Natural hydrogen soil gas emissions near Harvey, Perth Basin: a comparative study of survey methods

Quantifying natural hydrogen soil gas emissions and their controlling factors is critical for assessing hydrogen storage viability and improving exploration strategies. This study provides the first detailed comparison of hydrogen emissions near the DMP Harvey-2 well in the Perth Basin and compares the effectiveness of repeated point surveys and autonomous monitoring in capturing emission variability. Hydrogen concentrations ranged from 0 to >1000 ppm in point surveys, with transient pulses up to 598 ppm detected through continuous monitoring, indicating episodic release. Repeated point surveys successfully captured the overall range of emissions but failed to resolve dynamic processes, such as abrupt flux changes influenced by temperature, atmospheric pressure, and soil moisture. Continuous monitoring provided additional insights into these transient phenomena and the relationship between baseline emissions and geological processes. These findings help define the repeatability of point surveys and demonstrate the value of integrating continuous monitoring with single-point surveys to establish baselines and identify natural hydrogen microseepage hotspots. This integrated approach offers practical insights for hydrogen exploration and baseline monitoring, contributing to improved planning for subsurface hydrogen storage.