The Type and Characteristics of the First Member of Nantun Formation’s Sedimentary Facies in Wunan Sub Depression

Through the study of a large number of core, logging, and logging data, on the basis of previous research (Nantun Formation is divided into two period which are the first member of Nantun Formation and the second member of Nantun Formation), combined with the characteristics of the seismic, the sedimentary facies of Wunan sub depression is researched. The sedimentary facies characteristics in different periods are mainly controlled by tectonic evolution and sediment supply. The first member of Nantun formation mainly develops two kinds of sedimentary facies which are fan-delta facies and lake facies, and four subfacies which are fan-delta plain, frontal fan-delta, shore-shallow, deep lake and semi-deep lake.