Apparatus and method for setting a tubing anchor and tensioning tubing string thereabove

Abstract

A tensioning tool for connection with a tubing hanger and tubing string suspended from the tubing hanger retained in a dognut by a hanger retainer. Preferably the hanger retainer is temporarily engaged to the top of the tensioning pup for release therefrom once a lower end of the tubing has been fixed by a tubing anchor and the tubing has been lifted a tensioning distance. The hanger retainer is then engaged with the tubing hanger for suspending the tensioned tubing from the dognut locked in the wellhead. The dognut and the hanger retainer have co-operating locking faces which prevent rotation of the hanger retainer in the dognut once the locking faces are mated which assists in maintaining torque applied to the tubing string which may have been applied to rotationally set the tubing anchor. More preferably, the tensioning pup has a series of gradations marked on the pup for measuring the amount of tension applied to the tubing string.

1 . A tensioning tool for tensioning a tubing string suspended in a wellbore casing by a tubing hanger supported in a dognut in a wellhead and anchored at a downhole end by a tubing anchor comprising: 
 means adapted for engaging the tubing hanger for lifting the tubing hanger and tubing string suspended therefrom for tensioning the tubing string;    means for measuring a tensioning distance applied for tensioning the anchored tubing string; and    means adapted for engaging the tubing hanger in the dognut when the tubing string is in tension.    
   
   
       2 . The tensioning tool as described in  claim 1  wherein the means adapted for engaging the tubing hanger and for measuring the tensioning distance of the tubing hanger and anchored tubing string is a tensioning pup adapted for connection to the tubing hanger at a lower end and a lifting means at an upper end, the tensioning pup having a series of evenly spaced gradations marked thereon for measuring the amount of tension applied to the tubing hanger and suspended tubing string.  
   
   
       3 . The tensioning tool as described in  claim 1   wherein the dognut further comprises a bore for positioning the dognut about the tensioning pup and being axially moveable thereon and having a profiled inner circumferential locking face formed about an upper inner edge; and    the means adapted for engaging the top end of the tubing hanger in the dognut comprises a hanger retainer adapted for engagement with the top end of the tubing hanger and having an outer circumferential locking face about an upper outer edge,    wherein, in a secured position the hanger retainer is moving axially over the tensioning pup for connection to engagement means at the top end of the tubing hanger, the hanger retainer, tubing hanger and suspended tubing being lowered into and engaged in the dognut for supporting the tubing hanger and tensioned tubing therefrom and aligning and mating the circumferential locking faces of the hanger retainer and the donut, preventing release of the hanger retainer from the dognut.    
   
   
       4 . The tensioning tool as described in  claim 3  further comprising: 
 a temporary engagement means formed at an outer upper end of the tensioning pup; and    wherein in a connecting position, the hanger retainer is temporarily engageable at the upper end of the tensioning pup by the outer engagement means during connection of the tensioning pup to the tubing hanger; and in the secured position, the hanger retainer is releasable from the upper end of the tensioning pup for moving axially thereover for connection to the engagement means at the top end of the tubing hanger.    
   
   
       5 . The tensioning tool as described in  claim 4  wherein the engagement means at the outer upper end of the tensioning pup and the top end the tubing hanger are a plurality of threads formed thereon and the hanger retainer is threaded for engagement therewith.  
   
   
       6 . The tensioning tool as described in  claim 1  further comprising a seal formed about the hanger retainer for sealing between the hanger retainer and the dognut in the secured position.  
   
   
       7 . A tensioning tool for tensioning a tubing string suspended in a wellbore casing by a dognut supported in a wellhead, the tubing string being anchored at a downhole end by a tubing anchor comprising: 
 a tubing hanger having a top end movable through the dognut;    a tensioning pup adapted at a lower end for supportable connection to the tubing hanger and tubing string suspended therefrom and adapted for connection to a lifting means at an upper end for lifting the tubing hanger and suspended tubing string for tensioning the tubing string; and    a retainer for engaging the top end of the tubing hanger in the dognut once the subbing string is in tension.    
   
   
       8 . The tensioning tool as described in  claim 7  further comprising a series of gradations marked on the tensioning pup for measuring the amount of tension placed on the tubing string.  
   
   
       9 . The tensioning tool as described in  claim 7   wherein the dognut further comprises a bore for positioning the dognut about the tensioning pup and being axially moveable thereon and having a profiled inner circumferential locking face formed about an upper inner edge; and    the means adapted for engaging the top end of the tubing hanger in the dognut comprises a hanger retainer adapted for engagement with the top end of the tubing hanger and having an outer circumferential locking face about an upper outer edge,    wherein, in a secured position the hanger retainer is moving axially over the tensioning pup for connection to engagement means at the top end of the tubing hanger, the hanger retainer, tubing hanger and suspended tubing being lowered into and engaged in the dognut for supporting the tubing hanger and tensioned tubing therefrom and aligning and mating the circumferential locking faces of the hanger retainer and the donut, preventing release of the hanger retainer from the dognut.    
   
   
       10 . The tensioning tool as described in  claim 9  further comprising: 
 a temporary engagement means formed at an outer upper end of the tensioning pup; and    wherein in a connecting position, the hanger retainer is temporarily engageable at the upper end of the tensioning pup by the outer engagement means during connection of the tensioning pup to the tubing hanger; and in the secured position, the hanger retainer is releasable from the upper end of the tensioning pup for moving axially thereover for connection to the engagement means at the top end of the tubing hanger.    
   
   
       11 . The tensioning tool as described in  claim 10  wherein the engagement means at the outer upper end of the tensioning pup and the top end the tubing hanger are a plurality of threads formed thereon and the hanger retainer is threaded for engagement therewith.  
   
   
       12 . The tensioning tool as described in  claim 7  further comprising a seal formed about the hanger retainer for sealing between the hanger retainer and the dognut in the secured position.  
   
   
       13 . A method of tensioning a tubing string suspended in a wellbore, the tubing string having an upper end at a wellhead and a lower end having a tubing anchor, the wellhead having a bowl for lockably supporting a dognut therein, the method comprising: 
 supporting the tubing string at the wellhead with the upper end of the tubing string projecting from the wellhead;    fitting the upper end of the tubing string with a tubing hanger for suspending the tubing string therefrom, the tubing hanger having a threaded top end;    fitting a dognut over the top end of the tubing hanger, the dognut having a bore and a top end having a first circumferential locking face extending radially outwards from the bore;    releasing the tubing string at the wellhead;    lowering the tubing hanger and the tubing string so as to engage the dognut in the wellhead bowl;    continuing to lower the tubing hanger and tubing string so that the top end of the tubing hanger is below the top end of the dognut by a tensioning distance, the lower end of the tubing string being substantially at a target depth;    setting the tubing anchor to fix the position of the lower end of the tubing string at the target depth in the wellbore;    pulling up the tubing hanger and tubing string at least the tensioning distance to tension the tubing string and expose the top end of the tubing hanger;    engaging a hanger retainer having a second circumferential locking face extending radially outwards therefrom to the top end of the tubing hanger for supporting the tubing string therefrom;    aligning the first and second circumferential locking faces; and    lowering the hanger retainer supporting the tubing hanger and tubing string into the dognut for suspending the tensioned tubing string therefrom, the first and second circumferential locking faces being mated together for preventing rotation of the hanger retainer within the dognut.    
   
   
       14 . The method as described in  claim 13  wherein the tubing anchor is set rotationally, further comprising: 
 applying torque to the tubing string for setting the tubing anchor;    maintaining at least some of the torque on the tubing string while tensioning the tubing string, engaging the hanger retainer in the dognut,    wherein the mated first and second locked circumferential locking faces maintain the at least some of the torque by preventing rotation of the hanger retainer within the dognut.    
   
   
       15 . The method as described in  claim 13 , following fitting the dognut over the tubing hanger, further comprising: 
 engaging a tensioning pup with the tubing hanger for supportably lifting and lowering the tubing hanger and tubing string suspended therefrom.    
   
   
       16 . The method as described in  claim 15  further comprising: lowering the tubing hanger a tensioning distance by lowering the tensioning pup as measured against a series of gradations at evenly spaced intervals along the tensioning pup for measuring the relative tensioning distance.  
   
   
       17 . The method as described in  claim 16  wherein the gradations are spaced at one inch intervals.  
   
   
       18 . The method as described in  claim 15  wherein the tensioning pup has outer engagement means formed at a top end for temporarily retaining the hanger retainer thereon prior to engaging the hanger retainer with the tubing hanger.  
   
   
       19 . The method as described in  claim 18  wherein the hanger retainer is a hanger nut and wherein the top end of the tubing hanger is a plurality of threads for threadably engaging the hanger nut thereon.