US Patent 7125825 Amidoamine salt-based viscosifying agents and methods of use

Viscoelastic surfactants are described for use in aqueous systems to generate thickened fluids. The surfactants are alkyl amidoamine salts of inorganic acids and/or organic acids. The fluids may also contain inorganic salts, organic salts or mixtures thereof. Additionally, the fluids may contain a co-surfactant. These fluids are particularly useful in oilfield applications such as hydraulic fracturing, gravel packing, drilling, completion, etc. Viscoelastic fluids of the invention are also useful in industrial and consumer product fluid applications as rheology control agents.