###### Abstract  
To evaluate the reservoir characteristics of siliceous shale in the Dalong Formation within the late Permian intra-platform rift trough in Western Hubei (China), we studied a drill core from well ED-2 in Western Hubei. To analyze the physical characteristics, pore structure, methane adsorption performance, and their influences on the siliceous shale reservoir, we performed X-ray diffraction, total organic carbon (TOC) content, vitrinite reflectance (\(R_{o}\), indicating thermal evolution), total porosity and permeability, field emission scanning electron microscopy, CO\({}_{2}\) and N\({}_{2}\) physical adsorption, and methane isothermal adsorption analyses, among others. Our results show that the Dalong Formation in Western Hubei is an organic-rich (2.6-14.3 wt.%), highly thermally evolved (\(R_{o}\) = 2.59-2.76%), siliceous shale containing mainly type-I and type-II\({}_{1}\) organic matter. The Dalong siliceous shale has low porosity and permeability and belongs to a larger reservoir with low horizontal permeability (0.002-335.209 mD) and porosity (1.2-7.8%). Pores in the shale are mainly organic, inorganic, and microfractures; the organic pores are very developed. The pore volume and specific surface area of the shale are mainly due to micropores and mesopores and are positively correlated with TOC and clay mineral contents and weakly negatively correlated with quartz and carbonate contents. The micropores and mesopores are well developed, improving the methane adsorption capacity, which, in turn, is strongly positively correlated with TOC content. Comprehensive analysis shows that the high organic matter content of the Dalong siliceous shale has the greatest influence on its pore structure; the many organic pores generated after hydrocarbon generation have controlled the development of micropores and mesopores, which is conducive to the adsorption and storage of shale gas. The development of brittle minerals resistant to compaction, such as siliceous minerals, helps preserve organic pores. This study is informative for basin-scale petroleum system investigations, which are essential for understanding oil and gas exploration possibilities and regional petroleum systems. r 2023 13 1434 14 December 20  
detailed below. (1) Whereas the main producing layers of the Longmaxi Formation in the Sichuan Basin are shelf deposits [13; 14; 15], the dominant layers being explored in the Dalong Formation are in the rifted platform basin facies [16; 17]. (2) The total organic carbon (TOC) content of the Longmaxi Formation in the Sichuan Basin is mainly within the range of 0.5-6.0 wt.% [18; 19], whereas that of the Dalong Formation in Western Hubei is in the range 2.6-14.3 wt.%, which may impact the formation of organic matter pores. (3) Compared to shale gas resources in the Sichuan Basin (60% of which are buried to \(>\)3500 m depth), the Calong shale is shallowly buried (mostly 0-2000 m depth, except in the Lichuan region where it is buried to a 4000 m depth) and widely distributed. The Dalong Formation has undergone a moderate degree of thermal evolution (\(R_{\rm o}\) = 2.6-2.8%) [20], slightly less than the Longmaxi Formation (\(R_{\rm o}\) = 2.3-3.1%) [21]. Exploration efforts have demonstrated Permian rocks in Western Hubei to be good prospects for shale gas exploration [22; 23], and shale gas reservoirs have been discovered in many wells there. In 2021, a test of well Hongye 1 HF in the Ongxing area of Enshi, Hubei, produced 89,000 m\({}^{3}\) of industrial gas flow per day, setting off a boom in Permian shale gas exploration in Western Hubei. Recently, studies on Dalong Formation shale reservoirs in the Western Hubei trough have found these reservoirs to have poor physical properties, with total porosities of less than 3% [24]. Pores are mainly organic pores with parallel plate and ink bottle shapes. Micropores and mesopores are important components of a shale's pore structure, which is also influenced by the organic matter content and shale lithofacies [25; 26].