In situ combustion following sagd

Abstract

There is provided herein a method for recovering petroleum from a formation, wherein said formation is intersected by at least one wellpair consisting of a horizontal production well and a horizontal injection well, and wherein said formation comprises at least one steam chamber developed by a steam-assisted process, said method comprising: providing an oxidizing agent near the top of said formation; initiating in situ combustion (ISC); and recovering petroleum from said at least one production well.

1 . A method for recovering petroleum from a formation, wherein said formation is intersected by at least one wellpair consisting of a horizontal production well and a horizontal injection well, and wherein said formation comprises at least one steam chamber developed by a steam-assisted process, said method comprising:
 a) providing an oxidizing agent near the top of said formation;   b) initiating in situ combustion (ISC); and   c) recovering petroleum from said at least one production well.   
     
     
         2 . The method of  claim 1 , wherein the petroleum comprises heavy oil and/or bitumen. 
     
     
         3 . The method of  claim 1 , wherein said oxidizing agent is provided 1-10 meters below the overburden of said formation. 
     
     
         4 . The method of  claim 1 , wherein said oxidizing agent is selected from the group consisting of air, oxygen and oxygen-enriched air. 
     
     
         5 . The method of  claim 1 , wherein said steam-assisted process is selected from the group consisting of steam-assisted gravity drainage (SAGD), steam-assisted gravity push (SAGP), and cyclic steam stimulation (CSS). 
     
     
         6 . The method of  claim 1 , wherein said at least one wellpair is a SAGD wellpair. 
     
     
         7 . The method of  claim 1 , wherein said oxidizing agent is provided through a horizontal oxidant injection well. 
     
     
         8 . The method of  claim 7 , wherein said formation comprises at least two wellpairs and at least two steam chambers, and said oxidant injection well is disposed so that said oxidizing agent is supplied to said at least two steam chambers. 
     
     
         9 . The method of  claim 1 , wherein said formation attains a temperature of 500° C.-1000° C. during said ISC. 
     
     
         10 . The method of  claim 1  further comprising, repressurizing said formation to its virgin pressure after recovering the petroleum is complete. 
     
     
         11 . A method for recovering heavy oil and/or bitumen from a formation, comprising:
 a) providing an oxidizing agent through a horizontal oxidant injection well disposed 1-10 meters below the overburden of said formation,
 wherein said formation is intersected by at least one steam-assisted gravity drainage (SAGD) wellpair consisting of a horizontal production well and a horizontal injection well, 
 wherein said formation comprises at least one SAGD steam chamber, and 
 wherein said oxidizing agent is selected from the group consisting of air, oxygen and oxygen-enriched air; 
   b) initiating in situ combustion (ISC); and   c) recovering petroleum from said at least one production well.   
     
     
         12 . The method of  claim 11 , wherein said formation comprises at least two SAGD wellpairs and at least two SAGD steam chambers, and said oxidant injection well is disposed so that said oxidizing agent is supplied to said at least two SAGD steam chambers. 
     
     
         13 . The method of  claim 11  further comprising, repressurizing said formation to its virgin pressure after recovering the petroleum is complete. 
     
     
         14 . The method of  claim 11 , wherein said formation attains a temperature of 500° C.-1000° C. during said ISC. 
     
     
         15 . A method of enhanced oil recovery comprising:
 a. providing at least one horizontal production well and at least one horizontal injection well, said production well being at or near a bottom of a hydrocarbon reservoir, and said injection well being above said production well and at or near a top of said hydrocarbon reservoir;   b. injecting steam into said injection well and recovering a first amount of hydrocarbon from said production well;   c. injecting an oxidant into said injection well when hydrocarbon production in step b) begins to decrease;   d. initiating combustion; and   e. recovering a second amount of hydrocarbon from said horizontal production well.   
     
     
         16 . The method of  claim 15 , comprising a second horizontal injection well, wherein step c) uses said second horizontal injection well. 
     
     
         17 . The method of  claim 15 , comprising a second horizontal injection well, wherein step c) uses both horizontal injection wells. 
     
     
         18 . The method of  claim 15 , further comprising, repressurizing said hydrocarbon reservoir to its initial pressure after recovering said hydrocarbons is complete. 
     
     
         19 . The method of  claim 15 , wherein said hydrocarbon reservoir attains a temperature of 500° C.-1000° C. during said combustion.