Salinity influence on underground hydrogen storage: Insights from molecular dynamics and pore-scale analysis

• Published in: International journal of hydrogen energy 2024-03, Vol.60, p.959-975
• Main Authors: Medina, Oscar E., Gallego, Jhon F., Moncayo-Riascos, Ivan, Lysyy, Maksim, Benjumea, Pedro Nel, Cortés, Farid B., Franco, Camilo A.
• Format: Article
• Language: English
• Subjects: Aquifers; Hydrogen dissolution; Molecular dynamic simulation; Pore-scale analysis; Underground hydrogen storage
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2024.02.073

The main objective of this study is to investigate underground hydrogen storage in H2/brine systems, considering the different brines and the effect of hydrogen flow. This study is divided into four stages, including i) estimation of hydrogen-brine interfacial tension (IFT) varying type of brine, salinity, and pressure, ii) hydrogen drainage and imbibition experiments in a micromodel device to describe hydrogen displacement and trapping mechanisms, iii) quantification of hydrogen dissolution kinetics and contact angles in H2/brine/glass microfluidic system, and iv) hydrogen hysteresis cycles. H2/brine IFT was slightly modified with salinity and type of brine, while in the pressure range evaluated, there were no significant variations. The highest IFTs were found at 74.4, 77.9, and 83.0 mN m−1, for KCl + NaCl at 0.5, 2.0 and 4.0 M, respectively. Capillary numbers during drainage and imbibition were calculated according to IFTs. The capillary number is decreased with salinity and fell in the order KCl + NaCl > NaCl > KCl. Considering microfluidic experiments, the initial hydrogen saturation after drainage is affected by salinity, type of brine, and pressure, obtaining the increasing trends: KCl + NaCl