Effective stress law for the permeability of a limestone
Effective stress law for the permeability of a limestone
复制标题
DOI：
10.1016/j.ijrmms.2008.05.006
复制
发表时间：
2009-02-01
影响因子：
7.2
通讯作者：
Martineau, Francois
中科院分区：
文献类型：
--
作者：
Ghabezloo, Siavash;Sulem, Jean;Martineau, Francois
通过在三轴试验箱中进行的恒定水头渗透试验，在不同的孔压σ和孔压p（f）条件下，研究了有效应力对石灰岩渗透性的影响规律。试验结果表明，孔隙压力的增加和围压的减小均导致渗透率的增加，且孔隙压力的变化对渗透率变化的影响比围压的变化对渗透率变化的影响更大。提出了渗透率随有效应力变化的幂律关系（σ ' = σ-n（k）p（f））。渗透率有效应力系数n（k）随压差线性增加，当压差超过几巴时，n（k）大于1。试验结果很好地再现使用建议的渗透率有效应力法。提出了一个概念性的孔壳模型的基础上详细观察所研究的石灰石的微观结构。该模型能够解释总应力和孔隙压力对石灰岩渗透性影响的实验观察结果。得到了应力相关渗透率的有效应力系数大于1。结果表明，控制因素是不同的体积模量的岩石的各种成分的比例。通过显微硬度测试对该比率进行了实验研究。(C)2008爱思唯尔有限公司保留所有权利。
The effective stress law for the permeability of a limestone is studied experimentally by performing constant-head permeability tests in a triaxial cell with different conditions of con. ning pressure sigma and pore pressure p(f). Test results show that a pore pressure increase and a con. ning pressure decrease both result in an increase of the permeability, and that the effect of the pore pressure change on the variation of the permeability is more important than the effect of a change of the con. ning pressure. A power law is proposed for the variation of the permeability with the effective stress (sigma' = sigma-n(k)p(f)). The permeability-effective stress coefficient n(k) increases linearly with the differential pressure and is greater than unity as soon as the differential pressure exceeds few bars. The test results are well reproduced using the proposed permeability-effective stress law. A conceptual pore-shell model based on a detailed observation of the microstructure of the studied limestone is proposed. This model is able to explain the experimental observations on the effect of the total stress and of the pore pressure on the permeability of the limestone. Effective stress coefficients for the stress-dependent permeability which are greater than one are obtained. It is shown that the controlling factor is the ratio of the different bulk moduli of the various constituents of the rock. This ratio is studied experimentally by performing microhardness tests. (C) 2008 Elsevier Ltd. All rights reserved.