Nonwetting Behavior of Hydrogen with a Sandstone Reservoir and Shale Caprock

As interest in hydrogen (H₂) grows as an emerging energy resource, research is focused on quantifying the fundamental properties of H₂ storage in porous media. Here, we assessed the wetting properties of H₂ by measuring the captive contact angle of H₂ with brine-saturated subsurface caprock and reservoir rock at reservoir temperatures and pressures. We performed measurements on Upper Fayetteville Shale as a caprock analog and Berea Sandstone to represent a saline reservoir storage rock. We measured contact angle at three temperatures (23 °C, 45 °C, and 70 °C), three pressures (10.3, 34.5, and 51.8 MPa), one salinity (50,000 ppm of NaCl), and several bubble sizes ranging from 400 to 2500 μm. All contact angle values ranged between 7° and 30°, indicating a water-wet system. Our measurements showed that there was no trend or dependency of the contact angle value with sample type (shale and sandstone), temperature, pressure, surface roughness, or salinity. A weak negative linear correlation was observed between bubble size and contact angle; however, H₂ remained nonwetting.