Tapered setting wedge for swell packers and associated method

Abstract

A swell packer sealing element has a wedge on either or both ends that is driven axially when the packer is at the desired borehole location. The wedge releases an end bond of the sealing element and forces the end of the sealing element out radially against the surrounding borehole wall. The actuator for the wedge also forces out an extrusion barrier at the same time. The packer achieves the ability to handle the design differential pressure with aid of the end wedge even as portions of the packer sealing element beyond the end are still swelling into contact with the surrounding borehole wall whether in cased or open hole.

I claim: 
     
         1 . A swell packer assembly for borehole use, comprising:
 a mandrel;   a swelling element mounted to said mandrel having an end;   a selectively movable wedge on said mandrel movable past said end into a position between said mandrel and said end to force said end toward a surrounding borehole wall.   
     
     
         2 . The assembly of  claim 1 , wherein:
 said element at a location beyond said wedge remains in contact with said mandrel.   
     
     
         3 . The assembly of  claim 2 , wherein:
 said swelling element initially bonded to said mandrel and said movable wedge releasing said bond as a result of said selective movement.   
     
     
         4 . The assembly of  claim 2 , wherein:
 movement of said movable wedge extends an anti-extrusion ring radially toward the surrounding borehole wall.   
     
     
         5 . The assembly of  claim 2 , wherein:
 said movable wedge has a taper angle of about 3 degrees.   
     
     
         6 . The assembly of  claim 1 , wherein:
 said swelling element is not fully in contact along the length of said swelling element when said movable wedge advances said end radially into the borehole wall.   
     
     
         7 . The assembly of  claim 1 , wherein:
 said sealing element forms a differential pressure seal against the borehole at said end from advancement of said movable wedge.   
     
     
         8 . The assembly of  claim 1 , wherein:
 said wedge is moved with tubing passage pressure.   
     
     
         9 . The assembly of  claim 1 , wherein:
 said movable wedge is locked against reverse movement after movement toward said sealing element.   
     
     
         10 . The assembly of  claim 4 , wherein:
 said anti-extrusion ring is located on said mandrel between an actuating piston and said movable wedge.   
     
     
         11 . The assembly of  claim 10 , wherein:
 said piston is moved with tubing passage pressure.   
     
     
         12 . The assembly of  claim 11 , wherein:
 a lock ring prevents reverse movement of said piston after initial movement toward said end of said sealing element.   
     
     
         13 . A borehole treatment method, comprising:
 sealing a borehole with a swelling element mounted to a mandrel;   advancing a wedge past an end of said swelling element along said mandrel;   forcing said end of said swelling element away from said mandrel and toward a borehole wall with said wedge;   isolating one zone from another zone in the borehole from said sealing.   
     
     
         14 . The method of  claim 13 , comprising:
 performing a well treatment in one of said zones.   
     
     
         15 . The method of  claim 14 , comprising:
 providing as said treatment at least one of hydraulic fracturing, stimulation, tracer injection, cleaning, acidizing, steam injection, water flooding and cementing.   
     
     
         16 . The method of  claim 13 , comprising:
 breaking a bond between said sealing element and said mandrel with said wedge advancing.   
     
     
         17 . The method of  claim 13 , comprising:
 radially forcing said end away from said mandrel and toward the borehole wall with said advancing of said wedge.   
     
     
         18 . The method of  claim 13 , comprising:
 applying differential pressure to said end before the substantial length of said swelling element has swelled into contact with the borehole wall.   
     
     
         19 . The method of  claim 13 , comprising:
 extending an anti-extrusion ring with said advancing of said wedge.   
     
     
         20 . The method of  claim 13 , comprising:
 disposing an anti-extrusion ring on said mandrel between a piston and said wedge;   driving said wedge axially past said end and said anti-extrusion ring radially toward the borehole wall with piston movement using tubing passage pressure.   
     
     
         21 . The method of  claim 20 , comprising:
 locking reverse movement of said piston after said driving of said wedge;   disposing said swelling element in contact with said mandrel along its substantial length beyond a shifted position of said wedge.