In situ process to recover heavy oil and bitumen

Abstract

An in situ reservoir recovery process consisting of a horizontal injection well and a horizontal production well to extract bitumen or heavy oil from a reservoir. The process consists of a first phase operated at high-pressure in which steam, hydrocarbon solvent and non-condensable gases are injected into the reservoir and a second phase in which the injected fluids are transitioned to a high content of solvent and non-condensable gas and a reduced amount of steam to maintain a warm zone in the neighbourhood of the injection and production wells. The steam injection is sufficient to promote vapor transport of the solvent into the vapor depletion chamber and maintain the process at elevated temperatures in order to maintain low fluid viscosities in the production wellbore and to achieve preferred phase behaviour of the solvent hydrocarbon and the heavy oil or bitumen. The operating pressure of the process is controlled to prevent losses of the solvent hydrocarbon to the formation and to aid in solvent production to the production well in order for future re-cycling.

1 . A method for recovering heavy hydrocarbons from an underground reservoir containing heavy hydrocarbons, an injection well and a production well, comprising: 
 a) injecting steam into said reservoir to form a steam vapor chamber;    b) co-injecting predetermined quantities of non-condensable gas, hydrocarbon solvent and steam into said steam vapor chamber to maximize solubility of the solvent in said heavy hydrocarbons;    c) recovering produced hydrocarbons within said production well;    d) controlling the volume of said steam vapor chamber by progressively adjusting the volume of said steam, said non-condensable gas and hydrocarbon solvent injected into said reservoir, whereby said hydrocarbon solvent and non-condensable gas are predominant relative to the volume of said steam; and    e) recovering further produced heavy hydrocarbons.    
   
   
       2 . (canceled)  
   
   
       3 . The method as set forth in  claim 1 , wherein in step c) reservoir pressure is progressively increased.  
   
   
       4 . The method as set forth in  claim 3 , wherein reservoir temperature is progressively lowered  
   
   
       5 . The method as set forth in  claim 4 , wherein solvent solubility in said heavy hydrocarbons is increased.  
   
   
       6 . The method as set forth in  claim 5 , further including recovering said hydrocarbon solvent.  
   
   
       7 . The method as set forth in  claim 1 , wherein said hydrocarbon solvent comprises an alkane selected from the group consisting of C3 through C8 alkanes and mixtures thereof.  
   
   
       8 . The method as set forth  claim 1 , wherein said hydrocarbon solvent comprises an alkane derived from gas condensate.  
   
   
       9 . The method as set forth in  claim 1 , wherein said hydrocarbon solvent comprises an alkane derived from gas diluent.  
   
   
       10 . The method as set forth in  claim 1 , wherein said non-condensable gas comprises a gas selected from the group consisting of C1 through C3 hydrocarbons  
   
   
       11 . The method as set forth in  claim 10 , wherein said non-condensable gas comprises carbon dioxide.  
   
   
       12 . The method as set forth in  claim 11 , wherein said non-condensable gas comprises a gaseous component of flue gas.  
   
   
       13 . The method as set forth in  claim 1 , wherein said non-condensable gas is selected from the group consisting of C1 through C3 alkane hydrocarbons, carbon dioxide, a component of flue gas, natural gas and combinations thereof.  
   
   
       14 . A method for recovering heavy hydrocarbons from an underground reservoir containing heavy hydrocarbons, an injection well and a production well, comprising: 
 a) injecting steam into said reservoir, to form a steam vapor chamber;    b) co-injectinag predetermined quantities of steam, hydrocarbon solvent and non-condensable gas into said steam vapor chamber to maximize the solubility of the solvent in said heavy hydrocarbons;    c) recovering produced hydrocarbons through said production well;    d) determining the formation of said vapor chamber by calculating the ratio of cumulative injected steam to cumulative hydrocarbon production volume;    e) adjusting te volume of steam injected into said vapor chamber to be subordinate to the volume of hydrocarbon solvent and non-condensable gas whereby partial pressure of said steam in said chamber is reduced and hydrocarbon solvent solubility is elevated in said heavy hydrocarbons; and    f) recovering further produced hydrocarbons through said production well.    
   
   
       15 . (canceled)  
   
   
       16 . The method as set forth in  claim 14 , further including the step of selecting the quantity of steam, non-condensable gas and injection pressure to maximize the solubility of hydrocarbon solvent in said heavy hydrocarbons.  
   
   
       17 . (canceled)  
   
   
       18 . The method as set forth in  claim 14 , further including recovering said hydrocarbon solvent.  
   
   
       19 . A method for recovering heavy hydrocarbons from an underground reservoir containing heavy hydrocarbons, an injection well and a production well, comprising: 
 a) injecting steam into said reservoir, to form a steam vapor chamber,    b) co-injecting predetermined quantities of steam, hydrocarbon solvent and non-condensable gas into said steam vapor chamber to maximize the solubility of the solvent in said heavy hydrocarbons, while controlling the volume of said vapor chamber;    c) recovering produced hydrocarbons through said production well;    d) adjusting the volume of steam injected into said vapor chamber to be subordinate to the volume of hydrocarbon solvent and non-condensable gas whereby partial pressure of said steam in said chamber is reduced and hydrocarbon solvent solubility is elevated in said heavy hydrocarbons; and    e) recovering further produced hydrocarbons through said production well.