High Temperature, High Pressure Back-Off Shot Tool

Abstract

A back-off shot tool system includes a high-pressure resistant charge housing at least partially containing an explosive material. A booster charge is placed adjacent the explosive material to activate the explosive material upon actuation. The high-pressure resistant charge housing is formed from a material that is the material of the high-pressure resistant charge housing is frangible so that it will to withstand high temperatures and pressures, such as a ceramic. In addition, fragment into small pieces that can be process or extracted from the well with fluid that is extracted from the region in which the back-off shot tool is deployed.

1 . A back-off shot housing comprising:
 a high-pressure resistant charge housing that defines an internal cavity and is at least partially composed of a frangible material; and   an explosive material at least partially within the internal cavity.   
     
     
         2 . The back-off shot housing of  claim 1 , wherein the frangible material comprises a sintered metal. 
     
     
         3 . The back-off shot housing of  claim 1 , wherein the frangible material comprises a glass. 
     
     
         4 . The back-off shot housing of  claim 1 , wherein the frangible material comprises a ceramic. 
     
     
         5 . The back-off shot housing of  claim 4 , wherein the ceramic comprises transformation-toughened zirconium oxide. 
     
     
         6 . The back-off shot housing of  claim 4 , wherein the ceramic comprises yttria stabilized zirconia. 
     
     
         7 . The back-off shot housing of  claim 1 , wherein the explosive material comprises a plurality of wafers. 
     
     
         8 . The back-off shot housing of  claim 1 , wherein the explosive material comprises a plurality of pellets. 
     
     
         9 . A back-off shot tool system comprising:
 a high-pressure resistant charge housing comprising an explosive material disposed at least partially therein, the high-pressure resistant charge housing comprising a frangible material; and   a firing head module comprising a booster charge, wherein the booster charge is biased against the explosive material.   
     
     
         10 . The back-off shot tool system of  claim 9 , wherein the frangible material comprises a sintered metal. 
     
     
         11 . The back-off shot tool system of  claim 9 , wherein the frangible material comprises a glass. 
     
     
         12 . The back-off shot tool system of  claim 9 , wherein the frangible material comprises a ceramic. 
     
     
         13 . The back-off shot tool system of  claim 12 , wherein the ceramic comprises transformation-toughened zirconium oxide. 
     
     
         14 . The back-off shot tool system of  claim 12 , wherein the ceramic comprises yttria stabilized zirconia. 
     
     
         15 . The back-off shot tool system of  claim 9 , wherein the explosive material comprises a plurality of wafers. 
     
     
         16 . The back-off shot tool system of  claim 9 , wherein the explosive material comprises a plurality of pellets. 
     
     
         17 . A method of backing off a threaded joint in a wellbore, the method comprising:
 placing a high-pressure resistant charge housing at least partially composed of a frangible material and at least partially containing an explosive material proximate the threaded joint;   detonating the explosive material; and   applying a left-hand torque to said threaded joint.   
     
     
         18 . The method of  claim 17 , wherein the frangible material comprises a sintered metal. 
     
     
         19 . The method of  claim 17 , wherein the frangible material comprises a ceramic, and wherein the ceramic comprises transformation-toughened zirconium oxide. 
     
     
         20 . The method of  claim 17 , wherein the frangible material comprises a ceramic, and wherein the ceramic comprises yttria stabilized zirconia.