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Architecture Analysis of Underwater Distributary Channels—A Case Study of S2L4 in Wen 79 Southern Block


Chen Le1, Yin Taiju1, Liu Ying1, Xiong Yunbin2, Liu Yunjun2 1: School of Geosciences, Yangtze University, Wuhan, Hubei 430100, China; 2: Exploration and Development Research Institute of Zhongyuan oil field, He'nan, Puyang, 457000, China The Wen 79 block is located in the Southern Wenliu structure, the central uplift belt in Dongpu depression. The formation is relatively complete and the fracture is not developed, therefore the distribution of reservoir deposition has a significant influence on remaining oil. The sand body distribution is relatively limited in this block and the lens shaped sand body is more developed which result in the sand body'fast variation and the complex internal structure. It is necessary to utilize the reservoir structure analysis technology to carry out the research on the internal structure of the reservoir sand body. The internal configuration and distribution characteristics of single channel sand bodies are not very clear in the previous studies of sedimentary facies. In the study, the reservoir structure analysis technology was used to research the main reservoir of Lower Member of Es2 reservoir in the block. Based on core observation, we used geological, logging and production data to predict the spatial distribution of composite sandbody and did a further analysis of the evolution of single channel sandbody. Based on the overlapping relation of the sedimentary process of the river's swing, migration, procreation and diversion, the spatial distribution of sandbody was rebuilt and the internal structure model was constructed. The dynamic data were used to verify the remaining oil enrichment area. The analysis in the study is different from the traditional structural ones. The formation process of the reservoir sand body is emphasized and the evolution process of the channel is analyzed based on the sedimentary process. The internal structure of three small sandbodies S2L45, S2L411 and S2L413 was researched in the main reservoir of the Lower Member of Es2. It was concluded that the whole channel sand body on the plane was from northwest to southeast which distribution was dendritic and was constantly moving, swinging, branching and merging. The width was generally 50~200m and the length of the extension varied greatly. In the source profile, sand bodies moved forward progressively, superimposed vertically and the lithology changed quickly horizontally. Key words: sandbody internal structure; Zhongyuan Oilfield; Southern Wen79 Block.