A generalized model is presented to calculate the k-values of methane/bitumen, ethane/bitumen, propane/bitumen, and butane/bitumen systems. These data are required for phase behaviour modeling and simulation of solvent-aided bitumen recovery processes. The proposed model is evaluated by comparing the calculated results with the measured experimental k-values.
The proposed model provides generalized binary interaction parameters between each hydrocarbon solvent (methane, ethane, propane, and butane) and the defined components in bitumen and calculates the k-values of solvent/bitumen systems. Unlike the existing common approaches, experimental solubility data are not required to tune the model. The boiling point or carbon number distribution of bitumen or heavy oil obtained by simulated distillation (SimDist) test is the only required data to characterize and define the components of heavy oil or bitumen. The SimDist test is a very fast test and much less expensive than the common solubility measurements.
This model has been developed based on the experimental fractionation of bitumen. The Athabasca bitumen was experimentally fractioned to four bitumen cuts applying vacuum distillation method and the solubility of solvent in each bitumen cut were measured at wide ranges of temperature and pressure. The measured solubility data of methane, ethane, propane, and butane in each bitumen cut have been used to tune the PR-EoS and the generalized binary interaction parameter coefficients for each solvent and bitumen components have been found. To calculate the k-values of solvent/bitumen mixtures, the bitumen is defined as a mixture of n-alkanes based on simulated distillation results. The properties of n-alkanes have been assumed for each component. Employing the obtained binary interaction parameters in PR-EoS using experimental data of solvent/bitumen cut systems and considering the defined bitumen components as input to the proposed model, the k-values of solvent and any bitumen or heavy oil mixtures are calculated. The validity of the proposed model has been confirmed by calculating the k-values of methane, ethane, propane, and butane with two different bitumen samples with an average deviation of less than 3.0 %.
The proposed model predicts the k-values of methane/bitumen, ethane/bitumen, propane/bitumen, and butane/bitumen mixtures without requiring the time and cost intensive experimental PVT data for tuning. Providing the simulated distillation results of any bitumen or heavy oil samples, the k-values of hydrocarbon solvent/bitumen or heavy oil can be calculated in wide ranges of temperature and pressure. The outputs of this model can be directly used as k-values in simulation of solvent-aided thermal recovery processes.