A Study on Sedimentary Facies Features of Chang 2 oil-bearing formation in Jiyuan Region of Shanxi-Gansu-Ningxia Basin

Chang 2 oil-bearing formation is one of the important layers in the Yanchang formation of Jiyuan region,based on the core,logging and geological data,the sedimentary characteristics of meandering river were studied in Jiyuan region,then two types subfacies and five types microfacies were summarized.The identification mark was the sorted microfacies combination of underwater distributary channel,mouth bar and distal bar,where the structural characteristics of sediment were dominant.Furthermore,the plan distribution of sedimentary microfacies toward different sand section were mapped,and the distributive features and the evolvement rules.were analyzed,these are benefit for the discussion of enrichment factors and future exploratory development of oil and gas.