Experimental and modeling studies of phase behavior for propane/Athabasca bitumen mixtures

Recent developments in heavy oil recovery methods indicate that the co-injection of solvent and steam can result in higher oil production rates. To investigate the performance and gain a better understanding of this newly developed process, it is essential to study the phase behavior of solvent/heavy crude oil mixtures and measure the saturated phase properties. This study attempts to provide insight into the phase behavior of propane/bitumen mixtures over wide ranges of temperatures and pressures, where the conditions would be applicable for both Vapex and ES-SAGD processes. Thus, phase behavior experiments for propane/Athabasca bitumen mixtures were conducted over temperature range of 323–473 K and at pressures up to 10 MPa. The results indicate that the mixture of propane and bitumen forms vapor–liquid and liquid–liquid phase separations over the studied temperature and pressure ranges. The variation of solubility with equilibrium pressure was found to be more significant at low temperatures. There were crossovers for gas-saturated bitumen density and viscosity which highlights the effect of solubility at low temperatures that is more significant than the effect of temperature on the bitumen density and viscosity. Thus, lower saturated properties were obtained at low temperatures and high pressures. The solubility and saturated liquid density were well predicted by Peng–Robinson equation of state and the saturated bitumen viscosities were reasonably correlated with Pedersen’s correlation.