The Multiphase Flow Dynamic Simulator Application for Optimization for Well Performance

Abstract Multiphase flow modeling in wells is an important component of oil and gas field development, where accurate prediction of fluid dynamics in transient regimes directly affects production efficiency and operational safety. This paper presents Flow Simulator 1D (FS1D), a one-dimensional drift-flux-based numerical simulator designed for dynamic modeling of multiphase flow in wells and pipes. The simulator solves problems associated with unsteady multiphase behavior by solving the equations of conservation of mass, momentum and energy in a fully implicit formulation, allowing multiphase flows to be modeled under various flow regimes and well inclinations. FS1D integrates pre- and post-processing into a single platform and supports complex boundary conditions, inflow modeling, reservoir heat transfer, and modeling of various equipment such as electric submersible pumps (ESPs) and chokes. The use of a drift-flux flow model improves computational efficiency while maintaining the necessary accuracy for engineering analysis, especially in evaluating flow distribution, pressure drops, phase segregation, and thermal effects. The simulator has been validated on synthetic cases that reproduce field scenarios including transient flow dynamics, gas entry, gravity segregation, and non-isothermal flow behavior. FS1D's modular architecture and restart capabilities also make it a powerful tool for creating synthetic datasets and supporting digital oilfield applications.