Gas lift valve

Abstract

A gas lift valve is provided with increased longevity and reliability for preventing backflow. A wide cylindrical sliding member stabilizes axial movement of a valve element in the gas lift valve. A wide spring around the sliding member biases the valve element toward closure during back flow. The spring is physically supported and guided by the sliding member and protected from gas flow injection by the same sliding member. A one-piece poppet version of the valve element provides a consistent closing seal, and the sliding member protects the valve seat and poppet from full force of an injected gas. A dart version of the valve element includes a hexagonal race for movement of the sliding member, which prevents rotational wear of components and provides a straight flow path for the injection gas with no sharp transitions to wear and no sharp angles to erode.

1 . A gas lift valve, comprising:
 a first port for receiving a gas from a well annulus;   a second port for transferring the gas to a well production tube;   a valve seat;   a poppet valve element for allowing a one-way flow of the gas past the valve seat and for preventing a back flow of the gas;   a sliding barrel attached to the poppet valve element to maintain a sealing surface of the poppet valve element in alignment with a sealing surface of the valve seat; and   a spring coiled around the outside diameter of the sliding barrel to bias the poppet valve element in a closed position against the valve seat.   
     
     
         2 . The gas lift valve of  claim 1 , wherein the sliding barrel and the spring have a wide cross-sectional diameter substantially the same as a diameter of the poppet valve element to maintain a sealing interface of the poppet valve element and the valve seat in parallel-planar alignment with each other. 
     
     
         3 . The gas lift valve of  claim 1 , wherein the poppet valve element comprises a one-piece member for alignment of a sealing surface of the poppet valve element with a sealing surface of the valve seat. 
     
     
         4 . The gas lift valve of  claim 1 , wherein the spring is protected from a main flow of the gas by the barrel. 
     
     
         5 . The gas lift valve of  claim 1 , wherein a sealing interface between the poppet valve element and the valve seat is protected from a direct high speed flow of the gas by at least one valve component. 
     
     
         6 . The gas lift valve of  claim 1 , wherein a maximum open state of the poppet valve element is determined by the poppet valve element contacting an end housing of the gas lift valve. 
     
     
         7 . A gas lift valve, comprising:
 a first port for receiving a gas from a well annulus;   a second port for transferring the gas to a well production tube;   a valve seat;   a dart valve element for allowing a one-way flow of the gas past the valve seat and for preventing a back flow of the gas;   a sliding barrel attached to the dart valve element to maintain a sealing surface of the dart valve element in alignment with a sealing surface of the valve seat;   a spring coiled around the outside perimeter of the sliding barrel to bias the poppet valve element in a closed position against the valve seat; and   a race of hexagonal cross-section for a movement of the sliding barrel.   
     
     
         8 . The gas lift valve of  claim 7 , further comprising a flow path for gas substantially free from sharp angular transitions. 
     
     
         9 . The gas lift valve of  claim 7 , wherein a hex dart configuration counteracts erosion at sharp corners. 
     
     
         10 . The gas lift valve of  claim 7 , wherein the spring is fully-guided on an inside diameter (ID) of the spring for stability. 
     
     
         11 . The gas lift valve of  claim 7 , wherein a hex dart configuration prevents a rotation of a valve component caused by high velocity gas flow. 
     
     
         12 . The gas lift valve of  claim 7 , wherein the sliding barrel and the spring have a wide cross-sectional diameter substantially the same as a diameter of the dart valve element to maintain a sealing interface of the dart valve element and the valve seat in parallel-planar alignment with each other. 
     
     
         13 . The gas lift valve of  claim 7 , wherein the spring is protected from a main flow of the gas by the barrel. 
     
     
         14 . The gas lift valve of  claim 7 , wherein a sealing interface between the dart valve element and the valve seat is protected from a direct high speed flow of the gas by at least one valve component. 
     
     
         15 . A method, comprising:
 constructing a gas lift valve with a wide cylindrical sliding member to reliably seat a valve element; and   biasing the valve element toward a closed state with a wide spring around the wide cylindrical sliding member.   
     
     
         16 . The method of  claim 15 , wherein the wide cylindrical sliding member and the spring have a cross-sectional diameter substantially the same as a largest diameter of the valve element to maintain a sealing interface of the valve element and a valve seat in a parallel-planar alignment with each other; and
 wherein the wide cylindrical sliding member protects the valve element and a valve seat from a full force of a gas injection flow.   
     
     
         17 . The method of  claim 15 , wherein the spring is protected from a main flow of an injection gas by the wise cylindrical sliding member. 
     
     
         18 . The method of  claim 15 , further comprising attaching a one-piece poppet-shaped valve element to the wide cylindrical sliding member to reliably close the gas lift valve during a back flow condition. 
     
     
         19 . The method of  claim 15 , further comprising:
 incorporating a dart valve element in the gas lift valve to prevent a back flow condition; and   incorporating a hexagonal race for the wide cylindrical sliding member in the gas lift valve to prevent a rotation of the valve components caused by a high velocity gas flow.   
     
     
         20 . The method of  claim 19 , wherein the hexagonal race provides a flow path for a gas substantially free from sharp angular transitions; and wherein the hexagonal race counteracts erosion at sharp corners.