Knudsen-Like Scaling May Be Inappropriate for Gas Shales

The author writes that the generally accepted Knudsen diffusion in shales is based on a mistranslation of the flow physics and may give theoretically unsound predictions of the increased permeability of shales to gas flow. This increase of permeability comes from the micropores, fine-scale microfractures, and cracks. The nanopores in shales provide gas storage by sorption and capillary condensation of heavier gas components. In the smallest nanopores, even methane molecules are increasingly ordered and resemble liquid more than gas.