Abiotic evaluation of geochemical reactions of sandstone minerals and their impact on underground hydrogen storage

This research explores the geochemical aspects of underground hydrogen storage, focusing on the impact of mineral reactivity on sandstone rock samples. The initial phase investigates hydrogen solubility in brine, through the development of a solubility model validated by a dataset from Chabab et al. (2020), which is further coupled with a geochemical kinetics model. Additionally, a detailed evaluation of geochemical heterogeneous dissolution/precipitation (abiotic) reactions involving minerals such as quartz, K-feldspar, albite, muscovite, pyrite, illite, and kaolinite is performed. This evaluation seeks to resolve discrepancies in the literature, pinpoint their causes, and develop a comprehensive model to serve as a benchmark for future geochemical studies. A simplified geochemical approach is proposed, using the Saturation Index (SI) and kinetics modelling to assess mineral reactivity, providing insights into the duration and extent of geochemical reactions and the time needed to reach equilibrium after hydrogen injection. The findings reveal that quartz exhibits remarkable stability, even in extreme acidic and basic environments. In contrast, pyrite is the least stable mineral, showing the highest dissolution rate, particularly when exposed to oxidizing agents. The dissolution rates of quartz, K-feldspar, albite, and muscovite increase under both acidic and basic conditions, while they slow significantly at neutral pH. Although the dissolution of pyrite and clay minerals may vary, potentially leading to minor effects on the integrity of underground hydrogen storage, the reactions of other minerals are considered negligible or non-impactful. • A simplified numerical method evaluates mineral stability using Saturation Index. • Hydrogen solubility rises as salinity decreases from 100,000 ppm to 50,000 ppm. • Quartz remains stable, even in highly acidic and basic environments. • Illite, kaolinite, and pyrite dissolution rates are 2.17%, 3.01%, and 5.46%. • Quartz, feldspar, albite, and muscovite reactions are negligible, below 0.0001%.