Steam generation with carbon dioxide recycle

Abstract

Systems and methods relate to recovering hydrocarbons by injecting into a reservoir steam along with carbon dioxide recovered from flue gases produced while generating the steam and from separation of produced fluids. Due to benefits from the carbon dioxide injection, carbon dioxide capture rates from the flue gases selected below fifty percent in such combined recovery of the carbon dioxide enables lower fuel consumption even given that additional fuel is needed for the carbon dioxide capture versus steam only operations. As the capture rates from the flue gases increase above fifty percent like when employed for sequestration purposes, such approaches use more fuel than the steam only operations and may not be cost efficient. A carbon dioxide recovery unit coupled to an air-fired boiler or an auxiliary oxy-fired boiler may supply the carbon dioxide recovered from the flue gases.

1 . A method of recovering hydrocarbons with steam, comprising:
 generating the steam with combustion to heat and vaporize water;   injecting into a formation the steam and carbon dioxide;   producing a mixture including the hydrocarbons, condensate of the steam and a portion of the carbon dioxide; and   supplying flow of the carbon dioxide for sustaining the injecting by recovering the carbon dioxide from the mixture produced and capturing less than 50 percent of carbon dioxide content within exhaust from the combustion.   
     
     
         2 . The method of  claim 1 , wherein the steam is generated in an air-fired steam generator and the carbon dioxide content within the exhaust is separated from other gases of the exhaust. 
     
     
         3 . The method of  claim 1 , wherein the steam is generated in an air-fired steam generator and the carbon dioxide content within the exhaust is separated from other gases of the exhaust such that the carbon dioxide injected is mixed with less than 10 percent nitrogen by mass. 
     
     
         4 . The method of  claim 1 , wherein an amine based absorption unit captures the carbon dioxide content within the exhaust. 
     
     
         5 . The method of  claim 1 , wherein the steam is generated in an air-fired steam generator in which the carbon dioxide content in the exhaust thereof is released and an oxy-fired steam generator in which the carbon dioxide content in the exhaust thereof is used in the supplying of the flow of the carbon dioxide. 
     
     
         6 . The method of  claim 1 , wherein the carbon dioxide is injected with the steam and at a rate between 1 and 25 percent of the steam by mass. 
     
     
         7 . The method of  claim 1 , wherein the carbon dioxide that is injected is mixed with less than 10 percent nitrogen by mass. 
     
     
         8 . The method of  claim 1 , wherein the steam is generated in a once through steam generator. 
     
     
         9 . The method of  claim 1 , wherein the injecting is into a well disposed in the formation for a steam assisted gravity drainage operation. 
     
     
         10 . The method of  claim 1 , wherein less than 32 percent of the carbon dioxide content within the exhaust from the combustion is captured and a remainder is released to atmosphere. 
     
     
         11 . A method of recovering hydrocarbons with steam, comprising:
 producing the steam in an air-fired steam generator;   injecting into a formation the steam and carbon dioxide that is injected at a rate between 1 and 25 percent of the steam by mass and is recovered from production fluids and separated from other exhaust constituents of the steam generator such that capture of carbon dioxide content within exhaust from the steam generator is relied on to maintain the rate given retention of a portion of the carbon dioxide in the reservoir; and   recovering the production fluids including the hydrocarbons.   
     
     
         12 . The method of  claim 11 , wherein the carbon dioxide is separated from the other exhaust constituents of the steam generator to provide the carbon dioxide mixed with less than 10 percent nitrogen by mass. 
     
     
         13 . The method of  claim 11 , wherein the carbon dioxide is separated from the other exhaust constituents of the steam generator with an amine based absorption unit. 
     
     
         14 . The method of  claim 11 , wherein the carbon dioxide that is separated from the other exhaust constituents of the steam generator captures less than 50 percent of carbon dioxide content within the exhaust of the steam generator. 
     
     
         15 . The method of  claim 1 , wherein up to 16 percent of the carbon dioxide content within the exhaust from the combustion is captured and a remainder is released to atmosphere. 
     
     
         16 . A system for recovering hydrocarbons with steam, comprising:
 a steam generator that heats water with combustion to produce the steam;   at least one injection well coupled to the steam generator for introducing the steam and carbon dioxide into a formation;   at least one production well to recover from the formation a mixture including the hydrocarbons, condensate of the steam and a portion of the carbon dioxide; and   a carbon dioxide supply coupled to the at least one injection well for providing the carbon dioxide that is recovered from the mixture produced and captured from less than 50 percent of carbon dioxide content within exhaust from the combustion.   
     
     
         17 . The system of  claim 16 , wherein the steam generator includes an air-fired steam generator in which the carbon dioxide content in the exhaust thereof is released and an oxy-fired steam generator in which the carbon dioxide content in the exhaust thereof forms part of the carbon dioxide supply. 
     
     
         18 . The system of  claim 16 , wherein the carbon dioxide supply includes an amine based absorption unit to capture the carbon dioxide content within the exhaust. 
     
     
         19 . The system of  claim 16 , wherein the steam generator is a once through steam generator. 
     
     
         20 . The system of  claim 16 , wherein the injection well and the production well form a steam assisted gravity drainage well pair.