上三叠统延长组长6 油层组是鄂尔多斯盆地大路沟地区重要的勘探开发目的层。文章依据野外露头、岩心、测井及相关测试资料，对大路沟地区三叠纪长6 期的沉积类型、沉积微相特征及时空演化进行了系统分析。结果表明：大路沟地区三叠纪长6 油层组发育三角洲沉积体系，主要包括三角洲平原亚相和三角洲前缘亚相，缺前三角洲亚相；分流河道和水下分流河道砂为储集层骨架砂体；长6 油层组各微相经历了从三角洲前缘、三角洲平原到混合载荷高弯度河的沉积演化过程。同时对长6 油层组各小层沉积微相的时空展布特征进行了分析，认为油气聚集受沉积微相的控制，三角洲前缘亚相的水下分流河道微相和三角洲平原亚相的分流河道微相是砂岩储层分布和发育的最有利相带，也是今后勘探开发的方向。

The sixth member of Upper Triassic Yanchang Formation is the major exploration target zone in Dalugou area, Ordos Basin. Based on the outcrop observation, core description and logging analysis, the sedimentary systems, sedimentarymicrofacies and evolution ofUpper Triassic Yanchang Formation in Dalugou area are analyzed. The result shows that Chang 6 reservoir in Dalugou area mainly developed delta deposit system which includes delta plain facies and delta front facies. Distributary channel and subaqueous distributary channel sandstones are the skeletal sand bodies. In Chang 6 period, the sedimentary microfacies experienced delta front, delta plain to high curvature river of blending load. The distribution of the sedimentary microfacies of each sublayer of Chang 6 reservoir is studied. It is concluded that the hydrocarbon accumulation is controlled by sedimentary microfacies. The subaqueous distributary channel of delta front and distributary channel of delta plain are the most favorable facies belts for reservoir distribution and development.