The movability of water in shale nanopores intensely affects the transport and storage of other fluids, and plays an important role in the geological water cycle. To investigate the movability, three shale samples were used to conduct flow experiments using the “steady‐state and step‐by‐step depressurization” method. The experimental results show that the movability of water strongly depends on the pressure gradient. Two water‐related mechanisms, “shear fluidity” and “electro‐viscous effect”, are primarily responsible for the difference in movability between the free water and bound water. The flow of water in these samples deviates from Darcy’s law, and the threshold pressure gradient (TPG) is observed. When the pressure gradient is higher than the TPG, water starts to flow, and the permeability increases with increasing pressure gradient. Based on the analysis of the solid‐liquid interfacial forces, the water in the shale was quantitatively classified into four types (L1 , L2 , L3 and L4 ) according to its movability. The calculation results indicate that most of the water, which could be up to 74.46%~89.73%, is immovable under the experimental conditions. The proportion of movable water increases with increasing pressure gradient, and the relation can be expressed by a quadratic function. The moving ratio was defined as the ratio of the volume of water involved in flow to the total pore volume. The correlation between the moving ratio and permeability is a power function with exponents ranging from 1.16 to 1.43, indicating that the water permeability is sensitive to the moving ratio.

Shale gas equilibrates through gas‐liquid‐solid interactions in reservoirs, but the role of moisture is rarely investigated. To determine how adsorbed water influences methane behavior, three carboniferous shale samples from the Qaidam Basin, China, were humidified at five levels up to a relative humidity of 89%, and their methane capacities at pressures up to 12 MPa were studied. The experimental results indicate that two water‐related mechanisms, “water blocking for methane transport” and “surface competition for gas‐solid interaction,” are primarily responsible for the methane capacity variations. A compositional comparison suggests that a high abundance of clay minerals plays a favorable role in methane migration by retaining water in interlayer pores. Based on the experimental data, an optimized method for calculating the adsorption amount based on an approximation of density distribution is proposed. The model predicts the average thickness of the adsorption layer and the adsorbed methane density distribution on the surface at a given pressure. The methane adsorption layer “thins” in a stepped pattern by up to 45% in the presence of water, with little further change observed at relative humidities greater than 75% in the studied samples.