Microfluidics-based analysis of dynamic contact angles relevant for underground hydrogen storage.

Underground Hydrogen Storage (UHS) is an attractive technology for large-scale (TWh) renewable energy storage. To ensure the safety and efficiency of the UHS, it is crucial to quantify the H 2 interactions with the reservoir fluids and rocks across scales, including the micro scale. This paper reports the experimental measurements of advancing and receding contact angles for different channel widths for a H 2 /water system at P = 10 bar and T = 20 °C using a microfluidic chip. To analyse the characteristics of the H 2 flow in straight pore throats, the network is designed such that it holds several straight channels. More specifically, the width of the microchannels range between 50 μ m and 130 μ m. For the drainage experiments, H 2 is injected into a fully water saturated system, while for the imbibition tests, water is injected into a fully H 2 -saturated system. For both scenarios, high-resolution images are captured starting the introduction of the new phase into the system, allowing for fully-dynamic transport analyses. For better insights, N 2 /water and CO 2 /water flows were also analysed and compared with H 2 /water. Results indicate strong water-wet conditions with H 2 /water advancing and receding contact angles of, respectively, 13°–39°, and 6°–23°. It was found that the contact angles decrease with increasing channel widths. The receding contact angle measured in the 50 μ m channel agrees well with the results presented in the literature by conducting a core-flood test for a sandstone rock. Furthermore, the N 2 /water and CO 2 /water systems showed similar characteristics as the H 2 /water system. In addition to the important characterization of the dynamic wettability, the results are also crucially important for accurate construction of pore-scale simulators. [Display omitted] • Dynamic contact angles for H 2 /water/glass system were measured using a microchip. • H 2 dynamic contact angles decreased with increasing channel width. • H 2 advancing and receding contact angles were found, respectively, 13–39° and 6–23°. • Similar contact angles were found for H 2 , N 2 and gaseous CO 2. [ABSTRACT FROM AUTHOR]