Hydrogen storage in depleted gas reservoirs using methane cushion gas: An interfacial tension and pore scale study
Frank E. Viveros, Oscar E. Médina, Iván Moncayo-Riascos, Maksim Lysyy, Pedro Benjumea, Farid B. Cortés, Camilo A. Franco
Abstract
The flow behavior of hydrogen in the presence of other gases remains underexplored, creating a gap in its field implementation for large-scale seasonal storage in geological structures. This study investigates hydrogen flow in a multiphase system through rock-fluid interactions at the pore scale under high pressure. Molecular dynamic simulations were employed to determine interfacial tension (IFT) for H 2 , H 2 -CH 4 , and CH 4 systems with 72.01, 69.97, and 68.76 mN m −1 values, respectively. Experiments using a micromodel simulating a porous sandstone reservoir saturated with deionized water were conducted at 30 bar and room temperature (20 °C). Gas injections (CH 4 , H 2 , and H 2 -CH 4 in a 1:1 ratio) were performed at three rates (0.1, 1, 10 mL h −1 ). Image segmentation and analysis were performed to measure initial porous medium saturation, gas dissolution, contact angles, gas recovery, and residual gas saturation. Results show that at high N Ca (10.0 mL h −1 ), H 2 saturation exceeded 44 %, while at low N Ca (0.1 mL h −1 ), Sgi decreased threefold. H 2 -CH 4 mixtures exhibited higher porous medium saturation compared to individual gases. Dissolution times at low N Ca were 73,200 s for H 2 , 37,800 s for H 2 -CH 4 , and 37,600 s for CH 4 . During imbibition, N Ca increased in the order H 2 < H 2 -CH 4 < CH 4 , corresponding to decreasing IFT. Contact angles showed minimal variation, indicating weak wettability towards the gases, with H 2 /water systems ranging from 143 to 162°, CH 4 /water systems from 131 to 153°, and H 2 -CH 4 /water from 135 to 157°. These findings provide crucial insights into hydrogen flow in multiphase systems, contributing to its potential implementation for energy storage.