Methods and systems for in-situ extraction of bitumen

Abstract

Methods and systems for in situ extraction of bitumen from deposits of bitumen-containing material are described. The methods and systems can generally include establishing freeze walls within the deposit of bitumen-containing material to establish a confined zone into which solvents can be injected in order to extract bitumen from the bitumen-containing deposits. Different types of solvents can be sequentially injected in order to extract bitumen and also help reduce the amount of solvent left behind in the deposit.

We claim: 
     
         1 . A method of in-situ bitumen extraction comprising:
 forming one or more vertical freeze walls within or around a deposit of bituminous material and establishing a laterally confined deposit of bituminous material;   injecting a first solvent within the laterally confined deposit of bituminous material;   withdrawing a mixture of dissolved bitumen and first solvent from within the laterally confined deposit of bituminous material;   injecting a second solvent within the laterally confined deposit of bituminous material;   withdrawing a mixture of first solvent and second solvent from within the laterally confined deposit of bituminous material;   injecting water within the laterally confined deposit of bituminous material; and   withdrawing a mixture of second solvent and water from within the laterally confined deposit of bituminous material.   
     
     
         2 . The method as recited in  claim 1 , wherein the method further comprises forming one or more horizontal freeze walls within the deposit of bituminous material and vertically confining the laterally confined deposit of bituminous material. 
     
     
         3 . The method as recited in  claim 1 , wherein the one or more vertical freeze walls abut an impervious geological material located (within or) below the deposit of bituminous material. 
     
     
         4 . The method as recited in  claim 1 , wherein forming one or more vertical freeze walls within or around the deposit of bituminous material comprises:
 drilling a plurality of spaced apart vertical bores within or around the deposit of bituminous material; and   circulating a refrigerant through the vertical bores.   
     
     
         5 . The method as recited in  claim 1 , wherein injecting the first solvent within the laterally confined deposit of bituminous material comprises:
 drilling one or more vertical injection bores within the laterally confined deposit of bituminous material; and   injecting the first solvent within the laterally confined deposit of bituminous material through the one or more vertical injection bores.   
     
     
         6 . The method as recited in  claim 5 , wherein withdrawing the mixture of dissolved bitumen and first solvent from within the laterally confined deposit of bituminous material comprises:
 drilling one or more vertical production bores within the laterally confined deposit of bituminous material; and   withdrawing the mixture of dissolved bitumen and first solvent from the laterally confined deposit of bituminous material through the one or more vertical production bores.   
     
     
         7 . The method as recited in  claim 1 , wherein prior to injecting the first solvent within the laterally confined deposit of bituminous material, water is injected into the laterally confined deposit of bituminous material. 
     
     
         8 . The method as recited in  claim 7 , wherein the water comprises steam. 
     
     
         9 . The method as recited in  claim 5 , wherein injecting the second solvent within the laterally confined deposit of bituminous material comprises injecting the second solvent through the one or more vertical injection bores. 
     
     
         10 . The method as recited in  claim 6 , wherein withdrawing the mixture of first solvent and second solvent from within the laterally confined deposit of bituminous material comprises withdrawing the mixture of first solvent and second solvent through the one or more vertical production bores. 
     
     
         11 . The method as recited in  claim 5 , wherein injecting water within the laterally confined deposit of bituminous material comprises injecting water through the one or more vertical injection bores. 
     
     
         12 . The method as recited in  claim 6 , wherein withdrawing the mixture of second solvent and water from within the laterally confined deposit of bituminous material comprises withdrawing the mixture of second solvent and water through the one or more vertical production bores. 
     
     
         13 . The method as recited in  claim 1 , wherein the first solvent comprises an aromatic solvent. 
     
     
         14 . The method as recited in  claim 1 , wherein the second solvent comprises a polar solvent. 
     
     
         15 . The method as recited in  claim 6 , wherein:
 the one or more vertical injection bores are arranged in a straight line;   the one or more vertical production bores are arranged in a straight line parallel to and spaced a distance away from the straight line of vertical injection bores; and   the first solvent is injected into the laterally confined deposit of bituminous material in a direction towards the straight line of one or more vertical production bores.   
     
     
         16 . The method as recited in  claim 1 , further comprising:
 separating the mixture of dissolved bitumen and first solvent withdrawn from within the laterally confined deposit of bituminous material into a bitumen stream and a first solvent stream; and   reusing the first solvent stream in the step of injecting first solvent within the laterally confined deposit of bituminous material.   
     
     
         17 . A system for in-situ bitumen extraction comprising:
 a plurality of vertical freeze wall bores formed in a deposit of bituminous material and aligned in a geometric pattern;   a refrigerant source in fluid communication with the plurality of vertical freeze wall bores;   a plurality of vertical injection bores formed win the deposit of bituminous material and located within the geometric pattern of the plurality of freeze walls;   a water source in fluid communication with the plurality of vertical injection bores;   a solvent source in fluid communication with the plurality of vertical injection bores;   a second solvent source in fluid communication with the plurality of vertical injection bores; and   a plurality of vertical production wells formed in the deposit of bituminous material and located within the geometric pattern of the plurality of freeze walls.   
     
     
         18 . The system as recited in  claim 17 , further comprising:
 a bitumen-first solvent separator in fluid communication with the plurality of vertical production wells;   a first solvent-second solvent separator in fluid communication with the plurality of vertical production wells; and   a second solvent-water separator in fluid communication with the plurality of vertical production wells.   
     
     
         19 . The system as recited in  claim 17 , wherein the plurality of vertical freeze wall bores are in fluid communication with one another. 
     
     
         20 . The system as recited in  claim 17 , wherein the plurality of vertical injection bores each comprises:
 an inner passage;   a co-annular outer passage separated from the inner passage by a partition;   a plurality of inner passage injection ports extending from the inner passage to the exterior of the vertical injection bore; and   a plurality of outer passage injection ports extending to the exterior of the vertical injection bore.   
     
     
         21 . The system as recited in  claim 20 , wherein the inner passage is in fluid communication with only the water source and the outer passage is in fluid communication with only the first solvent source and the second solvent source.