The interaction between methane and water in shale nanopores governs gas recovery and water flowback efficiency yet remains poorly understood at the nanometer scale. Here we combine contrast-matching ultra- and small-angle neutron scattering, cryo-SEM, dynamic vapor sorption, and Wood’s metal impregnation to directly visualize and quantify gas–water distribution across connected pore-fracture networks in Longmaxi shale. We show that water preferentially occupies nanopores due to its stronger surface affinity, displacing methane and reducing adsorption capacity, while microfractures act as conduits for methane migration and early water return. Pore-fracture connectivity controls fluid accessibility, saturation dynamics, and long-term production performance. These findings provide direct experimental evidence of competitive adsorption and nanoconfined phase behavior in shale, offering a mechanistic framework for optimizing hydraulic fracturing and minimizing environmental impact in unconventional gas development.
Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025