Dual flapper back pressure valve and methods of use

Abstract

A wellhead includes a tubing head adapter, a tubing hanger arranged within the tubing adapter, and a dual flapper back pressure valve arranged within the tubing hanger and including an elongate body having opposing upper and lower ends, an inner flowpath defined within the body and extending between the opposing upper and lower ends, and a flapper assembly arranged within the inner flow path and including a flapper pivotably mounted to an inner wall of the inner flow path at a pivoting mechanism. When the flapper is in a closed position, the flapper forms a sealed interface with the inner wall of the inner flow path that prevents fluids from circulating through the tubing hanger and through the inner flowpath from the lower end to the upper end.

1 . A method, comprising:
 installing a dual flapper back pressure valve within a tubing hanger of a wellhead, the dual flapper back pressure valve including:
 an elongate body having opposing upper and lower ends and configured to be received and secured within the tubing hanger; 
 an inner flowpath defined within the body and extending between the opposing upper and lower ends; and 
 a flapper assembly arranged within the inner flow path and including a flapper pivotably mounted to an inner wall of the inner flow path at a pivoting mechanism and a flapper seat projecting into the inner flow path and engageable against the flapper when the flapper is moved to a closed position; 
   introducing an injection fluid into the inner flowpath at the upper end;   pivoting the flapper from the closed position to an open position with the injection fluid; and   circulating the injection fluid through the inner flow path at a flow rate greater than two barrels per minute.   
     
     
         2 . The method of  claim 1 , further comprising:
 reducing the flow rate of the injection fluid through the inner flow path;   pivoting the flapper to the closed position and thereby generating a sealed interface with the inner wall of the inner flow path; and   preventing a return fluid from circulating through the inner flowpath from the lower end to the upper end with the flapper.   
     
     
         3 . The method of  claim 2 , wherein the flapper assembly comprises a first flapper assembly and the dual flapper back pressure valve further includes a second flapper assembly arranged within the inner flow path and axially offset from the first flapper assembly, the method further comprising:
 circulating the injection fluid through the inner flow path and past the first and second flapper assemblies; and   preventing the return fluid from circulating through the inner flowpath from the lower end to the upper end with the flappers of the first and second flapper assemblies.   
     
     
         4 . The method of  claim 1 , wherein external threads are defined on an exterior of the elongate body, and internal threads are defined within the tubing hanger, and wherein installing the dual flapper back pressure valve within the tubing hanger comprises threadably engaging the external and internal threads. 
     
     
         5 . The method of  claim 4 , further comprising generating a sealed interface between the elongate body and an interior channel of the tubing hanger with a sealing ring arranged about the exterior of the body and above the external threads. 
     
     
         6 . The method of  claim 1 , wherein inner threads are defined within the inner flowpath at or near the upper end, and wherein installing the dual flapper back pressure valve within the tubing hanger is preceded by:
 threadably attaching a running tool to the dual flapper back pressure valve at the inner threads; and   advancing the dual flapper back pressure valve into the tubing hanger.   
     
     
         7 . The method of  claim 1 , wherein the injection fluid comprises an abrasive fluid, a corrosive fluid, a mud mixture, or any combination thereof. 
     
     
         8 . A wellhead, comprising:
 a tubing head adapter;   a tubing hanger arranged within the tubing head adapter; and   a dual flapper back pressure valve arranged within the tubing hanger and including:
 an elongate body having opposing upper and lower ends; 
 an inner flowpath defined within the body and extending between the opposing upper and lower ends; and 
 a flapper assembly arranged within the inner flow path and including a flapper pivotably mounted to an inner wall of the inner flow path at a pivoting mechanism and a flapper seat projecting into the inner flow path and engageable against the flapper when the flapper is moved to a closed position, 
   wherein, when the flapper is in the closed position, the flapper forms a sealed interface with the inner wall of the inner flow path that prevents fluids from circulating through the tubing hanger and through the inner flowpath from the lower end to the upper end.   
     
     
         9 . The wellhead of  claim 8 , further comprising:
 external threads defined on an exterior of the elongate body to threadably secure the elongate body within the tubing hanger of the wellhead; and   a sealing ring arranged about the exterior of the body above the external threads to generate a sealed interface between the elongate body and an interior channel of the tubing hanger.   
     
     
         10 . The wellhead of  claim 9 , further comprising inner threads defined within the inner flowpath at or near the upper end, wherein the inner threads are threadably attachable to a running tool for advancing the dual flapper back pressure valve into the tubing hanger. 
     
     
         11 . The wellhead of  claim 8 , wherein the flapper assembly comprises a first flapper assembly, the dual flapper back pressure valve further comprising a second flapper assembly arranged within the inner flow path and axially offset from the first flapper assembly. 
     
     
         12 . The wellhead of  claim 8 , wherein an injection fluid is circulated through the tubing hanger and through the inner flowpath from the lower end to the upper end at a flow rate greater than two barrels per minute. 
     
     
         13 . A dual flapper back pressure valve, comprising:
 an elongate body having opposing upper and lower ends and configured to be received and secured within a tubing hanger of a wellhead;   an inner flowpath defined within the body and extending between the opposing upper and lower ends; and   a flapper assembly arranged within the inner flow path and including a flapper pivotably mounted to an inner wall of the inner flow path at a pivoting mechanism and a flapper seat projecting into the inner flow path and engageable against the flapper when the flapper is moved to a closed position, wherein the pivoting mechanism naturally biases the flapper to the closed position, and   wherein, when the flapper is in the closed position, the flapper forms a sealed interface with the inner wall of the inner flow path that prevents fluids from circulating through the inner flowpath from the lower end to the upper end.   
     
     
         14 . The dual flapper back pressure valve of  claim 13 , further comprising external threads defined on an exterior of the elongate body to threadably secure the elongate body within the tubing hanger of the wellhead. 
     
     
         15 . The dual flapper back pressure valve of  claim 14 , further comprising a sealing ring arranged about the exterior of the body above the external threads to generate a sealed interface between the elongate body and an interior channel of the tubing hanger. 
     
     
         16 . The dual flapper back pressure valve of  claim 15 , further comprising inner threads defined within the interior channel at or near an uphole end of the tubing hanger, wherein the inner threads are threadably attachable to a running tool for placing the tubing hanger in a tubing head adapter of the wellhead. 
     
     
         17 . The dual flapper back pressure valve of  claim 13 , wherein the flapper assembly comprises a first flapper assembly, the dual flapper back pressure valve further comprising a second flapper assembly arranged within the inner flow path and axially offset from the first flapper assembly. 
     
     
         18 . (canceled) 
     
     
         19 . The dual flapper back pressure valve of  claim 13 , wherein an injection fluid is circulated through the inner flowpath at a flow rate greater than two barrels per minute. 
     
     
         20 . The dual flapper back pressure valve of  claim 13 , wherein the pivoting mechanism comprises a self-closing hinge. 
     
     
         21 . The dual flapper back pressure valve of  claim 13 , wherein the flapper assembly remains within the inner flow path when in the closed position.