针对鄂尔多斯盆地下侏罗统油藏规模小、分布散的特点，通过岩心观察和测井曲线分析，在建立鄂 尔多斯盆地吴起地区富县组沉积相识别标志的基础上，认为吴起地区富县组为辫状河沉积体系，发育辫状 河道、心滩、天然堤和漫滩等沉积微相，同时建立了河谷侵蚀背景下的辫状河沉积模式。以沉积相和砂体 展布为手段，恢复了富县组沉积期的古地貌背景。研究表明，宁陕古河与蒙陕古河在吴起地区交汇，形成 了吴起古河间丘。同时，对古河道斜坡上的次级河道进行了详细刻画，对在吴起地区寻找下侏罗统古地貌 控制下的油气藏分布规律的研究具有借鉴作用。

In view of the small scale and the scattered distribution characteristics of the Lower Jurassic reservoir in Ordos Basin, the identification sign of sedimentary facies in Wuqi area of Ordos Basin was defined based on the core observation and log analysis. The result shows that the Fuxian Formation is of braided river sedimentary system, and developed sedimentary microfacies such as braided channel, diara, natural levee, flood plain and so on. At the same time, the sedimentary model of braided river is built up under the background of erosion in the river valley. Based on the research on sedimentary facies and sand thickness, the paleogeomorphology background of the Fuxian Formation was restored. The result shows that Ningshan ancient river and Mengshan ancient river intersected in Wuqi area, and formed a ancient hill among the rivers. The secondary river channel in the ancient river channel slope was also despcribed, which is of great significance for looking for the distribution laws of reservoirs under the control of the sedimentary facies in the Lower Jurassic.