The Study of Sedimentary Characteristics of the Fan Delta of Yingcheng Formation in Lishu Fault Depression

On the base of drilling cores, summarizing some sedimentary facies marks, such as grain size characteristics, sedimentary structures, log curve, etc, it is analyzed the sedimentary characters of fan delta of Yingcheng formation in Lishu fault depression according to drilling well sedimentary analysis. The study area grows two subfacies, fan-delta plain and front fan-delta, existing 6 microfacies which are debris flow, distributary channels, interdistributary bay, submerged distributary channe, mouth bar and submerged distributary interchanne. Then the depositional model of gentle slope type fan delta is established.On the plane, fan delta existing in this area has characters of contiguous development and mixed-source deposition; In the longitudinal direction, deposition lithologic section developed in the period of water withdrawal is built on the retrograding lithologic section developed in the period of water inlet.