Viscoelastic surfactant based aqueous fluid systems useful as thickening
agents in various applications, e.g. to suspend particles produced during
the excavation of geologic formations. The surfactants are
zwitterionic/amphoteric surfactants such as dihydroxyl alkyl glycinate,
alkyl ampho acetate or propionate, alkyl betaine, alkyl amidopropyl
betaine and alkylimino mono- or di-propionates derived from certain waxes,
fats and oils. The thickening agent is used in conjunction with an
inorganic water-soluble salt or organic additive such as phthalic acid,
salicylic acid or their salts.
