PHASE-BEHAVIOR OF RESERVOIR FLUIDS .6. COSOLVENT EFFECTS ON BITUMEN FRACTIONATION WITH SUPERCRITICAL CO2

Equilibrium phase compositions (TPXY) are measured in a flow cell appa ratus for a bitumen + decane + CO2 system. Statistical Associated Flui d Theory (SAFT) [Huang, S.H. and Radosz, M., 1990a. Fluid Phase Equili bria, 60: 81-98; 1990b. Ind Eng. Chem. Res., 29: 2284-2294] and Peng-R obinson equations of state are found to give similar results for the c ondensed phase compositions. However, SAFT is found superior in predic ting the supercritical fluid phase compositions. Hence, the bitumen pa rtitioning coefficients (K-factors) can be reliably predicted with SAF T but not with PR. Moreover, the SAFT characterization approach based on measurable molecular properties is more appropriate for heavy, asso ciating bitumen components than is the PR characterization approach ba sed on hypothetical critical properties. Finally, SAFT-predicted K-fac tors allow for quantifying cosolvent selectivity and capacity in fract ionating bitumen with supercritical CO2.