Phase Equlibria and Physical Properties of Alberta Bitumen

摘要

The design and development of suitable processes for heavy oil or bitumen recovery from reservoirs need fundamental information on thermodynamic and transport properties of heavy oil or bitumen. Early in 1980, as per the request of Alberta Oil Sands Technology and Research Authority (AOSTRA), Dr. D. B. Robinson and his associates compiled a Data Book on the Thermodynamic and Transport Properties of Bitumens and Heavy Oils through reviewing, interpreting, and assessing numerous technical papers, books, theses, and reports (AOSTRA Technical Report, 1984)<'(1)>. Alberta bitumen is considered as a C<'n+> fraction with an average molecular weight of 544 g/mol and a specific gravity of 1.O1g/cm<'3>. In an attempt to develop thermodynamic models to represent fluid properties and phase behavior for heavy oil and bitumen, an effort is made in this work to apply the characterization procedure for plus fractions<'(2)> to predicting phase equilibria, density and viscosity of Alberta bitumen with and without solvents injection. The Peng-Robinson EOS <'(4)> with volume shift parameters is employed to describe the non-ideality of vapor and liquid phases and to predict the fluid densities. In addition, three viscosity models, Corresponding states. principle with one reference fluid (CSP1)<'(5)>, Corresponding states principle with two reference fluids (CSP2)<'(6)> and the Lohrenz-Bray-Clark model (LBC)<'(7)> are evaluated for heavy oil and bitumen through comparison of the predictions against the experimental data. It is demonstrated from this work that the calculated gas solubility in Alberta bitumen with and without water, and the calculated equilibrium ratios of gas and water in bitumen are in good agreement with the experimental data. The absolute average deviation of the predicted density for bitumen and bitumen-gas mixtures is within 1.3%. The CSP1 and CSP2 models give reasonable viscosity predictions for bitumen and bitumen-gas mixtures over a temperature range of 21- 200°C and a pressure range of 0.1-11MPa. The preliminary results indicate that the proposed models provide a useful tool to calculate phase equilibria and physical properties for bitumen and heavy oils with reasonable accuracy.