通过对岩心观察、测井曲线、岩石薄片、扫描电镜、物性和压汞资料的综合分析，对志丹探区西南部中生界储层特征进行了系统研究。认为三叠系侏罗系储层分布广，且厚度较大，除延10油层组为辫状河河道砂体外，延长组和延安组大量为三角洲前缘砂体，其中延长组大量为细粒、极细粒长石砂岩，延安组大量为中粒、中细粒次岩屑长石砂岩、长石砂岩，少量长石石英粗砂岩和含砾粗砂岩；储集空间主要为残余粒间孔和粒间溶蚀孔，其中延安组储层孔隙结构好，物性明显优于延长组，属中孔中渗型储层，部分高渗型，而延长组储层孔隙结构较差，属中低孔低渗—低孔低渗型、特低渗型储层；较好的储层主要发育于延8-延10和长2油层组，其次为长6油层段。

Based on drilling core, logging curve, petrographic thin section, SEM(scanning lectronic microscope), physical property and mercury penetration data, the characteristics of Mesozoic reservoirs in the southwest of the Zhidan district in the Ordos basin have been studied systematically. It indicates that the reservoirs of Triassic and Jurassic not only distribute widely but also possess great thickness. The Yanchang and Yan'an formations are mainly delta front sand-bodies, except that Yan10 is braid river sand-bodies. The Yanchang formation is fine and extremely fine-grained arkose, while the Yan'an formation is mesograin and meso-chondro-grain sub-lithic arkose, feldspar sandstones, and a little gritstones of feldspar-quartz and of gravel. Remnant inter-granular pore and solution pore are the dominant accumulation space. The reservoirs of the Yan'an formation have good pore structure and better physical properties than Yanchang's. They are middle-pore and middle-permeability reservoirs, and some of them are highly permeable. The Yangchang formation has the reservoirs of middle-low-pore, low-permeability, or low-pore, low-permeability. The better reservoirs are developed in Jurassic Yan8-10 and Triassic Chang 2 oil-bearing group, followed by the Chang 6.