Dynamic behavior of single drop and critical single drop carrying gas flow rate under the well condition of gas well

One of the important study contents on the continuous liquid carrying mechanism of gas well is to accurately understand the dynamic behaviors of single drop in the annular flow under the well conditions of gas well and correctly calculate the critical drop carrying gas flow rate. In order to deeply research the dynamic behaviors of drop under the high temperature and high pressure conditions in the well of gas well, this paper firstly established a numerical model of dynamic behavior of single drop in the gas flow field and its solution method. In addition, a numerical simulation solver of dynamic behavior of single drop was developed by using the volume of fluid method (VOF) to simulate the surface structure of drop and the direct numerical simulation method (DNS) to simulate the gas flow field around the drop. Then, taking the pressure and temperature of gas well as the simulation condition, simulation was carried out by increasing the gas flow rate gradually to increase the Weber number. It is shown that the drop ellipsoidity decreases and the drag coefficient increases with the increase of Weber number, and the critical Weber number of drop breakup is 12. Finally, a new model for the prediction of critical single drop carrying gas flow rate was deduced based on numerical simulation results and force balance principle. The composite coefficient of this new model is 3.31, which is closer to that of Li Min’s ellipsoid model, i.e., 2.5. The adaptability evaluation on existing single drop models by using published literatures and data indicates that under the gas well condition of low liquid rate (1 m³/d), the drops in the well are scattered and interact weakly and the new model and the Li Min’s ellipsoid model have higher accuracy.