The reservoiring period has traditionally been analyzed from the matching of source rock

reservoir rock

cap rock

migration

accumulation and preservation parameters

on the basis of trap formation history

hydrocarbon generating history of source rocks and dew point pressure method.Considering that most of the petroliferous basins in China are superimposed basins

which are characterized by multiple source rocks

multi-stage hydrocarbon generation

accumulation and destruction

fluid history analysis method was introduced in late 1990s.Utilization of several new methods

such as reservoir geochemistry

fluid inclusion

illite K-Ar dating

reservoir bitumen and tracing of oilgas-water contacts

has converted the traditional qualitative(period determining)study to quantitative or senti-quantitative study

thus the formation time of pools can be relatively accurately calculated.In view of the complexity of the formation of reservoirs in superimposed basins

attentions should still be paid to basic geologic studies.Traditional methods

such as trap formation period and hydrocarbon generating history

are the basis of application of new technologies.Future trends of reservoiring period studies are combining geochemistry method with geologic setting study

traditional method with new methods

and qualitative method with quantitative method.