Sedimentary facies research of complex lithologic reservoir of S2 section in Moliqing oilfield,Yitong Basin

Since 2008, Moliqing oilfield has always adhered to the integration of exploration and development, and made significant breakthrough in the field of increasing production efficiency. This reservoir has typical lithologic reservoir characteristics. The superposition of multiple phases and sediment sources has caused the lithology to change fast, with strong reservoir heterogeneity. With the increase of oil wells, the production kept rising before 2011. However, pressure began to went down and the energy can't be supplied in time afterwards, so the oil production has a trend of decline. The development encounters bottleneck with the addition of concealment and complexity of lithologic reservoir. From the perspect of reservoir development, we must strengthen the understanding of the geological aspects in order to improve the production efficiency of Moliqing oilfield.Under the regional sedimentary background, based on a large number of core observation and description, this paper made research from sediment formation conditions, source direction, sorting characteristics and sandbody connecting relations in order to identify the depositional model, and proposed slope apron model. Based on single well sand body statistics, sedimentary facies model and the analysis of log facies, 3 subfacies and 5 microfacies were identified.