Modeling and Control of Three-Phase Gravilty Separators in Oil Production Facilities

Oil production facilities exhibit complex and challenging dynamic behavior. A dynamic mathematical modeling study was done to address the tasks of design, control and optimization of such facilities. The focus of this paper is on the three-phase separator, where each phase's dynamics are modeled. The hydrodynamics of liquid-liquid separation are modeled based on the American Petroleum Institute design criteria. Given some simplifying assumptions, the oil and gas phases' dynamic behaviors are modeled assuming vapor-liquid phase equilibrium at the oil surface. In order to validate the developed mathematical model, an oil production facility simulation was designed and implemented based on such models. The simulation model consists of a two-phase separator followed by a three-phase separator. An upset in the oil component of the incoming oil-well stream is introduced to analyze its effect of the different process variables and produced oil quality. The simulation results demonstrate the sophistication of the model in spite of its simplicity.