Flow alterations induced by biofilm clogging in underground hydrogen storage

Underground hydrogen storage (UHS) is a promising option for large-scale, seasonal energy storage, but microbial activity poses significant challenges. Hydrogen can stimulate indigenous anaerobic microorganisms, leading to biofilm formation on pore surfaces and potential clogging. This study develops random and regular pore-scale models with biofilm coverage to simulate single- and two-phase flow. Key factors, including porosity, biofilm coverage, structural parameters, and wettability, are systematically analyzed. Results show that biofilms reduce flow velocity, create localized stagnant regions, and cause an exponential decline in hydraulic conductivity. Permeability reduction is negatively correlated with initial porosity, with throat size identified as the dominant controlling factor. In two-phase flow, biofilms enhance capillary-dominated hydrogen displacement, although reduced wettability partially offsets this effect. Overall, this work provides pore-scale insights into biofilm-induced flow alterations and offers guidance for optimizing UHS performance.