Evaluating Fluid/Rock Interactions for Energy Storage in Salt Caverns – Part II: Effect of Hydrogen on Salt Rock Dissolution in Brine
Lin Yuan, Adel Najafi‐Marghmaleki, Amirhossein Meysami, Hassan Dehghanpour
Abstract
Building upon our previous study that investigated the interactions between brine and impure salt rock, this study extends the understanding of salt rock behavior by examining the effects of hydrogen (H 2 ) in the brine–salt rock systems under underground hydrogen storage (UHS) conditions, but in the absence of microbial activities. To investigate the effect of hydrogen (H 2 ) on mineral dissolution and precipitation during underground hydrogen storage in salt caverns, we performed batch reaction experiments using impure salt rocks from the Lotsberg Formation and its caprock (Ernestina Formation) in Fort Saskatchewan, Alberta. The experiments were conducted with brine at a concentration of 250,000 ppm and deionized (DI) water at 10 MPa and 50 °C. We employed X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS) to analyze the salt rock samples before and after reactions in H 2 –brine–salt rock and helium–brine–salt rock systems. Also, inductively coupled plasma-optical emission spectroscopy (ICP-OES), and gas chromatography (GC) analyses were used to identify brine ion changes and gas generation, respectively. The analyses aimed to identify potential reactions of salt rocks in aqueous phases in the presence and absence of H 2 . Both XRD and SEM results reveal mineral dissolution in the aqueous phase, with H 2 having no observable impact on the dissolution processes. ICP-OES analysis shows that the presence of H 2 does not significantly affect the concentration of cations and anions in the solution compared to reactions without H 2 . Additionally, GC analysis indicates that there is no gas generation after reactions. These findings suggest that nonreductive dissolution is the predominant reaction in the H 2 –brine–salt rock systems and that the presence of H 2 does not induce observable redox reactions under experimental conditions. Redox reactions are undesirable as they can lead to byproduct generation, consuming and contaminating the stored hydrogen.