Research on Shale Reservoir Characterization and Control Factors

Abstract

This study focuses on the characterization of shale gas reservoirs in the Longmaxi Formation and their controlling factors in the east Sichuan Basin. Detailed mineralogical and reservoir characterization of shale samples in the region was carried out by various methods, including X-ray diffraction analysis and nitrogen adsorption experiments. The results show that the shale is mainly composed of clay minerals (illite content ranges from 34.9% to 55.7%), quartz and calcite. In terms of reservoir characteristics, the shale mesopore morphology is mainly “slit-type”, with BET specific surface area ranging from 7.12-25.63 m²/g and BJH pore volume from 0.0095-0.0262 mL/g. These reservoir characteristics show a significant positive correlation with the organic carbon content (1.82-3.87%). correlation. Petrographic analysis further reveals that the brittle mineral content has a significant effect on the brittleness, pore development and fracturing effectiveness of the rocks. In addition, diagenesis (including compaction, cementation, dissolution, and thermal evolution of organic matter) had a significant impact on the formation and characterization of shale pores. These findings provide a key scientific basis for understanding the geological characteristics and development potential of shale gas reservoirs in the Longmaxi Formation in the Sichuan Basin.