Objective The study aims to solve the problems of high content of resin and asphaltene in Shengli heavy oil and difficult exploitation of heavy oil.

Method The oil-soluble fatty acid transition metal salts were synthesized by the reacting metal Fe and Ni salts with aryl-fatty acids. The solvents and dispersants were screened, the composition of the catalytic system was optimized, and the effect of the composite system on the viscosity and composition of heavy oil was investigated.

Result The optimized catalytic system AOF composed of an equal mass of aryl fatty acid iron and C₉ solvent had good viscosity reduction performance. The viscosity of heavy oil decreased from 204 160 mPa·s to 34 520 mPa·s after the reaction at 160 ℃ for 12 h when the mass ratio of oil to water was 7∶3 and 1 wt% AOF was added. After compounding with 0.15 wt% dispersant, the viscosity could be further reduced to 485 mPa·s. The saturates and aromatics of heavy oil after the catalytic reaction increased by 7.84 percentage points and 5.83 percentage points, respectively. The content of high-carbon hydrocarbons decreased, and that of low-carbon hydrocarbons increased. With the increase of reaction temperature, the saturates and aromatics increased more after the reaction. Dispersants promoted the formation of petroleum acid soap, which was beneficial for the formation of O/W emulsions.

Conclusion The ¹HNMR test results of resin and asphaltene before and after the catalytic reaction detected indicate that the catalytic reaction between AOF and heavy oil belongs to hydrogen-donating catalytic cracking, which promotes the hydrogenation and ring-opening cracking of polycyclic aromatic hydrocarbons.