| Abstract
| - Vapor pressures, critical constants, and the acentric factor are generally used in thermodynamic correlations based on corresponding states to perform phase equilibrium and physical property calculations. These thermophysical properties cannot be measured for heavy hydrocarbons due to thermal decomposition at temperatures far below the critical point. An integrated method is described for predicting the critical constants as well as the vapor pressures over a broad range of temperatures, and it is the first step for the development of a comprehensive methodology for the characterization and simulation of heavy oil and bitumen systems. The method applies perturbation theory using n-paraffins as a reference system and correlates departures of the heavy hydrocarbons from paraffinic behavior. The critical constants and vapor pressures of heavy hydrocarbons were correlated as a function of only their molecular weight and specific gravity at 15.6 °C. The molecular weights ranged from 28.05 to 695.30 g/gmol, while the specific gravities ranged from 0.4327 to 1.4154. For the hydrocarbons used in this study, the predicted critical constants and vapor pressures showed a significant improvement over previously published correlations. The experimental critical temperatures and critical pressures were reproduced closely with an average absolute percentage deviation of 2 and 8%, respectively. The resultant vapor pressure equation fit the available vapor pressure data with an average absolute deviation of 17% between reduced temperatures of 0.37 and 0.95.
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