| This paper was based on sedimentology, high-resolution sequence stratigraphy, logging stratigraphy, seismic stratigraphy and reservoir geology theory, through the core that were detailed observed, combined the data of logging sequence stratigraphic analysis and seismic interpretation results, established the Chang8 in Yanchang Formation high-resolution sequence stratigraphic framework and division standards of the study area.The study formation has been detailed contrasted, according to step by control method, establishing the Yangchang group third-order, fourth-order, fifth-order sequence stratigraphy framework. Used the up and down domain of the fourth-order cycle to map, established a new formation classification system which was aimed to detailed contrast to the effective reservoir, and the formation's thick was about 30 meters(almost attained single-sand body). Within the fourth-order sequence framework, compared and divided the fifth-order sequence, detailed depicted the reservoir sedimentary microfacies and distribution feature of Chang 8 content formations.Through the description of the core, the single well logging facies and the connected wells' profile isochro nostratigraphic correlation, combined with the plane distribution of sand body shape, the Chang 8 is mainly in the delta front environment,we know it develops the sedimentary micro-facies of the submerged distributary channel Or water course, debouch bar, Delta front sheet sand, turbidite fan eg. The submerged distributary channel Or water course is the favorable facies,whose sand grain size is relatively coarse, well-sorted,Low matrix content,interparticle pore developed and very large.It is the basis for the formation of favorable reservoir and objective evaluation of the benefit.Used the distribution of the GR value to determine the main river sandstone's position, combined the logging facies and other technical to determine the distribution of sedimentary facies.
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