Sedimentary Characteristic And Sedimentary Facies Of Liaohe Western Beach In The First And Second Member Of Eogene Dongying Formation

Limited by the complex natural conditions and undergroud geologic conditions, the current proven reserves of Western Beaches are far from the potential reserves of this area, in the other words it means this area has a great prospects of further exploration and development.The study of sedimentary characteristics and sedimentary facies are restricted by the limitation of the exploration date. The recent research framework of Western Beaches is relativly rough and scholars can not make agreements with the sedimentary facies type and distribution. Therefore the futher deep study of the sedimentary characteristics and sedimentary facies are necessary and urgent.Therefore, in the sequence stratigraphy framework, the paper, based on sedimentology, seismic stratigraphy, well logging, integrated core, logging, seismic, paleontology and other analytical data, following the points (single well) - line (section) - surface (plane) research ideas, and combing with the characteristics of the basin tectonic setting, studies the sedimentary characteristics and sedimentary facies to make various types of sedimentary facies and distribution pattern of the sand body clear to the most extent on the four sequences of the first and second member of Dongying Formation in the work area and to point out the favorable reservoir zone and further exploration direction.Based on the integrated analysis of core facies, log facies, and seismic facies, fan delta, braided delta, delta , beach and bar and lacutrine deposits have been identified in the study area and the relevant sedimentary models have been established. The beach and bar deposition is first discovered in this area, which has great theoretical significance. Studies have shown that during the deposition of the second member of Dongying Formation, with the weaker activities of boundary faults, the more gentle relief, and the relatively wider drainage area, the above five kinds of sedimentary facies become the dominant types. During the deposition of the first member of Dongying Formation, a shallow water convergent basin existed in the study area, the western slope was still the main source, and the main facies in this area were shallow water braided fluvial delta and lacustrine deposition.The research on sedimentary facies distribution in the sequence stratigraphic framework can define the western beach sedimentary facies distribution characteristics and the three major stable sources area: the western slope, Huludao processes as well as the north-east axis source. And also discuss the controlling factors of sedimentology. The sedimentary facies distribution was effected by the palaeotectonics, palaeogeomorphology, palaeoclimate and palaeoprovenance,while the former two were the major factors.The No. 2 fault of Hainan controlled the distribution of semi-deep lacustrine subfacies,while the faults in western slope ,Lingnan and Yuedong area controlled the distribution of water systems flowing into the Lake and depositional fans.The other branches of Hainan fault had played certain controlling effects on the distribution of the beach and bar.