The behavior of gas/water migration in geomaterials has attracted much attention in many engineering practices, such as deep geological disposal for radioactive waste, municipal waste landfills, CO2 capture and geological storage, shale gas/sandstone gas/coal-bed methane extraction, and coal mining.

Owing to the prominent capillary sealing capacity of materials with low permeability, gas migration is normally triggered at relatively high gas pressures and is susceptible to changes in liquid saturation and external stress. These hydro-mechanical responses result in unconventional gas migration behaviors, such as non-Darcy flow, preferential flow, gas breakthrough, dilatancy-controlled gas flow, and fracture-controlled gas flow. In addition, it is important to study the migration of groundwater and gas in coal and rock mass for the safe and efficient exploitation of coal resources. These key issues present challenges to experimental and simulation research in gas migration in geomaterials, especially low permeability geomaterials, which cannot be solved using the traditional two-phase flow theory.

This Special Issue aims to deepen our understanding of gas/water migration in geomaterials. We encourage submissions focusing on experimental methodology, mechanism analysis, and numerical simulation that could explain hydro-mechanical responses and reveal the coupling mechanisms of gas migration in low permeability geomaterials at macro- and micro-scale. We welcome both original research and review articles.

Potential topics include but are not limited to the following:

• Water/gas transport in geomaterials
• Hydro-mechanical response of multi-field coupling non-Darcy flow
• Characteristics and mechanisms of capillary/mechanical gas breakthrough
• Capillary imbibition and snap-off pressure
• Dilatancy-controlled gas flow and changes in wettability and capillary resistance
• Characteristic and quantitative analysis of preferential flow
• Gas/hydraulic fracturing and fracture characterization
• Creative methodology for detecting tiny gas flux of ultra-low permeability geomaterials
• Microscopic tests at nano-scale
• Pore-scale modeling