Treating tar sands formations with karsted zones

• US 7,673,681 B2
• Filed: 10/19/2007
• Issued: 03/09/2010
• Est. Priority Date: 10/20/2006
• 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): SUCHFIELD, GEORGE A
• Application Number:
  US11/975,700
• Publication Number:
  US 20080135253A1
• Time in Patent Office: 872 Days
• Field of Search: 166/250.01, 166/252.1, 166/272.1, 166/272.3, 166/302, 166/369
• US Class Current: 166/252.1
• CPC Class Codes: C10G 1/02 by distillation
• CPC Class Codes: C10G 2300/4037 In-situ processes
• CPC Class Codes: E21B 36/04 using electrical heaters
• CPC Class Codes: E21B 43/243 Combustion in situ
• CPC Class Codes: E21B 43/30 Specific pattern of wells, e.g. optimising the spacing of wells
• CPC Class Codes: E21B 47/0228 using electromagnetic energy or detectors therefor

Abstract

Methods for treating a tar sands formation are described herein. The tar sands formation may have one or more karsted zones. Methods may include providing heat from one or more heaters to one or more karsted zones of the tar sands formation to mobilize fluids in the formation. At least some of the mobilized fluids may be produced from the formation.

Claims

1. A method for treating a tar sands formation with one or more karsted zones, comprising:

providing heat from one or more heaters to one or more karsted zones of the tar sands formation;

mobilizing hydrocarbon fluids in the formation; and

producing hydrocarbon fluids from the formation.

2. The method of claim 1, wherein one or more karsted zones are selectively heated.

3. The method of claim 1, further comprising flowing the mobilized hydrocarbon fluids in an interconnected pore network of the formation.

4. The method of claim 1, further comprising flowing the mobilized hydrocarbons fluids in an interconnected pore network of the formation, wherein the interconnected pore network comprises a plurality of vugs.

5. The method of claim 1, wherein the heat is provided to mobilize hydrocarbons in vugs of the formation.

6. The method of claim 1, further comprising pyrolyzing at least some hydrocarbons in the formation.

7. The method of claim 1, wherein the formation includes vugs having a porosity of at least 20 porosity units in a formation with a porosity of at most about 15 porosity units, and wherein the vugs include unmobilized hydrocarbons prior to heating.

8. The method of claim 1, further comprising draining mobilized hydrocarbon fluids to a production well in the formation.

9. The method of claim 1, further comprising draining mobilized hydrocarbon fluids to a production well in the formation, and heating unmobilized hydrocarbons with the draining hydrocarbon fluids.

10. The method of claim 1, further comprising assessing the degree of karsted in the karsted zones, and selectively providing more heat to karsted zones with higher degrees of karsted than to karsted zones with less degrees of karsted.

11. The method of claim 1, wherein the formation is a karsted carbonate formation containing viscous hydrocarbons.

12. The method of claim 1, further comprising injecting steam into the formation after mobilizing at least some of the hydrocarbon fluids.

13. The method of claim 1, further comprising heating another portion of the formation with the one or more heaters to create injectivity in the portion of the formation, and then injecting steam in the formation.

14. A method for treating a karsted formation containing heavy hydrocarbons, comprising:

providing heat to at least part of one or more karsted layers in the formation from one or more heaters located in the karsted layers;

allowing the provided heat to reduce the viscosity of at least some hydrocarbons in the karsted layers; and

producing at least some hydrocarbons from at least one of the karsted layers of the formation.

15. The method of claim 14, wherein one or more of the karsted layers are selectively heated so that more heat is provided to karsted layers with more karsted.

16. The method of claim 14, wherein the heat is provided to mobilize hydrocarbons in vugs of the formation.

17. The method of claim 14, further comprising pyrolyzing at least some hydrocarbons in the formation.

18. The method of claim 14, further comprising draining at least some of the hydrocarbon fluids having reduced viscosity to a production well in the formation.

19. The method of claim 14, further comprising injecting steam into the formation after providing heat to one or more of the karsted layers.

20. A method for treating a karsted formation containing heavy hydrocarbons, comprising:

providing heat to at least part of one or more karsted layers in the formation from one or more heaters located in the karsted layers;

allowing the provided heat to reduce the viscosity of at least some hydrocarbons in the karsted layers to get an mi ectivity in at least one of the karsted layers sufficient to allow a drive fluid to flow in the karsted layers;

providing the drive fluid into at least one of the karsted layers; and

producing at least some hydrocarbons from at least one of the karsted layers of the formation.

21. The method of claim 20, wherein the heat is provided to mobilize hydrocarbons in vugs of the formation.

22. The method of claim 20, further comprising pyrolyzing at least some hydrocarbons in the formation.

23. The method of claim 20, further comprising draining at least a portion of the hydrocarbon fluids with reduced viscosity to a production well in the formation.

24. The method of claim 20, wherein providing the drive fluid comprises injecting steam into the formation.