Multiphase Flow Behaviors and Wellhead Backpressure Responses During Managed Pressure Drilling Well Control Considering Gas Dissolution

The managed pressure drilling dynamic control (MPDDC) technology of has the advantages of short control time and no need to shut in the well to deal with the gas influx problem. Based on drift flow model and transient solubility calculation model of gas in oil-based drilling fluid, a multi-phase flow model of MPDDC is established. The accuracy and reliability of the model were verified based on the experimental data of gas kick in oil-based drilling fluid. The simulation results show that the change of wellhead back pressure and bottom hole pressure during MPDDC can be divided into three stages with the upward migration of intrusive gas. The multiphase flow behavior and pressure response characteristics of gas dissolution, wellbore heat transfer and kill rate on dynamic well control of managed pressure drilling are discussed and analyzed. Increase drilling fluid displacement (wellhead back pressure, pit gain) during MPDDC. Faster gas kick can be controlled, helping to reduce maximum wellhead back pressure and maximum pit gain. The research results are helpful to improve the calculation accuracy of wellhead back pressure in well control process and provide engineering guidance for MPDDC technology.