Vacuum pumping of conductor-in-conduit heaters

• US 7,424,915 B2
• Filed: 04/22/2005
• Issued: 09/16/2008
• Est. Priority Date: 04/23/2004
• Status: Expired due to Fees

• Current Assignee: Shell Oil Company (Shell Plc)
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: Vinegar, Harold J.
• Primary Examiner(s): KRECK, JOHN J
• Application Number:
  US11/112,856
• Publication Number:
  US 20050269092A1
• Time in Patent Office: 1,243 Days
• Field of Search: 166/250.01, 166/250.08, 166/302
• US Class Current: 166/302
• CPC Class Codes: E21B 36/04 using electrical heaters
• CPC Class Codes: E21B 43/12 Methods or apparatus for controlling the flow of the obtained fluid to or in wells E21B43/25 takes precedence; valve arrangements E21B34/00
• CPC Class Codes: E21B 43/122 Gas lift
• 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 43/2405 in association with fracturing or crevice forming processes E21B43/247 takes precedence
• CPC Class Codes: E21B 43/38 in the well
• CPC Class Codes: H05B 3/141 Conductive ceramics, e.g. metal oxides, metal carbides, barium titanate, ferrites, zirconia, vitrous compounds

Abstract

Certain embodiments provide a method that includes placing a heater element in an opening in a subsurface formation. The heater element is in a conduit. A pressure is reduced inside the conduit to a pressure below the vapor pressure of water at the temperature in the conduit.

Claims

1. A method, comprising:

placing a heater element in an opening in a subsurface formation, the heater element being in a conduit;

reducing a pressure inside the conduit to a pressure below the vapor pressure of water at the temperature in the conduit; and

providing at least some heat from the heater element while reducing pressure in the conduit.

2. The method of claim 1, further comprising vacuum pumping the inside of the conduit to reduce the pressure inside the conduit.

3. The method of claim 1, further comprising reducing the pressure below about 15 Pa.

4. The method of claim 1, further comprising reducing the pressure below the vapor pressure of ice at the temperature in the conduit.

5. The method of claim 1, further comprising filling the inside of the conduit with a substantially non-condensable gas.

6. The method of claim 1, further comprising filling the inside of the conduit with a substantially non-condensable gas at a pressure between about 101 kPa and about 10 MPa.

7. The method of claim 6, wherein the substantially non-condensable gas comprises nitrogen.

8. The method of claim 1, further comprising filling the inside of the conduit with substantially non-condensable gas having at most 50 ppm oxygen.

9. The method of claim 1, further comprising providing heat output from the heater element.

10. The method of claim 1, further comprising allowing heat to transfer from the heater element to at least part of the subsurface formation.

11. The method of claim 1, further comprising allowing heat to transfer from the heater element to at least part of the subsurface formation to pyrolyze at least some hydrocarbons in the subsurface formation.

12. The method of claim 1, further comprising reducing a pressure outside the conduit to a pressure below the vapor pressure of ice at the temperature outside the conduit.

13. The method of claim 1, wherein the heater element is an electric heater element.

14. A method, comprising:

placing a heater element in an opening in a subsurface formation, the heater element being in a conduit; and

reducing a pressure in the opening outside the conduit to a pressure below the vapor pressure of water at the temperature of the conduit.

15. The method of claim 14, further comprising vacuum pumping the outside of the conduit to reduce the pressure outside the conduit.

16. The method of claim 14, further comprising reducing the pressure below about 15 Pa.

17. The method of claim 14, further comprising reducing the pressure below the vapor pressure of ice at the temperature of the conduit.

18. The method of claim 14, further comprising providing at least some heat from the heater element while reducing the pressure outside the conduit.

19. The method of claim 14, further comprising providing a substantially non-condensable gas outside of the conduit.

20. The method of claim 19, wherein the substantially non-condensable gas comprises nitrogen.

21. The method of claim 14, further comprising providing heat output from the heater element.

22. The method of claim 14, further comprising allowing heat to transfer from the heater element to at least part of the subsurface formation.

23. The method of claim 14, further comprising allowing heat to transfer from the heater element to at least part of the subsurface formation to pyrolyze at least some hydrocarbons in the subsurface formation.

24. The method of claim 14, wherein the heater element is an electric heater element.

25. A method, comprising:

placing a heater element in an opening in a subsurface formation, the heater element positioned in a conduit;

reducing a pressure inside the conduit to a pressure below the vapor pressure of water at the temperature in the conduit;

providing heat while reducing the pressure inside the conduit;

pressure sealing the conduit; and

monitoring a pressure in the conduit to assess an amount of water remaining in the conduit.

26. The method of claim 25, further comprising reducing the pressure inside the conduit if the monitored pressure rises to near the vapor pressure of water at the temperature in the conduit.

27. The method of claim 25, further comprising reducing the pressure inside the conduit below the vapor pressure of ice at the temperature in the conduit.

28. The method of claim 25, further comprising reducing the pressure inside the conduit if the monitored pressure rises to near the vapor pressure of ice at the temperature in the conduit.

29. The method of claim 25, further comprising filling the conduit with a substantially non-condensable gas if the monitored pressure remains below the vapor pressure of water at the temperature in the conduit.

30. The method of claim 25, further comprising filling the conduit with a substantially non-condensable gas if the monitored pressure remains below the vapor pressure of ice at the temperature in the conduit.

31. The method of claim 25, further comprising assessing the conduit for a leak if the monitored pressure continuously rises above the vapor pressure of water at the temperature in the conduit.

32. The method of claim 25, further comprising allowing heat to transfer from the heater element to at least part of the subsurface formation.

33. A method, comprising:

placing a heater element in an opening in a subsurface formation, the heater element positioned in a conduit;

reducing a pressure in the opening outside the conduit to a pressure below the vapor pressure of water at the temperature of the conduit;

pressure sealing the opening outside the conduit; and

monitoring a pressure in the opening outside the conduit to assess an amount of water remaining in the opening outside the conduit.

34. The method of claim 33, further comprising reducing the pressure outside the conduit if the monitored pressure rises to near the vapor pressure of water at the temperature of the conduit.

35. The method of claim 33, further comprising reducing the pressure outside the conduit below the vapor pressure of ice at the temperature of the conduit.

36. The method of claim 33, further comprising reducing the pressure outside the conduit if the monitored pressure rises to near the vapor pressure of ice at the temperature of the conduit.

37. The method of claim 33, further comprising providing heat while reducing the pressure outside the conduit.

38. The method of claim 33, further comprising filling the opening outside the conduit with a substantially non-condensable gas if the monitored pressure remains below the vapor pressure of water at the temperature of the conduit.

39. The method of claim 33, further comprising filling the opening outside the conduit with a substantially non-condensable gas if the monitored pressure remains below the vapor pressure of ice at the temperature of the conduit.

40. The method of claim 33, further comprising assessing the conduit and/or the opening for a leak if the monitored pressure continuously rises above the vapor pressure of water at the temperature of the conduit.

41. The method of claim 33, further comprising allowing heat to transfer from the heater element to at least part of the subsurface formation.