In situ thermal processing of an oil shale formation to produce hydrocarbons having a selected carbon number range

• US 6,918,443 B2
• Filed: 04/24/2002
• Issued: 07/19/2005
• Est. Priority Date: 04/24/2001
• Status: Expired due to Fees

• Current Assignee: Shell Oil Company (Shell Plc)
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: de Rouffignac, Eric Pierre, Vinegar, Harold J., Wellington, Scott Lee, Ryan, Robert Charles, Fowler, Thomas David, Stegemeier, George Leo, Berchenko, Ilya Emil, Zhang, Etuan, Shahin, Gordon Thomas Jr.
• Primary Examiner(s): SUCHFIELD, GEORGE A
• Application Number:
  US10/131,285
• Publication Number:
  US 20030137181A1
• Time in Patent Office: 1,182 Days
• Field of Search: 166/57, 166/59, 166/60, 166/75.12, 166/245, 166/250.01, 166/250.15, 166/256, 166/257, 166/261, 166/266, 166/267, 166/272.1, 166/302, 299/2, 585/1
• US Class Current: 166/245
• 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: E21B 43/243 Combustion in situ
• CPC Class Codes: E21B 43/247 in association with fracturing processes or crevice forming processes
• CPC Class Codes: E21B 43/30 Specific pattern of wells, e.g. optimising the spacing of wells

Abstract

An oil shale formation may be treated using an in situ thermal process. A mixture of hydrocarbons, H₂, and/or other formation fluids may be produced from the formation. Heat may be applied to the formation to raise a temperature of a portion of the formation to a desired temperature. An average temperature and/or pressure within the formation may be controlled to inhibit production of hydrocarbons that have carbon numbers greater than a selected carbon number. In some embodiments, the selected carbon number may be 25. A small amount of hydrocarbons having carbon numbers greater than the selected carbon number may be entrained in vapor produced from the formation.

Claims

1. A method of treating an oil shale formation in situ, comprising:

providing heat from one or more heaters to at least a portion of the formation;

allowing the heat to transfer from the one or more heaters to a part of the formation;

producing a mixture from the formation; and

maintaining an average temperature within the part of the formation above a minimum pyrolysis temperature and below a vaporization temperature of hydrocarbons having carbon numbers greater than 25 to inhibit production of a substantial amount of hydrocarbons having carbon numbers greater than 25 in the mixture.

2. The method of claim 1, wherein the one or more heaters comprise at least two heaters, and wherein superposition of heat from at least the two heaters pyrolyzes at least some hydrocarbons within the part of the formation.

3. The method of claim 1, wherein maintaining the average temperature within the part of the formation comprises maintaining the temperature within a pyrolysis temperature range from about 270°

C. to about 400°

C.

4. The method of claim 1, wherein at least one of the one or more heaters comprises an electrical heater.

5. The method of claim 1, wherein at least one of the one or more heaters comprises a surface burner.

6. The method of claim 1, wherein at least one of the one or more heaters comprises a flameless distributed combustor.

7. The method of claim 1, wherein at least one of the one or more heaters comprises a natural distributed combustor.

8. The method of claim 1, wherein the minimum pyrolysis temperature is greater than about 270°

C.

9. The method of claim 1, wherein the vaporization temperature is less than approximately 450°

C. at atmospheric pressure.

10. The method of claim 1, further comprising controlling a pressure and a temperature within at least a majority of the part of the formation, wherein the pressure is controlled as a function of temperature, or the temperature is controlled as a function of pressure.

11. The method of claim 1, further comprising controlling the heat such that an average heating rate of the part of the formation is less than about 1°

C. per day in a pyrolysis temperature range of about 270°

C. to about 400°

C.

12. The method of claim 1, wherein providing heat from the one or more heaters to at least the portion of the formation comprises:

heating a selected volume (V) of the oil shale formation from the one or more heaters, wherein the formation has an average heat capacity (C_v), and wherein the heating pyrolyzes at least some hydrocarbons within the selected volume of the formation; and

wherein heating energy/day (Pwr) provided to the selected volume is equal to or less than h*V*C_v*ρ

_B, wherein ρ

_B is formation bulk density, and wherein an average heating rate (h) of the selected volume is about 10°

C./day.

13. The method of claim 1, wherein allowing the heat to transfer comprises transferring heat substantially by conduction.

14. The method of claim 1, wherein providing heat from the one or more heaters comprises heating the part of the formation such that a thermal conductivity of at least a portion of the part of the formation is greater than about 0.5 W/(m °

C.).

15. The method of claim 1, wherein the produced mixture comprises condensable hydrocarbons having an API gravity of at least about 25°

.

16. The method of claim 1, wherein the produced mixture comprises condensable hydrocarbons, and wherein about 0.1% by weight to about 15% by weight of the condensable hydrocarbons are olefins.

17. The method of claim 1, wherein the produced mixture comprises non-condensable hydrocarbons, and wherein about 0.1% by weight to about 15% by weight of the non-condensable hydrocarbons are olefins.

18. The method of claim 1, wherein the produced mixture comprises non-condensable hydrocarbons, wherein a molar ratio of ethene to ethane in the non-condensable hydrocarbons is less than about 0.15, and wherein the ratio of ethene to ethane is greater than about 0.001.

19. The method of claim 1, wherein the produced mixture comprises condensable hydrocarbons, and wherein less than about 1% by weight, when calculated on an atomic basis, of the condensable hydrocarbons is nitrogen.

20. The method of claim 1, wherein the produced mixture comprises condensable hydrocarbons, and wherein less than about 1% by weight, when calculated on an atomic basis, of the condensable hydrocarbons is oxygen.

21. The method of claim 1, wherein the produced mixture comprises condensable hydrocarbons, and wherein less than about 1% by weight, when calculated on an atomic basis, of the condensable hydrocarbons is sulfur.

22. The method of claim 1, wherein the produced mixture comprises condensable hydrocarbons, wherein about 5% by weight to about 30% by weight of the condensable hydrocarbons comprise oxygen containing compounds, and wherein the oxygen containing compounds comprise phenols.

23. The method of claim 1, wherein the produced mixture comprises condensable hydrocarbons, and wherein greater than about 20% by weight of the condensable hydrocarbons are aromatic compounds.

24. The method of claim 1, wherein the produced mixture comprises condensable hydrocarbons, and wherein less than about 5% by weight of the condensable hydrocarbons comprises multi-ring aromatics with more than two rings.

25. The method of claim 1, wherein the produced mixture comprises condensable hydrocarbons, and wherein less than about 0.3% by weight of the condensable hydrocarbons are asphaltenes.

26. The method of claim 1, wherein the produced mixture comprises condensable hydrocarbons, and wherein about 5% by weight to about 30% by weight of the condensable hydrocarbons are cycloalkanes.

27. The method of claim 1, wherein the produced mixture comprises a non-condensable component, wherein the non-condensable component comprises molecular hydrogen, wherein the molecular hydrogen is greater than about 10% by volume of the non-condensable component at 25°

and one atmosphere absolute pressure, and wherein the molecular hydrogen is less than about 80% by volume of the non-condensable component at 25° and

one atmosphere absolute pressure.

28. The method of claim 1, wherein the produced mixture comprises ammonia, and wherein greater than about 0.05% by weight of the produced mixture is ammonia.

29. The method of claim 1, wherein the produced mixture comprises ammonia, and wherein the ammonia is used to produce fertilizer.

30. The method of claim 1, further comprising controlling a pressure within at least a majority of the part of the formation, wherein the controlled pressure is at least about 2.0 bars absolute.

31. The method of claim 1, further comprising controlling formation conditions to produce a mixture of condensable hydrocarbons and H₂, wherein a partial pressure of H₂ within the mixture is greater than about 0.5 bars.

32. The method of claim 31, wherein the partial pressure of H₂ is measured when the mixture is at a production well.

33. The method of claim 31, wherein controlling formation conditions comprises recirculating a portion of hydrogen from the mixture into the formation.

34. The method of claim 1, further comprising:

providing hydrogen (H₂) to the part of the formation to hydrogenate hydrocarbons within the part of the formation; and

heating a portion of the part of the formation with heat from hydrogenation.

35. The method of claim 1, wherein the produced mixture comprises hydrogen and condensable hydrocarbons, the method further comprising hydrogenating a portion of the produced condensable hydrocarbons with at least a portion of the produced hydrogen.

36. The method of claim 1, wherein allowing the heat to transfer comprises increasing a permeability of a majority of the part of the formation to greater than about 100 millidarcy.

37. The method of claim 1, wherein allowing the heat to transfer comprises substantially uniformly increasing a permeability of a majority of the part of the formation.

38. The method of claim 1, further comprising controlling the heat to yield greater than about 60% by weight of condensable hydrocarbons, as measured by Fischer Assay.

39. The method of claim 1, wherein producing the mixture comprises producing the mixture in a production well, and wherein at least about 7 heaters are disposed in the formation for each production well.

40. The method of claim 39, wherein at least about 20 heaters are disposed in the formation for each production well.

41. The method of claim 1, further comprising providing heat from three or more heaters to at least a portion of the formation, wherein three or more of the heaters are located in the formation in a unit of heaters, and wherein the unit of heaters comprises a triangular pattern.

42. The method of claim 1, further comprising providing heat from three or more heaters to at least a portion of the formation, wherein three or more of the heaters are located in the formation in a unit of heaters, wherein the unit of heaters comprises a triangular pattern, and wherein a plurality of the units are repeated over an area of the formation to form a repetitive pattern of units.