Comparative analysis of hydrogen mixing with a selection of cushion gases in underground hydrogen storage during injection and production
Karol Dąbrowski, Łukasz Klimkowski, Rafał Smulski, Szymon Kuczyński, Stanisław Nagy
Abstract
This study investigates the dynamic mixing behavior of hydrogen with selection of cushion gases in the vicinity of the wellbore during the critical phases at the beginning of the injection cycle and the end of the production cycle. The evolution of the mixing zone during the displacement of hydrogen-methane, nitrogen, and carbon dioxide in the rock core is determined utilizing core flooding measurements. Berea sandstone sample and cores from the potential geological structure for underground hydrogen storage in Poland are studied. The evolution of breakthrough profiles during hydrogen-cushion gas displacement is measured using X-ray scanner and Raman spectroscopy at the core outlet. The procedure for different thermodynamic and kinematic conditions allowed us to find the effective relationship between diffusion and the experimental mixing coefficient. The simplified model is used for a direct comparison of a laboratory core-scale experiment with near-wellbore zone field simulations. The results show that the most favorable cushion gas for underground hydrogen storage is nitrogen while the least favorable is carbon dioxide.