Visbreaking of heavy oil with high metal and asphaltene content

•Visbreaking of heavy oil with high metal and asphaltene content was investigated.•Coupling of porphyrin metals with asphaltenes promotes asphaltene aggregation.•Asphaltene condensation is accelerated by high content and aggregation.•Asphaltenes with highest metal content participate in condensation to coke first. The visbreaking of Canadian oil sands bitumen (OSB) and Tahe atmospheric residue (AR) with high metal and asphaltene content was studied to deepen the understanding of the utilization of ultra-inferior heavy oil. The total content of nickel and vanadium in the asphaltenes contained in Canadian OSB reaches 1300 ppm, promoting large-scale aggregation of asphaltenes. Driven by high asphaltene content of 19.3 wt% and large-scale aggregation of asphaltenes, Canadian OSB with an initial boiling point (IBP) of 500 °C exhibits rapid condensation during visbreaking. Furthermore, those asphaltenes with the highest metal content participate in condensation first, producing metallic nickel in the formed coke. By changing cutting strategy, the group composition and metal distribution of Canadian OSB can be adjusted. A viscosity reduction rate above 99 % is obtained during the visbreaking of Canadian OSB with an IBP of 350 °C, similar to the visbreaking of Tahe AR with an asphaltene content of 15.4 wt% and a total metal content of 300 ppm.