The origins of natural hydrogen in natural gas systems of sedimentary basins and the capacity of these systems to store hydrogen remain inadequately understood, posing crucial questions for the large-scale exploration of natural hydrogen. This study reports on the natural gas composition, stable carbon and hydrogen isotopic values, and helium isotopic values of gas samples collected from the Qingshen gas deposit within volcanic rocks of the Songliao Basin. Natural hydrogen primarily originates from water radiolysis, water-rock interactions (WRI), and mantle. The Qingshen gas deposit contains 95.23 × 10 ⁹ cubic meters of abiotic CH ₄ , of which 15.24 × 10 ⁹ cubic meters was generated through hydrogen conversion via Fischer-Tropsch synthesis, with the maximum original hydrogen reserves calculated to be approximately 61.9 × 10 ⁹ cubic meters. We estimated that the study area has generated a maximum total of 572 × 10 ⁹ cubic meters of radiolytic hydrogen, 248 × 10 ⁹ cubic meters of WRI hydrogen, and 127 × 10 ⁹ cubic meters of mantle-derived hydrogen.

Fault networks play a critical role in controlling hydrocarbon flow within petroliferous basins; however, quantitative characterization of fault network systems and their specific influence on hydrocarbon preservation in tight sedimentary rocks remain insufficient. This study investigates the Luzhou shale gas production area in the Sichuan Basin, which has been modified by multi-stage tectonic superimposition, employing topological theory to quantitatively evaluate the structural architecture and connectivity of reservoir fault networks, and to elucidate their control on shale gas preservation. Our results reveal significant heterogeneity in the development and distribution of fault network systems within the study area. Faults are more developed in anticlinal belts, which experienced concentrated compressional stress, and the median connectivity of fault networks in shale reservoirs within these belts (C_B = 1.34) is substantially higher than that in synclinal belts (C_B = 0.95). The higher geometric connectivity observed in anticlinal belts may increase the continuity of potential migration pathways, whereas the generally lower connectivity of many synclinal areas may be more favorable for shale gas preservation. Estimated ultimate recovery data from shale gas wells in different structural zones show a spatial association broadly consistent with the fault-network connectivity pattern, although well performance may also be influenced by other geological and engineering factors. This study provides a quantitative analytical framework for characterizing fault-network connectivity in complex structural zones and offers insights into the potential role of fault-network connectivity in shale gas preservation and exploration.