Despite significant breakthroughs in exploration and development in the Ordos Basin, Qinshui Basin, SNCB, Central Hunan Area, Southeast Sichuan Area, and Guizhou Area, cost and technical challenges are expected due to the thin continuous thickness of shale, rapid vertical and horizontal changes, as well as frequent interbedding with coal seams and tight sandstones [10; 11]. The main component of shale gas is CH\({}_{4}\), which often occurs in reservoir rock dominated by organic-rich shale. It exists mainly in the adsorption state and free state, with a small amount being dissolved [12; 13]. The adsorbed gas primarily exists on the pore surface of organic matter and clay minerals, accounting for 20-85% of the total gas content. The free gas mainly occurs in microcracks and pores with a large pore size, constituting 15-80% of the total gas content. A small amount of dissolved gas is present in asphaltene, liquid hydrocarbon, kerogen, and formation water [13; 14; 15]. Numerous controlling factors affect the methane adsorption capacity of shale, including the content, type, and maturity of organic matter, the composition and content of minerals, PV, pore structure, water content, and so on [16; 17; 18]. Among them, [PERSON] et al. believed that organic matter is the primary controlling factor of gas adsorption in shale gas systems. Type III kerogen exhibits stronger aromatization, more pores, and higher shale adsorption capacity, while type I kerogen has the lowest adsorption capacity [19]. [PERSON] et al. concluded from their adsorption experiments and grand canonical Monte Carlo simulation that organic matter serves as the main adsorbent in shale due to the high distribution density and strong intensity of adsorption sites and large SSA [20]. [PERSON] and [PERSON] investigated the Langmuir volume (V\({}_{\rm L}\)) of coal-measure shale from the Shanxi-Taiyuan Formation in the central and southern Qinshui Basin. They found that V\({}_{\rm L}\) was positively correlated with TOC content, clay mineral content, and SSA, while it was negatively correlated with quartz content and average pore size. Additionally, they observed that as Ro increased, V\({}_{\rm L}\) initially increased but then decreased [21]. [PERSON] et al. investigated the relationship between the types of clay mineral and methane adsorption in over-mature shales, revealing that illite/smectite (I/S) mixed layer exhibits a stronger methane adsorption capacity than kaolinite, while illite exhibits the weakest methane adsorption capacity [22]. [PERSON] and [PERSON] analyzed the influence of pore structure on the adsorption capacity of Upper Paleozoic transitional shale in the Ordos Basin. Studies have shown that methane adsorption capacity is positively correlated with the SSA of micropores in shale, and TOC content and clay minerals also significantly contribute to the methane adsorption capacity of shale [23]. [PERSON] et al. elucidated the controlling factors of water in the nanopores of shale and its influence on methane adsorption [24]. The analysis revealed that the type and content of clay minerals were the primary factors affecting the water content or water absorption capacity of shale, while competitive adsorption between water and methane at adsorption sites was the main mechanism leading to a decrease in methane adsorption capacity of shale [24]. In recent years, the methane adsorption capacity of marine shale has been extensively studied. Due to differences in sedimentary environments, there are significant differences in reservoir material composition and gas occurrence mechanism between marine-continental transitional shale and marine shale [25]. These differences will cause a significant amount of uncertainty in determining the main controlling factors of gas enrichment in the marine-continentaltransitional shale [26]. Therefore, it is necessary to further clarify the reservoir characteristics and methane adsorption capacity of transitional shale to provide a scientific basis for accurately evaluating the potential of transitional shale gas.