A transient dual porosity/permeability model for coal multiphysics

Huang, Yifan; Liu, Jishan; Elsworth, Derek; Leong, Yee-Kwong

doi:10.1007/s40948-022-00348-8

Cited by 8 publications

(13 citation statements)

References 44 publications

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“…Coal permeability is a vital physical property of coal reservoirs that plays a significant role in determining the feasibility of CBM production . During CBM production, gas desorption and diffusion from the coal matrix to the fractures lead to coal matrix shrinkage and fracture expansion, which in turn increase the coal permeability.…”

Section: Mathematical Modelmentioning

confidence: 99%

“…Coal permeability is a vital physical property of coal reservoirs that plays a significant role in determining the feasibility of CBM production. 53 During CBM production, gas desorption and diffusion from the coal matrix to the fractures lead to coal matrix shrinkage and fracture expansion, which in turn increase the coal permeability. At the same time, the reduction of gas pressure results in an increase in effective stress within coal reservoirs, leading to pore and fracture closure and a reduction in coal permeability.…”

Section: Porosity and Permeability Equationsmentioning

confidence: 99%

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Spatiotemporal Relationship for Well-Type Selection and Layout Optimization of Surface Wells Based on the REV Permeability Model

Wang,

Lu,

Chen

et al. 2023

ACS Omega

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Section: Mathematical Modelmentioning

confidence: 99%

Section: Porosity and Permeability Equationsmentioning

confidence: 99%

Spatiotemporal Relationship for Well-Type Selection and Layout Optimization of Surface Wells Based on the REV Permeability Model

Wang,

Lu,

Chen

et al. 2023

ACS Omega

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“…As a porous medium with complex structures and multiple components, analyzing gas diffusion in the matrix and evaluating the pressure distribution during this process is challenging but can be dealt with by some simplifications and assumptions. In this study, gas diffusion within a matrix is conceptualized as one-dimensional pressure diffusion within a cubic region, with the fracture wall as the base and a half-matrix spacing as the height. ,, In this case, the boundary conditions can be treated as follows: pressure at the fracture wall is considered to align with fracture pressure, while at the matrix center (located half-matrix spacing away from the fracture wall), due to symmetry, the mass flux is regarded to be zero here. Moreover, in order to obtain an explicit closed-form solution for the one-dimensional diffusion equation to calculate the pressure distribution during gas diffusion, some assumptions need to be introduced to linearize the diffusion equation, including (a) gas contained within matrix is ideal; (b) gas viscosity, porosity, and permeability are uniform and remain unchanged; and (c) the impact of gas sorption is negligible.…”

Section: Model Developmentmentioning

confidence: 99%

“…Experimental measurements undeniably offer the most direct means of observing permeability and associated gas flow characteristics, but they typically come at the expense of timeconsuming and labor intensiveness, coupled with the limitations in the results obtained. 12,13 An alternative way is to explore how shale responds to gas extraction by developing theoretical models. Currently, continuum models (such as dual porosity/permeability models) are widely used because of their benefits of cost-effective computation and low input data requirements.…”

Section: Introductionmentioning

confidence: 99%

“…18,42−45 In existing models, the underlying RVE is treated as a mathematical construct (called the simulation cell). 13,34 This treatment results in the loss of spatial information within the RVE. Each physical property (such as Langmuir's strain constant) and state variable (such as pressure) for matrix and fractures in the RVE are represented by only one value.…”

Section: Introductionmentioning

confidence: 99%

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Shale Gas Production Evaluation Considering Gas Diffusion and Dispersed Distribution of Kerogen

Huang,

Liu,

Gao

et al. 2023

Energy Fuels

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In the shale matrix, organic matter (kerogen) is dispersed and embedded within an inorganic matrix, and its internal gas diffusion is a long-term process. Under the influence of the transient process and complex structure, pressure and Langmuir's strain constant in the matrix are typically distributed nonuniformly. This implies that the sorption-induced swelling/shrinkage in the matrix would also present a nonuniform distribution, and the resulting matrix−fracture mechanical interactions have significant impacts on gas flow in shale fractures as well as gas production. In this study, through the concepts of the swelling path and swelling triangle, the nonuniform swelling/shrinkage is characterized, thereby establishing the relationship between shale response and swelling/shrinkage behaviors. In addition, given that gas transport in organic and inorganic matrixes is typically governed by different mechanisms, the influence of the compositional heterogeneity on gas flow in the matrix is also investigated. Subsequently, novel shale permeability and gas flow models are developed, incorporating the effects of gas diffusion and the dispersed distribution of kerogen. The proposed concepts and developed models are validated by comparing simulation results with one set of experimental observations, as well as two sets of field production data. Our results suggest that neglecting the mechanisms induced by the transient process and complex structure would lead to inaccurate estimations of shale permeability during gas production and result in underestimations of both gas production rates and cumulative production.

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Multi‐porous extension of anisotropic poroelasticity: Consolidation and related coefficients

Adamus,

Healy,

Meredith

et al. 2024

Num Anal Meth Geomechanics

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We propose the generalization of the anisotropic poroelasticity theory. At a large scale, a medium is viewed as quasi‐static, which is the original assumption of Biot. At a smaller scale, we distinguish different sets of pores or fractures that are characterized by various fluid pressures, which is the original poroelastic extension of Aifantis. In consequence, both instantaneous and time‐dependent deformation lead to fluid content variations that are different in each set. We present the equations for such phenomena, where the anisotropic properties of both the solid matrix and pore sets are assumed. Novel poroelastic coefficients that relate solid and fluid phases in our extension are proposed, and their physical meaning is determined. To demonstrate the utility of our equations and emphasize the meaning of new coefficients, we perform numerical simulations of a triple‐porosity consolidation. These simulations reveal positive pore pressure transients in the drained behaviour of weakly connected pore sets, and these may result in the mechanical weakening of the material.

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A transient dual porosity/permeability model for coal multiphysics

Cited by 8 publications

References 44 publications

Spatiotemporal Relationship for Well-Type Selection and Layout Optimization of Surface Wells Based on the REV Permeability Model

Spatiotemporal Relationship for Well-Type Selection and Layout Optimization of Surface Wells Based on the REV Permeability Model

Shale Gas Production Evaluation Considering Gas Diffusion and Dispersed Distribution of Kerogen

Multi‐porous extension of anisotropic poroelasticity: Consolidation and related coefficients

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