CHARACTERISTICS AND EVOLUTIONARY HISTORY OF OVERPRESSURE IN PANYU 4 SAG,PEARL RIVER MOUTH BASIN

Overpressure,which is closely related to the generation,migration and preservation of hydrocarbon,plays an important role in petroleum accumulation dynamics.This paper confirms the existence of overpressure in the Panyu 4sag,Pearl River Mouth Basin based on logging,drilling,geological and geochemical data,discusses its forming mechanism,divides the area of overpressure,and reconstructs pressure evolution process in a two-dimensional framework.It suggests that overpressure,which is mainly controlled by lithology,exists widely in Panyu 4sag.Its forming mechanism includes both hydrocarbon generation and the compaction disequilibrium.The history of pressure evolution is complex.Overpressure in Wenchang Formation includes two stages:the eaily stage is due to compaction disequilibrium,and the later stage is related to hydrocarbon generation since 15Ma.