Gas Flow Behavior through Inorganic Nanopores in Shale Considering Confinement Effect and Moisture Content

Abstract

Previous attempts to characterize the gas transport through inorganic nanopores were not fully successful. The presence of an adsorption water film within nanopores is generally overlooked. Moreover, the compound influences of moisture content and confinement effect on critical properties of the gas phase have not been considered before. With the intent of overcoming these deficiencies, a fully coupled analytical model has been developed, in which complex bulk-gas transport mechanisms, moisture content, confinement effect, and various cross-section shapes of nanopores are incorporated. Results show that the confinement effect will significantly enhance the apparent gas permeability when the pore radius is smaller than 5 nm, and the real-gas effect can achieve an average increase of 4.38% when the pore radius falls in the range 1–2 nm. The stress dependence will greatly decrease the apparent gas permeability and the corresponding degree for slitlike inorganic nanopores will slightly increase with the incre...