Multi-scale Real Gas Transport in Shale Matrix

Date
2018-03-05
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Abstract
As one of the clean energy resources, shale gas significantly reduces greenhouse gas emissions. The description of the gas transport behavior in shale rocks is one of the numerous challenges for further studies on economically developing shale gas reservoirs. In this work, real gas transport in the multi-scale porous structure of shale matrix is studied. Three models are, respectively, built at scales of single pores, a dual-porosity shale rock and a shale gas reservoir. These models are well validated with experimental, simulation and field data. Results indicate that increasing a taper ratio and an aspect ratio weakens a real gas effect and lowers bulk gas transport, including viscous flow and Knudsen diffusion, while the surface diffusion conductance first increases and decreases afterwards. More tortuous and complex pores weak the dominancy of the shale matrix in a dual-porosity shale rock. Transport conductance owns negative relationships with fractal dimensions of pore size and tortuosity of shale matrix, and positive relationship with minimum pore size. Gas production is underestimated without considering nano-scale pore size distribution-based gas transport mechanisms. A higher fractal dimension of a pore size and a higher variance result in higher cumulative gas production and lower sensitivity of gas production to a nano-scale pore size distribution.
Description
Keywords
shale gas, nanopore, Energy
Citation
Xu, J. (2018). Multi-scale Real Gas Transport in Shale Matrix (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/13061