Accurate evaluation of shale microporous structure characteristics is crucial for the development of shale oil.In this study,TOC detection,X-ray diffraction whole-rock analysis,SEM scanning electron microscopy,and FIB-SEM technology were synthesized to conduct rock microphysical property experiments and microstructure observation experiments on two samples of Chang 7 shale from the Yanchang Formation of the Ordos Basin in Yijun County,Shanxi Province,which are characterized by a shiny oil surface.The micro-mineralogical characteristics,pore structure characteristics,physical properties,and dissection of the pore throat structure of the organic-rich shale in the Long 7 section of the Yanchang Formation have been investigated from multiple perspectives.The results show that:① The TOC contents of the two shale samples are 21.33％and 19.33％,respectively,exhibiting high TOC characteristics and indicating excellent organic matter abundance.(2)The mineral composition is complex,and samples is mainly composed of clay minerals,pyrite and quartz,accompanied by the occurrence of potassium feldspar,plagioclase feldspar,rhodochrosite and other minerals.③ The shale is very dense,but rich in pore types.There are four types of microscopic pores:intergranular pores,intragranular pores,organic matter pores and micro-fissures.The porosity of sample 1 and sample 2 are 0.39％,and 0.88％,the pore space is poorly developed,and the percentage of minerals is 3.95％and 8.03％,respectively.④ The size of the micropores in the shale samples is mostly at the microscale and nanoscale,and more than 90％of them are mesoporous and account for most of the pore volume,and the coordination numbers of the samples are mainly 0 and 1.Isolated pores make up the majority of the pores,and pore connectivity is poor.The observation results are critical for reliable petrophysical modeling in oil shales and accurate understanding of their intrinsic properties,as well as for shale exploration target siting.
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