Exploring the Potential and Geomechanical Implications of Underground Hydrogen Storage in the Broom Creek Saline Aquifer

ABSTRACT: This study evaluates the viability and safety of underground hydrogen storage (UHS) within the Broom Creek Formation, North Dakota's Williston Basin, focusing on enhancing the transition to sustainable energy sources. Employing a comprehensive approach that combines 3D hydro-mechanical simulations with field data, we investigate the formation's capacity for hydrogen storage, the implications of cyclic hydrogen injection and extraction, and the overall integrity of the storage method. The simulations, developed using CMG-Builder software, explore various operational scenarios, including different injection-production cycles and volumes, to assess recovery efficiency and geomechanical stability. Key findings indicate that hydrogen recovery ratios exceed 80% across scenarios, with the optimal scenario involving six months of continuous injection and production yielding the highest recovery ratio (84.85%). Furthermore, varying the injected hydrogen volume demonstrates the system's adaptability, with recovery efficiencies remaining robust. Geomechanical simulations confirm the absence of shear or tensile failures, ensuring the geomechanical safety of UHS operations under examined conditions. This research underscores the potential of the Broom Creek Formation for large-scale, cost-effective, and eco-friendly hydrogen storage, highlighting its significance in addressing seasonal energy demand fluctuations and contributing to environmental sustainability goals. 1. INTRODUCTION To meet the global target of keeping the average surface temperature rise below 2° Celsius, as set in the Paris Agreement, a shift from fossil fuels to sustainable energy sources is crucial. This transformation directly aligns with the urgent need to address climate change and the growing demand for sustainable energy (Merzoug & Okoroafor, 2023). Hydrogen emerges as a key player in this transition. It holds the potential to significantly reduce carbon emissions in major sectors such as petroleum industry, power generation, transport, and heating, thereby achieving environmental sustainability (Alms et al., 2023). Among various storage methods, underground hydrogen storage is distinguished by its high capacity and cost-effectiveness. This approach entails storing hydrogen in geological formations, including depleted oil and gas reservoirs, aquifers, or artificially created salt caverns (Zivar et al., 2021). Miocic et al. (2023) compared the above-ground options like pipelines and tanks, which have limited storage and discharge capacities (MW hours, lasting hours to days), to underground solutions like salt caverns and porous media, such as depleted oil and gas fields or saline aquifers, that can supply energy on a substantially larger scale. Specifically, deep saline aquifers offer significantly greater storage capacities than salt caverns, with differences spanning several orders of magnitude. Additionally, their widespread geographical availability and extensive storage potential render saline aquifers a highly promising and cost-effective choice for long-term hydrogen storage (Raad et al., 2022).