Bayes theory based credibility containing pore pressure correction method while drilling

Formation pressure prediction and monitoring has always been one important task of oil and gas well drilling, and accurate formation pressure prediction is the important prerequisite to ensure the smooth and safe process from design to construction. Pre-drilling formation pressure prediction method is to predict the formation pressure by using the seismic data, but its prediction accuracy is low and there is a larger error between the predicted pore pressure and the actual bottom hole pressure. In order to update the prediction results of pore pressure dynamically according to the measurement data while drilling and reduce its uncertainty further, this paper put forward the Bayes theory based credibility containing pore pressure correction method while drilling. Posterior probability information of pore pressure includes the pre-drilling pore pressure prediction information and the pore pressure monitoring information while drilling. Based on pre-drilling prediction, combined with while drilling data, pore pressure is corrected and upgraded to ensure the prediction accuracy of local pore pressure at the position of drilling bit in the process of drilling as high as possible. The research results provide the real-time accurate pore pressure for the dynamic risk evaluation in the process of drilling operation, assist drilling operators to make decision on the construction scheme fast and accurately and reduce the drilling risks caused by inaccurate pressure information.