Wellbore plug structure and method for pressure testing a wellbore

Abstract

A wellbore plug structure and a method for pressure testing a wellbore using the plug structure. The plug structure advantageously allows pressure testing of the wellbore casing without the use of a toe sleeve and without requiring the application of a pressure in excess of the wellbore pressure test after testing is completed. The wellbore plug structure includes a piston member that can be released at any time after placement of the structure in the wellbore casing to expose a dissolvable element to a pressurizing fluid. A pressure test may then be conducted before the fluid completely dissolves the dissolvable element. Once the dissolvable element is dissolved, a fluid pathway through the wellbore plug structure is created that many enable the placement of tooling through the plug structure.

1 . A wellbore plug structure, comprising:
 a tubular member defining a longitudinally-extending fluid conduit having a proximal fluid inlet and a distal fluid outlet;   a wiping member disposed around the tubular member;   a piston member comprising a piston body that is at least partially disposed in the fluid conduit; and   a temporary fluid stopper comprising a dissolvable fluid obstructing portion, where the dissolvable fluid obstructing portion is disposed in spaced-apart relation from the piston member toward the distal fluid outlet;   wherein the piston member and the dissolvable fluid obstructing portion define an interior chamber within the fluid conduit, the interior chamber being fluidly sealed from the proximal fluid inlet by the piston member and being fluidly sealed from the distal fluid outlet by the dissolvable fluid obstructing portion.   
     
     
         2 . The wellbore plug structure recited in  claim 1 , wherein the piston member is configured to release and move toward the distal fluid outlet when the piston member is exposed to a pressure difference across the piston member that is equal to or greater than a piston release pressure. 
     
     
         3 . The wellbore plug structure recited in  claim 2 , wherein the release and movement of the piston member creates a fluid pathway from the proximal fluid inlet to the interior chamber of the fluid conduit. 
     
     
         4 . The wellbore plug structure recited in  claim 1 , wherein the piston member comprises at least one shear element, wherein the at least one shear element operatively secures the piston member within the fluid conduit and is configured to shear when the piston member is exposed to the pressure difference across the piston member that is equal to or greater than the piston release pressure to release the piston body. 
     
     
         5 . (canceled) 
     
     
         6 . (canceled) 
     
     
         7 . The wellbore plug structure recited in  claim 1 , wherein the piston member is fully disposed within the fluid conduit. 
     
     
         8 - 12 . (canceled) 
     
     
         13 . The wellbore plug structure recited in  claim 1 , wherein the wiping member comprises at least a first wiper blade extending radially from the tubular member. 
     
     
         14 - 16 . (canceled) 
     
     
         17 . The wellbore plug structure recited in  claim 1 , wherein the dissolvable fluid obstructing portion is disposed across the fluid conduit. 
     
     
         18 . The wellbore plug structure recited in  claim 1 , wherein the dissolvable fluid obstructing portion is fabricated from a material that is dissolvable in an aqueous medium. 
     
     
         19 . The wellbore plug structure recited in  claim 1 , wherein the dissolvable fluid obstructing portion is fabricated from a material that is dissolvable in an aqueous chloride solution. 
     
     
         20 - 22 . (canceled) 
     
     
         23 . The wellbore plug structure recited in  claim 1 , wherein the dissolvable fluid obstructing portion has a thickness measured along a longitudinal axis of the fluid conduit that is at least about 0.5 mm. 
     
     
         24 - 30 . (canceled) 
     
     
         31 . The wellbore plug structure recited in  claim 1 , wherein the temporary fluid stopper comprises a cup-like temporary fluid stopper body comprising the dissolvable fluid obstructing portion and a wall portion extending from a circumferential edge of the dissolvable fluid obstructing portion along an interior wall of the fluid conduit. 
     
     
         32 - 34 . (canceled) 
     
     
         35 . The wellbore plug structure recited in any of  claim 31 , wherein the temporary fluid stopper body and the dissolvable fluid obstructing portion comprise the dissolvable material. 
     
     
         36 . The wellbore plug structure recited  claim 1 , wherein the dissolvable fluid obstructing portion comprises a dissolvable disk body. 
     
     
         37 . The wellbore plug structure recited in  claim 36 , wherein the dissolvable disk body is disposed across the longitudinally-extending fluid conduit. 
     
     
         38 - 41 . (canceled) 
     
     
         42 . The wellbore plug structure recited in  claim 36 , wherein the fluid conduit comprises at least a first conduit portion and a second conduit portion, the second conduit portion having a larger diameter than the first conduit portion, wherein the first conduit portion is disposed near the proximal end of the fluid conduit and wherein the piston member is at least partially disposed within the first conduit portion. 
     
     
         43 . A wellbore plug structure, comprising:
 a tubular member defining a longitudinally-extending fluid conduit having a proximal fluid inlet and a distal fluid outlet;   a wiping member disposed around the tubular member;   a piston member comprising a piston body that is at least partially disposed in the fluid conduit;   a collet member at least partially disposed within the fluid conduit, the collet member comprising a collet member body, the collet member body comprising a plurality of collet fingers, and a dissolvable ring component disposed within the collet body to resist inward collapse of the collet fingers;   wherein the collet member and the piston member define an interior chamber within the fluid conduit, the interior chamber being fluidly sealed from the proximal fluid inlet by the piston member and being fluidly sealed from the distal fluid outlet by the collet member.   
     
     
         44 . The wellbore plug structure recited in  claim 43 , wherein the piston member is configured to release and move toward the distal fluid outlet when the piston member is exposed to a pressure difference across the piston member that is equal to or greater than a piston release pressure. 
     
     
         45 . The wellbore plug structure recited in  claim 44 , wherein the release and movement of the piston member creates a fluid pathway from the proximal fluid inlet to the interior chamber of the fluid conduit. 
     
     
         46 . The wellbore plug structure recited in  claim 43 , wherein the piston member comprises at least one shear element, wherein the at least one shear element operatively secures the piston member within the fluid conduit and is configured to shear when the piston member is exposed to the pressure difference across the piston member that is equal to or greater than the piston release pressure to release the piston body. 
     
     
         47 . (canceled) 
     
     
         48 . (canceled) 
     
     
         49 . The wellbore plug structure recited in  claim 43 , wherein the piston member is fully disposed within the fluid conduit. 
     
     
         50 - 54 . (canceled) 
     
     
         55 . The wellbore plug structure recited in  claim 43 , wherein the wiping member comprises at least a first wiper blade extending radially from the tubular member. 
     
     
         56 - 68 . (canceled)