In-situ methods of extracting bitumen values from oil-sand deposits

• US 4,101,172 A
• Filed: 12/09/1976
• Issued: 07/18/1978
• Est. Priority Date: 12/22/1975
• Status: Expired due to Term

• Current Assignee: Leonard C. Rabbitts
• Original Assignee: Leonard C. Rabbitts
• Inventors: Rabbitts, Leonard C.
• Primary Examiner(s): Purser, Ernest R.
• Application Number:
  US05/748,822
• Time in Patent Office: 586 Days
• Field of Search: 299/2
• US Class Current: 299/2
• CPC Class Codes: E21B 43/24 using heat, e.g. steam injection
• CPC Class Codes: E21B 43/2405 in association with fracturing or crevice forming processes E21B43/247 takes precedence
• CPC Class Codes: E21B 43/35 specially adapted for separating solids down-hole drilling fluid separation systems E21B21/002; separating solids from drilling fluids E21B21/065
• CPC Class Codes: E21C 41/24 for oil-bearing deposits

Abstract

The present invention provides a method of in situ extraction of bitumen from an oil-sands body which method comprises sinking an access shaft through the oil-sands body, driving an access drift in the rock strata underlying the oil-sands body, delineating a rectangular block of oil-sands in said body by drilling and blasting the oil-sands body to provide substantially vertical planes of fractured oil-sands on all four sides of an enclosed mining room capable of retaining liquids and gases under pressure and comprising solid pillar walls, providing generally upwardly extending bores in said block of oil sands from the access drift in the said body, providing perforated pipes in those portions of the bores in said block, the perforations of said pipes being dimensioned to prevent sand particles from said block passing therethrough, increasing the permeability of the block of oil sands within said room by fracturing said block, flooding the mining room with a hot fluid at a temperature and for a residence time sufficient to raise the temperature of the block by an amount to cause the bitumen to become flowable with said fluid and removing the fluid-bitumen mixture so formed from said block, the passage of said fluid through said bed being via said perforated pipes and separating said bitumen from said fluid.

Claims

1. A method of in situ extraction of bitumen from an oil sands body which comprises sinking an access shaft through the oil sands body, driving a plurality of access drifts in the rock strata adjacent said oil sands body at least one access drift being in the rock strata underlying the oil sands body, providing at each of a plurality of locations spaced longitudinally along each access drift a plurality of bores extending in a fan-shaped pattern transversely of said access drift into said oil sands body to provide transverse rows of bores spaced longitudinally along said body in the direction of the access drifts, alternate transverse rows of bores defining rows of inlets and outlets for passage of fluid through said body, said outlets being in access drifts underlying said body, providing perforated pipes in those portions of the bores defining the outlets in said body, the perforations in the pipes being dimensioned to prevent said particles from said body passing therethrough, increasing the permeability of the body by causing fracturing of the body through the inlet bores to provide a fractured block of oil sands in said body defining an enclosed mining room capable of retaining liquids and gases under pressure surrounded by undisturbed solid pillar walls on all four sides of said room, sealing the ends of the access drifts to provide a closed reservoir system capable of delivering and removing fluid through said inlets and outlets and associated access drifts, flooding the block at all elevations at substantially the same time via said inlets at a temperature and for a residence time sufficient to raise the temperature of the block by an amount to cause the bitumen to become flowable with said fluid and removing the fluid-bitumen mixture so formed from all desired levels in said block substantially at the same time through said outlets and associated access drift and separating said bitumen from said fluid.

2. A method as claimed in claim 1 in which the bitumen content of various layers of the block through which each bore forming the outlets extends is determined and perforated pipes are inserted into said bores, the size, number and disposition of the perforations in the pipe being such as to selectively remove bitumen from the bitumen rich layers of the blocks.

3. A method as claimed in claim 1 in which each bore has a length determined by the bitumen content of the upper layers of the block so as to selectively remove bitumen only from bitumen rich portions of the upper layers of the block.

4. A method as claimed in claim 1 in which the block is fractured by removing, by means of high pressure hot water jets, the lower 20 to 30% by volume of the sand in the block whereby the upper portions of the block collapse to cause said fracturing.

5. A method as claimed in claim 1 in which the pillar walls of the room also contain perforated tubes for collecting fluid passing into said walls from said room, the fluid being removed from said room for recovery of bitumen therefrom.

6. A method as claimed in claim 1 in which the fluid is a hot liquid.

7. A method as claimed in claim 6 in which the room is flooded to a level only sufficient to remove bitumen from the bitumen rich layers of sand in said block.

8. A method as claimed in claim 7 in which the level to which the extent of flooding of the room is controlled by the rate of flow of liquid into the room and removal therefrom and also by a gas under pressure passed into said room.

9. A method as claimed in claim 6 in which the liquid is a water-immiscible low-viscosity organic solvent for said bitumen.

10. A method as claimed in claim 8 in which the organic solvent is introduced into said room under high pressure and at a temperature not in excess of 130°

F for a residence time sufficient to raise the temperature of the sand in the block to be in the range 90°

to 130°

F whereby to primarily remove bitumen from said block with a minimum of removal of water.

11. A method as claimed in claim 10 in which removed bitumen solution is heated to 250°

to 400°

F, allowed to settle in a pressure vessel whereby any water and sand present in said solution is separated therefrom by decantation and the solvent removed from the bitumen by flash evaporation by releasing the pressure in said vessel, the solvent being condensed by recycled to a reservoir from which the room is flooded therewith.

12. A method as claimed in claim 9 in which the residual solvent in said room when all the recoverable bitumen has been removed therefrom is recovered by sweeping the room with an inert hot gas.

13. A method as claimed in claim 12 in which the hot gas is steam or hot air admixed with steam.

14. A method as claimed in claim 12 in which the hot gas is a flue gas generated by burning a combustible product in an upper tunnel and feeding the gas through blast holes used in fracturing the block or by ignition of low grade bitumen deposits in the upper portion of the block.

15. A process as claimed in claim 9 in which the solvent is fed into said room at a high temperature sufficient to break down liquid water envelopes surrounding the sand particles and flush them from the block together with their fines until 20 to 30% of the bitumen has been removed thereby providing substantial cavities within the block, the temperature of the solvent being then reduced to a temperature not in excess of 130°

F.

16. A method as claimed in claim 9 in which the solvent is selected from liquified petroleum gases or light oils of boiling points from 70°

to 150°

C which are of saturated aliphatic composition.

17. A method as claimed in claim 6 in which the liquid is water which is fed into said room at a high temperature and at a high pressure to form an emulsion of water and bitumen which is removed from the room.

18. A method as claimed in claim 17 in which the pressure in the room is periodically reduced to cause ebullition of the water and generation of steam whereby to enhance rupture of bitumen envelopes around the sand the pressure being periodically increased to condense the generated steam.

19. A method as claimed in claim 17 in which the flooding and subsequent removal and separation of the bitumen from the water is at a pressure sufficient to substantially avoid the presence of froth in the emulsion.

20. A method as claimed in claim 17 in which an inert gas pressure is maintained in the room to assist in drainage of the emulsion therefrom.

21. A method as claimed in claim 17 in which the emulsion is removed from said room at a low velocity to minimize sand entrainment in said emulsion.

22. A method as claimed in claim 17 in which the water is passed into said room through said perforated pipes at a high velocity to effect flooding of the room to thereby sweep the interstices of the sand particles located near the pipe perforations essentially clean.

23. A method as claimed in claim 17 in which the water contains at least one of an emulsifying agent and a pH controlling agent.

24. A method as claimed in claim 17 in which the water contains an organic solvent for the bitumen.

25. A method as claimed in claim 17 in which the emulsion withdrawn from the room is passed to a sand separator at high temperature and under high pressure and at a velocity sufficient to maintain sand particles of less than 100 micron size in suspension, separating sand particles of over 100 micron size in said sand separator and passing of emulsion from said sand separator into an oil-water separation chamber, adding diluent to the emulsion after leaving said room and before passage to said separation chamber in an amount sufficient to form a combined oil of density less than 1, permitting separation of the oil, water and fine sand solids by gravity settling under conditions of high temperature and high pressure, removing the fine solids as a sludge from the separation chamber and at least part of the water and removing bitumen from the separation chamber by fluid under pressure, as a hot fluid for passage to the surface for refining thereof.

26. A method as claimed in claim 25 in which the diluent is added to the emulsion as it leaves the mining room and is mixed during passage of the emulsion to the sand separator.

27. A method as claimed in claim 26 in which the diluent is added to the emulsion as it passes from the sand separator to the separation chamber.

28. A method as claimed in claim 25 in which a back pressure is maintained in the separation chamber to provide for non-turbulent removal of bitumen from the separation chamber and the subsequent filling up of the separation chamber with further emulsion for separation.

29. A method as claimed in claim 25 in which the sand is removed from the sand separator and passed to a drying vessel where it is flash dried by reducing the pressure in the drying vessel.

30. A method as claimed in claim 25 in which the water separated from the emulsion is recycled to a reservoir for further flooding of a mining room.

31. A method as claimed in claim 17 in which recycled water is clarified by slow passage through the sand in a mining room from which the bitumen has previously been exhausted.

32. A method as claimed in claim 31 in which the recycled water or fresh water for flooding the mining room is heated by passage through the sand of a body of a mining room from which the bitumen has been exhausted.

33. A method as claimed in claim 1 in which conduits, pressure vessels and storage vessels are all formed out of the rock strata.

34. A method as claimed in claim 1 in which pressures and flows of the fluids are provided by gravity and gas pressure.

35. A method as claimed in claim 1 in which the block is selectively fractures to fracture essentially only those portions which are oil rich by selective placement of blasting charges in balsting bore forming the inlets, those portions of said blasting bores passing through low oil bearing portions of the block having a light gauge liner disposed therein which liner also subsequently serves for passage of hot fluid through the block.

36. A method as claimed in claim 1 in which the hot fluid is a hot gas.

37. A method as claimed in claim 36 in which the hot gas is steam air, carbon dioxide or a flue gas heated externally of the mining room.

38. A process as claimed in claim 1 in which the extraction of the bitumen with the fluid and separation of said bitumen from the fluid takes place in a closed pressurized circuit.

39. A method as claimed in claim 1 which comprises driving access drifts into the rock strata above and below the oil sands body providing at least two fan shaped sets of generally upwardly extending bores emanating from the lower access drifts into the oil sands body in a pattern of contiguous parallel planes transverse to the drifts, providing said perforated pipes in those portions of the bores within the oil sands body, providing at least two fan shaped sets of generally downwardly inclined bores emanating from the overhead drifts into the oil sands body in a pattern of contiguous parallel planes transverse to the drifts and located in a position midway between the initial planes of upwardly inclined bores containing the perforated pipes thereby producing an overlapping continuous pattern of alternate planes of bores, exploding explosive charges selectively placed in the bores emanating from the upper drifts to produce a series of intercommunicating fractures between the alternate planes of bores, providing sufficient sets of these alternate planes of bores to delineate the fractured block of oil sands containing a plurality of the perforated pipes which is surrounded by the undisturbed pillar walls on all four sides, thus forming an enclosed mining room substantially capable of retaining liquids and gases under pressure, sealing the branch tunnels with bulkheads to provide a closed reservoir system capable of delivering or removing fluids through a plurality of bores without the necessity of mechanical seals, valves or piping, flooding the oil sand block or room from the upper tunnel by forcing hot fluids down through the planes of fractured bores and into the intercommunicating fractures at essentially all elevations at essentially the same time and at a temperature and for a residence time sufficient to raise the temperature of the oil sand by an amount to cause the bitumen to become flowable with the said fluid and removing the said fluid bitumen so formed, the passage of the said fluid through the said bed being via the said perforated pipes into the lower access drifts and separating the said bitumen from the said fluid.

40. A method as claimed in claim 1 which comprises driving access drifts in the underlying rock strata, providing at least two fan shaped sets of generally upwardly extending bores emanating from the first access drifts into the oil sands body in a pattern of contiguous parallel planes transverse to the drifts, providing the perforated pipes in those portions of the bores within the oil sand body, providing at least two fan shaped sets of generally upwardly extending bores emanating from the second access drifts into the oil sand body in a pattern of contiguous parallel planes transverse to the drifts and located in positions midway between the initial planes of bores containing the perforated pipes therby producing an overlapping continuous pattern of alternate planes of bores, exploding explosive charges selectively placed in the bores emanating from the second drifts to produce a series of intercommunicating fractures between the alternate planes of bores, providing sufficient sets of these alternate planes of bores to delineate a fractured block of oil sands containing a plurality of perforated pipes which is surrounded by undisturbed pillar walls on all four sides thus forming an enclosed mining room substantially capable of retaining liquids and gases under pressure, sealing the branch tunnels with bulkheads to provide a closed reservoir system capable of delivering or removing fluids through a plurality of bore holes without the necessity of mechanical seals, valves or piping, suitably flooding the oil sand block from the second access drifts by forcing hot fluids up through the planes of fractured bores and into the intercommunicating fractures at essentially all elevations at essentially the same time and at a temperature and for a residence time sufficient to raise the temperature of the oil sands by an amount to cause the bitumen to become flowable with the said fluid and removing the said fluid-bitumen so formed, the passage of the said fluid through the said bed being via the said perforated pipes into the first access drifts and separating the said bitumen from said fluid.