Progress and prospective analysis of natural hydrogen investigation research in Shangyi-Zhangbei area

Under the background of the global energy transition, natural hydrogen has emerged as a research hotspot in the field of new energy, and many countries have successively launched investigations into natural hydrogen. On the basis of previous research findings, Zhangbei Basin, with the presence of H₂ escape, is designated as a key area for natural hydrogen research. Then, geological, soil gas geochemical, gravity, and magnetotelluric sounding investigations were carried out in Shangyi-Zhangbei area. The results reveal that soil H₂ anomaly in Shangyi-Zhangbei area exhibits a ring-shaped distribution pattern with high values in the periphery and low values in the center around Hujiawa-Majugou. H₂ concentration in some sampling points exceeds 5, 000×10^-6. Hydrogen isotope analysis (δD values ranging from -567‰ to -461‰) indicates that H₂ is predominantly of mantle-derived origin. Twelve hidden faults and 3 sedimentary depressions have been identified according to gravity and magnetotelluric sounding results, and the basement depth and tectonic framework of the basin have been interpreted. It is considered that faults are favorable channels connecting deep hydrogen sources. The sedimentary assemblages of the Cretaceous and the Paleogene-Neogene have the potential for gas storage. Mudstones and dense massive basalt flows play the role of trap caprocks. The sedimentary sag areas with less H₂ escape and covered by basalt flows were delimited as favorable areas for further exploration of natural hydrogen, after comprehensive analysis, with an area of approximately 590 km². This study could provide basis for further exploration of natural hydrogen in Shangyi-Zhangbei area.