Depositional Microfacies Study Of West Dualistic Experimental Site

During the exploration stage, the study of the depositional facies chiefly refers to magnafacies and subfacies. However, in the development stage of oil field, which is after the development stage of well patter, the study of the sedementary facies is mainly about micro-facies for depositional micro-facies study is absolutely necessary. Being the most basic composition of depositional systems, depositional microfacies reflect the formation of the depositional rock with the same depositional conditions and are also the basis of a single-well and multi-well reservoir evaluation. Moreover, it determines the macro-distribution of the reservoir sand body and the seepage barrier, while controlling the seepage variation of the reservoir sand body fluid. Therefore, in the development stage of oil field, the depositional micro-facies study is very important and indispensable in the geological study.Sazhong development area has been developed for more than 40 years. At present, it enters high water-cut stage and the crude oil decreases by degrees. Therefore, at the present stage, the main tasks are to seek and explore the remaining oil as well as find out the remaining oil distribution in the main reservoirs after polymer flooding, which can provide the fundamental basis for the next step of development adjustment.In this research, on the basis of depositional and geological characteristics at west district of Sazhong development area, combined with the modern sedimentology, sequence stratigraphy, well logging geology, petroleum geology and reservoir geology, the depositional micro-facies study will be improved greatly. In the research area, with good curve and reasonable dividing line, the well which can be easily divided and include almost all the layers, is selected as standard well for dividing layers. According to combining sedimentary cycle correlation, hierarchical control and discriminating different sedimentary facies association,100 wells in the west district are divided into 5 sedimentary units as well as 2 magnafacies,4 subfacies and 12 micro-facies are divided. By applying the principle of the well-log facies, summarizing typical logging curves'characteristics of the same depositional micro-facies, a variety of micro-facies patterns of well-log were established. With the fine well-log microfacies recognition and the combination of flat facies, sedimentary microfacies' maps of five depositional units were drawn up and analysed. It provides a favorable reference for the research area to adjust the encryption scheme, supplementarily analyze the distribution of remaining oil and develop quickly.