Method for natural gas production

• US 20050284628A1
• Filed: 08/30/2005
• Published: 12/29/2005
• Est. Priority Date: 07/22/2003
• Status: Active Grant

• Current Assignee: Precision Combustion, Inc.
• Original Assignee: Precision Combustion, Inc.
• Inventors: Pfefferle, William C.
• Granted Patent: US 7,343,971 B2
• Time in Patent Office: Days
• US Class Current: 166/260
• CPC Class Codes: E21B 41/0064 Carbon dioxide sequestration storing fluids in porous layers B65G5/005
• CPC Class Codes: E21B 41/0099 specially adapted for drilling for or production of natural hydrate or clathrate gas reservoirs; Drilling through or monitoring of formations containing gas hydrates or clathrates
• CPC Class Codes: E21B 43/243 Combustion in situ
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

The present invention is a method and system for dissociating methane hydrate deposits in-situ. An oxidizer fluid and a supply of fuel, both at a pressure higher than that of the methane hydrate deposit, are supplied and delivered to the methane hydrate deposit. The fuel is combusted downhole by reacting it with the oxidizer fluid to provide combustion products. The combustion products are placed in contact with a diluent fluid to produce a heated product fluid. The heated product fluid is injected into the methane hydrate deposit whereby methane is dissociated from the methane hydrate and made available for extraction. In addition, carbon dioxide may be made available to promote the formation of carbon dioxide hydrates from the liberated methane hydrate water.

Claims

1. A method of dissociating methane hydrate deposits in-situ comprising:

a) providing a supply of an oxidizer fluid at a pressure higher than that of the methane hydrate deposit;

b) providing a supply of fuel at a pressure higher than that of the methane hydrate deposit;

c) combusting the fuel downhole by reacting it with the oxidizer fluid to provide hot combustion products;

d) contacting the combustion products with a diluent fluid to produce a cooled product fluid at a temperature higher than the prevailing methane hydrate decomposition temperature;

e) injecting the cooled product fluid into contact with the methane hydrate deposit, and

f) decomposing hydrate releasing natural gas.

2. The method of claim 1 wherein the fuel is combusted utilizing a catalytic combustor.

3. The method of claim 2 wherein the fuel is supplied in excess of the stoichiometric ratio.

4. The method of claim 2 wherein the fuel is supplied in a stoichiometric ratio.

5. The method of claim 2 wherein the fuel is mixed with a portion of the oxidizer fluid to form a fuel rich mixture and the fuel rich mixture reacted in the presence of a catalyst prior to combustion with the remainder of the oxidizer admixture.

6. The method of claim 1 wherein the diluent fluid comprises water.

7. The method of claim 1 wherein the diluent fluid comprises carbon dioxide.

8. The method of claim 7 wherein carbon dioxide reacts with water forming carbon dioxide hydrate and heat.

9. The method of claim 1 wherein the fuel comprises a hydrocarbon, the combustion products comprise carbon dioxide, and carbon dioxide in the cooled product fluid reacts with the methane hydrate deposits to form carbon dioxide hydrates releasing methane.

10. The method of claim 1 including the additional step of recovering dissociated methane via a conduit in fluid communication with the dissociated methane.

11. The method of claim 10 wherein the cooled product fluid is injected at a lower elevation than said conduit.

12. The method of claim 5 wherein the fuel comprises methane.

13. The method of claim 5 wherein the diluent fluid comprises water.

14. The method of claim 5 wherein the diluent fluid comprises carbon dioxide.

15. The method of claim 14 wherein the fuel comprises methane, the combustion products comprise carbon dioxide, and the carbon dioxide in the cooled product fluid reacts to form carbon dioxide hydrate.

16. The method of claim 15 including the additional step of recovering dissociated methane via a conduit in fluid communication with the dissociated methane.

17. The method of claim 15 wherein the cooled product fluid is injected at a lower elevation than said conduit.

18. The method of claim 3 wherein the fuel comprises methane, the combustion products comprise carbon dioxide, and the carbon dioxide in the cooled product fluid reacts to form carbon dioxide hydrate.

19. A method of dissociating methane hydrate deposits in-situ, comprising:

a) providing a supply of oxygen at a pressure higher than that of the methane hydrate deposit;

b) providing a supply of carbon dioxide at a pressure higher than that of the methane hydrate deposit;

c) mixing oxygen with at least a portion of the carbon dioxide to form an oxidizer admixture;

d) providing a fuel;

e) reacting the fuel with the oxidizer admixture downhole to form a heat of reaction and hot combustion products containing carbon dioxide;

f) contacting the combustion products with a diluent fluid to produce a cooled product fluid at a temperature higher than the prevailing methane hydrate decomposition temperature;

g) injecting the cooled product fluid into contact with the methane hydrate deposit, and

h) decomposing methane hydrate and liberating methane.

20. The method of claim 19 wherein the diluent comprises water.

21. The method of claim 20 wherein carbon dioxide reacts with water to form carbon dioxide hydrate and heat.

22. The method of claim 19 wherein the diluent comprises carbon dioxide.

23. The method of claim 22 wherein the diluent reacts with methane hydrate to produce carbon dioxide hydrate and methane.

24. The method of claim 19 wherein the fuel is mixed with a portion of the oxidizer admixture to form a fuel rich mixture and the fuel rich mixture reacted in the presence of a catalyst prior to combustion with the remainder of the oxidizer admixture.

25. The method of claim 24 wherein the fuel is methane.

26. The method of claim 19 wherein the fuel is reacted by gas phase flame combustion.

27. The method of claim 19 including the additional step of recovering dissociated methane via a conduit in fluid communication with the dissociated methane.

28. The method of claim 25 including the additional step of recovering dissociated methane via a conduit in fluid communication with the dissociated methane.