Figure 6.

Permeability evolution across scale. (a) Fold of increase (FOI) of laboratory hydraulic fracturing test with different injection protocols: Flow-rate-controlled tests (CC3, SC1, CP1) and pressure-controlled tests (SP1, SPP3, CPP1). (b) Permeability enhancement for six field tests carried out in Äspö Hard Rock Laboratory: Conventional (HF1, HF2, HF4, HF6) and fatigue hydraulic tests (HF3, HF5). (c) Permeability development and seismicity observed during the field hydraulic test in the well PX1 in Pohang, South Korea.