The observation of the cores and thin sections of rocks shows that the Paleogene Ganchaigou Formation in the Qaidam Ba⁃sin is composed of five lithofacies, i.e., laminated and non-laminated mudstone/shale, laminated and non-laminated lime mudstone/shale, silt limestone, laminated and non-laminated silty mudstone/shale, and argillaceous siltstone. The Ganchaigou Formation con⁃tains 0.2%~1.4%organic carbon (TOC). The organic matter is mature and dominated by type Ⅱ-kerogen. The mineral composition is dominantly clastic quartz and clay minerals, together with such minor components as calcite, dolomite, feldspar and pyrite. Five types of reservoir space, namely primary pore, pore of hydrocarbon generation, secondary dissolution pore, pore by illitization and mi⁃cro-fracture. The development of reservoir space is strongly controlled by the lithofacies, mineral composition, diagenesis, organic carbon content and organic matter maturity. The shale of Ganchaigou Formation is characterized by low organic carbon content. However, the organic matter is generally mature. Several types of reservoir space, high content of brittle minerals and illite clay miner⁃al were found in the Ganchaigou shale. Therefore, the Paleogene Ganchaigou Formation in the Qaidam Basin is a favorable reservoir for shale gas exploration and may have an optimistic shale gas potential.%岩心观察和岩石薄片鉴定显示，柴达木盆地西部古近系干柴沟组存在层状-非层状泥页岩、层状-非层状灰质泥页岩、泥灰岩、层状-非层状粉砂质泥岩和泥质粉砂岩5种岩相。总有机质含量（TOC）为0.2%~1.4%，有机质以Ⅱ型干酪根为主，普遍处于成熟阶段。泥页岩矿物成分以碎屑石英和粘土矿物为主，并含有不等量的方解石、白云石、长石、黄铁矿等；发育原生孔隙、有机质生烃形成的孔隙、次生溶蚀孔隙、粘土矿物伊利石化体积缩小形成的微孔隙及微裂缝5种页岩气储集空间类型。研究表明，储集空间发育主要受岩相类型、矿物成分、成岩作用、有机碳含量和有机质成熟度的影响。虽然研究区泥页岩中有机质含量普遍较低，但有机质普遍处于成熟阶段，储层中发育多种储集空间类型，并富含脆性矿物和富伊利石的粘土矿物。因此，柴达木盆地西部干柴沟组泥页岩为良好的页岩气储集层，具有一定的页岩气勘探前景。
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