Thermodynamic Evaluation of Crude Oil Using ASTM Characterization and Aspen HYSYS Simulation

Accurate characterization of crude oil fractions is critical for optimizing refining strategies and ensuring efficient utilization of petroleum resources. This study systematically investigates the physical and thermodynamic properties of Hasera crude oil, focusing on its molecular composition, phase behavior, and energy storage capabilities. The crude oil exhibits an API gravity of 42 and undergoes fractionation into seven distinct boiling ranges, with ASTM and Sybolt color values indicating variations in hydrocarbon distribution. The ASPEN HYSYS simulation provides detailed insights into surface tension, viscosity index (VI), and heat capacity (Cp), revealing significant trends across different fractions. Surface tension increases from 15.69 dyne/cm in light fractions to 35.36 dyne/cm in heavy fractions, correlating with stronger intermolecular forces. The VI transitions from negative values in volatile fractions to 26.40 in the heaviest fraction, reflecting increased temperature-dependent viscosity variations. Cp values progressively rise from 177.4 J/mol·K in the light fractions to 448.6 J/mol·K in the middle fractions, before slightly decreasing in the heavier fractions due to molecular condensation effects. Similarly, the heat capacity ratio (Cp/Cv) declines, indicating a shift from highly compressible light hydrocarbons to denser, thermally stable fractions. These findings provide a comprehensive thermodynamic framework for refining Hasera crude oil, aiding process optimization and product formulation. Understanding the thermophysical behavior of each fraction enhances refining efficiency and supports sustainable petroleum utilization strategies.