Abstract: High viscosity and high pour point brings many difficulties to exploitation and transportation of heavy oil with high resins and asphaltenes contents. One broad-spectrum oil-soluble viscosity reducer with branches (YGZ) was prepared from monomers of isomeric acrylate, maleic anhydride and styrene using methanol as a solvent and dibenzoyl peroxide as an initiator and the preparation conditions were optimized as well. The viscosity reduction performance for variety of crudes was investigated and the mechanism was analyzed preliminarily. The results indicate the best preparation conditions are: mole ratio of isomeric acrylate, maleic anhydride and styrene of 5:1:3, initiator of 1.0%, 90 ℃ for 6 h. The viscosity of Iraq crude oil ( 2 106 mPa?s at 50 ℃) reduces by 70.4% using the prepared viscosity reducer. It is concluded the prepared broad-spectrum oil-soluble viscosity reducer with branches has a better viscosity reduction effect than the n-type viscosity reducer and is suitable to variety of crudes.

Key words: oil-solublity, viscosity reducer, branch-shaped, broad-spectrum, viscosity reducing effect, mechanism