Abstract: Aiming at the problems of large excess of FCC diesel fuel in refineries and high aromatic content in FCC diesel fuel, and the present situation of heavy oil production by blending dilute and viscosity reduction with high blending ratio and scarce resources of diluted oil, extraction and separation of polycyclic aromatic hydrocarbons from FCC diesel fuel were used for the study of ultra-heavy oil blending dilute and viscosity reduction. Orthogonal experiments were carried out for the extraction of polycyclic aromatic hydrocarbons. Under the selected optimal operating conditions (agent-oil volume ratio 1.4, extraction temperature 45 ℃, extraction time 5 min and phase separation time 5.5 min), the yield of polycyclic aromatic hydrocarbons was 29.87%, and the content of aromatic hydrocarbons was as high as 99.07%. At the same dilution ratio of 0.10, the viscosity reduction rates of polycyclic aromatic hydrocarbons and Tahe thin oil were 68.58% and 94.20%, respectively. The fitting results showed that when the polycyclic aromatic hydrocarbon consumption was only 16.32% of Tahe oilfield thin oil, the heavy oil blending with thin oil could meet the viscosity reduction requirements of Tahe oilfield. Taking the heavy oil self-flowing wells in Tahe oilfield as an example, compared with thin oil, when the water content of heavy oil was 0, 30% and 50%, the daily oil production growth rate of single well with polycyclic aromatic hydrocarbons reached 115.90%, 84.57% and 62.20%, respectively.

Key words: Tahe ultra heavy oil, FCC diesel, polycyclic aromatic hydrocarbons, Tahe thin oil, dilute to reduce viscosity