Patent ID: 7157409

Claim:
A wellbore fluid comprising: an aqueous fluid; a viscoelastic surfactant; a thickener soluble in the aqueous fluid, wherein the thickener has a hydrophobic oligomeric or polymeric backbone made from the reaction of alkene monomer or alkyne monomer, or mixtures thereof, and wherein zwitterionic surfactant functional groups are attached to the hydrophobic backbone, wherein the thickener has a molecular conformation such that the surfactant functional groups are hydrophilic and the hydrophobic oligomeric or polymeric backbone is hydrophobic; and wherein the combination of viscoelastic surfactant and thickener form micellar assemblies such that the wellbore fluid thickener develops viscoelastic characteristics, and wherein the thickener has the following structure: wherein x+y=2 to 300,000.