Patent ID: 7749944

Claim:
A method of shortening the shear recovery time of a viscoelastic surfactant fluid system comprising: (a) providing a viscoelastic surfactant fluid system comprising a major portion of a surfactant selected from cationic, anionic, zwitterionic, and amphoteric viscoelastic surfactants, and mixtures thereof, and a rheology enhancer in a concentration by weight from about 0.0005% to about 0.2% sufficient to shorten shear recovery time of the fluid system compared to shear recovery time of the fluid system absent the rheology enhancer, the rheology enhancer selected from aromatic sulfonates having a molecular weight of at least 500 and comprising one or more sulfonated lignin; b) adjusting the concentration of the sulfonated lignin rheology enhancer to be sufficient to shorten the shear recovery time of the fluid system compared to the shear recovery time of the viscoelastic surfactant absent the sulfonated lignin rheology enhancer; and (c) injecting the fluid system down a well.