Fracture stiffness and flow properties have been measured in the laboratory using naturally fractured fault rock samples from the Little Grand Wash fault, Utah, USA. We compare fracture closure and related flow change during isotropic loading of two fractures which have been subject to various amounts of paleoreactive flow. The two tested fractures are described as (i) a small‐aperture fracture (0.1 mm) with negligible geochemical alterations of the fracture surface and (ii) a large‐aperture fracture (0.53 mm) where precipitates are observed on the fracture surface. X‐ray imaging is used for quantification of fracture aperture and fracture surface contact distribution. The petrographical characterization using scanning electron microscopy and X‐ray powder diffraction is performed pretest and describes burial and uplift diagenesis as well as pulses of reactive fluid flow within the fault. The stress‐dependent flow and deformation experiment provides new data on fracture stiffness and flow for naturally developed fractures in siliciclastic rock. Fracture stiffness is found to be highest for the small‐aperture fracture due to its high‐fracture contact ratio and well‐developed surface mating during closure. For the naturally altered and rougher, large‐aperture fracture, fracture stiffness is lower and a highly stress dependent decay in flow is observed during initial closure. The results illustrate that a natural fracture with high contact ratio and well‐mated surfaces will close during loading, whereas a fracture associated with high flow rates and affected by previous geochemical alteration maintains a high flow rate compared to the host rock during similar loading.

中文翻译：

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断层二氧化碳旁路系统中自然断裂刚度和流动特性的实验研究（美国犹他州）

在实验室中，使用来自美国犹他州Little Grand Wash断层的天然断裂断层岩石样品测量了断裂刚度和流动特性。我们比较了两个裂缝的各向同性加载过程中裂缝闭合和相关的水流变化，这两个裂缝已经经历了不同数量的古反应流。这两个测试裂缝描述为（i）裂缝表面的地球化学变化可忽略不计的小孔径裂缝（0.1 mm）和（ii）裂缝表面上观察到沉淀的大孔径裂缝（0.53 mm）。X射线成像用于量化骨折口和骨折表面接触分布。使用扫描电子显微镜和X射线粉末衍射进行岩石学表征是预先测试的，并描述了埋藏和隆升成岩作用以及断层内反应流体的流动脉动。应力相关的流动和变形实验提供了关于硅质碎屑岩自然发育裂缝的断裂刚度和流动的新数据。小孔裂缝的断裂刚度最高，这是由于其高裂缝接触率和闭合过程中良好的表面配合。对于自然变化且较粗糙的大孔径裂缝，其裂缝刚度较低，在初始闭合过程中观察到高度依赖于应力的流量衰减。结果表明，在加载过程中，具有高接触比且表面配合良好的自然裂缝将闭合，