PHASE-BEHAVIOR OF RESERVOIR FLUIDS .5. SAFT MODEL OF CO2 AND BITUMEN SYSTEMS

Statistical associating fluid theory (SAFT) is extended to bitumen-CO2 systems. SAFT parameters are found to be well behaved and easy to generalize, the pure component parameters in terms of molecular weight and aromaticity, and the binary parameters in terms of temperature and molecular weight. The current set of parameters can be used with confidence at pressures up to 8 MPa above 50-degrees-C, and also at higher pressures (we tested up to 16 MPa) at and above 100-degrees-C. In addition to well behaved parameters, compared to other equations of state, SAFT predictions of bitumen-in-CO2 solubilities are more accurate, especially at higher molecular weights. Also, SAFT can account for molecular association that is key to understanding the phase behavior of reservoir fluids.