The deep borehole (DB) experiment gave the opportunity to acquire hydraulic parameters in a hydraulically undisturbed zone of the Opalinus Clay at the Mont Terri rock laboratory (Switzerland). Three methods were used to estimate hydraulic conductivity and specific storage values of the Opalinus Clay formation and its bounding formations through the 248 m deep borehole BDB-1: application of a Poiseuille-type law involving petrophysical measurements, spectral analysis of pressure time series and in situ hydraulic tests. The hydraulic conductivity range in the Opalinus Clay given by the first method is 2 × 10−14–6 × 10−13 m s−1 for a cementation factor ranging between 2 and 3. These results show low vertical variability whereas in situ hydraulic tests suggest higher values up to 7 × 10−12 m s−1. Core analysis provides economical estimates of the homogeneous matrix hydraulic properties but do not account for heterogeneities at larger scale such as potential tectonic conductive features. Specific storage values obtained by spectral analysis are consistent and in the order of 10−6 m−1, while formulations using phase shift and gain between pore pressure signals were found to be inappropriate to evaluate hydraulic conductivity in the Opalinus Clay. The values obtained are globally in good agreement with the ones obtained previously at the rock laboratory.

中文翻译：

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水力稳定的蛋白石粘土中水力参数估算方法的比较研究（瑞士）

深井（DB）实验为在Mont Terri岩石实验室（瑞士）的Opalinus粘土的不受水力扰动的区域中获取水力参数提供了机会。通过三种方法来估算深达248 m的BDB-1井眼的Opalinus粘土地层及其边界地层的水力传导率和比储能值：应用涉及岩石物理测量的Poiseuille型定律，压力时间序列和原位水力测试。第一种方法给出的Opalinus粘土的水力传导率范围是2×10−14–6×10−13 ms−1（胶结系数介于2和3之间）。这些结果显示出较低的垂直变化性，而现场水力测试表明最高值为7×10-12 ms-1。岩心分析提供了均质基体水力特性的经济估算，但并未考虑较大范围的异质性，例如潜在的构造导电特征。通过光谱分析获得的特定储水值是一致的，约为10-6 m-1，而使用相移和孔隙压力信号之间的增益的配方被发现不适用于评估Opalinus粘土中的水力传导率。所获得的值在全球范围内与之前在岩石实验室获得的值高度吻合。而使用相移和孔隙压力信号之间的增益的配方不适用于评估Opalinus粘土中的水力传导率。全球获得的值与之前在岩石实验室获得的值完全一致。而使用相移和孔隙压力信号之间的增益的配方不适用于评估Opalinus粘土中的水力传导率。全球获得的值与之前在岩石实验室获得的值完全一致。