Pulling clamp for continuous rod or coiled tubing strings

Abstract

A pulling clamp is provided for releasable connection to a blunt, uphole string end of a continuous string. A main clamp body has clamp bore therethrough and having a string-receiving opening at the pulling end for receiving the string end, an actuating bore at the pulled end and a tapered bore therebetween. A taper insert having a radially compressible gripping bore is locatable in the tapered bore and axially actuable between a passive first receiving position, for receiving the string end, and the active second gripping position for radially compressing the taper insert about the string end for actively gripping the string end therein. The taper insert can be axially actuated using a threaded main body and threaded top cap for sandwiching the taper insert therebetween, the top cap being threaded axially into and out of the pulled end of the main body between the passive and active positions.

1 . A pulling clamp for connection to a blunt, uphole string end of a continuous string comprising:
 a main body having a lower pulling end and an upper pulled end, the main body having a clamp bore formed therethrough, the clamp bore comprising a string-receiving opening at the pulling end for receiving the string end, an actuating bore at the pulled end and a tapered bore therebetween;   a taper insert having a compressible gripping bore; and   a top cap engageable with the actuating bore, the top cap being axially movable between passive and active positions to actuate the taper insert between a first receiving position and second gripping position respectively, wherein
 in the first receiving position, the gripping bore receives the string end and is passively uncompressed thereabout; and 
 in the second gripping position, the top cap axially engages the taper insert for driving the taper insert axially into the tapered bore for radially compressing the taper insert about the string end for actively gripping the string end therein. 
   
     
     
         2 . The pulling clamp of  claim 1  wherein:
 the actuating bore is threaded; and 
 the top cap is threaded for threading axially into and out of the pulled end of the main body between the passive and active positions. 
 
     
     
         3 . The pulling clamp of  claim 1  wherein in the second gripping position the gripping bore is compressed to a gripping diameter smaller than a diameter of the received string end. 
     
     
         4 . The pulling clamp of  claim 1  wherein the taper insert further comprises an upper driven shoulder and the top cap further comprises a lower driving shoulder, the lower driving shoulder engaging the upper driven shoulder upon axial movement of the top cap into the actuating bore for actuating the top cap and taper insert to the second gripping position. 
     
     
         5 . The pulling clamp of  claim 1  wherein, in the second gripping position, the string-receiving opening has an effective diameter smaller than a combined diameter of the taper insert and the string end. 
     
     
         6 . The pulling clamp of  claim 1  further comprising a lock releasably actuable between the top cap and the main body, for locking engagement between the driving shoulder of the top cap and the driven shoulder of the taper insert in the second gripping position. 
     
     
         7 . The pulling clamp of  claim 2  further comprising a jam nut actuable between the top cap and the main body, for locking engagement between the driving shoulder of the top cap and the driven shoulder of the taper insert in the second gripping position. 
     
     
         8 . The pulling clamp of  claim 7  wherein:
 a threaded portion of the threaded top cap has a length greater than a depth of the actuating bore for forming an axial clearance therebetween; and 
 the jam nut is axially threadably actuable along the threaded portion between
 an unlocked position wherein the jam nut is spaced above the main body; and 
 a locked position wherein the jam nut engages the main body. 
 
 
     
     
         9 . The pulling clamp of  claim 1  wherein the taper insert has an elastic compressible range to permit the radial compression and a radial release between the first released position and second gripping position. 
     
     
         10 . The pulling clamp of  claim 1  wherein the taper insert further comprises axial fluting along an effective extent to enable elastic radial compression without plastic deformation. 
     
     
         11 . The pulling clamp of  claim 1  wherein the taper insert is discontinuous about a circumference at a slot extending axially therealong to enable circumferential reduction upon compression in the gripping position. 
     
     
         12 . The pulling clamp of  claim 1  wherein the gripping bore of the taper insert further comprises a plurality of horizontally extending wickers for engaging the string end in the gripping position. 
     
     
         13 . The pulling clamp of  claim 1  for use with a lifting apparatus, wherein the top cap further comprises:
 a pulling connection for engagement with the lifting apparatus when the top cap and taper insert are in the second gripping position, axial pulling load being transferred from the continuous rod through the taper insert, to the main body and through the top cap to the lifting apparatus. 
 
     
     
         14 . The pulling clamp of  claim 13  wherein the pulling connection comprises:
 a pony rod connected at a first end to a free end of the pulling clamp and engaging the lifting apparatus at a second upset end. 
 
     
     
         15 . The pulling clamp of  claim 14  wherein the first end of the pony rod is threaded for connection to a threaded bore in the top cap. 
     
     
         16 . The pulling clamp of  claim 1  wherein the continuous string is connected at a downhole end to a downhole tool, the continuous string being rotatable for driving the downhole tool. 
     
     
         17 . The pulling clamp of  claim 16  wherein the downhole tool is a progressive cavity pump. 
     
     
         18 . A pulling clamp for connection to a blunt, uphole string end of a continuous string comprising:
 a main body having a bore for releasably gripping the string end and a lower pulling end, the main body forming an upset, the pulling end engageable by pulling apparatus.   
     
     
         19 . The pulling clamp of  claim 18  wherein
 the main body has an upper pulled end, the main body having a clamp bore formed therethrough, the clamp bore comprising a string-receiving opening at the pulling end for receiving the string end, an actuating bore at the pulled end and a tapered bore therebetween; 
 a taper insert having a compressible gripping bore; and 
 a top cap engageable with the actuating bore, the top cap being axially movable between passive and active positions to actuate the taper insert between a first receiving position and second gripping position respectively, wherein
 in the first receiving position, the gripping bore receives the string end and is passively uncompressed thereabout; and 
 in the second gripping position, the top cap axially engages the taper insert for driving the taper insert axially into the tapered bore for radially compressing the taper insert about the string end for actively gripping the string end therein. 
 
 
     
     
         20 . The pulling clamp of  claim 19  wherein:
 the actuating bore is threaded; and 
 the top cap is threaded for threading axially into and out of the pulled end of the main body between the passive and active positions.