Regional sedimentary pattern and its exploration significance in early stage of lower member of Minghuazhen Formation in Bohai Sea
Neogene is an important layer for reserve and production increase in the Bohai Sea.However,due to the lack of systematic research on regional sedimentary systems,the development laws of large-scale sand bodies and exploration directions of lithology remain unclear.The early stage of the lower member of the Minghuazhen Formation was studied in this paper,and key issues were addressed,such as high-precision stratigraphic framework,river-lake distribution patterns,distribution characteristics of the sedimentary system,and forming mechanism of large-scale sand bodies.An internal"paleoclimate cycle-based"regional isochronous sequence framework in the lower member of the Minghuazhen Formation was established,laying a foundation for sedimentary system research under high-frequency phase changes.The regional sedimentary environment pattern during the basin contraction period,which was characterized by"dominant plains with associated lakes",was clarified.A regional sedimentary pattern with"dominant river facies and interacted local rivers and lakes"was developed.In addition,three sedimentary development models including stable meandering rivers,migrating meandering rivers,and river-lake interaction were built.The forming mechanism and distribution laws of different types of large-scale sand bodies were explored.These new insights provided theoretical support for the discovery of a series of medium and large oilfields of the Neogene and played an important role in guiding the future lithological exploration of the Neogene in Bohai Sea.
Bohai Sealower member of Minghuazhen Formationsedimentary environmentsedimentary patternmeandering riverriver-lake interaction
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