Inverted tail plug and assembly for gas lift valve

Abstract

Embodiments of the present invention relate to an improved tail plug and assembly for a gas lift valve for use in oil and gas wells. The tail plug assists in preventing a pressurized component of the gas lift valve from depressurizing through leaks in the valve to the ambient. At least portion of the tail plug may be maintained in the gas lift valve via a treaded connection. The tail plug may further prevent leaks via an O-ring and/or a crush washer, where the O-ring and/or the crush washer are located on the tail plug below its threaded connection.

1 . A gas lift valve, comprising:
 a gas chamber;   a bore including a first end in fluid communication with the gas chamber and a second end in fluid communication with an ambient atmosphere outside the gas lift valve; and   a removable tail plug for sealing at least a portion of the bore, wherein the tail plug is removable via a threaded connection with the bore, and wherein the threaded connection comprises a first set of threads on an upper end of the tail plug and a corresponding second set of threads on an upper end of the gas lift valve.   
     
     
         2 . The gas lift valve of  claim 1  wherein the tail plug seals at least a portion of the bore to substantially prevent a gas in the gas chamber from leaking through the bore to the ambient atmosphere outside the gas lift valve. 
     
     
         3 . The gas lift valve of  claim 2  wherein the removable tail plug includes an O-ring groove. 
     
     
         4 . The gas lift valve of  claim 3  wherein the O-ring groove is located below the first set of threads. 
     
     
         5 . The gas lift valve of  claim 4  wherein the removable tail plug includes an O-ring in the O-ring groove, and wherein the O-ring assists in substantially preventing a gas in the gas chamber from leaking through the bore to the ambient atmosphere outside the gas lift valve. 
     
     
         6 . The gas lift valve of  claim 5  wherein the removable tail plug includes a crush washer groove. 
     
     
         7 . The gas lift valve of  claim 6  wherein the crush washer groove is located below the first set of threads. 
     
     
         8 . The gas lift valve of  claim 7  wherein the removable tail plug includes a crush washer in the crush washer groove, and wherein the crush washer assists in substantially preventing a gas in the gas chamber from leaking through the bore to the ambient atmosphere outside the gas lift valve. 
     
     
         9 . The gas lift valve of  claim 8  wherein the O-ring grove is located below the crush washer groove. 
     
     
         10 . The gas lift valve of  claim 9  including a gas injection valve core mounted in the bore. 
     
     
         11 . The gas lift valve of  claim 10  wherein the gas injection valve core is mounted in the bore between the gas chamber and the tail plug. 
     
     
         12 . The gas lift valve of  claim 11  wherein the first set of threads are male threads. 
     
     
         13 . The gas lift valve of  claim 12  wherein the second set of threads are female threads. 
     
     
         14 . The gas lift valve of  claim 13  wherein the threaded connection is an NPT connection. 
     
     
         15 . The gas lift valve of  claim 14  wherein the threaded connection is a brass to stainless steel connection. 
     
     
         16 . The gas lift valve of  claim 15  wherein the bore is a bore in a dome cap. 
     
     
         17 . The gas lift valve of  claim 16  wherein the dome cap is detachable from the gas lift valve. 
     
     
         18 . The gas lift valve of  claim 11  wherein the crush washer is made from copper. 
     
     
         19 . The gas lift valve of  claim 18  wherein the tail plug includes a head located above the first set of threads.