Multiparameter Analysis of Gas Transport Phenomena in Shale Gas Reservoirs: Apparent Permeability Characterization

The large amount of nanoscale pores in shale results in the inability to apply Darcy’s law. Moreover, the gas adsorption of shale increases the complexity of pore size characterization and thus decreases the accuracy of flow regime estimation. In this study, an apparent permeability model, which des...

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Bibliographic Details
Published in:Scientific reports 2018-02, Vol.8 (1), p.2601-14, Article 2601
Main Authors: Shen, Yinghao, Pang, Yu, Shen, Ziqi, Tian, Yuanyuan, Ge, Hongkui
Format: Article
Language:English
Subjects:
639/4077/4082/4090
704/2151/2809
Adsorption
Compressibility
Diffusion
Flow
Gas flow
Humanities and Social Sciences
Membrane permeability
multidisciplinary
Permeability
Pore size
Regression analysis
Science
Science (multidisciplinary)
Shale
Shale gas
Shales
Size distribution
Transition flow
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Summary:The large amount of nanoscale pores in shale results in the inability to apply Darcy’s law. Moreover, the gas adsorption of shale increases the complexity of pore size characterization and thus decreases the accuracy of flow regime estimation. In this study, an apparent permeability model, which describes the adsorptive gas flow behavior in shale by considering the effects of gas adsorption, stress dependence, and non-Darcy flow, is proposed. The pore size distribution, methane adsorption capacity, pore compressibility, and matrix permeability of the Barnett and Eagle Ford shales are measured in the laboratory to determine the critical parameters of gas transport phenomena. The slip coefficients, tortuosity, and surface diffusivity are predicted via the regression analysis of the permeability data. The results indicate that the apparent permeability model, which considers second-order gas slippage, Knudsen diffusion, and surface diffusion, could describe the gas flow behavior in the transition flow regime for nanoporous shale. Second-order gas slippage and surface diffusion play key roles in the gas flow in nanopores for Knudsen numbers ranging from 0.18 to 0.5. Therefore, the gas adsorption and non-Darcy flow effects, which involve gas slippage, Knudsen diffusion, and surface diffusion, are indispensable parameters of the permeability model for shale.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-018-20949-2