In this paper, we firstly investigate the natural gas storage and transport behavior in simple geometries such as two parallel-plates model and carbon nanotube model by using molecular dynamics simulation. Then, we combined molecular simulation (MS) with digital rock reconstruction technique to investigate the natural gas storage and transport behavior in ultra-low permeable shale matrices containing nano-scale pore structures. 3-D nano-pore structure is recreated using the Markov Chain Monte Carlo (MCMC) simulation based on the 2-D scanning electron microscopy (SEM) image of shame sample. Generally, single molecular layer adsorption in simple geometries is observed and the adsorption isotherm can be fitted by Langmuir type of adsorption isotherm. Besides, non­continuum features of gas transport behaviors such as slippery boundary and Knudsen diffusion dominated flow demonstrate that conventional Darcy’s equation may not adequately describe the flow behavior in shale reservoir. Knudsen diffusivity is obtained by molecular simulation which could be beneficial in reservoir simulation. The combination of MCMC and molecular simulation (MS) offers a unique approach towards investigating gas transport in complex porous networks in the shale formation.

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