Apparatus and method for generating inert gas and heating injected gas

• US 5,488,990 A
• Filed: 09/16/1994
• Issued: 02/06/1996
• Est. Priority Date: 09/16/1994
• Status: Expired due to Fees

• Current Assignee: Marathon Oil Company (Marathon Oil Corporation)
• Original Assignee: Marathon Oil Company (Marathon Oil Corporation)
• Inventors: Ellwood, David E., Compton, Albert C., Wadleigh, Eugene E.
• Primary Examiner(s): BUIZ, MIKADO RYAN
• Application Number:
  US08/308,021
• Time in Patent Office: 508 Days
• Field of Search: 166/53, 166/57, 166/59, 166/260, 166/302, 166/303
• US Class Current: 166/260
• CPC Class Codes: E21B 36/02 using burners
• CPC Class Codes: E21B 43/243 Combustion in situ

Abstract

A downhole burner that economically generates hot inert gas and injects this gas into a subterranean formation. The burner has a nipple attached to a first tubing string that carries an oxidizer to the burner. The first tubing string also contains a coil tubing string that carries fuel to a movable nozzle inside the nipple. A small orifice in the nozzle increases the velocity of the fuel, and the nozzle extends out through a small orifice in a burner shroud that increases the velocity of the oxidizer flowing around the nozzle. The high velocity of the fuel and oxidizer keeps the flame front below the shroud and nozzle. A second tubing string supplies coolant gas around the burner shroud. Injection of an oxygen containing coolant gas provides a method for enhancing in situ combustion reactions through superheating the oxygen containing mix of coolant and exhaust gas.

Claims

1. A burner for heating a hydrocarbonaceous formation or reservoir and for producing economical inert injectant, to thereby recover hydrocarbonaceous materials from said formation, said burner comprising:

a combustion chamber having an open lower end and having an upper end attached to an air supply conduit;

a nozzle, movably contained within said combustion chamber, and having a first end connected to a fuel supply conduit contained within said air supply conduit;

stopping means located within said combustion chamber for preventing said nozzle from being positioned beyond a predefined location toward said open lower end of said combustion chamber.

2. The burner of claim 1 wherein said nozzle further comprises a plurality of vanes symmetrically arranged about an outside surface of said nozzle, said vanes for centrally positioning said nozzle within said combustion chamber to allow air from said air supply conduit to flow around said nozzle, and wherein said vanes contact said stopping means to prevent said nozzle from being positioned beyond said predefined location.

3. The burner of claim 1 wherein said nozzle further comprises an elongated nozzle end opposite said first end, and wherein said combustion chamber further comprises a restriction below said stopping means and further wherein said elongated nozzle end protrudes through said restriction, wherein a length of said elongated nozzle end is sufficient to prevent said elongated nozzle end from moving above said restriction when a relative position of said nozzle and said combustion chamber changes from thermal expansion.

4. The burner of claim 3 wherein said restriction has a larger inside diameter than an outside diameter of said elongated nozzle end and wherein a cross-sectional area of an area between said restriction and said elongated nozzle end is smaller than a cross-sectional area of said air supply conduit, wherein air passing from said air supply conduit through said restriction is accelerated.

5. The burner of claim 4 wherein said elongated nozzle end of said nozzle further comprises a fuel exit orifice having a cross-sectional area smaller than a cross-sectional area of said fuel supply conduit, wherein fuel passing from said fuel supply conduit through said fuel exit orifice is accelerated.

6. The burner of claim 3 wherein said combustion chamber further comprises a liner attached to said combustion chamber, said liner extending from said restriction to said lower end of said combustion chamber.

7. The burner of claim 1 wherein combustion of said fuel is started by passing a pyrophoric fluid through said fuel supply conduit, and wherein said combustion begins when said pyrophoric fluid passes through said nozzle into air from said air supply conduit.

8. The burner of claim 1 wherein said combustion chamber further comprises a plurality of vanes symmetrically arranged about an outside surface of said combustion chamber, said vanes causing said combustion chamber to be centrally positioned within a casing liner to allow a gas to flow around said combustion chamber said gas being supplied by a gas conduit terminating above said combustion chamber.

9. The burner of claim 1 wherein said combustion chamber comprises a burner nipple having a first end attached to said air supply conduit, and a burner shroud attached to a second end of said burner nipple opposite said first end and wherein said stopping means is located within said burner nipple.

10. The burner of claim 1 wherein said combustion chamber contains a cross-sectional profile for accepting a wireline plug, wherein said combustion chamber can be placed in a well containing fluid by placing a wireline retrievable plug in said profile, and removing said plug after said combustion chamber is placed in said well.

11. The burner of claim 1 wherein said nozzle contains a cross-sectional profile for accepting a wireline plug, wherein said nozzle can be placed in a well containing fluid by placing a wireline retrievable plug in said profile, and removing said plug after said nozzle is placed in said well.

14. The burner of claim 1 wherein said burner shroud further comprises a restriction and further wherein said elongated nozzle end protrudes through said restriction, wherein a length of said elongated nozzle end is sufficient to prevent said elongated nozzle end from moving above said restriction when a relative position of said nozzle and said burner shroud changes from thermal expansion.

15. The burner of claim 14 wherein said restriction has a larger inside diameter than an outside diameter of said elongated nozzle end and wherein a cross-sectional area of an area between said restriction and said elongated nozzle end is smaller than a cross-sectional area of said air supply conduit, wherein air passing from said air supply conduit through said restriction is accelerated.

16. The burner of claim 15 wherein said elongated nozzle end of said nozzle further comprises a fuel exit orifice having a cross-sectional area smaller than a cross-sectional area of said fuel supply conduit, wherein fuel passing from said fuel supply conduit through said fuel exit orifice is accelerated.

17. The burner of claim 14 wherein said burner shroud extension further comprises a liner attached to said burner shroud extension, said liner extending from said restriction to said lower end of said burner shroud extension.

12. A burner for heating a hydrocarbonaceous formation or reservoir and for producing economical inert injectant, to thereby recover hydrocarbonaceous materials from said formation, said burner comprising:

a combustion chamber comprising

a burner nipple having a first end attached to an air supply conduit,

a burner shroud having a first end attached to a second end of said burner nipple opposite said first end of said burner nipple, and

a burner shroud extension attached to a second end of said burner shroud, said burner shroud extension having an open lower end to allow combustion gasses to exit said combustion chamber;

a nozzle, movably contained within said combustion chamber, said nozzle having a nozzle body contained within said burner nipple, a first end connected to a fuel supply conduit contained within said air supply conduit, and having an elongated second end extending through said burner shroud;

stopping means located within said burner nipple for preventing said nozzle from being positioned beyond a predefined location toward said open lower end of said combustion chamber.

13. The burner of claim 12 wherein said nozzle further comprises a plurality of vanes symmetrically arranged about an outside surface of said nozzle, said vanes for centrally positioning said nozzle within said combustion chamber to allow air from said air supply conduit to flow around said nozzle, and wherein said vanes contact said stopping means to prevent said nozzle from being positioned beyond said predefined location.

18. The burner of claim 12 wherein combustion of said fuel is started by passing a pyrophoric fluid through said fuel supply conduit, and wherein said combustion begins when said pyrophoric fluid passes through said nozzle into air from said air supply conduit.

19. The burner of claim 12 wherein said combustion chamber further comprises a plurality of vanes symmetrically arranged about an outside surface of said combustion chamber, said vanes causing said combustion chamber to be centrally positioned within a casing liner to allow a gas to flow around said combustion chamber said gas being supplied by a gas conduit terminating above said combustion chamber.

20. The burner of claim 12 wherein said combustion chamber contains a cross-sectional profile for accepting a wireline plug, wherein said combustion chamber can be placed in a well containing fluid by placing a wireline retrievable plug in said profile, and removing said plug after said combustion chamber is placed in said well.

21. The burner of claim 12 wherein said nozzle contains a cross-sectional profile for accepting a wireline plug, wherein said nozzle can be placed in a well containing fluid by placing a wireline retrievable plug in said profile, and removing said plug after said nozzle is placed in said well.

22. A method for in situ combustion of hydrocarbons present in a subterranean formation which is penetrated by a well in fluid communication therewith, the method comprising:

raising the temperature of the formation adjacent the well to an ignition temperature which is sufficient to ignite hydrocarbons present in the formation;

superheating an oxygen-containing gas within the well to a temperature which is greater than said ignition temperature; and

injecting said superheated oxygen-containing gas into the formation to sustain and propagate the combustion of hydrocarbons present in the formation.

23. The method of claim 22 wherein said subterranean formation is fractured.

24. The method of claim 22 wherein said formation adjacent the well is heated to said ignition temperature by means of a burner positioned within the well.

25. The method of claim 24 said oxygen-containing gas is superheated while serving as a coolant gas for said burner.

26. The method of claim 22 wherein said oxygen-containing gas is air or oxygen enriched air.

27. The method of claim 22 wherein said oxygen-containing gas is superheated to between about 600°

F. and about 1000°

F.