Preconditioning for bitumen displacement

Abstract

Methods and systems produce petroleum products with multiple horizontal wells through which injection processes precondition and displace the hydrocarbons in a formation. The wells extend through the formation spaced apart from one another in a lateral direction. Before fluid communication is established between the wells, cyclic injections and production of resulting backflow initiates conditioning of immobile products. Alternating between injection and production at adjacent wells may then facilitate establishing the fluid communication. After the fluid communication is established, a displacement procedure sweeps the hydrocarbons from one of the wells used for injection toward an adjacent one of the wells used for production.

1 . A method of recovering hydrocarbons, comprising:
 injecting during a first time a conditioning fluid through first and second wells and into a formation along lateral spaced apart and parallel horizontal lengths of the first and second wells;   producing the hydrocarbons recovered as backflow along the lengths of the first and second wells during a second time after the first time; then   alternating between injecting the conditioning fluid into the formation along the length of the second well while producing the hydrocarbons along the length of the first well and injecting the conditioning fluid into the formation along the length of the first well while producing the hydrocarbons along the length of the second well, thereby establishing fluid communication between the first well and the second well; and then   injecting a displacement fluid into the formation along the length of the first well to sweep the hydrocarbons toward the second well and while producing, along the length of the second well, the hydrocarbons being displaced.   
     
     
         2 . The method according to  claim 1 , further comprising cycling during additional time intervals between the injecting of the conditioning fluid and the producing of the hydrocarbons recovered as backflow. 
     
     
         3 . The method according to  claim 1 , wherein the conditioning fluid includes a solvent for the hydrocarbons. 
     
     
         4 . The method according to  claim 1 , wherein the conditioning fluid includes a solvent for the hydrocarbons that includes a liquid component under reservoir conditions and a gaseous component under reservoir conditions. 
     
     
         5 . The method according to  claim 1 , wherein the displacement fluid includes steam. 
     
     
         6 . The method according to  claim 1 , wherein the conditioning fluid includes a hydrocarbon solvent with between one and twenty carbon atoms per molecule and the displacement fluid contains steam. 
     
     
         7 . The method according to  claim 1 , wherein the displacement fluid includes at least one constituent selected from solvent for the hydrocarbons, water, steam, emulsifiers, air, oxygen and carbon dioxide. 
     
     
         8 . The method according to  claim 1 , wherein the conditioning fluid and the displacement fluid contain like constituents. 
     
     
         9 . The method according to  claim 1 , wherein the first and second wells are spaced between 5 meters and 50 meters apart in a common horizontal plane without intervening wells between the first and second wells. 
     
     
         10 . A method of recovering hydrocarbons, comprising:
 injecting a conditioning fluid through first and second wells and into a formation at dispersed locations along parallel horizontal lengths of the first and second wells such that the injecting via the first well is offset in a lateral direction from the second well and aligned between the dispersed locations of the second well across from portions of the second well without fluid communication to the formation;   producing the hydrocarbons recovered as backflow at the dispersed locations along the first and second wells after the injecting of the conditioning fluid; and then   injecting a displacement fluid into the formation via the dispersed locations along the first well to sweep the hydrocarbons toward the second well and while producing, at the dispersed locations along the second well, the hydrocarbons being displaced.   
     
     
         11 . The method according to  claim 10 , further comprising injecting the conditioning fluid into the formation via the dispersed locations along the second well while producing the hydrocarbons at the dispersed locations along the first well. 
     
     
         12 . The method according to  claim 10 , further comprising, following simultaneous injection through the first and second wells and simultaneous production through the first and second wells and until fluid communication is established between the first well and the second well, alternating between:
 injecting the conditioning fluid into the formation via the dispersed locations along the second well while producing the hydrocarbons at the dispersed locations along the first well; and   injecting the conditioning fluid into the formation via the dispersed locations along the first well while producing the hydrocarbons at the dispersed locations along the second well.   
     
     
         13 . The method according to  claim 10 , further comprising cycling multiple times between the injecting of the conditioning fluid and the producing the hydrocarbons recovered at the dispersed locations along the first and second wells. 
     
     
         14 . The method according to  claim 10 , wherein the injecting of the conditioning fluid occurs simultaneously through the first and second wells and the producing the hydrocarbons recovered as backflow occurs simultaneously through the first and second wells. 
     
     
         15 . The method according to  claim 10 , wherein the first and second wells lack fluid communication with one another across the formation upon initiating the injecting of the conditioning fluid. 
     
     
         16 . The method according to  claim 10 , wherein the displacement fluid includes steam. 
     
     
         17 . The method according to  claim 10 , wherein the displacement fluid includes at least one constituent selected from solvent for the hydrocarbons, water, steam, emulsifiers, air, oxygen and carbon dioxide. 
     
     
         18 . The method according to  claim 10 , wherein the conditioning fluid is injected alone and consists of a solvent for the hydrocarbons. 
     
     
         19 . The method according to  claim 10 , wherein the conditioning fluid includes a solvent for the hydrocarbons that includes a liquid component under reservoir conditions and a gaseous component under reservoir conditions. 
     
     
         20 . The method according to  claim 10 , wherein the first and second wells are spaced between 5 meters and 50 meters apart.