Liquid-Liquid Equilibrium Studies of Solvent and Bitumen Systems
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2021-01-13
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Abstract
Solvent-aided and solvent-based heavy oil recovery methods have gained interest as alternatives to the conventional steam-based thermal recovery methods. Dimethyl ether (DME), propane, butane, and their mixtures (LPG) are considered proper solvents for low temperature upgrading and solvent-based bitumen and heavy oil recovery processes. One key prerequisite for simulation and optimization of these recovery processes is the liquid-liquid thermodynamic equilibrium (LLE) data of solvent and bitumen mixtures. This study presents measurements and modeling studies of the LLE of solvent (butane, DME, and LPG) and Athabasca bitumen mixtures. Phase behavior measurements including equilibrium compositions (K-value), density, and viscosity of the light phase as well as saturation pressures of the mixtures are measured at temperatures and pressures up to 100 °C and 3.5 MPa, respectively. To model LLE data of solvent/bitumen system, detailed characterization of the light and heavy cuts (upgraded oil and asphaltenes) are conducted using a methodology that combines the gel permeation chromatography (GPC) with the simulated distillation results (SD) to provide a molecular weight distribution. Then, two pseudocomponents (one representative of maltenes and the other representative of asphaltenes) are defined based on the characterization, and LL K-values are estimated for each component. Non-Random Two Liquid (NRTL) model is then tuned to represent the experimental compositional data and K-values. Finally, the implementation of LL K-values for simulation of asphaltene deposition in porous media is described. A modified approach is presented based on the LL K-values and a reaction-based non-equilibrium mass transfer model. The interplay of viscous fingering and asphaltene deposition during the injection of solvent is studied and sensitivity of the simulation results on grid size is investigated.
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Sadeghi Yamchi, H. (2020). Liquid-Liquid Equilibrium Studies of Solvent and Bitumen Systems (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.