Use of steam-assisted gravity drainage with oxygen ("sagdox") in the recovery of bitumen in lean zones ("lz-sagdox")

Abstract

A process to recover hydrocarbons from a reservoir having at least one lean zone, wherein said lean zone has an initial bitumen saturation level less than about 0.6, said process including: i) Initially injecting of oxygen into said reservoir; ii) Allowing for combustion of said oxygen to vaporize connate water in said at least one lean zone; and iii) Recovering said hydrocarbons from said reservoir.

1 . A process to recover hydrocarbons from a reservoir having at least one lean zone, wherein said lean zone has an initial bitumen saturation level less than about 0.6, said process comprising:
 i) Initially injecting of oxygen into said reservoir;   ii) Allowing for combustion of said oxygen to vaporize connate water in said at least one lean zone; and   iii) Recovering said hydrocarbons from said reservoir.   
     
     
         2 . A process according to  claim 1  further comprising initial steam injection with oxygen into the reservoir then terminating said steam injection. 
     
     
         3 . The process of  claim 1  where combustion occurs at temperatures higher than 400° C. 
     
     
         4 . The process of  claim 1  where the oxygen has an oxygen content of 95 to 99.9 (v/v) percent. 
     
     
         5 . The process of  claim 1  where the oxygen is air. 
     
     
         6 . The process of  claim 5  where the air is enriched air with an oxygen containing content of 21 to 95 (v/v) percent. 
     
     
         7 . The process of  claim 1  where the hydrocarbons are bitumen API density (<10; in situ viscosity>100,000 cp.). 
     
     
         8 . The process of  claim 1  where the hydrocarbons are heavy oil (10<API<20); in situ viscosity>1000 cp.). 
     
     
         9 . A steam assisted gravity drainage with oxygen system for recovery of hydrocarbons from a reservoir having at least one lean zone, wherein said lean zone has an initial bitumen saturation level less than about 0.6, said system comprising:
 i) A first well, having a toe and a heel, said first well within said lean zone containing reservoir, for capturing said hydrocarbons;   ii) A second well within said lean zone containing reservoir, for injection of oxygen into said lean zone containing reservoir;   iii) Said second well being located proximate said toe of said first well; and   iv) At least one vent gas means for venting any gas produced in said reservoir.   
     
     
         10 . A steam assisted gravity drainage with oxygen system for recovery of hydrocarbons for a reservoir having at least one lean zone, wherein said lean zone has an initial bitumen saturation level less than about 0.6, said system comprising:
 i) A well, having a toe and a heel, said well being located within said lean zone containing reservoir; wherein said well further comprises:
 a. At least one oxygen injection site proximate said toe, for injecting oxygen into said reservoir; 
 b. A hydrocarbon recovery site for recovery of said hydrocarbons from said reservoir; and 
 c. At least one vent gas site for venting any gas produced in said reservoir. 
   
     
     
         11 . The system of  claim 9  where the vent gas means is selected from a group consisting of a single substantially vertical well or a plurality of substantially vertical wells. 
     
     
         12 . The system of  claims 9  and  10  where the vent gas means is a segregated annulus section in the heel section of the horizontal well. 
     
     
         13 . The system of  claim 9  where the at least one oxygen injection site is selected from a group consisting of a single substantially vertical well or a plurality of substantially vertical wells. 
     
     
         14 . The system of  claim 10  where the at least one oxygen injection site is a segregated toe section of the horizontal well. 
     
     
         15 . The system of  claim 10  wherein said toe of said well is at a level in said reservoir different than said heel of said well. 
     
     
         16 . The system of  claim 10  wherein said toe level is at a level higher in said reservoir than said heel of said well. 
     
     
         17 . The system of  claims 9  and  10  wherein said at least one vent gas site is distant said toe of said well. 
     
     
         18 . A process according to  claim 1 ,  9  or  10  where the lean zone thickness is less than 25 metres.