Hydrogen-induced calcite dissolution in Amaltheenton Formation claystones: Implications for underground hydrogen storage caprock integrity

With the rising potential of underground hydrogen storage (UHS) in depleted oil and gas reservoirs or deep saline aquifers, questions remain regarding changes to geological units due to interaction with injected hydrogen. Of particular importance is the integrity of potential caprocks/seals with respect to UHS. The results of this study show significant dissolution of calcite fossil fragments in claystone caprock proxies that were treated with a combination of hydrogen and 10 wt% NaCl brine. This is the first time it has been exper-imentally observed in claystones. The purpose of this short communication is to document the initial results that indicate the potential alteration of caprocks with injected hydrogen, and to further highlight the need for hydrogen-specific studies of caprocks in areas pro-posed for UHS.(c) 2022 The Author(s). Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC. This is an open access article under the CC BY license (http://creativecommons.org/ licenses/by/4.0/).

Automated summary

With the potential of underground hydrogen storage (UHS) in depleted oil and gas reservoirs or deep saline aquifers, it is important to understand the changes to geological units caused by the interaction with injected hydrogen. This study reveals significant dissolution of calcite fossil fragments in claystone caprock proxies when treated with hydrogen and NaCl brine, a phenomenon observed for the first time in claystones. These findings highlight the need for hydrogen-specific studies of caprocks in areas proposed for UHS.