Abstract: The Longmaxi Formation in the Sichuan Basin has a cumulative proven reserve of shale gas of 3$\times$10$^{12}$ m$^3$, with an annual production exceeding 250$\times$10$^{8}$ m$^3$. But the Qiongzhusi Formation, has just achieved commercial exploration discoveries and is currently undergoing exploration evaluation. Based on a comprehensive study of the characteristics of shale deposition, reservoir properties, geochemistry, fracability, and gas content in the Qiongzhusi Formation of the Cambrian System in southern Sichuan, along with extensive basic experimental data and a comparative analysis with the shale gas formation conditions in the Longmaxi Formation, the results indicate that the shale gas of the Qiongzhusi Formation exhibits significant differences from that of the Longmaxi Formation in terms of depositional environment, hydrocarbon generation capacity, storage space, gas content, mineral composition, and fracability, representing a new type. This new type of shale gas predominantly develops in trough-and-platform depositional systems, with strong hydrothermal activity, diverse hydrocarbon-generating organisms, and high hydrocarbon generation capacity. The storage space is dominated by inorganic pores, with organic pores serving as a beneficial supplement. The high content of feldspar and quartz minerals contributes to its overall good fracability. Comprehensive predictions suggest that the Mianyang—Changning trough is a favorable zone for shale gas in the Qiongzhusi Formation. Multiple wells in the Ziyang, Jingyan, and Weiyuan areas have achieved high-yield industrial gas flows, confirming that shale, ranging from deepwater to shallow water and from high to low TOC, can be enriched and form reservoirs. These areas are key regions for the exploration and development of this new type of shale gas. The research findings not only enrich the theoretical foundation of shale gas exploration and development but also establish a series of supporting exploration technologies, providing important demonstrative significance for shale gas exploration and development in different formations and regions.

Key words: Qiongzhusi Formation, inorganic pores, trough-and-platform deposition, new type of shale gas, exploration discovery