Two experiments have been installed at Mont Terri in 2004 and 2009 that allowed gas circulation within a borehole at a pressure between 1 and 2 bar. These experiments made it possible to observe the natural gases that were initially dissolved in pore-water degassing into the borehole and to monitor their content evolution in the borehole over several years. They also allowed for inert (He, Ne) and reactive (H2) gases to be injected into the borehole with the aim either to determine their diffusion properties into the rock pore-water or to evaluate their removal reaction kinetics. The natural gases identified were CO2, light alkanes, He, and more importantly N2. The natural concentration of four gases in Opalinus Clay pore-water was evaluated at the experiment location: N2 2.2 mmol/L ± 25%, CH4 0.30 mmol/L ± 25%, C2H6 0.023 mmol/L ± 25%, C3H8 0.012 mmol/L ± 25%. Retention properties of methane, ethane, and propane were estimated. Ne injection tests helped to characterize rock diffusion properties regarding the dissolved inert gases. These experimental results are highly relevant towards evaluating how the fluid composition could possibly evolve in the drifts of a radioactive waste disposal facility.

中文翻译：

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蒙特特里岩石实验室（瑞士）Opalinus Clay的天然气提取和人工气体注入实验

2004年和2009年，在蒙特里（Mont Terri）安装了两个实验，这些实验允许气体在井眼中以1至2 bar的压力循环。这些实验使观察最初溶解在脱气到井眼的孔隙水中的天然气成为可能，并监测了其在井眼中的含量历时数年。他们还允许将惰性气体（He，Ne）和反应性气体（H2）注入井眼，目的是确定其在岩石孔隙水中的扩散特性或评估其去除反应动力学。鉴定出的天然气为CO2，轻烷烃，He，更重要的是N2。在实验位置评估了Opalinus粘土孔隙水中四种气体的自然浓度：N2 2.2 mmol / L±25％，CH4 0.30 mmol / L±25％，C2H6 0.023 mmol / L±25％，C3H8 0。012 mmol / L±25％。估计了甲烷，乙烷和丙烷的保留特性。氖气注入试验有助于表征与溶解惰性气体有关的岩石扩散特性。这些实验结果与评估流体成分在放射性废物处置设施的漂移中如何演化有关。