Based on a study of core, logging and seismic data, this paper studied characteristics of high-resolution sequence stratigraphy of Chang-6 Subsection of Yanchang Formation. The authors found that from northeast to southwest, the distribution model of base-level cycle varies in order of typeAl-typeA2 -typeB1-typeB2-typeC or typeA2, and recognized one long-term and four medium-term cyclic sequences (MSC1, MSC2, MSC3 and MSC4) . A high-resolution sequence stratigraphic framework of medium-term cyclic sequences was established. With the medium-term cyclic sequences as mapping units, four sequence-based lithofacies and paleogeography were drawn which show that the delta was mainly developed during the MSC1 stage and MSC3 stage. The sand bodies were mainly developed at the same time. It is found that sand bodies were mainly developed in the subaquatic distributary channels of prograding deltas whose base -level cycle was of type Al and type A2, and the sand bodies were also developed in the alluvial fan whose base -level cycle type was type A2. Consequently, the distribution regularity of sand bodies revealed by sequence-based lithofacies and paleogeography has an important guiding significance for the petroleum exploration in the prospecting area of Fuxian located in the southeast hydrocarbon-enriched belt of Shanbei slope, Ordos Basin.%本文以钻井岩心、测井和地震等资料为基础,对鄂尔多斯盆地富县地区延长组长6段进行了高分辨率层序地层研究.基准面旋回结构类型分析揭示了从研究区的东北至西南,具有A1型→A2型→B1型→B2型→C型的分布模式;以中期旋回为等时对比单元,建立了富县地区长6段的高分辨率层序格架,将长6段划分为一个长期旋回层序、4个中期旋回层序(MSC1、MSC2、MSC3和MSC4)和若干个短期及超短期旋回层序；按中期旋回编制的层序-岩相古地理图揭示出MSC1期和MSC3期为三角洲的高度建设期,发育大型的进积型三角洲水下分流河道砂体(A1型或A2型)和较大规模的湖底扇砂体(A2型),是研究区最有利的勘探目标.总之,层序格架内的砂体对比及层序岩相古地理揭示的鄂尔多斯盆地陕北斜坡油气富集带东南部的富县探区的砂体展布规律,对该地区的石油勘探部署具有重要的指导意义.
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