Gas generating compositions

1. A method comprising:

preparing a gas-generating aqueous composition comprising an azo compound, a viscosifier, and an organic amine, the azo compound comprising the Formula (I):

or a salt thereof, where:

X 1 and X 2 are each independently selected from the group consisting of C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, OR a1 , and NR c1 R d1 ; and

each R a1 , R c1 , and R d1 is independently selected from the group consisting of H, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-7 cycloalkyl, and C 6-10 aryl, wherein the gas-generating composition has a pH of between about 4 and about 9, and wherein the molar ratio between the azo compound and the organic amine is between 1:10 and 1:1;

storing the gas-generating aqueous composition before application;

mixing the gas-generating aqueous composition with a wellbore fluid to form a mixture; and

flowing the mixture of the wellbore fluid with the gas-generating aqueous composition into a subsurface, hydrocarbon-bearing formation to perform a well operation.

2. The method of claim 1 , comprising adding to the wellbore fluid a composition comprising an oxidizing compound.

3. The method of claim 2 , where the oxidizing compound is selected from: a peroxysulfate, a peroxycarbonate, a peroxyborate, a peroxide, a hypochlorite, and an organic peracid.

4. The method of claim 1 , wherein an amount of the azo compound in the gas-generating aqueous composition is in a range from about 1 weight percent (wt. %) to about 10 wt. %.

5. The method of claim 1 , wherein the organic amine comprises an ethyleneamine.

6. A method comprising:

adding an aqueous gas-generating composition comprising an azo compound, a viscosifier, and an organic amine to a wellbore fluid to increase compressibility and affect density of the wellbore fluid as applied downhole in a hydrocarbon-bearing formation, the azo compound comprising the Formula (I):

or a salt thereof, where:

X 1 and X 2 are each independently selected from the group consisting of C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, OR a1 , and NR c1 R d1 ; and

each R a1 , R c1 , and R d1 is independently selected from the group consisting of H, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-7 cycloalkyl, and C 6-10 aryl, wherein the gas-generating composition has an acid added to adjust a pH to between about 4 and about 9, and wherein the molar ratio between the azo compound and the organic amine is between 1:10 and 1:1; and

pumping the wellbore fluid having the gas-generating composition into a wellbore in the hydrocarbon-bearing formation.

7. The method of claim 6 , comprising preparing the gas-generating composition comprising mixing the azo compound with the organic amine, wherein the gas-generating composition is an aqueous composition, and wherein the wellbore fluid is a wellbore treatment fluid.

8. The method of claim 6 , comprising storing the gas-generating composition, wherein the wellbore fluid comprises a drilling fluid or a cement slurry.

9. The method of claim 6 , wherein adding the gas-generating composition comprises mixing the gas-generating composition with the wellbore fluid before pumping the wellbore fluid into the wellbore.

10. The method of claim 6 , wherein adding the gas-generating composition comprises injecting the gas-generating composition into the wellbore fluid as the wellbore fluid is being pumped into the wellbore.

11. The method of claim 6 , comprising activating the azo compound in the wellbore to generate nitrogen gas to increase the compressibility of the wellbore fluid, wherein the organic amine comprises hydrazine or a hydrazide.

12. The method of claim 6 , wherein a molar ratio of the organic amine to the azo compound in the gas-generating composition is in a range of 3:1 to 1:1.

13. The method of claim 6 , wherein a volume ratio of the gas-generating composition to the wellbore fluid is in a range of about 5:1 to about 1:5.

14. The method of claim 6 , wherein an amount of the azo compound in the wellbore fluid is in a range of about 0.2 weight percent (wt. %) to about 8 wt. %.

15. A method comprising:

preparing a gas-generating composition at a production facility comprising an azo compound, a viscosifier, and an organic amine, wherein the gas-generating composition comprises a pH of between about 4 and about 9, and wherein the molar ratio between the azo compound and the organic amine is between 1:10 and 1:1;

transporting the gas-generating composition to a wellbore site;

pumping a wellbore treatment fluid into a wellbore in a hydrocarbon-bearing formation; and

adding the gas-generating composition to the wellbore treatment fluid as the wellbore treatment fluid is being pumped into the wellbore, wherein the gas-generating composition produces nitrogen gas in the wellbore treatment fluid as the wellbore treatment fluid is applied downhole in the hydrocarbon-bearing formation.

16. The method of claim 15 , wherein preparing the gas-generating composition comprising mixing the azo compound with the organic amine, wherein the gas-generating composition is an aqueous composition, wherein the azo compound comprises azodicarbonamide, and wherein the organic amine comprises hydrazine or a hydrazide.

17. The method of claim 15 , wherein the wellbore treatment fluid comprises a drilling fluid or a cement slurry, and wherein the organic amine comprises an ethyleneamine.

18. The method of claim 15 , comprising modulating density of the wellbore treatment fluid in the wellbore via the adding of the gas-generating composition, wherein a molar ratio of the organic amine to the azo compound in the gas-generating composition is in a range of 3:1 to 1:1.