Continental mixed shale reservoirs are characterized by complex lithology and varying physical properties. The pore structure characteristics and controlling factors are crucial for understanding the physical properties of such reservoirs. Through analysis of rock thin section, casting thin section, scanning electron microscopy, high-pressure mercury intrusion, constant-rate mercury intrusion, and X-ray diffraction, the lithologies of the shale oil reservoirs in the Permian Lucaogou formation in the Jimsar sag were identified, and the pore structure characteristics of different lithologies and their relationships with diagenesis were analyzed. 6 lithologies are found in the shale reservoirs of the Lucaogou formation, namely micrite dolomite, silty sandy dolomite, calcareous siltstone, calcareous mudstone, silty tuff and calcareous tuff. The silty sandy dolomite, calcareous siltstone, and silty tuff are moderately compacted, with well-developed dissolution pores which are effectively connected and have large and well-sorted pore throats, indicating good physical properties. The calcareous tuff is also moderately compacted, and mainly composed of calcite, authigenic quartz and analcite cements, indicating moderate physical properties. The micritic dolomite and calcareous mudstone are simple in composition, strongly compacted, and weakly dissolved, with small pore throats, indicating poor physical properties.
