Pump Out Plug Barrier

Abstract

A barrier assembly for a wellbore is disclosed. The barrier assembly includes a housing, a shroud in the housing, and a plug in the shroud. The shroud and plug are made of a dissolvable material that will establish a fluid barrier until such time as the shroud and/or plug dissolves thereby releasing from the housing. The plug is held to the shroud with a shear screw which is susceptible to shearing with application of sufficient pressure to terminate the fluid barrier before the plug and/or shroud dissolves.

1 . A barrier assembly, comprising:
 a generally cylindrical housing having:
 an interior bore through the housing; 
 a small inner diameter region in the interior bore defining a narrowest portion of the housing; 
 a shoulder transverse to an axis of the housing, the axis being generally parallel with the generally cylindrical housing; and 
 a barrier unit receptacle defined by the shoulder and the housing; and 
   a barrier unit comprising:
 a shroud having a generally cylindrical main body defining a central bore through the shroud, wherein the shroud is carried by the barrier unit receptacle; and 
 a plug having a generally cylindrical body and a head, wherein the generally cylindrical main body is axially coextensive with the shroud and is located within the central bore through the shroud, wherein the head protrudes from the central bore through the shroud, wherein the shroud is secured to the housing, wherein the plug is secured to the shroud, and wherein one or more of the shroud and the plug is made of a dissolvable material. 
   
     
     
         2 . The barrier assembly of  claim 1 , further comprising:
 a mandrel coupled to the housing;   a pump coupled to the mandrel, wherein the barrier unit forms a fluid barrier that prevents fluid from reaching the pump through the barrier unit.   
     
     
         3 . The barrier assembly of  claim 1 , further comprising:
 a mandrel coupled to the housing;   a packer coupled to the mandrel, wherein the barrier unit forms a fluid barrier that prevents fluid from reaching the packer through the barrier unit.   
     
     
         4 . The barrier assembly of  claim 1 , wherein the shroud is coupled to the housing via a set screw. 
     
     
         5 . The barrier assembly of  claim 1 , wherein the plug is coupled to the shroud via a shear screw. 
     
     
         6 . The barrier assembly of  claim 5  wherein the shear screw is shearable via pressure application upon the barrier unit through the housing. 
     
     
         7 . The barrier assembly of  claim 1 , further comprising one or more seals between the shroud and the housing. 
     
     
         8 . The barrier assembly of  claim 1 , further comprising one or more seals between the plug and the shroud. 
     
     
         9 . The barrier assembly of  claim 1 , further comprising a catcher below the barrier assembly configured to permit fluid to pass through the catcher and to prevent the plug and/or shroud from passing through the catcher. 
     
     
         10 . A method, comprising:
 providing a barrier assembly in a wellbore, the barrier assembly comprising:
 a housing having a primary axis and a passageway therethrough and being generally aligned with the primary axis, wherein the passageway has a shoulder that is transverse to the primary axis; 
 a shroud in the housing contacting the shoulder, the shroud having a central bore; 
 a plug in the central bore of the shroud, wherein the plug has a head that protrudes from the shroud at a lower end, and wherein the shroud and plug are dissolvable; and 
   positioning the barrier assembly in the wellbore where the shroud and plug form a fluid barrier that persists until the shroud and/or plug dissolves sufficiently to release from the housing.   
     
     
         11 . The method of  claim 10  wherein the shroud is held to the housing via a set screw. 
     
     
         12 . The method of  claim 10  wherein the plug is held to the shroud via a shear screw. 
     
     
         13 . The method of  claim 12 , the method further comprising pressurizing the barrier assembly such that the shear screw is sheared, thereby releasing the plug from the shroud. 
     
     
         14 . The method of  claim 10 , the barrier assembly further comprising a seal between the shroud and the housing. 
     
     
         15 . The method of  claim 10 , the barrier assembly further comprising a seal between the plug and the shroud. 
     
     
         16 . The method of  claim 10 , the barrier assembly further comprising a ball seat in the passageway in the housing above the shoulder. 
     
     
         17 . The method of  claim 10 , further comprising providing a pump below the barrier assembly, wherein the barrier assembly is configured to prevent fluid from reaching the pump until such time as the shroud and/or plug is released from the housing. 
     
     
         18 . The method of  claim 10 , further comprising providing a packer above the barrier assembly, wherein the barrier assembly is configured to prevent fluid from reaching the packer until such time as the shroud and/or plug is released from the housing. 
     
     
         19 . A system for establishing a barrier in a wellbore, the system comprising:
 a plug having a generally cylindrical body and a head, the head being wider than the body;   a shroud around the body of the plug with the head protruding from the shroud, wherein at least one of the plug and shroud is made of a dissolvable material;   a housing having a passageway through the housing having a narrowest region and a shoulder below the narrowest region, the housing having a shoulder configured to receive the shroud, wherein the housing is located in the wellbore to establish a fluid barrier using the shroud and plug, wherein when the dissolvable material dissolves the fluid barrier is terminated.   
     
     
         20 . The system of  claim 19 , further comprising:
 a set screw holding the housing to the shroud;   a shear screw holding the shroud to the plug;   the plug has a head protruding from the shroud at a lower end of the shroud;   a first seal between the shroud and the housing; and   a second seal between the plug and the shroud.