Investigation of methane adsorption and its effect on gas transport in shale matrix through microscale and mesoscale simulations

• Published in: International journal of heat and mass transfer 2016-07, Vol.98 (C), p.675-686
• Main Authors: Li, Zhong-Zhen, Min, Ting, Kang, Qinjun, He, Ya-Ling, Tao, Wen-Quan
• Format: Article
• Language: English
• Subjects: Adsorption; Earth Sciences; Energy Sciences; Lattice Boltzmann method; Mathematical analysis; Methane; Molecular dynamics; Navier-Stokes equations; Permeability; Shale; Shale matrix; Simulation; Slippage
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2016.03.039

•Methane adsorption in nanopores of shale matrix is simulated by molecular dynamics.•Effects of pressure, pore size and solid surface on adsorption are studied.•Upscaling of molecular dynamics simulation results to lattice Boltzmann simulations.•Effects of adsorption and slippage on shale matrix permeability are explored. Methane adsorption and its effect on fluid flow in shale matrix are investigated through multi-scale simulation scheme by using molecular dynamics (MD) and lattice Boltzmann (LB) methods. Equilibrium MD simulations are conducted to study methane adsorption on the organic and inorganic walls of nanopores in shale matrix with different pore sizes and pressures. Density and pressure distributions within the adsorbed layer and the free gas region are discussed. The illumination of the MD results on larger scale LB simulations is presented. Pressure-dependent thickness of adsorbed layer should be adopted and the transport of adsorbed layer should be properly considered in LB simulations. LB simulations, which are based on a generalized Navier–Stokes equation for flow through low-permeability porous media with slippage, are conducted by taking into consideration the effects of adsorbed layer. It is found that competitive effects of slippage and adsorbed layer exist on the permeability of shale matrix, leading to different changing trends of the apparent permeability.