Observations on tens-of-meter scale experiments of fault activation by fluid injection conducted in shales allow exploring how aseismic and seismic events may jeopardize the integrity of a sealing caprock overlying a CO₂ sequestration reservoir. We contrast the behavior of shale faults with another set of experiments conducted in carbonates. Significant fluid leakage occurs along the initially low-permeability shale faults when rupture is activated. Most of the leakage pathway closes when fluid injection ceases and fluid pressure drops. Dilatant slip on the fault plane alone does not explain the observed leakage behavior, which is also caused by fault opening favored by the softness of the shale, and by the structure of the fault zone that prevents fluids from diffusing into the adjacent damage zone. Experiments show a large amount of aseismic deformation. Small-magnitude seismicity (M_w < -2.5) is observed outside the pressurized leakage patch. Stress transferred from this aseismic deformation patch can build up to stress-criticality and favor seismicity. Thus, in terms of fault activation in caprocks, aseismic fault slip leading to increased permeability and a loss of seal integrity is of great concern.

通过在页岩中进行流体注入的数十米规模的断层激活实验的观察，可以探索地震和地震事件如何危害覆盖在 CO ₂上的密封盖层的完整性封存水库。我们将页岩断层的行为与在碳酸盐岩中进行的另一组实验进行对比。当破裂被激活时，沿着最初低渗透性的页岩断层会发生显着的流体泄漏。当流体注入停止且流体压力下降时，大部分泄漏路径关闭。断层平面上的剪胀滑动本身并不能解释观察到的泄漏行为，这也是由于页岩的柔软性有利于断层开放，以及断层带的结构阻止流体扩散到相邻的损坏带。实验表明有大量的抗震变形。小震级地震活动（M _w < -2.5) 在加压泄漏补片外观察到。从这个抗震变形块转移的应力可以累积到应力临界状态并有利于地震活动。因此，就盖层中的断层激活而言，导致渗透率增加和密封完整性丧失的抗震断层滑动是非常令人担忧的。