The testing results of fluid inclusion indicate that there were three charging stages of the oil and gas reservoirs in the eastern sag of Liaohe basin. The early stage (36 Ma) is equivalent to the deposition of the first member of Shahejie Formation to early Dongying; the middle stage (24～24 Ma) is corresponding to middle-late Dongying; and the late stage corresponds to Neogene up to the present time. The episodic and multiphase charging result in the heterogeneity of fluid properties both laterally and vertically.The deep crude in Oulituozi area has lower maturity than that in the shallow part

that is a phenomenon of reversed maturity. However

the crude maturity in the higher part of high horst zone in Ciyutuo area is higher than that in the relatively low position in Niuqing area. It is then suggested that exploration activity might be launched to enhance success ratio by using this feature.