Abstract: The properties of Indonesian tar sand oil were analyzed by thermogravimetric analysis. The visbreaking process for upgrading the oil was tested by autoclave at the conditions of 380-440 ℃，N2 pressure of (1±0.1) MPa, reaction time of 5-60 min, and stirring rate of 200 r/min to investigate the changes of viscosity reduction rate, coking rate, and reaction depth. The results show that at the reaction conditions of 420 ℃, 30 min, the coking rate is 0.91%, the kinetic viscosity of product is 395 mPa?s at 50 ℃ and the viscosity reduction rate reaches 99.62%.

Key words: tar sand oil, heavy oil, visbreaking, coking