Multiple Spring Subsurface Safety Valve

Abstract

A subsurface safety valve features vertically stacked springs that are each independently supported in the valve housing and each having an opposite end that bears on a shoulder connected to the flow tube. When mounted this way their applied force is additive as they are in effect mounted in parallel between the housing and the flow tube for overcoming hydrostatic pressure in deep set applications that can exceed 20,000 feet. The stacking also allows the cross-sectional area of the flow tube to be maximized for a given housing outside diameter dictated by well conditions.

1 . A valve for downhole use, comprising:
 at least one housing having a flow path therethrough;   a valve member mounted and subject to a biasing assembly for selectively opening and closing said flow path;   said biasing assembly comprising a plurality of biasing members arranged in a generally axial orientation in said housing and each supported proximate to one end by said housing and operatively coupled to said valve member proximate to an opposite end.   
   
   
       2 . The valve of  claim 1 , wherein:
 said biasing members comprise springs;   said springs are disposed outside said flow path.   
   
   
       3 . The valve of  claim 1 , wherein:
 said biasing members comprise springs;   said springs are coiled springs.   
   
   
       4 . The valve of  claim 1 , wherein:
 said biasing members comprise discrete springs in axial alignment one above another;   said valve member is defined by a flow tube with said springs bearing directly or indirectly on said flow tube.   
   
   
       5 . The valve of  claim 4 , wherein:
 said flow tube operates a flapper that rotates a quarter turn.   
   
   
       6 . The valve of  claim 4 , wherein:
 said flow path extends through said flow tube and said springs are mounted outside said flow tube.   
   
   
       7 . The valve of  claim 4 , wherein:
 said springs overcome a hydrostatic force acting on said flow tube at mounting depths of said housing of more than 20,000 feet.   
   
   
       8 . The valve of  claim 4 , wherein:
 said housing and said flow tube are modular.   
   
   
       9 . The valve of  claim 4 , wherein:
 said housing and said flow tube are each made of one piece.   
   
   
       10 . The valve of  claim 1 , wherein:
 said biasing members comprise springs;   said plurality of springs comprises two springs.   
   
   
       11 . The valve of  claim 2 , wherein:
 said springs are coiled springs.   
   
   
       12 . The valve of  claim 11 , wherein:
 said valve member is defined by a flow tube with said springs bearing directly or indirectly on said flow tube.   
   
   
       13 . The valve of  claim 12 , wherein:
 said flow tube operates a flapper that rotates a quarter turn.   
   
   
       14 . The valve of  claim 13 , wherein:
 said flow path extends through said flow tube and said springs are mounted outside said flow tube.   
   
   
       15 . The valve of  claim 14 , wherein:
 said springs overcome a hydrostatic force acting on said flow tube at mounting depths of said housing of more than 20,000 feet.   
   
   
       16 . The valve of  claim 15 , wherein:
 said housing and said flow tube are modular.   
   
   
       17 . The valve of  claim 16 , wherein:
 said plurality of springs comprises two springs.