Abstract. We aimed to evaluate various factors that control the frictional and transport properties of gouge-filled faults cutting carbonate-bearing shales or claystone formations. The research experimentally determined the effect of shear displacement, dynamic shearing, static holding, and effective normal stress on fault gouge permeability, both parallel and perpendicular to the fault boundaries, as well as on frictional behaviour. The simulated gouge was prepared from crushed Opalinus Claystone (OPA), on which we performed direct shear experiments. The direct-shear experiments (σ_n^eff = 5–50 MPa, P_f = 2 MPa, and T ≈ 20 °C) showed ~1 order of magnitude decrease in permeability with shear displacement (up to ~6 mm), for both along- and across-fault fluid flow orientation. Moreover, our data showed an initial, pre-shear permeability anisotropy of up to ~1 order of magnitude, which decreased with increasing shear displacement (maturity) to ~0.5, with the along-fault permeability being consistently higher. Our results have important implications for calcite-rich claystones and shale formations, and in particular any pre-existing faults therein, that seal hydrocarbon reservoirs and potential CO₂ storage reservoirs, as the current results point to a higher leakage potential of pre-existing faults compared to the intact caprock.

中文翻译：

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模拟富粘土断层泥的各向异性输运和摩擦特性

摘要。我们旨在评估各种因素，这些因素可控制充满碳酸盐岩的页岩或粘土岩地层的凿孔充填断层的摩擦和输运性质。该研究通过实验确定了剪切位移，动态剪切，静态保持力和有效法向应力对平行于或垂直于断层边界的断层泥渗透率以及摩擦行为的影响。模拟的凿子是用碎的Opalinus粘土石（OPA）制备的，我们在其上进行了直接剪切实验。直剪切实验（σ _Ñ ^EFF  = 5-50兆帕，P _˚F  = 2兆帕，和Ť 沿断层和跨断层的流体流动方向，≈20°C）的渗透率随剪切位移（最大〜6 mm）降低了约1个数量级。此外，我们的数据显示，剪切前的初始渗透率各向异性高达〜1个数量级，随着剪切位移（成熟度）增加到〜0.5而减小，沿断层渗透率一直较高。我们的结果对于富含方解石的粘土岩和页岩地层，尤其是其中任何先前存在的断层，对烃类储层和潜在的CO ₂储层进行了密封，具有重要的意义，因为当前的结果表明，已有的断层具有更高的泄漏潜力与完整的翻盖相比。