Gas lift valve with ball-orifice closing mechanism and fully compressible dual edge-welded bellows

Abstract

A valve for performing gas lift operations is provided that incorporates two edge-welded bellows and a ball-orifice closing mechanism. The gas lift valve incorporates features enabling enhanced compression of one of the bellows, beyond an initial closure point of the valve. For example, a stem with the sealing ball is divided into two components, wherein one of the stem components is configured to continue moving in relation to the other stem component with the ball, which is fixed in position when the ball seals the orifice and initially closes the valve. This continued movement allows one of the bellows to be fully compressed in the ultimately closed valve position, thereby protecting the bellows from high pressures and potential failure that could occur to bellows in a partially compressed state.

What is claimed is: 
     
         1 . A valve for downhole gas lift operations, comprising:
 a housing having an inlet and an outlet for fluid flow;   a seat disposed in the housing for controlling the fluid flow from the inlet to the outlet;   a stem configured to move in the housing, wherein a sealing element associated with the stem is configured to mate with an orifice in the seat to prevent the fluid flow from the inlet to the outlet, thereby closing the valve;   first bellows coupled to the housing and to the stem; and   second bellows coupled to the housing and to a movable piston of a variable volume dome in the housing, wherein the second bellows are fully compressed when the valve is closed.   
     
     
         2 . The valve of  claim 1 , wherein the sealing element comprises a ball disposed at a tip of the stem. 
     
     
         3 . The valve of  claim 1 , wherein the stem comprises a first stem component and a second stem component mechanically coupled to the first stem component, and wherein the first and second stem components are configured to move in relation to one another. 
     
     
         4 . The valve of  claim 3 , wherein the first stem component has a slot and wherein the second stem component has a pin configured to travel within the slot as the first or the second stem component moves in relation to the other stem component. 
     
     
         5 . The valve of  claim 3 , wherein the first and second stem components are mechanically coupled by a spring. 
     
     
         6 . The valve of  claim 3 , wherein a portion of the second stem component is hollow and is filled with a non-compressible fluid for protecting at least one of the first or second bellows from gas pressures. 
     
     
         7 . The valve of  claim 6 , wherein the non-compressible fluid comprises silicone oil. 
     
     
         8 . The valve of  claim 6 , wherein the non-compressible fluid is configured to prevent chatter in at least one of the first or second bellows as the non-compressible fluid is transferred between the first and second bellows via the hollow portion of the second stem component. 
     
     
         9 . The valve of  claim 3 , wherein the first stem component is mechanically stopped by the seat when the sealing element mates with the orifice and wherein the second stem component is configured to continue moving in relation to the first stem component until the second bellows are fully compressed. 
     
     
         10 . The valve of  claim 1 , wherein at least one of the first or second bellows are edge-welded bellows. 
     
     
         11 . The valve of  claim 1 , wherein the valve is configured to operate in external pressures of at least 10,000 psi. 
     
     
         12 . The valve of  claim 1 , wherein the first bellows are fully compressed when the valve is open. 
     
     
         13 . A method for performing downhole gas lift operations, comprising:
 providing a valve, comprising:
 a housing having an inlet and an outlet for fluid flow; 
 a seat disposed in the housing for controlling the fluid flow from the inlet to the outlet; 
 a stem configured to move in the housing, wherein a sealing element associated with the stem is configured to mate with an orifice in the seat to prevent the fluid flow from the inlet to the outlet, thereby closing the valve; 
 first bellows coupled to the housing and to the stem; and 
 second bellows coupled to the housing and to a movable piston of a variable volume dome in the housing, wherein the second bellows are fully compressed when the valve is closed; and 
   opening the valve by injecting gas downhole, wherein an injected gas pressure is greater than a dome gas pressure in the variable volume dome, such that the stem moves away from the seat to allow the fluid flow between the inlet and the outlet via the orifice.   
     
     
         14 . The method of  claim 13 , further comprising closing the valve by discontinuing to inject the gas downhole, wherein the dome gas pressure is greater than an external gas pressure external to the housing such that the stem moves and the sealing element mates with the orifice in the seat. 
     
     
         15 . The method of  claim 13 , wherein the stem comprises a first stem component and a second stem component mechanically coupled to the first stem component, and wherein the first and second stem components are configured to move in relation to one another. 
     
     
         16 . The method of  claim 15 , wherein the first stem component is mechanically stopped by the seat when closing the valve and wherein the second stem component continues to travel until the second bellows are fully compressed. 
     
     
         17 . The method of  claim 15 , wherein injecting the gas downhole compresses the first bellows. 
     
     
         18 . A system for downhole gas lift operations, comprising:
 casing disposed in a wellbore;   production tubing disposed in the casing; and   at least one valve, comprising:
 a housing having an inlet and an outlet for fluid flow, wherein the fluid flow enters the inlet from an annulus between the casing and the production tubing and exits the outlet into the production tubing; 
 a seat disposed in the housing for controlling the fluid flow from the inlet to the outlet; 
 a stem configured to move in the housing, wherein a sealing element associated with the stem is configured to mate with an orifice in the seat to prevent the fluid flow from the inlet to the outlet, thereby closing the valve; 
 first bellows coupled to the housing and to the stem; and 
 second bellows coupled to the housing and to a movable piston of a variable volume dome in the housing, wherein the second bellows are fully compressed when the valve is closed. 
   
     
     
         19 . The system of  claim 18 , wherein the stem comprises a first stem component and a second stem component mechanically coupled to the first stem component, and wherein the first and second stem components are configured to move in relation to one another. 
     
     
         20 . The system of  claim 19 , wherein the first stem component has a slot, wherein the second stem component has a pin configured to travel within the slot as the first or the second stem component moves in relation to the other stem component, and wherein the first and second stem components are mechanically coupled by a spring 
     
     
         21 . The system of  claim 18 , wherein the at least one valve is disposed in a side pocket mandrel of the production tubing.