Method for predicting pore pressure of whole well interval in slope zone in Yinggehai Basin

In order to explore the method for predicting pore pressure with multiple sources and multiple mechanisms, and to accurately predict the pore pressure of the whole well interval in the slope zone of the Yinggehai Basin, by comprehensively considering the evolution process of regional sedimentary structure and the response characteristics of logging data, the cause of abnormally high pressure in each interval was clarified. For formations with conventional high-pressure mechanisms, the models for predicting pore pressure in different intervals were optimally screened. For formations with complex genesis, a new method for accurately predicting pore pressure was studied. The research shows that the abnormally high pressure in the upper intervals of the Ying 1-Ying 2 member is caused by under-compaction, where the pore pressure can be predicted by the Eaton method. The cause of the abnormal high pressure in the lower intervals of the Ying 2 member is that, under-compaction primarily, supplemented with fluid expansion, where the pore pressure can be predicted with the Bowers loading method. The cause of the abnormal high pressure in the Huang 1 member is that, fluid expansion primarily and supplemented with under compaction, where the pore pressure can be predicted with the Bowers unloading method. The causes of the abnormal high pressure in the Huang 2 member are complex, which is a combined pattern composed of overpressure transmission+fluid expansion primarily, supplemented with under compaction, and aiming at this special cause, a new multivariable pore pressure prediction model was proposed. Comparing the prediction results with the measured pore pressure data, the prediction accuracy of the whole well interval is up to 97%, which can meet the engineering requirements. The research results can provide a basis and guidance for drilling design and construction in the slope zone of Yinggehai Basin.