Assessment of Natural Hydrogen Prospectivity in the JeJu Basin, Northern East China Sea

The northern East China Sea Shelf Basin records a complex history of Mesozoic–Cenozoic tectonism and volcanism. This study focuses on the Hupijiao Rise and Jeju Basin, where seismic and geochemical data acquired for hydrocarbon exploration. We assessed natural hydrogen potential by integrating AI-driven seismic interpretation with geochemical and petrophysical analyses. Specifically, we examined fracture zones in the crystalline basement and analyzed kerogen composition to investigate generation mechanisms. The fractured basement is well developed in the study area. NNE–SSW striking faults are predominant; dip azimuths within the sedimentary basin are clustered between 11.25° and 45°. More variable orientations are observed in the volcanic structural high. Elemental analysis of kerogen from cuttings in two wells revealed hydrogen contents ranging from 1.49–5.93 wt% in Well A and 2.04–5.89 wt% in Well B, indicating heterogeneity in thermal maturity and organic facies. The granite intervals identified from well logs exhibit elevated neutron log responses. These results suggest that the volcanic uplift and Hupijiao Rise provide favorable structural and geochemical conditions for natural hydrogen generation and migration, and they offer a basis for future exploration in offshore East Asian rift basins.