Storable gas generating compositions
The present application provides an aqueous fluid containing a gas-generating compound such as an azo compound, a hydrazide compound, or a semicarbazide compound. The aqueous fluid may also contain an amine compound, an oxidizer, or viscosifier, and a foaming surfactant. The aqueous composition may be storable at pH of less than about 5 without any appreciable gas generation, and may be activated to produce gas when mixed with a wellbore fluid for use in downhole applications.
1. A method comprising:
storing an aqueous composition comprising an azo compound of Formula (I):
or a salt thereof, wherein:
X 1 and X 2 are each independently selected from C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, OR a1 , and NR c1 R d1 ;
each R a1 , R c1 , and R d1 is independently selected from H, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-7 cycloalkyl, and C 6-10 aryl; and
an acid to adjust the pH of the composition to be less than about 5;
adding the aqueous composition to a wellbore fluid; and
flowing a mixture of the aqueous composition and the wellbore fluid in a subterranean formation.
2. The method of claim 1 , wherein pH of the wellbore fluid after addition of the aqueous composition is greater than about 5.
3. The method of claim 1 , wherein pH of the wellbore fluid after addition of the aqueous composition is greater than about 7.
4. The method of claim 1 , comprising adding a composition comprising an oxidizing compound to the wellbore fluid.
5. The method of claim 4 , wherein the oxidizing compound is selected from: a peroxysulfate, a peroxycarbonate, a peroxyborate, a peroxide, a hypochlorite, and an organic peracid.
6. The method of claim 1 , wherein storing the aqueous composition comprises storing the aqueous composition for at least 24 hours.
7. The method of claim 1 , wherein storing the aqueous composition comprises storing the aqueous composition for at least 24 hours without producing substantial amount of gas in the aqueous composition.
8. The method of claim 1 , wherein the aqueous composition is stable and storable without producing substantial amount of gas for at least 24 hours.
9. The method of claim 1 , wherein pH of the aqueous composition is less than about 4.
10. The method of claim 1 , wherein an amount of the azo compound in the aqueous composition is from about 1 wt. % to about 10 wt. % of the aqueous composition.
11. The method of claim 1 , wherein the azo compound is azodicarbonamide, or a salt thereof.
12. The method of claim 1 , wherein the wellbore fluid comprises a wellbore treatment fluid comprising a cement slurry.
13. The method of claim 1 , wherein the wellbore fluid comprises a drilling fluid.
14. The method of claim 1 , wherein adding the aqueous composition comprises adding the aqueous composition to the wellbore fluid before pumping the wellbore fluid into a wellbore in the subterranean formation.
15. The method of claim 14 , wherein adding the aqueous composition to the wellbore fluid comprises batch mixing the aqueous composition with the wellbore fluid.
16. The method of claim 1 , wherein adding the aqueous composition comprises injecting the aqueous composition into the wellbore fluid as the wellbore fluid is being pumped into a wellbore in the subterranean formation.
17. The method of claim 1 , wherein the aqueous composition comprises triethanolamine, or a salt thereof.
18. The method of claim 1 , wherein the aqueous composition comprises at least one a hydrazine compound or a hydrazide compound, wherein the hydrazine compound comprises at least one of hydrazine, hydrazine monohydrobromide, hydrazine hydrate, hydrazine sulfate, hydrazine acetate, hydrazine dihydrochloride, hydrazine monohydrochloride, or hydrazine acetate, and wherein the hydrazide compound comprises at least one of carbohydrazide or p-toluenesulfonyl hydrazide, or a salt thereof.
19. The method of claim 1 , wherein the aqueous composition comprises an ethyleneimine compound.
20. The method of claim 19 wherein the ethyleneimine compound comprises at least one of ethylene diamine (EDA), tetraethylene pentamine (TEPA), diethyletriamine (DETA), or polyethyleneimine, or a salt thereof.