Retrievable bridge plug with dual check valves

Abstract

A retrievable bridge plug includes both an expandable packer mechanism to seal to a casing and a slip mechanism to anchor to the casing, and defines a flow path including a check valve for restricting fluid flow through the bridge plug.

1 . A retrievable bridge plug having both an expandable packer mechanism to seal to a casing and a slip mechanism to anchor to the casing, and defining a flow path including at least one check valve for restricting fluid flow through the bridge plug. 
     
     
         2 . The retrievable bridge plug of  claim 1 , comprising:
 (a) a coupling, an inner mandrel and a bottom sub;   (b) a lock ring housing bearing at least one packing element between upper and lower gage rings;   (c) an upper mandrel disposed within the lock ring housing and defining an annular space therebetween and a lower mandrel bearing the slip mechanism comprising at least one slip and a slip actuating mechanism;   (d) the flow path comprises a fluid passage permitting fluid flow downwards through the bridge plug, the passage including the annular space and comprising the least one check valve sealed within the annular space;   (e) a burst disc closing an inlet to the fluid passage;   
       wherein relative movement of the lock ring housing to the lower mandrel actuates the at least one slip, and relative movement of lock ring housing to the lower mandrel actuates the at least one packing element; and 
       wherein sufficient fluid pressure above the plug opens the burst disc allowing fluid to flow through the fluid passage through the at least one check valve. 
     
     
         3 . The retrievable bridge plug of  claim 1 , comprising two check valves arranged sequentially within the annular space. 
     
     
         4 . The retrievable bridge plug of  claim 1 , wherein the at least one check valve has a crack pressure between about 1 psi and 1000 psi. 
     
     
         5 . The retrievable bridge plug of  claim 1 , wherein the coupling is configured to connect to a wireline, slickline, coiled tubing or drill pipe. 
     
     
         6 . The retrievable bridge plug of  claim 1 , wherein the at least one check valve comprises a flow sleeve disposed concentrically around the mandrel and defining at least one passageway for fluid flow downwards through the flow sleeve, at least one piston and a biasing means urging a moveable valve member upwards, the valve member comprising a pin sealed within a passageway formed in a valve block, wherein the pin is sealed within the valve block, and wherein the valve member and pin are moveable between a closed position where the valve member bears on the valve block, and an open position wherein fluid flows around the pin and between the valve member and the valve block, through the flow sleeve passageway, wherein the check valve is opened by a force which overcomes the biasing means. 
     
     
         7 . A method of controlling pressure in a wellbore, comprising the steps of:
 (a) installing a first bridge plug in the wellbore, the first bridge plug having at least one check valve oriented to allow fluid from passing through to below the first bridge plug; and   (b) installing a second bridge plug above the first bridge plug, with a space therebetween.   
     
     
         8 . The method of  claim 7  wherein the second bridge plug comprises at least one check valve oriented to allow fluid from passing through to below the second bridge plug. 
     
     
         9 . The method of  claim 8  wherein either or both the first and second bridge plugs comprise a bridge plug of  claim 1 . 
     
     
         10 . The method of  claim 9  wherein the first bridge plug has a crack pressure greater than a crack pressure of the second bridge plug.