Sequential Packer Sealing Element and Slip Release Mechanism

Abstract

A retrievable compression set packer is sequentially released. First the sealing element is allowed to relax. Then the upper slip has wedging action that forces it against a surrounding tubular relaxed. After that the upper slips are pulled up to retract them fully allowing the packer to come out. These sequential actions are done with a mandrel movement in one direction. The sealing element is released with undermining a collet by aligning collet heads with a recess on the mandrel. The slip force release happens with mandrel movement forcing a ring into a wedge such that circumferential force on slip segments is reduced or eliminated when the wedge is pushed out of its conforming slot allowing for circumferential flexibility of the slip seat. The mandrel then picks up a slip ring that retracts the slip segments on the slip seat and the packer is removed.

We claim: 
     
         1 . A retrievable packer for subterranean use against a borehole wall, comprising:
 an outer assembly comprising at least one slip and a sealing element mounted to a relatively movable mandrel;   said outer assembly compressible for radial extension of said at least one slip and said sealing element against the borehole wall for pressure isolation, defining a set position of said outer assembly;   said outer assembly retractable toward a retrieve position away from the borehole wall with relative movement of said mandrel to sequentially relieve pressure in said sealing element and then reduce gripping force on said at least one slip.   
     
     
         2 . The retrievable packer of  claim 1 , wherein:
 movement of said mandrel allows said sealing element to extend axially.   
     
     
         3 . The retrievable packer of  claim 2 , wherein:
 movement of said mandrel unlocks a locking mechanism to allow said sealing element to extend axially.   
     
     
         4 . The retrievable packer of  claim 3 , wherein:
 said outer assembly comprising a telescoping sleeve held in an initial position by said locking mechanism with support from said mandrel.   
     
     
         5 . The retrievable packer of  claim 4 , wherein:
 movement of said mandrel removes support for said locking mechanism allowing said telescoping sleeve to shorten and said sealing element to axially extend toward said retrieve position.   
     
     
         6 . The retrievable packer of  claim 5 , wherein:
 said locking mechanism comprises at least one collet or dog that prevents telescoping of said sleeve when supported by said mandrel until a recess in said mandrel opposes said collet or dog to allow radial movement releasing said sleeve to telescope to a shorter dimension.   
     
     
         7 . The retrievable packer of  claim 1 , wherein:
 movement of said mandrel reduces circumferential force acting on said at least one slip by a slip seat.   
     
     
         8 . The retrievable packer of  claim 7 , wherein:
 said slip seat comprising spaced extending members flanking said at least one slip and having an elongated slot initially filled with a movable member having a conforming shape to said elongated slot to support delivery of a circumferential force to said at least one slip in said set position from said flanking extending members.   
     
     
         9 . The retrievable packer of  claim 8 , wherein:
 said movable member and said slot having conforming tapers such that axial movement of said movable member creates gaps in said slot to allow said extending members to flex and reduce circumferential force on said at least one slip toward said set position.   
     
     
         10 . The retrievable packer of  claim 9 , wherein:
 movement of said mandrel moves said movable member after earlier movement has relieved pressure in said sealing element.   
     
     
         11 . The retrievable packer of  claim 10 , wherein:
 further mandrel movement after moving said movable member engages said mandrel to a slip ring for tandem movement to pull said at least one slip axially with respect to said spaced extending members which moves said at least one slip toward said mandrel.   
     
     
         12 . The retrievable packer of  claim 11 , wherein:
 said at least one slip comprises a plurality of circumferentially spaced slips each mounted between opposed extending members that define a conforming slip slot in said slip seat to form a ring structure with said spaced extending members of said slip seat and said slips.   
     
     
         13 . The retrievable packer of  claim 6 , wherein:
 movement of said mandrel reduces circumferential force acting on said at least one slip by a slip seat.   
     
     
         14 . The retrievable packer of  claim 13 , wherein:
 said slip seat comprising spaced extending members flanking said at least one slip and having an elongated slot initially filled with a movable member having a conforming shape to said elongated slot to support delivery of a circumferential force to said at least one slip in said set position from said flanking extending members.   
     
     
         15 . The retrievable packer of  claim 14 , wherein:
 said movable member and said slot having conforming tapers such that axial movement of said movable member creates gaps in said slot to allow said extending members to flex and reduce circumferential force on said at least one slip toward said set position.   
     
     
         16 . The retrievable packer of  claim 15 , wherein:
 movement of said mandrel moves said movable member after earlier movement has relieved pressure in said sealing element.   
     
     
         17 . The retrievable packer of  claim 16 , wherein:
 further mandrel movement after moving said movable member engages said mandrel to a slip ring for tandem movement to pull said at least one slip axially with respect to said spaced extending members which moves said at least one slip toward said mandrel.   
     
     
         18 . The retrievable packer of  claim 17 , wherein:
 said at least one slip comprises a plurality of circumferentially spaced slips each mounted between opposed extending members that define a conforming slip slot in said slip seat to form a ring structure with said spaced extending members of said slip seat and said slips.