Abstract: A new oil-soluble viscosity reducer SMN was synthesized in two steps from styrene, maleic anhydride, and nonylphenol polyoxyethylene ether, in order to reduce the viscosity and enhance oil recovery. The viscosity reduction effect of SMN on Shengli high viscosity crude oil was investigated. It was found that the maximum viscosity reduction rate could reach 68.5%. It was inferred that the polar groups such as benzene ring, carboxyl group and ester group in SMN could enter the asphaltene layer through hydrogen bond and π-π stacking, and the polyoxyethylene group with larger steric hindrance in the molecule could prevent asphaltenes from accumulating, thus dispersing heavy components in crude oil and reducing the viscosity of crude oil.

Key words: high viscosity crude oil, viscosity reducing agent, viscosity reducing mechanism