Downhole upgrading of oils

Abstract

Oils present in oil reservoirs can be upgraded by high temperature cracking through the injection of oxygen into the reservoir and combusting the oils to generate heat. By employing injection wells and production wells, the oxygen may be placed into the reservoir increasing the flux of oxygen present as well as the temperature and cracking severity needed to produce upgraded oil.

Having thus described the invention, what I claim is:  
     
         1 . A method for cracking oil in an oil reservoir comprising injecting oxygen into said oil reservoir and igniting said oil.  
     
     
         2 . The method as claimed in  claim 1  further comprising a production well.  
     
     
         3 . The method as claimed in  claim 1  wherein said cracked oil is recovered through said production well.  
     
     
         4 . The method as claimed in  claim 1  wherein said oil comprises heavy oil and tar sands.  
     
     
         5 . The method as claimed in  claim 1  wherein said cracking is performed at a temperature greater than 400° C.  
     
     
         6 . The method as claimed in  claim 1  wherein said cracking is performed at a temperature greater than 500° C.  
     
     
         7 . The method as claimed in  claim 1  wherein said oxygen is pure oxygen or oxygen-enriched air.  
     
     
         8 . The method as claimed in  claim 7  wherein said oxygen or oxygen-enriched air is produced by an air separation facility.  
     
     
         9 . The method as claimed in  claim 1  wherein ignition is provided by an electronic device or by steam heat.  
     
     
         10 . The method as claimed in  claim 1  further comprising injecting water into said oil reservoir.  
     
     
         11 . An in-situ combustion process for recovering oil from an underground oil containing reservoir comprising the steps of: 
 injecting oxygen into said reservoir through an injection well,    combusting and cracking said oil;    producing cracked oil, and    recovering said cracked oil through a production well.    
     
     
         12 . The process as claimed in  claim 11  wherein said injection well is vertical and said production well is horizontal.  
     
     
         13 . The process as claimed in  claim 11  wherein said injection well and said production well are horizontal.  
     
     
         14 . The process as claimed in  claim 11  wherein said production well and said injection well are perpendicular to each other.  
     
     
         15 . The process as claimed in  claim 11  wherein there are a plurality of injection wells.  
     
     
         16 . The process as claimed in  claim 11  wherein there are a plurality of production wells.  
     
     
         17 . The process as claimed in  claim 11  wherein said combustion takes place at temperatures greater than 400° C.  
     
     
         18 . The process as claimed in  claim 11  wherein said combustion takes place at temperatures greater than 400° C.  
     
     
         19 . The process as claimed in  claim 11  further comprising recovering carbon dioxide from said production well.  
     
     
         20 . The process as claimed in  claim 11  wherein said injection well is located near the top of said oil bearing reservoir and said production well is located near the bottom of said oil bearing reservoir.  
     
     
         21 . The process as claimed in  claim 11  wherein a catalyst is present in said production well.