In this paper, we present the results of steady-state methane flow in carbon nanotubes under reservoir conditions by use of nonequilibrium-molecular-dynamics simulations. The results show that the nanotubes contain a mobile adsorbed phase. The mobility leads to a significant shift up in the flow-velocity profile of the fluid across the diameter of the nanotube. The contribution of the adsorbed phase to transport is significant in capillaries with size smaller than 10 nm. The results indicate that gas transport in organic nanocapillaries in resource shales could be influenced by the adsorbed phase. Hence, a new kerogen-permeability model is proposed that considers the presence of a mobile adsorbed phase. We use the bundle-of-capillaries approach and estimate that the permeability correction for the organic nanopores of Marcellus shale increases more than 50%. Further research is required to consider the transport of the other hydrocarbons and their mixtures.