Supercritical fluid extraction of oil sand bitumen

The supercritical fluid extraction of bitumen from the PR Spring oil sand deposit (Utah) was studied using commercial propane as the solvent . The bitumen volatility was 36.3 wt % and its asphaltene content was 19.3 wt %. Experiments were performed at five different operating conditions which included three pressures (5.6 MPa, 10.4 MPa and 17.2 MPa) and temperatures (339 K, 3X0 K and 422 K). The extracted phase yield increased as the extraction pressure increased at constant temperature. This effect was directly related to the increase in the pure solvent density with pressure. It was also observed that at higher extraction pressures, relatively heavier hydrocarbons were extracted. The asphaltene content of the residual fraction was compared with the asphaltene content of the bitumen and was observed to be higher, even on an absolute weight basis. The extraction process was modeled using the Peng-Robinson cubic equation of state and Lee-Kesler pseudocomponent characterization correlations. The experimental extraction results were in reasonable agreement with the predicted phase compositions based on a flash calculation using seven pseudocomponents.