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The Tertiary strata in the Bohai Bay basin consist of the Lower Tertiary sequence deposited at the rift stage and the Upper Tertiary sequence deposited at the post-rift stage. The Lower Tertiary sequence is composed of the three second-order sequences Ek, Es4-3, and Es2-Ed. Every second-order sequence corresponding to one rifting episode can be divided into the lowstand, transgressive, and highstand third-order sequence sets, which are represented as sedimentary products of the initial rifting, lacustrine expanding and contracting stages. The late transgressive and early highstand sequence sets are favorable periods for forming regional source and seal rocks. Three sets of major source and seal rocks and four sets of source-reservoir-seal combinations are recognized in the Tertiary strata. Differences of Tertiary tectonic history in different sags or depressions result in differences of developing periods and features of source-reservoir-seal combinations.
The Tertiary strata in the Bohai Bay basin consists of the Lower Tertiary sequence deposited at the rift stage and the Upper Tertiary sequence deposited at the post-rift stage. The Lower Tertiary sequence is composed of the three second-order sequences Ek, Es4-3 , and Es2-Ed. Every second-order sequence corresponding to one rifting episode can be divided into lowstand, transgressive, and highstand third-order sequence sets, which are represented as sedimentary products of the initial rifting, lacustrine expanding and contracting stages. The late transgressive and early highstand sequence sets are favorable periods for forming regional source and seal rocks. Three sets of major source and seal rocks and four sets of source-reservoir-seal combinations are recognized in the Tertiary strata. Differences of Tertiary tectonic history in different sags or depressions result in differences of developing periods and features of source-reservoir-seal combinations.