Dynamic Simulator for Three-Phase Gravity Separators in Oil Production Facilities.

In this study, a dynamic simulator for three-phase gravity separators in oil production facilities is proposed. The mass conservation equation is established to calculate the pressure, water level, and oil level in the separator and the mass balance equation of the dispersed phase to calculate the oil-water separation efficiency. The proportional integral controllers are applied to control the water level, oil level, and pressure in the separator by setting the opening of the three outlet valves of oil, gas, and water. The model is verified using field data by means of the given valve opening and given proportional integral controller parameters, respectively. Subsequently, the verified simulator is applied to study the dynamic behavior of the separator filling process and the effect of pressure, oil level, and water level setpoint changes on the separator operating status. A detailed analysis of the changes in the liquid level, pressure, and opening of three outlet valves is presented. Then, the effects of operating conditions such as the inlet flow, water setpoint, and weir height on the separation efficiency are discussed. This simulator can be applied for the design of oil, gas, and water three-phase separation processes. In addition, through this simulator, the parameters that are difficult to be measured by instruments during the operation of the separator can be calculated, providing technical support for the construction of the digital twin of the separator.