Viscosity of Characterized Visbroken Heavy Oils

Abstract Visbroken products from a Western Canadian bitumen were generated at five different reaction conditions (temperature and residence time) in an in-house lab-scale continuous reactor unit. Visbroken products from a second Western Canadian bitumen and an Arabian vacuum bottoms were obtained from other sources. Densities and viscosities were measured for the whole oil, the maltenes, the distillates, the distillation residue, and the SARA (saturates, aromatics, resins and asphaltenes) cuts of the residue. The Expanded Fluid (EF) viscosity model was adapted to predict the viscosity of visbroken heavy oils characterized into pseudo-components corresponding to the distillate fraction and the residue SARA cuts. Using data from the first bitumen, the EF model parameters and densities for the cuts (an input for the EF model) were correlated to conversion and the feedstock cut densities and model parameters. The correlated cut properties were then recombined to obtain the whole oil density and viscosity using previously established mixing rules. The proposed approach matched the density and viscosity of all the visbroken products from the first bitumen with average absolute deviations of 1.1 kg/m3 and 8%, respectively. It predicted the product properties from the second bitumen with average absolute deviations of 2.4 kg/m3 and 17%, respectively, but was not accurate for the chemically dissimilar Arabian oil. A generalized methodology to predict visbroken product viscosity was provided for Western Canadian bitumens. The required inputs are the composition (distillate content and residue SARA assay) of the feed and visbroken oils, pressure, temperature, and conversion.