Constitutive relationships and pore structure of undisturbed fracture zone samples with cohesionless fault gouge layers
Constitutive relationships and pore structure of undisturbed fracture zone samples with cohesionless fault gouge layers
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无粘性断层泥层原状断裂带样品本构关系及孔隙结构
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
H. Flühler
中科院分区：
文献类型：
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作者：
U. Fischer;Beatrice Kulli;H. Flühler
裂隙岩体中的多相流过程对于地下污染的修复、工程油藏的开发以及核废料处置库的安全分析都具有重要意义。我们开发了在实验室中确定具有无粘性断层泥层的原状断裂带样品的保水曲线、气体渗透率函数和孔隙结构的程序。在Grimsel试验中心（瑞士）采集糜棱岩样品。断层泥层的固有渗透率高出5个数量级，并且在比周围花岗闪长岩低约10倍的毛细管压力头处发生显著的去饱和，从而表明在该位置，气体流动将主要发生在断裂带中。所测得的持水率和气体渗透率数据很好地表示为多孔介质设计的参数模型。只有在水饱和度低于约0.8时才能检测到气流，因此在高水饱和度时显示出强的相位干扰。为了将这些发现与样品的孔结构相关联，使用荧光树脂吸液和图像分析技术在不同尺度下获得了对孔空间的定性和定量描述。结果表明，断裂带由一个连续和互连的裂缝网络，填充有多孔介质类材料，从而解释了上述模型的适用性和相当强的相位干扰。
Multiphase flow processes in fractured rocks are of major importance for the remediation of subsurface contamination, for engineering petroleum reservoirs, and for the safety analysis of nuclear waste repositories. We developed procedures for determining the water retention curve, gas permeability function, and pore structure of undisturbed fracture‐zone samples with cohesionless fault gouge layers in the laboratory. Mylonitic samples were taken at Grimsel Test Site (Switzerland). Intrinsic permeabilities of the fault gouge layers were 5 orders of magnitude higher, and significant desaturation occurred at capillary pressure heads about 10 times lower than in the surrounding granodiorite, thus showing that at this site gas flow would take place mainly in the fracture zone. The measured water retention and gas permeability data were well represented by parametric models designed for porous media. Gas flow could only be detected at water saturations below about 0.8, thus showing strong phase interference at high water saturations. To relate these findings to the pore structure of the samples, a qualitative and quantitative description of the pore space was obtained at different scales using fluorescent resin imbibition and image analysis techniques. Results show that the fracture zone consists of a continuous and interconnected fracture network that is filled with a porous medium‐like material, thus explaining the applicability of the above mentioned models and the rather strong phase interference.