PRESSURE-DEPENDENCE OF PERMEABILITY AND EARTH TIDE INDUCED FLUID-FLOW

New in situ measurements of the pressure dependence of permeability at the Continental-Deep-Drilling Project in Windisch-Eschenbach/Germany (KTB) indicate a much stronger sensitivity compared to measurements of core samples. The non-linear pressure-dependent permeability combined with the oscillating tidal forces provide the basis for a pumping mec hanism in porous rocks. Numerical simulations of the interaction betwe en tidal strain and fluid pore pressure show a residual flow beside fl uid oscillations for the simplified model of a u-shaped fault system. The magnitude of the residual flow is dependent on the permeability an d the scale of the area considered. A residual Darcy velocity of 4.10( -14) m/s was calculated with KTB permeabilities.