Method for stimulating well production

Claim 1

The method of claim 1, wherein the said formation is a hydrocarbon-bearing formation.

Claim 3

A method of increasing the production of fluids from a subterranean fluid bearing formation having present therein acid-soluble components and being without water-sensitive shales or clays comprising injecting down the well bore penetrating said formation and injecting therefrom into said formation under a pressure greater than the formation pressure an aqueous well acidizing composition comprising an aqueous solution of a mineral acid having dissolved therein a vinylpyrrolidone polymer present in a concentration of from about 0.1 to about 10 percent by weight, the said acid being present in an amount capable of reacting with the acid-soluble components of a subterranean fluid-bearing formation and wherein the said polymer comprises recurring units of the formula:

Claim 4

A method of increasing the production of fluids from a subterranean calcareous fluid-bearing formation having present therein acid-soluble components and being without water-sensitive shales or clays comprising injecting down the well bore penetrating said formation and injecting therefrom into said formation under a pressure greater than the formation pressure an aqueous well acidizing composition comprising about 3 to about 30 percent by weight of hydrochloric acid having dissolved therein from about 0.1 to about 10 percent by weight based on the total weight of the composition of polyvinylpyrrolidone having an average molecular weight of about 100,000 to about 400,000, maintaining said composition in contact with the formation for a time sufficient for the acid to chemically react with the acid-soluble components of the formation to etch passageways therethrough thereby increasing substantially the flow capacity of the said subterranean formation.

Claim 5

A method of increasing the production of fluids from a subterranean limestone fluid-bearing formation having present therein acid-soluble components and being without water-sensitive shales or clays comprising injecting down the well bore penetrating said formation and injecting therefrom into said formation under a pressure greater than the formation pressure an aqueous well acidizing composition comprising about 3 to about 30 percent by weight of hydrochloric acid having dissolved therein from about 0.1 to about 10 percent by weight based on the total weight of the composition of polyvinylpyrrolidone having an average molecular weight of about 100,000 to about 400,000, maintaining said composition in contact with the formation for a time sufficient for the acid to chemically react with the acid-soluble components of the formation to etch passageways therethrough thereby increasing substantially the flow capacity of the said subterranean formation.