Use of a borate-acid buffer in oil and gas operations

1. A method for stimulating a subterranean formation, the method comprising:

introducing an aqueous composition comprising (i) a borate-acid buffer, (ii) a surfactant package; (iii) water; and (iv) optionally a water-soluble polymer into the subterranean formation through a wellbore in fluid communication with the subterranean formation; and

allowing the aqueous composition to imbibe into a rock matrix of the subterranean formation for a period of time;

wherein the borate-acid buffer exhibits a capacity to buffer at a pH of from 6.0 to 8.5;

wherein the borate-acid buffer is present in an effective amount to chelate divalent metal ions present in the water or in water present in the subterranean formation.

2. The method of claim 1 , wherein the method further comprises producing fluids from the subterranean formation through the wellbore.

3. The method of claim 2 , wherein the producing fluids comprise hydrocarbons.

4. The method of claim 3 , wherein the hydrocarbons further comprise CO 2 , H 2 S, or any combination thereof.

5. The method of claim 1 , wherein the subterranean formation comprises an unconventional subterranean formation.

6. The method of claim 5 , wherein the method comprises stimulating a naturally fractured region of the unconventional subterranean formation proximate to a new wellbore, stimulating a naturally fractured region of the unconventional subterranean formation proximate to an existing wellbore, stimulating a previously fractured or previously refractured region of the unconventional subterranean formation proximate to a new wellbore, stimulating a previously fractured or previously refractured region of the unconventional subterranean formation proximate to an existing wellbore or any combination thereof.

7. The method of claim 1 , wherein the method further comprises ceasing introduction of the aqueous composition through the wellbore into the subterranean formation before said allowing step.

8. The method of claim 1 , wherein the period of time is from one day to six months.

9. The method of claim 1 , further comprising:

adding a tracer to the aqueous composition prior to introducing or along with the aqueous composition or through the wellbore into the subterranean formation;

recovering the tracer from the fluids produced from the subterranean formation through the wellbore, from fluids produced from a different well in fluidic communication with the subterranean formation, or any combination thereof; and

comparing the quantity of tracer recovered from the fluids produced to the quantity of tracer introduced.

10. The method of claim 1 , wherein the borate-acid buffer is present in the aqueous composition in an amount of from 0.01% to 2% by weight, based on the total weight of the aqueous composition.

11. The method of claim 1 , wherein the borate-acid buffer exhibits a capacity to buffer at a pH below a point of zero charge of the subterranean formation.

12. The method of claim 1 , wherein the borate-acid buffer comprises a borate compound and a conjugate base of an acid, wherein the borate compound and the conjugate base of the organic acid are present at a weight ratio of from 1:1 to 5:1.

13. The method of claim 1 , wherein the aqueous composition comprises a surfactant package, and wherein the surfactant package comprises a primary surfactant and optionally one or more secondary surfactants.

14. The method of claim 13 , wherein the primary surfactant comprises an anionic surfactant selected from a sulfonate, a disulfonate, a sulfate, a disulfate, a sulfosuccinate, a disulfosuccinate, a carboxylate, a dicarboxylate, or any combination thereof.

15. The method of claim 14 , wherein the anionic surfactant comprises one of the following:

a branched or unbranched C6-C32:PO(0-65):EO(0-100)-carboxylate;

a C10-C30 internal olefin sulfonate;

a C8-C30 alkyl benzene sulfonate (ABS);

a sulfosuccinate surfactant;

a surfactant defined by the formula below

R 1 —R 2 —R 3

wherein

R 1 comprises a branched or unbranched, saturated or unsaturated, cyclic or non-cyclic, hydrophobic carbon chain having 6-32 carbon atoms and an oxygen atom linking R 1 and R 2 ;

R 2 comprises an alkoxylated chain comprising at least one oxide group selected from the group consisting of ethylene oxide, propylene oxide, butylene oxide, and combinations thereof; and

R 3 comprises a branched or unbranched hydrocarbon chain comprising 2-12 carbon atoms and from 2 to 5 carboxylate groups; or

a surfactant defined by the formula below

wherein

R 4 is, individually for each occurrence, a branched or unbranched, saturated or unsaturated, cyclic or non-cyclic, hydrophobic carbon chain having 6-32 carbon atoms; and

M represents a counterion.

16. The method of claim 13 , wherein the primary surfactant has a concentration within the composition of from 0.05% to 5% by weight, based on the total weight of the aqueous composition.

17. The method of claim 1 , wherein when present the water-soluble polymer comprises a synthetic polymer.

18. The method of claim 1 , wherein when present the water-soluble polymer comprises polyacrylamide or a copolymer thereof.

19. The method of claim 1 , wherein the surfactant package comprises a primary surfactant comprising a branched or unbranched C6-C32:PO(0-65):EO(0-100)-carboxylate, a dicarboxylate, or any combination thereof.

20. The method of claim 1 , wherein the subterranean formation comprises a conventional subterranean formation.

21. The method of claim 1 , wherein the period of time is from two weeks to one month.