High-Resolution Upwind Numerical Modeling of One-Dimensional Gas-Liquid Two-Phase Drift in Wellbore Transients

As reservoir geological conditions in China's oil and gas exploration and development become increasingly complex, drilling operations exhibit narrower safety margins. Drilling risks such as blowouts and losses are more likely to occur, leading to complex flow patterns within the wellbore. Accurately capturing the gas-liquid interface position is crucial for the precise determination of multiphase flow parameters during gas invasion. In this study, we address transient multiphase flow within wellbores and propose a high-resolution upwind numerical method based on the AUSMV scheme and the MC limiter. This method employs the drift-flux equation, AUSMV scheme, third-order Runge-Kutta discretization, and the MC limiter. The reliability of the numerical scheme is validated through typical cases of variable-density gas-liquid two-phase flow, demonstrating that its numerical accuracy is consistent with that of the Roe approximate Riemann solver. Furthermore, a 3500 m straight well is simulated for gas invasion, and the numerical simulations of gas-liquid two-phase flow during wellbore gas invasion show that the use of the third-order high-precision AUSMV scheme can accurately capture the gas-liquid interface during gas invasion, significantly improving the accuracy of multiphase flow parameter calculations during gas invasion in comparison to the traditional first-order AUSMV scheme. This research provides important technical guidance for the development of oil and gas resources and well control safety.