Patent ID: 7858563

Claim:
A method of treating a subterranean formation which comprises at least one hydrocarbon-bearing zone, comprising providing a hydrocarbon-responsive thickening agent which is an oligomeric surfactant with a structure consisting of from 2 to 8 linked surfactant monomer subunits, each monomer subunit having a formula (R 1 —X)pZm, where X is a carboxylate charged group, R 1 is a C 10 -C 50 organic tail group comprising a C 10 -C 25 straight chain bonded at a terminal atom thereof to X, Z is an alkali metal counterion, and p and m are equal to 1 so that each surfactant monomer subunit is charge neutral, mixing electrolyte and a thickening amount of said oligomeric surfactant with an aqueous liquid to make a viscoelastic treatment fluid which is an aqueous micellar solution of said surfactant the amounts of electrolyte and said oligomeric surfactant being sufficient that micellar aggregation of said oligomeric surfactant makes said solution viscoelastic, pumping said viscoelastic treatment fluid through a wellbore and into the subterranean formation, causing or allowing contact between at least some of said viscoelastic fluid and hydrocarbons within the formation, where contact with hydrocarbons dissipates the viscosity of said treatment fluid.