections is smaller than the one or more release passages to enable entry of the one or more projections into the one or more release passages. 
     
     
         17 . The release tool of  claim 16 , wherein a height of the one or more projections is substantially equal to a height of the gripper block. 
     
     
         18 . A method for disengaging a gripper block secured to a carrier mounted on a gripper chain of a coiled tubing injector using a release tool, the method comprising:
 supporting a base of the release tool on the gripper block using a handle of the release tool to disengage the gripper block from the carrier, the gripper block being coupled and secured at a working position within the carrier using one or more locking pins extending between the gripper block and the carrier and extending through an attachment surface of the gripper block;   pushing the release tool using the handle to enable one or more projections extending out from the base to contact and displace the one or more releasable locking pins extending through the attachment surface into a retracted, released position which enables disengagement of the gripper block from the carrier; and   lifting the disengaged gripper block off the carrier using the handle.   
     
     
         19 . The method of  claim 18 , wherein before securement, the gripper block is coupled at the working position by aligning and engaging complementary mating structures supported at a mounting surface of the carrier and the gripper block's attachment surface and wherein the disengagement step further comprises misaligning and disengaging the complementary mating structures before lifting the disengaged gripper block.