Differential transgression of rift basin and characteristic response of sedimentary system within sequence framework: An example from the Paleogene Shahejie Formation in Baxian sag,Bohai Bay Basin |
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| Authors: | Zhang Zi-Li Zhu Xiao-Min Li Qi Zhang Rui-Feng Geng Rong-Yan Cao Lan-Zhu Shi Rui-Sheng |
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| Institution: | 1.College of Geosciences, China University of Petroleum(Beijing),Beijing 102249,China;2.State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing 102249,China;3.School of Ocean Sciences, China University of Geosciences(Beijing),Beijing 100083,China;4.PetroChina Huabei Oilfield Company,Hebei Renqiu 062552,China |
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| Abstract: | Multi-stage differential transgression controls sequence architecture and its sedimentary type and distribution during the tectonic evolution of lacustrine rift basin. Combined with the seismic data of the Baxian sag as well as drilling,logging,core and paleontological materials from 800 exploration wells,the study targeted the Members 1 and 3 of the Shahejie Formation to analyze sequence architecture and sedimentological difference within the sequence framework during the differential lake transgression,based on the investigation of the Paleogene lake basin evolution. The results showed that the fault slope-break slope architecture was well developed with back-stepping deltas and fan deltas during the slow lake transgression of the Member 3 of Shahejie Formation,in which forms thick high quality source rocks. The flexural-gentle slope architecture was well developed with mixed beach bar and small scale nearshore subaqueous fans(fan deltas)during the rapid transgression of the Member 1 of Shahejie Formation. The differential subsidence controlled the sequence architecture,paleogeomorphology and provenance supply,regulating the spatial lithological distribution. And there are significant differences in sequence architecture and sedimentary system during the different evolution stages of the lake basin. On this basis,the response model of sedimentary system characteristics under differential lacustrine transgression is established,which can be used for reference for oil and gas exploration,especially for lithologic oil and gas reservoir in the same type of basin. |
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| Keywords: | Baxian sag Paleogene rift basin sequence architecture sedimentary system differential lake transgression |
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