The Study On The Sedimentary Microfacies Of Dongying Formation Of Yuke Oil Field Of Shenxian Depression

The article had studied the sedimentary microfacies in the period of Dongying formation—mainly in the second-third member of it in Yuke Oilfield which lies in Shenxian depression, by analyzing the relevant information such as drilling core description, well-log ,seismic data and analysis of information-based with the direction of sedimentological theory and seiscic stratigraphy.Based on the analysis of lithologic character, grainsize analysis, thin section identification well-log and seismic data, combining with the correlations of single well facies and profile facies, the systemic studies of sedimentary characterization, diagenesis, spacial spreads of sandbodies and controlling factors of Ed2-Ed3 of Yu ke Oilfield are done. The results of the study show that Shenxian depression is a double-fault cenozoic sag between the Jiucheng northern boundary fault and the Hengshui fault. The Dongying Formation developed a regressive clastic sedimentary system under the sedimentary background of the Shahejie Formation and water in the depression became shallow. There is river facise in Ed2-Ed3 fomation, mainly meandering river, however,there is some sedimentary feature of braided river facies,too. By analying these feature,we think this area is located in up reaches of the meandering river. Channel sand is the most important sand. The main lithologic character is grey fine sandstone, the featur of grain size accumulation curve which is"one intermediate between one saltation population and one mid suspension population"and"two lengthpassage"shows that the size characteristic in region of interest is between them of meandering river and braided river. The profile facies sequence indicates that the river in this area is not a typical meandering river.For Yuke oil Field is mainly meandering river sedimentary, and part is atypical meandering river sedimentary, with reference in the latest achievement of recent years for classifying river type, this paper contrasted the sedimentary characteristics of atypical meandering river and establish its depositional model of Yuke Oil Field Dongying fomation . And on the basis of above research, did a fine depict of the sedimentary microfacies for the main sand layer and single sand body, restored the ancient landform, which all beneficial for finding the favorable position of sand body and its exhibition rule.For previous sedimentary micro-facies mapping method relying on sand body thickness lines is not well combined to oilfield actual production material, and the sand body exhibition is not fine enough, this paper adopted newer sedimentary micro-facies mapping method and added the river mainstream line and no-filling abandoned channel flow into the sedimentary microfacies figure for better recovered the geographical outlook. And owing to developers'understanding for fluvial sandstone heterogeneity is not accurate enough, it resulted in the contradiction of"water above while oil underneath", which is not in line with general hydrocarbon enrichment regular. Therefore, this paper analyzed the transverse seal of river mainstream line and abandoned channel for trying to explain oil and water contradiction from the angle of sedimentary microfacies, which providing a reliable geological basis for making rational development adjustment scheme for the field, and affording a reference for oil and gas exploration.