Varying properties of in situ heat treatment of a tar sands formation based on assessed viscosities

• US 8,662,175 B2
• Filed: 04/18/2008
• Issued: 03/04/2014
• Est. Priority Date: 04/20/2007
• Status: Expired due to Fees

• Current Assignee: Shell Oil Company (Shell Plc)
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: Karanikas, John Michael, Vinegar, Harold J.
• Primary Examiner(s): DiTrani, Angela M
• Application Number:
  US12/105,997
• Publication Number:
  US 20090095478A1
• Time in Patent Office: 2,146 Days
• Field of Search: 166/302
• US Class Current: 166/302
• CPC Class Codes: C09K 8/845 containing inorganic compounds
• CPC Class Codes: C09K 8/86 containing organic compounds
• CPC Class Codes: C10G 1/008 Controlling or regulating of liquefaction processes
• CPC Class Codes: C10G 1/02 by distillation
• CPC Class Codes: C10G 1/04 by extraction
• CPC Class Codes: C10G 1/042 by the use of hydrogen-donor solvents
• CPC Class Codes: E21B 36/04 using electrical heaters
• CPC Class Codes: E21B 43/16 Enhanced recovery methods for obtaining hydrocarbons
• CPC Class Codes: E21B 43/24 using heat, e.g. steam injection
• CPC Class Codes: E21B 43/2401 by means of electricity
• CPC Class Codes: Y10T 29/49083 Heater type

Abstract

A method for treating a tar sands formation includes providing heat to at least part of a hydrocarbon layer in the formation from a plurality of heaters located in the formation. The heat is allowed to transfer from the heaters to at least a portion of the formation. A viscosity of one or more zones of the hydrocarbon layer is assessed. The heating rates in the zones are varied based on the assessed viscosities. The heating rate in a first zone of the formation is greater than the heating rate in a second zone of the formation if the viscosity in the first zone is greater than the viscosity in the second zone. Fluids are produced from the formation through the production wells.

Claims

1. A method for treating a tar sands formation, comprising:

providing heat to at least part of a hydrocarbon layer in the formation from a plurality of heaters located in the formation;

assessing a viscosity of two or more zones of the hydrocarbon layer;

varying the heater spacing in the zones based on the assessed viscosities, wherein the heater spacing in a first zone of the formation is denser than the heater spacing in a second zone of the formation if the viscosity in the first zone is greater than the viscosity in the second zone;

allowing the heat to transfer from the heaters to the zones in the formation;

allowing fluids to drain from the first zone directly into the second zone; and

producing fluids from one or more openings located in at least one selected zone to maintain a pressure in the selected zone below a selected pressure.

2. The method of claim 1, wherein the selected zone is the first zone of the formation.

3. The method of claim 1, wherein the selected pressure is the fracture pressure of the formation.

4. The method of claim 3, wherein the selected pressure is between about 1000 kPa and about 15000 kPa.

5. The method of claim 1, wherein the selected pressure is a pressure below which substantial hydrocarbon coking in the formation occurs when the average temperature in the formation is less than 300°

C.

6. The method of claim 5, wherein the selected pressure is between about 100 kPa and about 1000 kPa.

7. The method of claim 1, further comprising providing a drive fluid to the formation.

8. The method of claim 1, further comprising providing steam to the formation.

9. The method of claim 1, further comprising producing fluids from at or near the bottom of the zones.

10. The method of claim 1, wherein at least a portion of the first zone is located vertically above a portion of the second zone.

11. The method of claim 1, wherein the viscosity in the first zone is greater than the viscosity in the second zone.

12. The method of claim 1, wherein the viscosity in the first zone is greater than the viscosity in the second zone, and wherein the heater spacing in the first zone is denser than the heater spacing in the second zone.

13. The method of claim 1, further comprising assessing the viscosity of the first zone and the second zone of the hydrocarbon layer, and providing a heater spacing in the first zone that is denser than a heater spacing in the second zone.

14. The method of claim 1, further comprising heating such that an average viscosity in the two zones is within about 20% of each other.

15. The method of claim 1, further comprising mobilizing formation fluids such that formation fluids flow from at least one the selected zone to another selected zone;

and producing formation fluids from the another selected zone.

16. A method for treating a tar sands formation, comprising:

providing heat to at least part of a hydrocarbon layer in the formation from a plurality of heaters located in the formation;

assessing a viscosity of two or more zones of the hydrocarbon layer;

providing heater spacing in the zones based on the assessed viscosities, wherein the heater spacing in a first zone of the formation is denser than the heater spacing in a second zone of the formation when the viscosity in the first zone is greater than the viscosity in the second zone, the first zone contacting the second zone;

allowing the heat to transfer from the heaters to the zones in the formation; and

producing fluids from one or more openings located in at least one selected zone to maintain a pressure in the selected zone below a selected pressure.

17. The method of claim 16, further comprising providing a drive fluid to the formation.

18. The method of claim 16, further comprising allowing fluids to drain from the first zone to the second zone.

19. The method of claim 16, further comprising producing fluids from at or near the bottom of the zones.

20. The method of claim 16, further comprising heating such that an average viscosity in the two zones is within about 20% of each other.

21. A method for treating a tar sands formation, comprising:

providing heat to at least part of a hydrocarbon layer in the formation from a plurality of heaters located in at least a first zone and a second zone of the formation, wherein the first zone has a higher assessed viscosity than the second zone, and the heater spacing in the first zone is denser than the heater spacing in the second zone, the first zone contacting the second zone; and

allowing the heat to transfer from the heaters to the hydrocarbon layer; and

producing fluids from one or more openings located in at least one of the first or second zones to maintain a pressure in such zone below a selected pressure.

22. The method of claim 21, further comprising providing a drive fluid to the formation.

23. The method of claim 21, further comprising allowing fluids to drain from the first zone to the second zone.

24. The method of claim 21, further comprising producing fluids from at or near the bottom of the zones.

25. The method of claim 21, further comprising heating such that an average viscosity in the two zones is within about 20% of each other.