Enhanced Natural Gas Liquid Recovery Process

Abstract

A method comprises receiving a hydrocarbon feed stream; separating the hydrocarbon feed stream into a heavy hydrocarbon rich stream and a recycle stream, wherein the recycle stream comprises a gas selected from the group consisting of carbon dioxide, nitrogen, air, and water; and separating the recycle stream into a natural gas liquids (NGL) rich stream and a purified recycle stream. A plurality of process equipment configured to receive a hydrocarbon feed stream, separate the hydrocarbon feed stream into a heavy hydrocarbon rich stream and a recycle stream comprising at least one C 3+ hydrocarbon and a gas selected from the group consisting of carbon dioxide, nitrogen, air, and water, and separate the recycle stream into a NGL rich stream and a purified recycle stream.

1 . A method comprising:
 receiving a hydrocarbon feed stream;   separating the hydrocarbon feed stream into a heavy hydrocarbon rich stream and a recycle stream, wherein the recycle stream comprises a gas selected from the group consisting of carbon dioxide, nitrogen, air, and water; and   separating the recycle stream into a natural gas liquids (NGL) rich stream and a purified recycle stream.   
     
     
         2 . The method of  claim 1 , further comprising injecting the purified recycle stream into a subterranean formation. 
     
     
         3 . The method of  claim 1 , further comprising:
 separating the recycle stream into a vapor recycle stream and a liquid recycle stream; and   dehydrating the vapor recycle stream.   
     
     
         4 . The method of  claim 3 , further comprising dehydrating the liquid recycle stream. 
     
     
         5 . The method of  claim 1 , further comprising:
 separating the recycle stream into a vapor recycle stream and a liquid recycle stream; and   dehydrating the liquid recycle stream.   
     
     
         6 . The method of  claim 1 , further comprising separating the recycle stream into a vapor recycle stream and a liquid recycle stream, wherein the vapor recycle stream and the liquid recycle stream are fed to the separation of the recycle stream as separate streams. 
     
     
         7 . The method of  claim 6 , wherein separating the vapor recycle stream and the liquid recycle stream comprises using a three-phase separator. 
     
     
         8 . The method of  claim 1 , further comprising dehydrating at least a portion of the recycle stream prior to separating the recycle stream into the NGL rich stream and the purified recycle stream. 
     
     
         9 . The method of  claim 1 , wherein separating the recycle stream comprises:
 separating the recycle stream into the purified recycle stream and a sour NGL rich stream; and   sweetening the sour NGL rich stream, thereby producing the NGL rich stream.   
     
     
         10 . The method of  claim 9 , further comprising:
 cooling the sour NGL rich stream prior to sweetening the sour NGL rich stream; and   throttling the sour NGL rich stream prior to sweetening the sour NGL rich stream.   
     
     
         11 . The method of  claim 9 , wherein the NGL rich stream comprises no more than about 5 percent acid gases. 
     
     
         12 . The method of  claim 1 , further comprising:
 separating the NGL rich stream into a heavy NGL stream and a light NGL stream; and   mixing the heavy NGL stream with the heavy hydrocarbon rich stream.   
     
     
         13 . The method of  claim 12 , further comprising:
 separating the recycle stream into a vapor recycle stream and a liquid recycle stream, wherein the vapor recycle stream and the liquid recycle stream are fed to the separation of the recycle stream as separate streams; and   dehydrating at least one of the vapor recycle stream and the liquid recycle stream.   
     
     
         14 . The method of  claim 12 , wherein the heavy hydrocarbon rich stream has a Reid vapor pressure of less than 6 after being mixed with at least a portion of the heavy NGL stream. 
     
     
         15 . The method of  claim 12 , wherein the light NGL stream has an energy content of between about 1,000 British thermal units per cubit foot (Btu/ft 3 ) and about 1,200 Btu/ft 3 . 
     
     
         16 . The method of  claim 12 , wherein the light NGL stream has a vapor pressure of less than about 250 pounds per square inch gauge (psig) at a standard temperature. 
     
     
         17 . The method of  claim 12 , further comprising:
 combining a second NGL rich stream with the NGL rich stream prior to separating the NGL rich stream; and   separating the second NGL rich stream along with the NGL rich stream to form the heavy NGL stream and the light NGL stream.   
     
     
         18 . A plurality of process equipment configured to:
 receive a hydrocarbon feed stream;   separate the hydrocarbon feed stream into a heavy hydrocarbon rich stream and a recycle stream comprising at least one C 3+  hydrocarbon and a gas selected from the group consisting of carbon dioxide, nitrogen, air, and water; and   separate the recycle stream into a natural gas liquid (NGL) rich stream and a purified recycle stream.   
     
     
         19 . The process equipment of  claim 18 , further configured to:
 separate the NGL rich stream into a heavy NGL stream and a light NGL stream; and   mix at least a portion of the heavy NGL stream with the heavy hydrocarbon rich stream.   
     
     
         20 . The process equipment of  claim 18 , wherein the NGL rich stream comprises less than about 70 percent of the C 3+  hydrocarbons from the recycle stream. 
     
     
         21 . The process equipment of  claim 18 , wherein the NGL rich stream comprises from about 10 percent to about 50 percent of the C 3+  hydrocarbons from the recycle stream. 
     
     
         22 . The process equipment of  claim 18 , wherein the process equipment configured to separate the recycle stream into the NGL rich stream and the purified recycle stream is configured to:
 separate the recycle stream into a vapor recycle stream and a liquid recycle stream; and   separate the vapor recycle stream and the liquid recycle stream into the NGL rich stream and the purified recycle stream.   
     
     
         23 . The process equipment of  claim 22 , wherein the recycle stream is separated in a separator, and wherein the vapor recycle stream and the liquid recycle stream enter the separator as separate streams. 
     
     
         24 . The process equipment of  claim 19 , wherein the heavy hydrocarbon rich stream has a Reid vapor pressure of less than 6 at a temperature of about 100° F. after being mixed with the heavy NGL stream. 
     
     
         25 . The process equipment of  claim 19 , further configured to:
 combine a second NGL rich stream with the NGL rich stream prior to separating the NGL rich stream; and   separate the second NGL rich stream along with the NGL rich stream to form the heavy NGL stream and the light NGL stream.