Abstract
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.