Patent ID: 8012914

Claim:
A method comprising: providing a viscoelastic surfactant gel comprising an acid selected from the group consisting of: hydrochloric acid, hydrofluoric acid, formic acid and acetic acid, an aqueous base fluid, and a viscoelastic surfactant and having a first viscosity; wherein the viscoelastic surfactant is selected from a group consisting of a quaternary ammonium compound, a methyl ester sulfonate, a taurate; and an ethoxylated fatty amine; providing an ortho ester breaker; placing the viscoelastic surfactant gel into a portion of a subterranean formation; contacting the viscoelastic surfactant gel with the ortho ester breaker; and, allowing the ortho ester breaker to hydrolyze to produce an alcohol wherein the alcohol interacts with the viscoelastic surfactant gel to reduce the first viscosity to a lower, second viscosity.