Evolution of fluvial pattern and analysis of dominated factors in the Paleogene Yabus Formation of Palogue Oilfield in Melut Basin,South Sudan
Jin Jian-Li1, 2, Huang Qi-Zhi1, Zhao Guo-Liang1, Li Sheng-Li3, Zhang Jin-Lin1, Li Xian-Bing1, Zhang Yu-Pan4
1 Research Institute of Petroleum Exploration & Development,PetroChina,Beijing 100083; 2 China National Oil-Gas Exploration & Development Corporation,Beijing 100034; 3 School of Energy Resources,China University of Geosciences(Beijing),Beijing 100083; 4 China Huayou Group Corporation,Beijing 100101;
Abstract：Unique braided-meandering depositional systems were developed in the Yabus Formation of Palogue Oilfield. The vertical lithofacies sequences of braided and meandering rivers were thoroughly summarized by quantitative statistics and dynamic cause analysis method with introducing the variable index of microfacies sandbody. The differentiated depositional processes and fluvial pattern transformation between the braided and meandering rivers were elaborated from the perspective of spatial evolution. Subsequently,depositional models of the fluvial pattern transformation in different stages under the individual provenance system were established and the dominated factors were further clarified. The study indicates that evolution of the fluvial depositional system in the Yabus Formation experienced three stages. During the early stage,the braided river deposition were dereloped and the downstream accreting longitudinal bars were formed. In the middle stage,there was combined deposition between braided and meandering rivers with significant decrease of fluvial incision. Because of the lateral accretion,the diagonal bars were generated and the braided channel bars migrated to river bank to which transformed into meandering point bars. Eventually,it completely became meandering river with high sinuosity and small-scale depositional sandbody.
Jin Jian-Li,Huang Qi-Zhi,Zhao Guo-Liang et al. Evolution of fluvial pattern and analysis of dominated factors in the Paleogene Yabus Formation of Palogue Oilfield in Melut Basin,South Sudan[J]. JOPC, 2018, 20(6): 951-962.
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