Journal of Engineering Research and Reports

The transient dynamics of three-phase separators play a critical role in upstream oil and gas production facilities. However, conventional steady-state design methodologies rarely account for time-dependent operational effects with sufficient rigor.. In this study, a dynamic simulation framework for a horizontal three-phase separator was developed and evaluated using Aspen HYSYS Dynamics to investigate time-dependent separation behaviour under realistic operating disturbances. The model integrates mass, momentum, and energy balances with thermodynamically consistent phase equilibrium calculations and embedded process control logic. The separator performance was analysed using field operating data comprising a total inlet molar flow rate of 21.15 kmol·h⁻¹, separator pressure of 350 kPa, feed temperature of 337.65 K, gas mole fraction of 0.41, oil mole fraction of 0.44, water mole. The deviation between the field data and the simulated results were gas outlet rate (1.4 %), oil out rate (1.6 %), water outlet rate (1.5 %), separator pressure (0.2 %), and total liquid level (1.4 %). The low deviations confirms that the dynamic model reliably reproduces vapor–liquid–liquid phase separation behaviour, gravitational separation efficiency, controller interaction with separator inventories, and steady operational throughput under realistic field conditions. The results further indicate that separator efficiency and operational stability are governed by coupled thermodynamic and hydraulic interactions that can only be fully resolved through dynamic modelling. The developed framework therefore provides a robust basis for operational optimization, control strategy development, and design support for upstream oil and gas production facilities.