Patent ID: 7261160

Claim:
A method comprising: providing a viscoelastic surfactant fluid that comprises an aqueous-base fluid, and a surfactant; providing a metal ion having at least two oxidation states wherein at least one of the oxidation states interferes with the ability of the surfactant to form a viscosifying micelle, wherein at least a portion of the metal ion is present in an oxidation state that interferes with the ability of the surfactant to form a viscosifying micelle in an amount above about 1000 parts per million by volume of the viscoelastic surfactant fluid; allowing the metal ion to interact with viscoelastic surfactant fluid so as to interfere with the ability of the surfactant to form a viscosifying micelle; and introducing the viscoelastic surfactant fluid into at least a portion of a subterranean formation.