Patent ID: 8418761

Claim:
A method comprising: providing a treatment fluid having a first viscosity comprising: an aqueous base fluid; a viscoelastic surfactant; and a stimuli-responsive water-soluble polymer that comprises a hydrophobically modified polymer that comprises a backbone polymer comprising at least one selected from the group consisting of vinylpyrrolidone, vinylpyridine, polyvinylpyrrolidone, polyvinylpyridine, polybutylene succinate, polybutylene succinate-co-adipate, polyhydroxybutyrate-valerate, polyhydroxybutyrate-covalerate, polyethylene terephthalate, sulfonated polyethylene terephthalate, polypropylene, a protein, polylactic acid, poly(glycolide), poly(ε-caprolactone), poly(hydroxy ester ether), poly(hydroxybutyrate), polycarbonate, a poly(amino acid), poly(phosphazene), polyester amide, polystyrene, any derivative thereof, any copolymer thereof, any homopolymer thereof, any terpolymer thereof, and any combination thereof; introducing the treatment fluid into a subterranean formation; and allowing the treatment fluid viscosity to change to a second viscosity in response to a stimulus.