In-situ hydrogen wettability characterisation for underground hydrogen storage

Abstract

Hydrogen storage in subsurface aquifers or depleted gas reservoirs represents a viable long-term energy storage solution. There is currently a scarcity of subsurface petrophysical data for the hydrogen system. In this work, we determine the wettability and Interfacial Tension (IFT) of the hydrogen-brine-quartz system using captive bubble, pendant drop and in-situ 3D micro-Computed Tomography (CT) methods. Effective contact angles ranged between 29° and 39° for pressures 6.89–20.68 MPa and salinities from distilled water to 5000 ppm NaCl brine. In-situ methods, novel to hydrogen investigations, confirmed the water-wet system with the mean of the macroscopic and apparent contact angle distributions being 39.77° and 59.75° respectively. IFT decreased with increasing pressure in distilled water from 72.45 mN/m at 6.89 MPa to 69.43 mN/m at 20.68 MPa. No correlation was found between IFT and salinity for the 1000 ppm and 5000 ppm brines. Novel insights into hydrogen wetting in multiphase environments allow accurate predictions of relative permeability and capillary pressure curves for large scale simulations. • Comprehensive characterisation of hydrogen-brine-quartz wettability. • Novel investigation of in-situ contact angle for underground hydrogen storage. • Contact angle on smooth rock surface 27–39° and at in situ conditions 39.77–59.75°. • Deficit curvature analysis confirms a water-wet system. • IFT from 72.45 mN/m at 6.89 MPa to 69.43 mN/m at 20.68 MPa.