A thermodynamic model to predict propane solubility in bitumen and heavy oil based on experimental fractionation and characterization

Propane has been suggested as suitable solvent for solvent-aided bitumen recovery methods such as Vapour Extraction (VAPEX), N-Solv (hot solvent injection), and Expanding Solvent-Steam Assisted Gravity Drainage (ES-SAGD). Characterization of bitumen and phase behaviour study of solvent/bitumen systems are the initial steps towards an optimized and successful solvent-aided bitumen recovery process. In this study, Athabasca bitumen is experimentally fractionated to four cuts using modified vacuum distillation and then each cut is characterized. The phase behaviour data including solubility, density, and viscosity of propane/bitumen cuts are measured in wide ranges of temperature and pressure. Using the measured solubility data of propane/bitumen cuts, the PR-EoS is tuned and a binary interaction parameter correlation between propane and bitumen components is developed. The bitumen is then characterized using the boiling point or carbon number distribution obtained by Simulated Distillation test (ASTM D7169). The generalized model is then implemented to calculate the propane solubility in two bitumen samples from different reservoirs (Athabasca and Cold Lake). Our proposed model in this paper, predicted the propane solubility in Athabasca bitumen sample with an average deviation of 1.8 mol.% without using any experimental data of propane/bitumen system or tuning parameter. The proposed model was also evaluated by predicting the propane solubility in Cold Lake bitumen. The propane solubility in Cold Lake bitumen was calculated with an average deviation of 3.0 mol.%, which shows the generality of the proposed model.