Abstract: In order to reduce the viscosity and improve the fluidity of heavyoil,molecular dynamics simulation combined with orthogonal test was carried out.Octadecyl methacrylate(SMA),N-phenylmaleimide（N-PMI) and vinylacetate (VA) were used as monomers,and oil-soluble viscosity reducer(SNV) was synthesized by copolymerization.The simulation results showed that the density of heavy oil decreased and the potential energy increased after adding SNV,which means that SNV could destroy the three-dimensional network structure between resins and asphaltenes,and inhibit the association of resins and asphaltenes.The test results showed that the optimum synthesis conditions of SNV were as follows:monomer molar ratio of SMA,N-PMI,VA of 10∶1∶6, initiator amount of 0.5%,reaction time of 6h and reaction temperature of 50 ℃.Under this synthetic condition,the viscosity reduction rate of heavy oil could reach 43.76%,which was better than some commerciall viscosity reducer.The molecular dynamics simulation results were consistent with the test results.

Key words: viscosity reduction for heavy oil, molecular dynamics simulation, oil-soluble viscosity reducer, viscosity reduction mechanis