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.