Viscosity Blending Behavior And Mixing Rules Of Canadian Oil Sand Bitumen

As crude oil becomes more inferior and heavier,it is important to obtain an indepth understanding for high efficient utilization of heavy oil.Canadian oil sand bitumen is an unconventional oil resource with abundant reserves.It has high viscosity,density and rich amount of contaminants,which forms challenges during its utilization and transportation.In the presented work,based on the deep separation of Canadian oil sand bitumen,the viscosity variation and blending behavior of different fractions and diluents were investigated.Then reasonable mixing rules and prediction model were put forward,providing guidance for its pipeline transportation and subsequent processing.Removing heavy components through solvent separation is a potential routine for the viscosity reduction of Canadian oil sand bitumen.The mixing rule for the viscosity of extracted fraction is the basis of cutting point selection and component blending optimization.In this study,supercritical fluid extraction fractionation(SFEF)was applied to separate Canadian oil sand bitumen vacuum residue into various fractions and properties of these fractions were analyzed and characterized.Fractions with similar properties and quite different properties were selected and viscosity blending behavior of extracted fractions was experimentally evaluated.Several available viscosity mixing rules were tested and the optimal model was obtained.In order to predict the viscositytemperature profile of derived fractions,a new mixing rule based on empirical equation parameters was proposed.We also correlated the viscosity-temperature parameters to conventional bulk property.The new rule represented good agreement between calculated and experimental viscosities,providing a method for the rapid viscosity estimation on the premise of unknown viscosity and viscosity temperature correlation.As a component with the largest molecular weight and the strongest polarity in heavy oil,asphaltene contributes greatly to the high viscosity of bitumen.It can't be detected from supercritical extracted fractions.Two groups of fractions with different asphaltene content were selected to investigate the influence of asphaltene on mixture viscosity and blending behavior.Five commonly used models and viscosity-temperature parameter mixing rule were evaluated and the optimal model was obtained.The effect of asphaltene addition on the viscosity and flow pattern were invesitgated and the virtual viscosity was used to fit and predict the residue viscosity.In addition to the blending of heavy oil components,the dilution process also facilitates its pipeline transportation for viscosity reduction.In this paper,we compared the amount of dilution required to meet the requirements of pipeline transportation before and after deasphalting,indicating that deasphalting process improves the viscosity-temperature characteristics and optimizes the process of dilution.Then the influence of solvent and heavy oil composition was investigated.Two alkanes with different chain lengths,aromatics and two naphthenes with different side chains were chosen to compare their effects in the blending process of oil sand bitumen and LDAO blending oil,offering reference for the diluents selection and allocation in the future dilution process.