Compressed natural gas artificial gas lift

Abstract

A gas lift capable oil well is artificially gas lifted by transferring compressed natural gas (CNG) from a compressed natural gas vessel of a mobile CNG storage system to a tubing-casing annulus of the gas lift capable well via a pathway. The CNG transfer occurs without the use of a compressor. A mobile unloader monitors and controls the flow of CNG from the vessel to the annulus.

What is claimed is: 
     
         1 . A method for gas lifting a gas lift capable well, the method comprising:
 transferring compressed natural gas from a compressed natural gas vessel of a mobile compressed natural gas storage system to a tubing-casing annulus of the gas lift capable well via a first pathway, wherein said transferring occurs without the use of a compressor.   
     
     
         2 . The method of  claim 1 , wherein, during said transferring, a pressure of compressed natural gas within the vessel is higher than a pressure of compressed natural gas received by the tubing-casing annulus from the vessel. 
     
     
         3 . The method of  claim 2 , wherein a pressure of compressed natural gas received by the tubing-casing annulus from the vessel during the transferring is greater than 500 psig. 
     
     
         4 . The method of  claim 2 , further comprising:
 disposing an unloader in the first pathway; and   using the unloader to control a pressure of the compressed natural gas being provided to the tubing-casing annulus during the transferring.   
     
     
         5 . The method of  claim 4 , wherein the unloader comprises:
 a high-pressure outlet configured to provide compressed natural gas to the tubing-casing annulus without the use of a compressor, the high-pressure outlet being disposed in the first pathway, and   a low-pressure outlet configured to provide compressed natural gas to a gas lift compressor of the gas-lift well.   
     
     
         6 . The method of  claim 5 , wherein the high-pressure outlet is configured to provide compressed natural gas at a pressure of over 500 psig, and the low-pressure outlet is configured to provide compressed natural gas at a pressure of under 500 psig. 
     
     
         7 . The method of  claim 4 , further comprising using the unloader to control a flow rate of the compressed natural gas from the vessel to the tubing-casing annulus during the transferring. 
     
     
         8 . The method of  claim 1 , further comprising, during the transferring, actively controlling a flow rate of the compressed natural gas from the vessel to the tubing-casing annulus through the first pathway. 
     
     
         9 . The method of  claim 1 , further comprising monitoring, via computer, operational conditions relating to the transferring. 
     
     
         10 . The method of  claim 9 , further comprising automatically controlling via the computer specific parameters of the transferring based on information collected during the monitoring. 
     
     
         11 . The method of  claim 1 , wherein the transferring causes an upward flow of downhole fluid within a tubing of the well. 
     
     
         12 . The method of  claim 1 , wherein the transferring increases an upward flow of downhole liquid within a tubing of the well. 
     
     
         13 . The method of  claim 1 , wherein the transferred compressed natural gas flows down the tubing-casing annulus, enters a tubing of the gas lift capable well, and flows upwardly within the tubing. 
     
     
         14 . The method of  claim 1 , wherein:
 the mobile compressed natural gas storage system comprises a wheeled frame that supports the vessel; and   the method further comprises delivering the mobile compressed natural gas storage system to a site of the well before said transferring.   
     
     
         15 . The method of  claim 1 , further comprising:
 transferring compressed natural gas from the vessel to the tubing-casing annulus by way of a compressor via a second fluid pathway.   
     
     
         16 . The method of  claim 15 , wherein the transferring via the second fluid pathway occurs after the transferring via the first fluid pathway. 
     
     
         17 . The method of  claim 15 , wherein the compressor receives recycle natural gas from production equipment of the well, compresses the recycle gas along with natural gas received from the vessel, and forces both recycle natural gas and natural gas received from the vessel into and down the tubing-casing annulus. 
     
     
         18 . A compressed natural gas artificial gas lift system comprising:
 a mobile compressed natural gas storage system including a compressed natural gas vessel supported by a wheeled frame, the compressed natural gas vessel containing compressed natural gas at a supply pressure;   a gas lift capable well comprising a tubing and a tubing-casing annulus; and   a first fluid pathway that connects the vessel to the tubing-casing annulus,   wherein there is not a compressor disposed in the fluid passageway, and   wherein the system is configured to transfer compressed natural gas from the vessel to the tubing-casing annulus via the first fluid pathway.   
     
     
         19 . A compressed natural gas artificial gas lift system comprising:
 a mobile compressed natural gas storage system including a compressed natural gas vessel supported by a wheeled frame; and   an unloader configured to transfer compressed natural gas from the vessel to a tubing-casing annulus of a gas lift capable well via a first fluid pathway that does not include a compressor,   wherein the unloader comprises an adjustable flow rate regulator disposed in the first fluid pathway.