Experimental characterization of $${\text {H}}_2$$/water multiphase flow in heterogeneous sandstone rock at the core scale relevant for underground hydrogen storage (UHS)

Abstract

Geological porous reservoirs provide the volume capacity needed for large scale underground hydrogen storage (UHS). To effectively exploit these reservoirs for UHS, it is crucial to characterize the hydrogen transport properties inside porous rocks. In this work, for the first time in the community, we have performed $${\text {H}}_2$$ H 2 /water multiphase flow experiments at core scale under medical X-ray CT scanner. This has allowed us to directly image the complex transport properties of $${\text {H}}_2$$ H 2 when it is injected or retracted from the porous rock. The important effective functions of capillary pressure and relative permeability are also measured, for both drainage and imbibition. The capillary pressure measurements are combined with MICP data to derive a receding contact angle for the $${\text {H}}_2$$ H 2 /water/sandstone rock system. The rock core sample is a heterogeneous Berea sandstone (17 cm long and 3.8 cm diameter). Our investigation reveals the interplay between gravitational, capillary, and viscous forces. More specifically, it illustrates complex displacement patterns in the rock, including gravity segregation, enhancement of spreading of $${\text {H}}_2$$ H 2 due to capillary barriers, and the formation of fingers/channel during imbibition which lead to significant trapping of hydrogen. These findings shed new light on our fundamental understanding of the transport characteristics of $${\text {H}}_2$$ H 2 /water relevant for UHS.

Pore-scale visualization of hydrogen storage in a sandstone at subsurface pressure and temperature conditions: Trapping, dissolution and wettability

“…Similar to other fluid-fluid displacement processes such as CO 2brine and CH 4 -brine, capillary trapping and wettability are of importance to H 2 -brine systems [32], as the amount of fluid trapping directly affects recovery efficiency [33][34][35]. The cyclic nature of an underground H 2 storage system renders these phenomena (capillary trapping and wettability) even more critical due to the repeated occurrence of drainage and imbibition cycles.…”

Lab on a chip for a low-carbon future

“…To our knowledge, only few laboratory studies assessing porous media H 2 flow are available at the time of writing. [95][96][97] Relevant publications mostly use numerical simulation 98 to test new conceptual approaches towards e.g., feasible strategies and impact of geological heterogeneity. Overall, most simulations use scaled or extrapolated flow data not specifically measured for H 2 ; this approach represents a significant uncertainty.…”

“…Overall, pore-scale displacement and trapping mechanisms are widely investigated for CO 2 storage, [104][105][106] but remain largely unaddressed for hydrogen. To the best of our knowledge, the first systematic experimental study on a H 2 / water/sandstone rock system at the core scale (mm cm −1 scale) under shallow and deep aquifer pressure and temperature conditions was only performed recently, 96 providing useful X-ray CT visualization of the flow behavior of hydrogen in initially water saturated rock for both drainage and imbibition. The authors also determined the wettability of the system and identified complex displacement patterns including gravity segregation and enhancement of spreading.…”

“…To our knowledge, only few laboratory studies assessing porous media H 2 flow are available at the time of writing. 95–97 Relevant publications mostly use numerical simulation 98 to test new conceptual approaches towards e.g. , feasible strategies and impact of geological heterogeneity.…”

Pore‐Scale Observations of Hydrogen Trapping and Migration in Porous Rock: Demonstrating the Effect of Ostwald Ripening

“…However, the hydrogen needs to be stored until needed, particularly bearing in mind the intermittent nature of renewable power generation. At the scale required, running to several Gt (10 12 kg) at a global scale, underground storage in depleted hydrocarbon reservoirs, saline aquifers or salt caverns is required (Aftab et al., 2022; Ali et al., 2021; Boon & Hajibeygi, 2022; Hematpur et al., 2023; Muhammed et al., 2022; Raad et al., 2022).…”