Managed Pressure Drilling (MPD) usage have shown increasing demand in both offshore and onshore market especially for wells with narrow drilling margins. MPD due to its inherent ability to maintain desired constant bottom-hole pressure (BHP) is a clear choice when mitigating gas influx while drilling thus increasing safety and reducing non-productive time.

MPD removes pore / fracture pressure uncertainties by measuring the drilling window on real time. An enhanced hydraulics modeling that accounts for change in downhole conditions such as temperature, compressibility is key component for successful MPD operations to alter the surface back pressure (SBP) to maintain desired BHP. Aside from enhanced hydraulics model for BHP estimation, an accurate prediction of the gas influx propagation from the bit to the surface is critical for managing BHP dynamically while circulating influx out of annulus.

This work underscores development and usage of advanced multi-phase model to simulate gas influx transport and its effects on BHP during MPD operations. This work elucidates recent advances in the gas influx modeling, specifically single bubble model and kinematic two-phase model formulations are discussed in detail. The results of the single bubble model and two-phase model are compared using industry accepted software during gas influx control and circulation out of the well.

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