Gas kick represents one of the primary hazards during oil and gas drilling operations. If not properly handled, it can pose serious threats to both engineer safety and the surrounding environment. To facilitate accurate and early control of gas kicks in ultra-deep wells, a gas–liquid two-phase flow model for managed pressure drilling (MPD) was developed based on the drift flux model, incorporating the effects of ultra-high temperature and pressure on the rheology and density of drilling fluids. The model's accuracy was validated using field data from gas kick handling operations. It was subsequently used to simulate the entire micro-gas kick handling process in MPD, examining the influence of pump rate, drilling fluid density, formation pressure, and borehole diameter on wellhead backpressure regulation and mud pit gain. A control chart for wellhead backpressure during micro-gas kick handling in MPD was established. The findings reveal that during micro-gas kick handling, variations in wellhead backpressure and mud pit gain exhibit synchronized peaks as the gas front reaches the wellhead. Higher pump rates, increased fluid density, and larger borehole diameters are associated with lower peak wellhead backpressure. Moderately increasing the pump rate can delay the mud pit gain from reaching the warning threshold, thereby reducing the risk associated with gas kick handling. Pump rate and drilling fluid density emerge as critical parameters influencing the control range of wellhead backpressure during MPD-based micro-gas kick handling and thus require precise real-time monitoring. These insights provide valuable operational guidance for maintaining wellbore flow safety in ultra-deep drilling and contribute significantly to protecting both personnel and the environment.
Zhang et al. (Tue,) studied this question.