Measurement and Correlation of Solubility and Physical Properties for Gas-Saturated Athabasca Bitumen

The addition of hydrocarbon or nonhydrocarbon gases to steam can have a beneficial effect on the performance of steam-based processes for recovery of heavy and extraheavy oils. The performance of these newly developed techniques depends on the amount of solvent dissolved in the oil and the variation of oil viscosity with temperature. Thus, full understanding of the quantitative effects of the solvent on heavy-oil viscosity and phase behaviors is crucial for feasibility studies, design, and prediction of field-scale processes. Thus, the aim of this research is the development of an understanding of the phase behavior of carbon dioxide (CO2)/Athabasca-bitumen mixtures. It includes both experimental and modeling studies of solubilities and saturated-liquid densities and viscosities over a wide range of temperatures (up to 200 degrees C), approaching the conditions of in-situ steam processes and pressures up to 6 MPa. Experimental results indicate that the dissolved gas in bitumen leads to a significant oil-viscosity reduction, and the effect is greater at lower temperature and higher pressure. The gas-saturated-bitumen densities change slightly with the dissolution of CO2. The modeling results show that the measured solubilities are represented adequately by the modified Peng-Robinson equation of state (Robinson and Peng 1978), with an average absolute relative deviation (AARD) of 7.5%. The saturated-liquid densities are also correlated with equation-of-state and effective-liquid-density approaches, with 0.77 and 0.41% AARDs, respectively. The viscosity data are reasonably matched with the modified Pedersen corresponding state (Pedersen and Fredenslund 1987).