为评价和预测鄂尔多斯盆地上三叠统延长组长6段低渗储层,根据岩石薄片、铸体薄片、扫描电镜等资料对长6段储层进行了分析研究。结果表明:①长6段砂岩在该盆地北部具“高长石、低石英”、南部具“低长石、高石英”特点,分选性较好、磨圆度较差;②主要建设性成岩作用为溶蚀作用、环边绿泥石形成、烃类侵位作用及高岭石化作用等,压实作用强烈是导致该储层早期砂岩孔隙丧失的根本原因,胶结作用是造成后期储层岩石致密的主要因素。在此基础上,进一步分析了鄂尔多斯盆地南部的成岩作用演化序列。 In order to evaluate and predict the low permeability reservoirs in Chang 6 Member of Upper Triassic Yanchang Formation in the Ordos Basin, the reservoirs of Chang 6 Member were analyzed based on the information of thin rock slices, cast thin slices and scanning electron microscope. The results show that: ① Chang 6 Member sandstone has “high feldspar and low quartz” in the northern part of the basin and “low feldspar and high quartz” in the south with good sorting and poor roundness; ② The main constructive diagenesis is dissolution, formation of chlorite around the rim, hydrocarbon emplacement and kaoliniteification, and the compaction is the fundamental reason leading to the loss of early sandstone pores in the reservoir. The cementation is caused by The main factor of late reservoir rock densification. On this basis, further analysis of diagenesis evolution sequence in the southern Ordos Basin.