A gas kick may occur when drilling with a narrow pressure margin, leading to potential dangers and significant non-productive time. With the help of Managed Pressure Drilling (MPD) and accurate simulations of wellbore two-phase flow dynamics, it is possible to enhance the security and efficiency of gas kick handling. To obtain a high degree of simulation accuracy, wellbore state parameters and model coefficients must maintain correct. An Extended Kalman Filter (EKF) is used as a Data Assimilation method for updating multi-dimensional flowing parameters and calibrating two-phase flow models in real-time.Data from a full-scale experimental well is used in this study. Gas kick in a water-based mud system is replicated in the experiments. Multi-dimensional state parameters of the wellbore annulus including pressures, flowrates, and volume fractions are estimated using the Drift Flux model (DFM). By applying the EKF, real-time multi-depth pressure measurements are used to update the model estimations as well as the system uncertainties, including measurement uncertainty and model imperfections. The DFM slip coefficients and frictional factors are calibrated in real-time during this process. Experiments with different sizes of gas influx and flow rates were performed to test the performance of this methodology.The surface and bottom-hole pressure measurements in the experimental well are used for validation of both the DFM and the EKF. Simulation results from an individual DFM (without data assimilation) and a DFM based data assimilation method using only single depth measurement are also compared to analyze the simulation accuracy. Results show that by taking into account real-time measurements, the filtered estimation results to flowing parameters are more accurate than the DFM only. Meanwhile, compared to the data assimilation method with single-dimensional estimation, the EKF with multi-depth measurements gives better accuracy in estimating kick size and downhole kick positions.In this study, the EKF is first used as a data assimilation method to estimate wellbore flow dynamics at multiple depths instead of only at the surface of the bottom. Benefits of this work are seen by better estimation of gas kick migration behaviors when downhole measurements are available, which are of great importance for MPD based dynamic well control.

On Gas Kick Simulation: Multi-Dimensional Wellbore State Estimation and Real-Time Model Calibration Using Extended Kalman Filter

Paper Proceedings: https://asmedigitalcollection.asme.org/OMAE/OMAE2021/volume/85116

OMAE 2021

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