Investigation of Pore-Scale Phenomena for Underground Gas Storage Through Micromodels

The global need to reduce carbon emissions and improve energy security is driving the development of innovative energy production and storage strategies. One promising solution for large-scale energy storage is Underground Hydrogen Storage (UHS), which benefits from the long-standing experience in Underground Gas Storage (UGS). However, targeted analyses are essential to assess the limits and potential of this application by properly characterizing the differences in the behavior of hydrogen compared to natural gas in underground saturated porous media. Phenomena at the macro scale are intrinsically linked to behaviors at much smaller scales, highlighting the necessity of detailed experimental investigations. Thus, addressing challenges like storage capacity, injectivity, and safety in underground systems demands a deep comprehension of fluid dynamics at the pore scale. Microfluidic devices are recognized as valuable tools for such a scope. These small-scale systems can mimic porous media networks, enabling direct observation of fluid dynamics and chemical interactions at the pore-scale. Despite limitations, such as their two-dimensional nature, they offer significant advantages over traditional methods, including real-time fluid flow visualization, reusability, and customizable flow patterns. This research focuses on the investigation of pore-scale phenomena through microfluidic devices, with an emphasis on the experimental setup and procedures for fluid flow tests. Early results on gas drainage and water imbibition tests revealed variations in percolation patterns and saturations due to key factors such as fluid type and injection velocity. These findings provide a foundation for advancing our understanding of hydrogen storage in depleted gas reservoirs.