A significant relation between hydraulically conductive structures and fault and fractures with respect to the current stress field. The hydraulically highly conductive structures are critically stressed faults. They are characterized by a component of high shear stress.

Critically stressed fractures affect permeability in rocks with relatively low matrix porosity. In reservoirs with low matrix permeability, there might be no significant fluid flow in the absence of permeable fractures and faults. Moreover, it is frequently the case that relatively few fractures and faults serve as the primary conduits for flow. The faults that are hydrologically conductive today are those that are critically stressed in the current stress field. It is important to have a criterion that allows us to determine which of the faults are hydrologically conductive today. The critically-stressed-fault hypothesis suggests that faults that are mechanically active are hydraulically active and faults that are mechanically dead are hydraulically dead.

a) Seismic cross section with clear fault zones

d) Factures for short small scale faults (with minimal displacements) show high intensities in the country rocks. e) Fractures for long small scale faults show high intensities along fault zones. With a high likelihood of more faults displacements, critically stressed and hydraulically conductivity. High intensities present good reservoirs.