A Critical Analysis of Hydrodynamic Models in 1D Multiphase Methods: An Assessment of Transient Solutions in LedaFlow

Summary The oil and gas industry is strongly interested in the numerical solution of transient multiphase flows in pipelines. Transient processes are often present in operational procedures, and their effects on the production systems are frequently predicted numerically. 1D commercial simulators are used to better design, monitor, and define any intervention protocol in oil production systems. This study assesses the transient accuracy of two 1D modeling strategies available in commercial software, benchmarked against two experimental data sets, and 1D hydrodynamic modeling for problems in which thermodynamic modeling can be neglected. A comparison of two simulation approaches [regime capturing (RC) and unit cell model (UCM)] is presented in the prediction of horizontal slug flow. A filtering and averaging methodology is used to enable a consistent comparison between the two modeling approaches, improving the reliability of transient predictions in hydrodynamic slugging problems. Accuracy and stability considerations regarding transient 1D multiphase modeling are discussed based on how well-posed is the problem and the lack of transient friction factor models. The commercial simulator successfully predicted the initial steady-state experimental data but failed to model transient phenomenon in part of the selected experimental benchmarks. Nonphysical solutions are evaluated based on theoretical convergence criteria and experimental data.