Fracture apertures normal stress-permeability

Figure 2. TOUGH-FLAC simulation of the DST (a) schematics of two-dimensional model geometry (b) conceptual model for stress-permeability coupling (c) normal stress versus aperture relationship for fractures...

The intrinsic permeability k = k(e, volumetric strain or in the case of fractured rock it can be formulated as a function of the effective normal stress using e.g. the following definition of the void aperture... 

A smali-scale stress-permeability (or aperture) relationship is generally obtained from laboratory tests on single fractures. As an example, Figure 3 shows measured normal stress-aperture relations for a rock sample collected from the Shellafield site. The observed function can be fitted by ... 

A key parameter for modeling the T-H-M-C processes is the relationship between in situ stress and permeability. Assuming several different relations between local permeability and fracture apertures. we developed two upscaling relationships between normal stress and permeability for fractured rock characterized by fLm. While more rigorous upscaling relationships are desirable, the proposed relationships capture relevant large-scale effects of normal stress changes on rock permeabilities. 

The permeability in the x, y and z directions, is strongly affected by the fracture distribution and fracture dimensions. Since the fracture apertures depend on pressure in the fluid and normal and shear stresses (see equations (3) and (4)), the permeability of the reservoir (defined by its components AT,), should be treated as a... 

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