Methods of generating gas in well fluids

• US 6,715,553 B2
• Filed: 05/31/2002
• Issued: 04/06/2004
• Est. Priority Date: 05/31/2002
• Status: Expired due to Term

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Inventors: Zamora, Frank, Griffith, James E., Dennis, John L. Jr., Cox, Ricky A., Ravi, Krishna M., Reddy, B. Raghava, Luke, Karen
• Primary Examiner(s): Bagnell, David
• Assistant Examiner(s): BOMAR, THOMAS S
• Application Number:
  US10/159,590
• Publication Number:
  US 20030221832A1
• Time in Patent Office: 676 Days
• Field of Search: 166/300, 166/309, 166/312, 166/305.1, 175/69, 175/72, 507/102, 507/202, 106/820, 106/677, 106/672
• US Class Current: 166/309
• CPC Class Codes: C09K 8/38 Gaseous or foamed well-drilling compositions

Abstract

Improved methods of generating gas in and foaming aqueous well fluids introduced into a subterranean zone are provided. A method of the invention includes the steps of combining with an alkaline aqueous well fluid one or more gas generating chemicals and a mixture of foaming and foaming stabilizing surfactants so that the gas generating chemical or chemicals react with the alkaline aqueous well fluid and gas and foam are formed in the well fluid while it is being pumped, and then pumping the well fluid into the subterranean zone.

Claims

1. An improved method of generating gas in and foaming an alkaline aqueous well fluid such as an aqueous drilling fluid, an aqueous spacer fluid and the like introduced into a subterranean zone penetrated by a well bore comprising the steps of:

(a) combining with said alkaline aqueous well fluid one or more gas generating chemicals present in said aqueous well fluid in an amount in the range of from about 10% to about 100% by weight of water in said aqueous well fluid and a mixture of foaming and foam stabilizing surfactants whereby said gas generating chemical or chemicals react with said alkaline aqueous well fluid and gas and foam are formed in said well fluid while it is being pumped; and

(b) pumping said alkaline aqueous well fluid formed in step (a) into said well bore and said subterranean zone.

2. An improved method of generating gas in and foaming an aqueous well fluid such as aqueous drilling fluid, an aqueous spacer fluid and the like introduced into a subterranean zone penetrated by a well bore comprising the steps of:

(a) combining with said aqueous well fluid a gas generating chemical, a mixture of foaming and foam stabilizing surfactants and when needed, an activator for said gas generating chemical comprising a buffer selected from the group consisting of a mixture of potassium phosphate and potassium monohydrogenphosphate and a mixture of sodium carbonate and sodium bicarbonate for increasing the pH of said aqueous well fluid to in the alkaline range of from about 10 to about 14 so that said gas generating chemical reacts with said alkaline aqueous well fluid and gas and foam are formed in said aqueous well fluid while it is being pumped; and

(b) pumping said aqueous well fluid formed in step (a) into said well bore and said subterranean zone.

3. An improved method of generating gas in and foaming an aqueous well fluid such as an aqueous drilling fluid, an aqueous spacer fluid and the like introduced into a subterranean zone penetrated by a well bore comprising the steps of:

(a) combining with said aqueous well fluid a gas generating chemical, a mixture of foaming and foam stabilizing surfactants and when needed, an activator for said gas generating chemical comprising one or more oxidizing chemicals selected from the group consisting of ammonium persulfate, sodium persulfate, potassium persulfate, sodium chlorite, sodium chlorate, hydrogen peroxide, sodium perborate and sodium peroxy carbonate so that said gas generating chemical reacts with said one or more oxidizing chemicals and gas and foam are formed in said aqueous well fluid while it is being pumped; and

(b) pumping said aqueous well fluid formed in step (a) into said well bore and said subterranean zone.

4. An improved method of generating gas in and foaming an aqueous well fluid such as an aqueous drilling fluid, an aqueous spacer fluid and the like introduced into a subterranean zone penetrated by a well bore comprising the steps of:

(a) combining with said aqueous well fluid a gas generating chemical, a mixture of foaming and foam stabilizing surfactants and when needed, an activator for said gas generating chemical comprising one or more oxidizing chemicals present in said aqueous well fluid in an amount in the range of from about 200% to about 1500% by weight of said gas generating chemical therein so that said gas generating chemical reacts with said one or more oxidizing chemicals and gas and foam are formed in said aqueous well fluid while it is being pumped; and

(b) pumping said aqueous well fluid formed in step (a) into said well bore and said subterranean zone.

5. An improved method of generating gas in and foaming an aqueous well fluid such as an aqueous drilling fluid, an aqueous spacer fluid and the like introduced into a subterranean zone penetrated by a well bore comprising the steps of:

(a) combining with said aqueous well fluid a gas generating chemical comprised of azodicarbonamide in an amount in the range of from about 0.3% to about 8% by weight of water in said aqueous well fluid, a mixture of foaming and foam stabilizing surfactants present in an amount in the range of from about 0.5% to about 5% by weight of water in said aqueous well fluid and an activator for said gas generating chemical comprising a base selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides and alkali metal silicates for increasing the pH of said well fluid to in the alkaline range of from about 10 to about 14 so that said gas generating chemical reacts with said alkaline well fluid and gas and foam are formed in said well fluid while it is being pumped; and

(b) pumping said well fluid formed in step (a) into said well bore and said subterranean zone.

6. An improved method of generating gas in and foaming an aqueous well fluid such as an aqueous drilling fluid, an aqueous spacer fluid and the like introduced into a subterranean zone penetrated by a well bore comprising the steps of:

(a) combining with said aqueous well fluid a gas generating chemical comprised of azodicarbonamide in an amount in the range of from about 0.3% to about 8% by weight of water in said aqueous well fluid, a mixture of foaming and foam stabilizing surfactants present in an amount in the range of from about 0.5% to about 5% by weight of water in said aqueous well fluid and an activator for said gas generating chemical comprising a buffer selected from the group consisting of a mixture of potassium phosphate and potassium monohydrogen phosphate and a mixture of sodium carbonate and sodium bicarbonate for increasing the pH of said well fluid to in the alkaline range of from about 10 to about 14 so that said gas generating chemical reacts with said alkaline well fluid and gas and foam are formed in said well fluid while it is being pumped; and

(b) pumping said well fluid formed in step (a) into said well bore and said subterranean zone.

7. An improved method of generating gas in and foaming an aqueous well fluid such as an aqueous drilling fluid, an aqueous spacer fluid and the like introduced into a subterranean zone penetrated by a well bore comprising the steps of:

(a) combining with said aqueous well fluid a gas generating chemical comprised of azodicarbonamide in an amount in the range of from about 0.3% to about 8% by weight of water in said aqueous well fluid, a mixture of foaming and foam stabilizing surfactants present in an amount in the range of from about 0.5% to about 5% by weight of water in said aqueous well fluid and an activator for said gas generating chemical comprised of an oxidizing chemical selected from the group consisting of ammonium persulfate, sodium persulfate, potassium persulfate, sodium chlorite, sodium chlorate, hydrogen peroxide, sodium perborate and sodium peroxy carbonate so that said gas generating chemical reacts with said oxidizing chemical and gas and foam are formed in said aqueous well fluid while it is being pumped; and

(b) pumping said aqueous well fluid formed in step (a) into said well bore and said subterranean zone.

8. An improved method of generating gas in and foaming an aqueous well fluid such as an aqueous drilling fluid, an aqueous spacer fluid and the like introduced into a subterranean zone penetrated by a well bore comprising the steps of:

(a) combining with said aqueous well fluid a gas generating chemical comprised of azodicarbonamide in an amount in the range of from about 0.3% to about 8% by weight of water in said aqueous well fluid, a mixture of foaming and foam stabilizing surfactants present in an amount in the range of from about 0.5% to about 5% by weight of water in said aqueous well fluid and an activator for said gas generating chemical comprised of an oxidizing chemical present in said aqueous well fluid in an amount in the range of from about 200% to about 1500% by weight of said gas generating chemical or chemicals therein so that said gas generating chemical reacts with said oxidizing chemical and gas and foam are formed in said aqueous well fluid while it is being pumped; and

(b) pumping said aqueous well fluid formed in step (a) into said well bore and said subterranean zone.

9. An improved method of chemically generating gas and foaming an aqueous acid solution which is introduced into a subterranean zone penetrated by a well bore to increase the hydrocarbon permeability of the zone comprising the steps of:

(a) combining an aqueous solution or dispersion of one or more gas generating chemicals with an activator for the gas generating chemicals selected from the group consisting of a base or buffer for increasing the pH of the aqueous solution or dispersion to in the alkaline range of from about 10 to about 14 and an oxidizing chemical or chemicals so that the gas generating chemicals react with the alkaline solution or dispersion or the oxidizing chemicals to generate gas;

(b) combining said gas with said aqueous acid solution in an amount sufficient to foam said aqueous acid solution as said aqueous acid solution is pumped into said well bore and said subterranean zone whereby said aqueous acid solution is foamed.

10. The method of claim 9 wherein said gas generating chemical or chemicals in said aqueous solution or dispersion are selected from the group consisting of hydrazine and its salts with acids, azodicarbonamide, azobis(butyronitrile), p-toluene sulfonyl hydrazide, p-toluene sulfonyl semicarbazide, carbohydrazide, p-p′

-oxybis(benzenesulfonylhydrazide) and mixtures thereof.

11. The method of claim 9 wherein said gas generating chemical is selected from the group consisting of azodicarbonamide and carbohydrazide.

12. The method of claim 9 wherein said gas generating chemical or chemicals are present in said aqueous solution or dispersion in an amount in the range of from about 0.1% to about 10% by weight of water therein.

13. The method of claim 9 wherein when said activator is a base, it is selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides and alkali metal silicates.

14. The method of claim 9 wherein when said activator is a buffer, it is selected from the group consisting of a mixture of potassium phosphate and potassium monohydrogen phosphate and a mixture of sodium carbonate and sodium bicarbonate.

15. The method of claim 9 wherein when said activator is an oxidizing chemical, it is selected from the group consisting of ammonium persulfate, sodium persulfate, potassium persulfate, sodium chlorite, sodium chlorate, hydrogen peroxide, sodium perborate and sodium peroxy carbonate.

16. The method of claim 9 wherein when said activator is an oxidizing chemical, it is present in said aqueous solution or dispersion in an amount in the range of from about 200% to about 1500% by weight of said gas generating chemical therein.

17. The method of claim 9 wherein said acid in said aqueous acid solution is an inorganic acid selected from the group consisting of hydrochloric acid, hydrofluoric acid, fluoboric acid and mixtures thereof.

18. The method of claim 17 wherein said inorganic acid is present in said aqueous acid solution in an amount in the range of from about 5% to about 30% by weight of said aqueous acid solution.

19. The method of claim 9 wherein said acid in said aqueous acid solution further comprises an organic acid selected from the group consisting of formic acid, acetic acid, citric acid, lactic acid, thioglycolic acid, glycolic acid and mixtures thereof.

20. The method of claim 19 wherein said organic acid is present in said aqueous acid solution in an amount in the range of from about 0% to about 10% by weight of aqueous acid solution.