Modelling the flow of a gas mixture through a porous medium, with account being taken of the modelling scale

The flow of gases through porous media is a common physical phenomenon occurring not only in the natural environment but also in a number of technical applications, including the industry. The flow of gases through rock porous media takes place during exploitation of numerous energy resources – not only during the excavation of hard coal (the flow of a gas mixture through goaf with caving) but also in the course of exploiting crude oil and natural gas (the flow through shale rocks). The issue of gases flowing through porous media is also related to the underground sequestration of acid gases in the rock mass, including inactive headings of liquidated underground mines. During gas injection into the rock mass, gases with different physical properties, i.e. the gas being injected and the gas present in the rock mass, mix together. The mechanism responsible for this phenomenon is the physical dispersion in the porous medium. The article presents the results of numerical tests on the mixing process of gases with different physical properties in a porous medium for the flow defined by the N-S equations (the pore scale-microscale) and for flow defined by the Darcy’s model (the deposit scale-macroscale). The numerical tests conducted helped to determine the concentration distributions for the gases in the media under analysis.