Integrated process utilizing nitrogen and carbon dioxide streams for enhanced oil recovery

Abstract

Disclosed is an integrated enhanced oil recovery process and system for use in recovering relatively light oil from an oil-producing reservoir utilizing the injection of nitrogen produced by air separation in a cryogenic air separation unit and/or carbon dioxide produced by combustion in an oxygen fired steam generator fed by oxygen from the air separation unit. The steam produced may be utilized for suitable uses other than injection into an oil-producing reservoir, including heat generation and driving steam turbines, which in turn drive rotary equipment such as electrical generators, pumps and compressors.

1 . An enhanced oil recovery process, comprising:
 a. feeding air to a cryogenic air separation unit;   b. operating the cryogenic air separation unit to produce an oxygen stream and a nitrogen stream;   c. feeding the oxygen stream, water and a fuel to an oxygen fired steam generator;   d. combusting the fuel in the oxygen fired steam generator to convert the water to steam and produce a carbon dioxide stream;   e. utilizing the steam for a use other than injection into an oil-producing reservoir;   f. compressing at least one of the carbon dioxide stream and the nitrogen stream to form an injection gas stream; and   g. injecting the injection gas stream into a first oil-producing reservoir.   
     
     
         2 . The process of  claim 1 , further comprising compressing the other of the carbon dioxide stream and the nitrogen stream to form a second injection gas stream; and injecting the second injection gas treatment into a second oil-producing reservoir. 
     
     
         3 . The process of  claim 1 , wherein the steam is utilized to drive steam turbines which in turn drive compressors in the air separation unit. 
     
     
         4 . The process of  claim 1 , wherein the steam is utilized to generate power. 
     
     
         5 . The process of  claim 4 , further comprising utilizing the power to drive motor-driven compressors in the air separation unit. 
     
     
         6 . The process of  claim 1  wherein the oxygen stream comprises at least 90% purity oxygen. 
     
     
         7 . The process of  claim 1 , further comprising dehydrating the carbon dioxide stream. 
     
     
         8 . The process of  claim 1 , further comprising purifying the carbon dioxide stream prior to the compressing step. 
     
     
         9 . The process of  claim 1  wherein the injection gas stream comprises carbon dioxide, further comprising compressing the nitrogen stream to form a second injection gas stream and injecting the second injection gas stream into the first oil-producing reservoir. 
     
     
         10 . The process of  claim 1  wherein the injection gas stream comprises nitrogen, further comprising compressing the carbon dioxide stream to form a second injection gas stream and injecting the second injection gas stream into the first oil-producing reservoir. 
     
     
         11 . A system for enhanced oil recovery, comprising:
 a. a cryogenic air separation unit having an air inlet, and oxygen outlet and a nitrogen outlet;   b. an oxygen fired steam generator in fluid communication with the oxygen outlet of the cryogenic air separation unit and further having a fuel inlet, water inlet, exhaust gas outlet and steam outlet, the steam outlet being in fluid communication with equipment selected from the group consisting of a steam turbine, a heater and a boiler;   c. a means for carbon dioxide dehydration;   d. a compressor for compressing at least one of the carbon dioxide stream and the nitrogen stream to form an injection gas stream; and   e. a means for injecting the injection gas stream into an oil-producing reservoir.   
     
     
         12 . The system of  claim 11  wherein the cryogenic air separation unit comprises at least one steam turbine driven compressor in fluid communication with the steam outlet.