针对鄂尔多斯盆地南部镇泾地区勘探开发前景，为寻找有利储层，利用砂岩薄片、铸体薄片、扫描电镜和恒速压汞等技术对取心井资料进行分析。结果表明，该储层岩性主要为长石岩屑砂岩和岩屑长石砂岩，成分和结构成熟度偏低；储集空间以粒间孔和溶蚀孔为主；储集性能差到中等，原始产能低，非均质性强。结合生产动态，选用喉道半径、可动流体百分数、启动压力梯度和有效孔隙度等低渗透储层评价参数，将长81储层划分为3 类：Ⅰ类为较好储层；Ⅱ类为中等储层；Ⅲ类为较差储层。研究区主要发育Ⅱ类和Ⅲ类储层，有少量的Ⅰ类储层，分类结果符合该地区实际。

In order to open up a vast range of prospects for oil and gas exploration and development in Zhenjing area, southern Ordos Basin, series of research methods such as rock thin sections, cast sections, scanning electron microscope and mercury penetration of constant speed are used to analyze core hole data for surveying fair reservoirs. The result shows that feldspar lithic sandstone and lithic feldspar sandstone are the main reservoir lithologies, with low compositional maturity and low textural maturity, the main reservoir spaces are intergranular pores and dissolved pores, and the reservoir is characterized by poor-middle property, poor original productivity and strong heterogeneity. Combined with production performance, the evaluation parameters for lowpermeability reservoir such as throat radius, percentage of mobile fluid, start-up pressure gradient and active porosity are selected to evaluate Chang 81 reservoir. According to the result, Chang 81 reservoir can be divided into three types. The typeⅠis better reservoir, type Ⅱ is medium reservoir, and type Ⅲ is poor reservoir. The typeⅡand type Ⅲ are the main reservoir in the study area, while typeⅠis seldom.