Ostwald Ripening in Underground Gas Storage

Underground gas storage supports climate mitigation and energy transition strategies by enabling long-term carbon sequestration and seasonal hydrogen storage. A key mechanism governing gas redistribution is Ostwald ripening—curvature-driven mass transfer between trapped gas ganglia. While ripening is well understood in open systems, its dynamics in geometrically confined porous media remain poorly characterized. We present high-resolution microfluidic experiments that capture the evolution of trapped hydrogen over weeks in heterogeneous pore structures. A two-stage dynamic emerges: rapid local equilibration among neighboring bubbles, followed by slow global depletion driven by long-range diffusion. Based on these insights, we develop a continuum model that couples microscale P_c–S relationships with macroscopic diffusion. The model, validated without fitting parameters, accurately predicts saturation evolution and collapses data across conditions. This work provides the first predictive link between pore-scale structure and reservoir-scale gas redistribution.