Liquefied Gas-Driven Gas-Lift System

Abstract

One illustrative artificial lift method includes deriving compressed natural gas (CNG) from liquefied natural gas (LNG) and injecting the CNG into the well as a lift gas that aids in conveying fluid from the well. An illustrative system embodiment includes an evaporator and a controller. The evaporator converts LNG into CNG, which the controller injects into a well to enter a lift conduit as a lift gas to aid in conveying fluid from the well. Further disclosed herein is the use of a virtual pipeline to supply LNG for such artificial lift systems and methods. It includes: liquefying natural gas to fill a transport trailer at an offsite facility; transporting the trailer to a site of a well; and coupling the trailer to surface equipment to supply LNG as needed for supplying gas lift in the well. Once emptied, the trailer may be returned to the offsite facility for refilling.

I claim: 
     
         1 . An artificial lift method that comprises:
 deriving compressed natural gas (CNG) from liquid natural gas (LNG); and   injecting the CNG into a well, wherein the CNG enters a lift conduit as a lift gas that aids in conveying fluid from the well.   
     
     
         2 . The method of  claim 1 , wherein said deriving includes raising a temperature of LNG trapped in a restricted volume. 
     
     
         3 . The method of  claim 1 , further comprising:
 transporting liquid natural gas (LNG) to a site of the well.   
     
     
         4 . The method of  claim 1 ,
 wherein the well includes an inner production tubular defining an inner conduit,   wherein the well further includes an outer production tubular defining an annular conduit between the inner and outer production tubulars,   wherein the outer production tubular is terminated by a check valve that permits fluid to enter the outer production tubular.   
     
     
         5 . The method of  claim 4 , wherein said inner conduit serves as the lift conduit, and wherein said injecting is performed via the annular conduit. 
     
     
         6 . The method of  claim 4 , wherein said annular conduit serves as the lift conduit, and wherein said injecting is performed via the inner conduit. 
     
     
         7 . The method of  claim 4 , further comprising:
 pausing said injecting operation to enable fluid to accumulate in the outer production tubular.   
     
     
         8 . The method of  claim 7 , wherein said pausing is contingent upon detecting a change in injection pressure or flow rate. 
     
     
         9 . The method of  claim 7 , wherein said pausing is contingent upon detecting a flow rate or pressure condition at an upper end of the lift conduit. 
     
     
         10 . The method of  claim 7 , further comprising:
 repeating said injecting and pausing operations to provide intermittent lift.   
     
     
         11 . The method of  claim 10 , further comprising:
 adapting one or more parameters of the injecting or pausing operations to optimize a performance measure.   
     
     
         12 . The method of  claim 11 , wherein the performance measure accounts for at least one of the following: fluid production rate; usage rate of natural gas; and a ratio of produced fluid to injected CNG. 
     
     
         13 . An artificial lift system that comprises:
 an evaporator that converts liquid natural gas (LNG) into compressed natural gas (CNG); and   a controller that injects the CNG into a well, wherein the CNG enters a lift conduit as a lift gas to aid in conveying fluid from the well.   
     
     
         14 . The system of  claim 13 , further comprising a transport trailer coupled to provide LNG to the evaporator. 
     
     
         15 . The system of  claim 13 , wherein the well includes:
 an inner production tubular that defines an inner conduit;   an outer production tubular that defines an annular conduit between the inner and outer production tubulars; and   a check valve that terminates the outer production tubular and that permits fluid to enter the outer production tubular.   
     
     
         16 . The system of  claim 15 , wherein said inner conduit serves as the lift conduit, and wherein the controller injects the CNG via the annular conduit. 
     
     
         17 . The system of  claim 15 , wherein the controller periodically pauses the injection of CNG to enable fluid to accumulate in the outer production tubular. 
     
     
         18 . The system of  claim 17 , wherein the controller adapts timing parameters of the injection and pausing operations to optimize a ratio of produced fluid to injected CNG. 
     
     
         19 . A virtual pipeline method for providing artificial lift, the method comprising:
 liquefying natural gas to fill a transport trailer at an offsite facility;   transporting the trailer to a site of a well; and   coupling the trailer to surface equipment to enable the surface equipment to obtain liquid natural gas (LNG) as needed for supplying gas lift in the well.   
     
     
         20 . The method of  claim 20 , further comprising:
 replacing an emptied trailer at the site with a non-empty trailer of LNG; and   returning the emptied trailer to the offsite facility for filling.