Experimental measurements and water transfer models for the drying of argillite

► A gas overpressure appears in COx argillite at the beginning of a drying process. ► Water effective permeability can be back-calculated from the mass vs. time monitoring. ► A purely darcean model is not adapted to explain COx argillite drying due to the material low permeabilities. ► A purely darcean model provides a satisfactory approximation of the water effective permeability. ► The relative permeabilities cannot be deduced from the van Genuchten approximation of the capillary curve.