Patent ID: 7238648

Claim:
A method of fracturing a subterranean formation comprising the step of pumping a strongly acidic viscoelastic fluid through a wellbore and into a subterranean formation at a pressure sufficient to fracture the formation, wherein said viscoelastic fluid comprises: a) an aqueous medium; b) a surfactant selected from at least one of amphoteric surfactants, zwitterionic surfactants, and mixtures thereof; c) a member selected from the group consisting of organic acids, organic acid salts, and combinations of one or more organic acids or organic acid salts with one or more inorganic salts; wherein said fluid exhibits the property of viscoelasticity, and wherein said member comprises an aromatic moiety selected from sulfonic moieties, sulfonate moieties, carboxylic moieties, and carboxylate moieties; and d) an acid at a concentration sufficient to reduce the pH of said viscoelastic fluid to about 3 or less.