Wellhead backpressure control strategies and outflow response characteristics for gas kick during managed pressure drilling

摘要

This study proposes a transient gas-liquid-solid multiphase flow model for gas kick during MPD, considering the effect of dynamic wellhead back-pressure, temperature field, and velocity relation of different phases. Based on this model, the gas kick control strategies and outflow response characteristics during MPD are thoroughly investigated. The simulated results reveal that, with the upward migration and expansion of the invading gas, the hydrostatic pressure and frictional pressure in the annulus changes accordingly, resulting in a non-linear relationship between the wellbore back-pressure and the bottom-hole pressure. Moreover, the effects of an underbalance pressure at the bottom hole, the pressure balance relationship between the formation and the bottom hole, the kick detection level, the well depth on the wellhead back-pressure control and the response behaviors of the outlet flow rate are discussed. The results of this investigation can provide engineering guidance for MPD to address the issue of gas kick.