Effect of flow patterns and velocity field on oil-water two-phase flow rate in horizontal wells

In a wellbore, any change in flow rate will result in a change in flow pattern and velocity. The flow pattern and velocity are the key parameters that determine the pressure gradient and liquid holdup. To study the effect of the flow pattern and velocity field on the flow rate of oil-water flow in horizontal wells, we apply the commercial software package ANSYS Fluent 2020 R2 to predict the flow patterns, water holdups, pressure gradients, flow rates, and velocity fields of horizontal wells. Trallero’s flow pattern chart and existing experimental data are used to verify the reliability of the model. We develop a simplified mathematical model of water holdup and compare it with existing models. This mathematical model may be limited to the range of fluid properties in the simulated method. The water holdup of the numerical simulation has a definite correlation with the experimental data. By comparing the numerical simulation results of the Nicolas model, the relationship between the slip velocity and water holdup is verified, and the reliability of the simulation results is verified. The simulation results demonstrate that the change in flow pattern is highly sensitive to the change in flow rate. When the flow pattern is stratified flow, the relative error of the simulated flow is small. When the flow pattern is dispersed flow, the relative error of the simulated flow is slightly larger. The oil is mainly concentrated in the high-velocity core area. At a higher total mixing velocity, the flow pattern is that of dispersed flow, with one phase uniformly mixed in the other phase. The simulation results have good qualitative and quantitative agreement with the experimental results.