A model of random porous media degradation is investigated via several fluid displacing, freezing and thawing cycles. The fluid transport is based on the deterministic method with dispersion effect. Research shows that the topology and the geometry of the porous media have a strong effect on displacement processes. The distribution of throat size N(r) after displacement but before freezing damage shows that the major change, after successive cycles, happens at the throat radius r > 0.9. The distribution of velocities normal to the interface of viscous fingering in percolation cluster is also studied. When iterations n 10, the scaling function distribution is very sharp.