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The rock types of the tight sandstone reservoir in the Lianggaoshan Formation of the Sichuan Basin are complex. Clarifying the micro pore structure characteristics and main controlling factors of physical properties of the reservoir is beneficial for evaluating the sweet spots of tight oil and selecting favorable areas. This article selects samples from the tight sandstone reservoir of the Lianggaoshan Formation, and uses methods such as XRD, field emission scanning electron microscopy, and Cast Thin Section to reveal the microscopic pore structure of the tight sandstone reservoir and explore the influence of diagenesis on the physical properties of the tight sandstone reservoir. The results show that the pores of the tight sandstone in the Lianggaoshan Formation are mainly secondary pores, and the reservoir space is mainly composed of residual intergranular pores, intergranular dissolution pores, and intragranular dissolved pores. When the clay content increases, the intergranular pores of clay minerals are more developed, visible micro-fracture. The heterogeneity of the physical properties of tight sandstone is mainly controlled by diagenesis, with compaction and cementation playing a destructive role. Compaction is the most important reason for the decline of the physical properties of the Lianggaoshan Formation reservoir. In addition, the primary pores are cemented by calcium, which can also lead to a deterioration of the physical properties; The organic acids produced by hydrocarbon generation interact with mineral particles to create dissolved pores, which can greatly improve the physical properties of the reservoir. When chlorite develops, a chlorite rim is formed, and quartz growth is limited. Autogenic chlorite inhibits the growth of autogenic quartz, thereby maintaining the original pores and improving the physical properties.
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