Effective stress effect and slippage effect of gas migration in deep coal reservoirs

Liu, Chao; Yu, Beichen; Zhao, Hongbao; Hong, Zequn; Tian, Zhuangcai; Zhang, Dongming; Liu, Yixin

doi:10.1016/j.ijrmms.2022.105142

Cited by 15 publications

(5 citation statements)

References 36 publications

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“…Within tight coal where micropores and nanopores are predominant, the contribution of the slippage effect on coal permeability should not be discounted. Therefore, a series of experiments and analytical solutions were developed to quantify the slippage effect in tight coal. − Since the pore structure in coal possessed stress-dependent properties, Zhang et al . considered porosity pressure sensitivity and derived the Knudsen diffusion coefficient and slippage factor based on the concept of the dust gas model (DGM) proposed by Mason and Malinauskas .…”

Section: Introductionmentioning

confidence: 99%

Fractal Apparent Permeability Model for Coal under the Coupling Actions of Stress and Water

Duan

Gao

et al. 2023

Energy Fuels

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The environment of coal reservoirs is complex and variable, with various factors, not independent, but interlocking and coupled. However, their coupling effects have rarely been considered in previous theoretical studies. In addition, when a fractal theory was applied to analyze the permeability of coal, the linkage between fractal dimensions and the pore radius under external factors has usually been ignored. In this study, two parameters, pore compressibility and dynamic water saturation, were introduced to quantitatively represent the internal interactions between stress and water. Based on the results, dynamic fractal dimensions under the coupling actions of stress and water were obtained by considering variation in the pore radius and the assignment status of gas and water, following which an apparent permeability model of coal, with dynamic fractal dimensions, was established. The newly developed model was verified by reference to published experimental data. The results showed that stress dominated changes in the fractal dimension for pore-size distribution under the coupling actions of stress and water; however, changes in the fractal dimension for tortuosity was dominated, in turn, by stress and water. Subsequently, it was found that the fractal apparent permeability model could match the experimental data well. It revealed that the newly developed model could predict the evolution of coal permeability under dynamic changes in stress and water. Further, under the coupling actions of stress and water, the apparent permeability of coal possessed a positive correlation with the fractal dimension for pore-size distribution or water-dominated fractal dimension for tortuosity, while it was negatively correlated with the critical capillary radius or stress-dominated fractal dimension for tortuosity. In addition, the evolution of the apparent permeability was consistent with specific fractal dimensions and dynamic fractal dimensions, but the evolution of the slippage factor revealed an opposite result. Consequently, this initiates a new analytical perspective into investigating change mechanisms relating to coal permeability.

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Section: Introductionmentioning

confidence: 99%

Fractal Apparent Permeability Model for Coal under the Coupling Actions of Stress and Water

Duan

Gao

et al. 2023

Energy Fuels

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“…e damage variable is introduced according to the characteristics of microdefects in the studied material, which is a measure of the degree of damage and deterioration in the material. However, in engineering practice, more attention is paid to the deterioration evolution of macro physical and mechanical properties during the damage process [24,27,[41][42][43]. erefore, macro quantity is often used to de ne the damage variable, and the macro quantity as the damage variable must have clear physical meaning, easy to measure (determine), and the variation law is consistent with the evolution process of material fatigue mechanical properties.…”

Section: Discussionmentioning

confidence: 99%

Study on Damage Law of Raw Coal Based on Different Characterization Methods

Duan

Tang

et al. 2022

Advances in Civil Engineering

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The different damage variables equation based on strain, energy dissipation, acoustic emission (AE), and permeability characteristics under tiered cyclic loading were defined. The damage variables based on different characteristics were compared, analyzed, and found that there are similarities and differences between them. The results show that: (1) the law curve of single cycle damage based on residual deformation and permeability is the same. With the increase of cycle times, it decreases first and then gently increases, increased sharply before the failure. However, the law curve of single cycle damage based on energy dissipation and AE ring count shows that it first increases slowly and the adjacent failure increases rapidly. (2) The cumulative damage evolution law based on residual deformation and permeability show an obvious three-stage pattern; that is, first accelerates, then slows down, and then accelerates again. However, the cumulative damage evolution law based on energy dissipation and AE ring count shows an obvious two-stage pattern, that is, first gently increases, and increased sharply before the failure.

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“…The effects of effective stress may be comparable to those of slippage effects. Liu et al 39 studied the effective stress effect and slippage effect of gas migration in deep coal reservoirs. They found that the decrease in the pore pressure during the coalbed methane extraction can induce significant slippage effects and effective stress change.…”

Section: Dynamic Hydro‐mechanical Coupling Problems In Heterogeneous ...mentioning

confidence: 99%

High‐order models for hydro‐mechanical coupling problems in multiscale porous media

Zuo,

Yang,

Cui

et al. 2024

Numerical Meth Engineering

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An accurate prediction of nonlinear hydro‐mechanical (HM) coupling in subsurface structures with pronounced heterogeneity at multiple spatial scales is still an open topic and crucial for numerous engineering applications, for example, hydraulic fracturing and enhanced geothermal systems. In this study, novel high‐order multi‐scale asymptotic solutions are developed to accurately capture the locally oscillating characteristics of gas flow and solid displacement fields at multiple scales. First, the formal macro‐meso two‐scale asymptotic expansion is performed to establish the homogenized solutions and macro‐meso high‐order models which can predict the HM coupling problems at the macroscale and mesoscale. By directly expanding the cell functions defined at the mesoscale to the microscopic levels, the high‐order two‐scale expansion for the mesoscopic cell functions is built, and the upscaled relations for the flow parameters and constitutive coefficients from the microscale to the mesoscale and macroscale are developed correspondingly. The multi‐scale low/high‐order models are established by combining the high‐order expansion of all cell functions at the mesoscale and the developed macro‐meso two‐scale models. The main contributions are that the present approaches follow the reverse thought processes of reiteration homogenization methods, and offer a very innovative and efficient way to establish high‐accuracy high‐order models for the nonlinear HM coupling problems in the heterogeneous porous medium with any number of spatial scales. The effectiveness and accuracy of the present solution are validated by several representative cases with different constitutive coefficient contrasts. The results demonstrate that the high‐order solutions provide an accurate prediction for gas transport and solid deformation of heterogeneous porous media with multi‐scale configurations.

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Effective stress effect and slippage effect of gas migration in deep coal reservoirs

Cited by 15 publications

References 36 publications

Fractal Apparent Permeability Model for Coal under the Coupling Actions of Stress and Water

Fractal Apparent Permeability Model for Coal under the Coupling Actions of Stress and Water

Study on Damage Law of Raw Coal Based on Different Characterization Methods

High‐order models for hydro‐mechanical coupling problems in multiscale porous media

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