Recovery of heavy oils through in-situ combustion process

Abstract

An in-situ combustion process heats an oil-bearing formation so as to reduce the viscosity of heavy oil, and/or to extract oil from solid or semi-solid materials in the formation. Oxygen-enriched air for the combustion is generated non-cryogenically at the surface, preferably with a membrane system or a pressure swing adsorption (PSA) unit. The oxygen-enriched air may be blended with other air to adjust its oxygen content, and is then compressed at the surface, and conveyed into an injection well. The oxygen-enriched air is especially intended for use in a toe-to-heel in-situ combustion process, in which combustion proceeds along a horizontal well. Nitrogen resulting from the production of the oxygen-enriched air may be used to compress the oxygen-enriched air, or for other purposes.

1 . In an in-situ combustion process for oil recovery from a formation located below a surface, the combustion process including combusting a portion of an oil-bearing formation so as to generate heat in the formation in order to reduce viscosity of heavy oil in the reservoir and/or to cause oil trapped in a solid or semi-solid material to be released, in liquid form, from the material, 
 the improvement comprising non-cryogenically generating an oxygen-enriched gas stream above the surface and injecting said oxygen-enriched gas stream into the formation so as to support in-situ combustion in the formation.    
   
   
       2 . The improvement of  claim 1 , wherein the non-cryogenic generating step includes conveying air through a membrane system.  
   
   
       3 . The improvement of  claim 1 , wherein the non-cryogenic generating step includes conveying air through a pressure swing adsorption system.  
   
   
       4 . The improvement of  claim 2 , further comprising the step of blending air with the oxygen-enriched gas stream so as to produce a gas stream having a desired oxygen content.  
   
   
       5 . The improvement of  claim 3 , further comprising the step of blending air with the oxygen-enriched gas stream so as to produce a gas stream having a desired oxygen content.  
   
   
       6 . The improvement of  claim 1 , wherein the generating step produces an oxygen-enriched stream and an oxygen-depleted stream, the process further comprising using the oxygen-depleted stream to operate a compressor for compressing the oxygen-enriched stream.  
   
   
       7 . The improvement of  claim 1 , wherein the in-situ combustion process is selected to be a toe-to-heel combustion process.  
   
   
       8 . The improvement of  claim 7 , wherein the in-situ combustion process is selected to be a process which uses a catalyst to upgrade oil before the oil has been withdrawn from the formation.  
   
   
       9 . The improvement of  claim 1 , further comprising compressing the oxygen-enriched gas stream before injecting said stream into the formation.  
   
   
       10 . A method of enhancing an amount of oil recoverable from a formation, the formation being located beneath a surface, the method comprising: 
 a) non-cryogenically generating an oxygen-enriched gas stream above the surface of the formation, and    b) injecting said oxygen-enriched gas stream into the formation so as to support combustion of a portion of the formation, wherein the formation is heated by said combustion so as to reduce viscosity of heavy oil in the reservoir and/or to cause oil trapped in a solid or semi-solid material to be released, in liquid form, from the material.    
   
   
       11 . The method of  claim 10 , wherein the non-cryogenic generating step includes conveying air through a membrane system.  
   
   
       12 . The method of  claim 10 , wherein the non-cryogenic generating step includes conveying air through a pressure swing adsorption system.  
   
   
       13 . The method of  claim 11 , further comprising the step of blending air with the oxygen-enriched gas stream so as to produce a gas stream having a desired oxygen content.  
   
   
       14 . The method of  claim 12 , further comprising the step of blending air with the oxygen-enriched gas stream so as to produce a gas stream having a desired oxygen content.  
   
   
       15 . The method of  claim 10 , wherein the generating step produces an oxygen-enriched stream and an oxygen-depleted stream, the process further comprising using the oxygen-depleted stream to operate a compressor for compressing the oxygen-enriched stream.  
   
   
       16 . The method of  claim 10 , wherein the in-situ combustion process is selected to be a toe-to-heel combustion process.  
   
   
       17 . The method of  claim 16 , wherein the in-situ combustion process is selected to be a process which uses a catalyst to upgrade oil before the oil has been withdrawn from the formation.  
   
   
       18 . The method of  claim 10 , further comprising compressing the oxygen-enriched gas stream before injecting said stream into the formation.  
   
   
       19 . A method of recovering oil from an oil-bearing formation, comprising: 
 a) selecting a location of the formation, and determining parameters relating to the formation,    b) choosing a level of oxygen content for air to be injected downhole in said formation to support in-situ combustion, the oxygen content being chosen in accordance with said parameters,    c) generating an oxygen-enriched gas above a surface of said formation, and adjusting an oxygen concentration of said oxygen-enriched gas according to the level chosen in step (b), and    d) injecting said oxygen-enriched gas to a combustion site below the surface of the formation.    
   
   
       20 . The method of  claim 19 , wherein step (c) is performed by a portable system, and wherein method further comprises the steps of repeating steps (a) and (b) for a different formation, moving the portable system to a vicinity of said different formation, and repeating steps (c) and (d) in the vicinity of said different formation.