Viscoelastic surfactants for self-diverting acid under high temperature and preparation method

Abstract

A viscoelastic surfactant (VES) for a self-diverting acid under high temperature has a structural formula shown as formula (I), wherein, n is saturated hydrocarbon with 2 to 8 carbon atoms; R1 is saturated or unsaturated hydrocarbon with 18 to 28 carbon atoms; R2 and R3 are independently methyl, ethyl or hydrogen, and R2 and R3 can be the same or different; and X− is any one of Cl−, Br−, CO32−, SO42−, HCOO− and CH3COO−. The method for preparing the surfactant includes subjecting a fatty acid and an organic amine to acid-amine condensation to obtain an intermediate. The intermediate reacts with a metal hydride to obtain a fatty amine. Then, an acid solution is used to protonate the fatty amine to obtain an ultra-long-chain viscoelastic cationic surfactant. The present invention also provides use of the surfactant as a thickener for a self-diverting acid.

Dependencies are inferred from the claim text.