Abstract The permeability of porous rocks is a fundamental property describing the capability for conducting fluid through them and is of vital importance across diverse fields, including hydrocarbon exploration, groundwater resource management, geothermal energy production, and carbon sequestration, among others. Recent studies have revealed that the coupling effect of total stress and pore pressure can affect the permeability of porous rock. In this study, we propose a model, in which the directional permeabilities of rocks are decomposed into three components: the initial permeabilities, the component induced by the variation in total stresses, and the component induced by the variation in pore pressure. For the second component, the influence of total stresses is described with a linear matrix function of three principal total stresses, while for the third component, the influence of pore pressure is described with a linear vector function of pore pressure. We introduce a method for determining the model parameters using true triaxial compression-flow tests. The robustness of this model and parameter determination method is comprehensively evaluated through a series of coupled true triaxial compression-flow experiments performed on sandstone specimens. In the tests, the directional permeability-principal total stresses and directional permeability–pore pressure relationships exhibit linear relations in the regime of elastic deformation for the tested sandstone specimen. The parameter matrix for the directional permeability-principal total stresses relationship is asymmetric attributing to the transverse isotropic properties of the sandstone. Furthermore, the effective stress coefficients for anisotropic porous media are expressed with the parameters in the directional permeability-principal total stresses and directional permeability–pore pressure relationships. These effective stress coefficients are determined for the tested sandstone and the anisotropy in the effective stress coefficients is evident. Highlights <UnorderedList Mark="Bullet"> <ItemContent> We investigate the dependency of permeability of sandstone on total stress and pore pressure. </ItemContent> <ItemContent> An anisotropic permeability model was proposed to describe the dependency. </ItemContent> <ItemContent> Coupled ture triaxial compression-flow tests are performed to verify the dependency. </ItemContent> <ItemContent> Effective stress coefficients in term of permeability are formulated with model parameters. </ItemContent> </UnorderedList>

Unraveling the Dependency of Anisotropic Permeability of Sandstone on Total Stress and Pore Pressure with Coupled True Triaxial Compression-Flow Tests

期刊论文
发表日期：

2025年1月6日

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Zhechao Wang,
Yunjia Yi,
Xia-Ting Feng,
Jinjin Yang,
Liping Qiao

摘要

Abstract

The permeability of porous rocks is a fundamental property describing the capability for conducting fluid through them and is of vital importance across diverse fields, including hydrocarbon exploration, groundwater resource management, geothermal energy production, and carbon sequestration, among others. Recent studies have revealed that the coupling effect of total stress and pore pressure can affect the permeability of porous rock. In this study, we propose a model, in which the directional permeabilities of rocks are decomposed into three components: the initial permeabilities, the component induced by the variation in total stresses, and the component induced by the variation in pore pressure. For the second component, the influence of total stresses is described with a linear matrix function of three principal total stresses, while for the third component, the influence of pore pressure is described with a linear vector function of pore pressure. We introduce a method for determining the model parameters using true triaxial compression-flow tests. The robustness of this model and parameter determination method is comprehensively evaluated through a series of coupled true triaxial compression-flow experiments performed on sandstone specimens. In the tests, the directional permeability-principal total stresses and directional permeability–pore pressure relationships exhibit linear relations in the regime of elastic deformation for the tested sandstone specimen. The parameter matrix for the directional permeability-principal total stresses relationship is asymmetric attributing to the transverse isotropic properties of the sandstone. Furthermore, the effective stress coefficients for anisotropic porous media are expressed with the parameters in the directional permeability-principal total stresses and directional permeability–pore pressure relationships. These effective stress coefficients are determined for the tested sandstone and the anisotropy in the effective stress coefficients is evident.

Highlights

We investigate the dependency of permeability of sandstone on total stress and pore pressure.

An anisotropic permeability model was proposed to describe the dependency.

Coupled ture triaxial compression-flow tests are performed to verify the dependency.

Effective stress coefficients in term of permeability are formulated with model parameters.