Patent ID: 8044106

Claim:
A method for affecting the viscosity of an aqueous fluid gelled with a viscoelastic surfactant (VES) comprising: providing an aqueous fluid gelled with at least one amine oxide VES; adding to the aqueous fluid, in any order, a fatty acid, an alkaline compound selected from the group consisting of alkali metal halide salts, alkaline earth metal halide salts, ammonium salts and combinations thereof, and a water soluble base selected from the group consisting of alkali metal bases, ammonia, ammonium hydroxide, methylamine, trimethylamine, ethylmethylamine, ethanolamine, triethanolamine, urea, choline, and mixtures thereof; and forming in situ a soap reaction product of the fatty acid with the alkaline compound in the presence of the water soluble base; where the soap reaction product is present in an amount effective to increase or decrease the viscosity of the gelled aqueous fluid.