Precise detection technology of formation pressure while drilling in BZ19-6 structure of Bozhong sag

In order to ensure the drilling safety in BZ19-6 Block in the process of exploration and development and avoid the problems induced by the low prediction accuracy of formation pressure before drilling, the formation pressure monitoring while drilling technology was studied and applied.Based on d_c index method and Enton method, real-time drilling performance and on-site mud logging data were linked remotely by using Drillworks software.Furthermore, the optimized calculation model was embedded into the software.And trend line (slope, intercept) and Enton index multiple regression, phased correction, comprehensive gas logging correction were adopted.In this way, 9 wells (drilling depth exceeding 4 000 m) in BZ19-6 Block are monitored successfully.It is shown that the accuracy of pressure monitoring while drilling is over 97% referring to the pressure calculated by means of the post-drilling interval transit time and the pressure measured in some wells.It is revealed that this method can be used to monitor effectively the starting point and the highest pressure point of abnormal formation pressure induced by undercompaction, e.g.BZ19-6 Block.In conclusion, this method can be popularized and applied to the formation pressure monitoring of undercompacted strata.