Prediction of pressure distribution and formation mechanism in low exploration area: A case study of Xihu Depression, East China Sea Basin

The distribution of pressure was predicted in Xihu Depression, East China Sea Basin by combining with the existing measured drilling pressure, log data analysis results and seismic velocity spectrum geophysical data. The results show that there are two sets of pressure systems, normal pressure system and overpressure system in Xihu Depression. The overpressure is mainly developed in Huagang Formation and Pinghu Formation, and the formation gradually changes younger from west to east. Mudstone is also characterized by shallow atmospheric pressure and deep overpressure, but varies in different zones. The interface of overpressure is mainly located in the lower part of Huagang Formation and the upper part of Pinghu Formation. The characteristics of the interface distribution of the overpressure are mainly controlled by the formation, and the depth has little effect on the distribution of the interface. The overpressure zone of the key interface covers a good continuity and has a certain regional distribution direction. There are obvious differences in large scale faults, which play a certain role in transporting, dividing and destroying the accumulation of pressure. Under-compaction and hydrocarbon generation are the main factors that produce overpressure in Xihu Depression, but there are great differences in different areas.