Mechanical-Chemical-Mineralogical Controls on Permeability Evolution of Shale Fractures

Figure 4

Effective hydraulic aperture evolution with time under different confining stresses for Longmaxi shale. (a) Fluid pH = 4.0 condition and the subplot is an expanded figure during the period of effective hydraulic aperture increase, (b) fluid pH = 5.0, (c) fluid pH = 6.0, and (d) fluid pH = 7.0. A monotonic increase in effective hydraulic aperture until a maximum aperture is observed for fluid pH = 4.0 and 5.0 condition. Following this, the fracture aperture has a relatively small change. Sustained decrease of effective hydraulic aperture is observed during the 12-hour core flooding experiments when fluid pH = 6.0 and 7.0.

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