According to abnormal pressure fluid compartments or expulsion fluid assemblages

a basin can be divided into many accumulating dynamic systems.There are 6 accumulating dynamic systems in Bohai Bay Basin by expulsion expulsion fluid assemblages and 3 accumulating dynamic systems in Yinggehai Basin by abnormal pressured compartrment.The classification of accumulating systems is various according to different criteria

that is:normal pressure

overpressure and low pressure by distribution of fluid pressure systems;external source

internal source and compound source systems by oil source;and open

closed and semi closed systems by sealing condition.Hydrocarbon migrates mainly within particular dynamic systems

and the basic migration model of cross systems is periodic migration along large faults and fluid diapirs.The structural zones associated with large faults and fluid diapirs are favorable to form complex oil and gas zones of multiple accumulating dynamic systems.