Subsurface injection valve system

Abstract

A technique facilitates control over fluid flow via controlled operation of an injection valve. The technique enables control over operation of the injection valve in a variety of subsurface applications. The injection valve comprises a flapper which may be selectively shifted to and held in an open position. Depending on the operational configuration of the injection valve, the flapper may be shifted to the open position via fluid flow along a primary flow passage. However, the injection valve also may be shifted to the open position via a separate actuator controllable via pressure applied independently of fluid flow along the primary flow passage.

What is claimed is: 
     
         1 . A system for controlling fluid flow, comprising:
 a well string having an injection valve and a secondary valve, the secondary valve being operated by pressure applied along an interior of the well string through the injection valve, the injection valve comprising:
 a flapper; 
 a flow tube movable into engagement with the flapper to shift the flapper to an open position, the flow tube being movable by flow of fluid along the interior of the well string; and 
 a piston actuator coupled with the flow tube to enable selective shifting of the flow tube and thus the flapper to the open position, the piston actuator being movable via pressure applied independently of flow of fluid along the interior. 
   
     
     
         2 . The system is recited in  claim 1 , wherein the flow tube is coupled with a flow restrictor. 
     
     
         3 . The system is recited in  claim 2 , wherein the flow restrictor comprises an orifice. 
     
     
         4 . The system is recited in  claim 1 , wherein the flow tube is spring biased toward a disengaged position relative to the flapper. 
     
     
         5 . The system is recited in  claim 1 , wherein the flapper is pivotably mounted in a valve housing and the piston actuator is disposed in a wall of the valve housing. 
     
     
         6 . The system as recited in  claim 5 , wherein the piston actuator comprises a rod piston. 
     
     
         7 . The system as recited in  claim 1 , wherein the secondary valve comprises a ball valve. 
     
     
         8 . The system as recited in  claim 1 , wherein the flapper is oriented to normally block flow along the interior in an uphole direction when the flow tube is in a disengaged position with respect to the flapper. 
     
     
         9 . The system as recited in  claim 1 , wherein the well string further comprises a packer positioned to enable isolation of an injection zone. 
     
     
         10 . A method, comprising:
 providing an injection valve with a flapper pivotably mounted in a valve housing along a flow passage;   slidably positioning a flow tube in the valve housing for movement between a disengaged position with respect to the flapper and an engaged position which holds the flapper in an open position to fluid flow along the flow passage;   coupling a flow restrictor to the flow tube to enable selective shifting of the flow tube to the engaged position via sufficient fluid flow along the flow passage through the flow restrictor; and   using a piston actuator in cooperation with the flapper to enable selective shifting of the flapper to the open position independently of fluid flow along the flow passage.   
     
     
         11 . The method as recited in  claim 10 , wherein using comprises coupling the piston actuator to the flapper via the flow tube to enable selective shifting of the flow tube to the engaged position independently of fluid flow along the flow passage. 
     
     
         12 . The method as recited in  claim 10 , further comprising incrementally shifting the piston actuator via sequential pressure inputs. 
     
     
         13 . The method as recited in  claim 10 , further comprising positioning the injection valve in a well string. 
     
     
         14 . The method as recited in  claim 13 , further comprising deploying the well string downhole into a wellbore. 
     
     
         15 . The method as recited in  claim 14 , further comprising shifting the actuator piston via internal pressure applied along an interior of the well string. 
     
     
         16 . The method as recited in  claim 14 , further comprising shifting the actuator piston via pressure applied along an annulus surrounding the well string. 
     
     
         17 . The method as recited in  claim 10 , wherein coupling comprises coupling an orifice to the flow tube. 
     
     
         18 . A system, comprising:
 an injection valve having:
 a flapper pivotably mounted in a valve housing; 
 a flow tube movably mounted in the valve housing for selective movement into an engaged position with the flapper in which the flapper is pivoted and held in an open position, the flow tube being movable by flow of fluid through the injection valve; and 
 a piston actuator positioned for cooperation with the flapper to enable selective shifting of the flapper to the open position, the piston actuator being movable via pressure applied independently of flow of fluid along the interior. 
   
     
     
         19 . The system is recited in  claim 18 , wherein the piston actuator is coupled to the flow tube to enable selective shifting of the flow tube to the engaged position. 
     
     
         20 . The system is recited in  claim 19 , wherein the injection valve is part of a well string deployed in a wellbore.