Evaluation of permeability of a fracture system under true triaxial compression

真三轴压缩下裂缝系统渗透率评价

基本信息

批准号：
15206098
负责人：
MATSUKI Koji
金额：
$ 18.47万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15206098/
关键词：
Sheared fracture Large synthetic fracture Permeability of a fracture Fracture aperture Size effect Anisotropy in permeability Heterogeneity in permeability Localization of water flow 真三軸圧縮応力透水性人工き裂引張き裂フラットジャッキ花崗岩せん断変形き

项目摘要

In this study, we performed both experimental studies on permeability of a fracture under true triaxial compression and theoretical studies on aperture and permeability of a fracture utilizing large synthetic fractures of up to 12.8m.Main results obtained by experimental studies can be summarized as follows :1. An experimental system developed in this study can evaluate the heterogeneity in the permeability of a fracture under uniform normal stress for a pore pressure of less than 0.3MPa and shear displacement of less than 50mm.2. Experiments on an artificial fracture showed that the permeability of the fracture varied by 7.5 to 11.5% and that the hydraulic aperture gradually decreased with an increase in both normal and shear stresses.3. Experiments on a tensile fracture showed that the experimental system could evaluate the permeability for a pore pressure of less than 0.3MPa, but a problem to be solved remained since air was trapped in the fracture.Main results obtained by theoretic … More al studies can be summarized as follows :1. A computer code for creating a synthetic fracture reproduced the ratio of the power spectral densities (PSDs) between aperture and surface height, measured for a tensile fracture of 1m in granite.2. The size effect on the permeability of a normally closed fracture disappears when the fracture exceeds 0.2m since the size effect on the standard deviation (SD) of the initial aperture disappears when the fracture size exceeds 0.2m. We proposed an empirical formula for the permeability of a normally closed fracture, which is independent of the fracture size and the SD of the aperture. Similarly, the size effect on the permeability of a sheared fracture disappears when the shear displacement is less than about 3.1% of the fracture size since the size effect on the standard deviation (SD) of the initial aperture disappears under such conditions.3. The anisotropy in the permeability of a sheared fracture increases with both shear displacement and closure. This anisotropy is caused by the difference in the aperture PSDs between two directions of macroscopic water flow ; perpendicular and parallel to the shear displacement. Furthermore, water flow is more localized with the shear displacement since a fewer channels with a greater area are formed as the shear displacement increases. Less

在这项研究中，我们对在真实三轴压缩下断裂的渗透性以及对孔径的孔隙和渗透性的理论研究进行了两项实验研究，该研究利用大量的合成裂缝（最高为12.8m）进行了骨折的裂缝性，可如下总结通过实验研究获得的结果：1。这项研究中开发的实验系统可以评估骨折在均匀的正常应力下骨折的渗透性的异质性，孔隙压力小于0.3MPa，而剪切位移小于50mm.2。对人造断裂的实验表明，裂缝的渗透率差异为7.5％至11.5％，而水解孔径随着正常和剪切应力的增加而逐渐减少。3。拉伸断裂的实验表明，实验系统可以评估孔隙压力小于0.3MPa的渗透性，但是由于空气被困在断裂中，因此要解决的问题是通过理论获得的。更多的AL研究可以汇总，可以汇总到以下内容：1。用于创建合成裂缝的计算机代码再现了孔径和表面高度之间的功率谱密度（PSD）的比例，该比值在花岗岩中的拉伸裂缝为1m。当断裂超过0.2m时，正常闭合断裂的大小影响消失，因为当裂缝尺寸超过0.2m时，初始光圈对标准偏差（SD）的尺寸影响消失了。我们提出了一种经验公式，用于正常闭合断裂的渗透性，该裂缝与骨折大小和孔径的SD无关。同样，当剪切位移小于裂缝尺寸的3.1％左右，剪切断裂的尺寸影响消失了，因为在这种情况下，初始孔径的尺寸效应对标准偏差（SD）的尺寸影响消失了。3。剪切断裂的渗透性的各向异性随着剪切位移和闭合而增加。这种各向异性是由两个宏观水流两个方向之间的孔径PSD差异引起的。垂直于剪切位移。此外，随着剪切位移的增加而形成较大面积的较大通道，水流更具位置，因为剪切位移。较少的