鄂尔多斯盆地长7段泥页岩层系储层特征及其页岩油意义

Reservoir Characteristics and Shale Oil Significance of the Shale Strata in the Chang 7 Member of the Ordos Basin

陆相页岩油气资源是当前非常规油气研究领域热点。综合使用多种实验手段对鄂尔多斯盆地三叠系长7段泥页岩的岩性特征、成因类型、储集空间及地球化学特征进行分析。结果表明:岩石组分以泥质矿物为主、有机组分和陆源粉砂其次;成因类型主要为深湖—半深湖相页岩、三角洲相泥岩和沼泽相泥岩;储集空间类型主要为页理缝和基质微孔;实际地质样品的地球化学分析表明,样品中烃类组分随热演化程度的不断升高,呈规律性变化。泥页岩层系的热演化程度接近生油窗结束阶段时,已生成的烃类中有相当一部分进入了临近的非源岩夹层中,砂岩夹层含油性优于泥页岩段,烃类组分以饱和烃、芳香烃含量高为主要特征;H317井长7段泥页岩层系中砂岩夹层及部分块状泥岩具有较好的含油性,物性相对较好,脆性矿物含量较高,加之该段泥页岩层系中烃类流体的黏度和密度相对较低,流动性较好,因此砂岩夹层及部分块状泥岩可以作为页岩油勘探的有利目标。针对黑色页岩,可参考油页岩原位改质等相关技术方法进行试探性开采页岩油。

Lacustrine shale oil and gas resource is a spotlight field in current unconventional resources research field.A variety of comprehensive experimental methods are used to analyze the lithology characteristics and genetic types of Chang 7 member in Yanchang formation of Triassic Ordos Basin.The results show that the rock components are mainly argillaceous minerals,organic components and terrestrial silt sands.The genetic types are mainly deep lake-semi-deep lake facies,delta facies and marsh facies.The types of reservoir space are mainly page seams and matrix micropores.Geochemical analysis of geological samples indicates that the thermal evolution degree of hydrocarbon component raise continuously and show regular changes.A considerable number of generated hydrocarbons have migrated into the adjacent non-source rock interlayer at the end of the thermal evolution degree which is close to the oil window period,sandstone interbedded oil content is better than that of shale section.High content of saturated hydrocarbon and aromatic hydrocarbon are the main characteristic of the hydrocarbon components;the sandstone interlayer and some massive mudstones in the Chang 7 member of the H317 well have good oil-bearing properties,good physical properties,high brittle mineral content,and the better viscosity and density of hydrocarbon fluids in the shale layer,sandstone interlayers and some massive mudstones can be used as favorable targets for shale oil exploration.For black shale,with reference to oil shale in situ upgrading and other related technical methods for exploratoring shale oil.