Small deviations of ambient pressure p(t, {\bf r}) from initial pressure fromarion p_0(t, {\bf r}) lead to the exponential changes in permeability:
| (1) | k=k_0 \, e^{\beta_p (p-p_0)} |
The substantial reduction of formation pressure leads to shrinking a lot of pore throats and massive reduction in permeability deviating from exponential.
The substantial increase of formation pressure leads to microfracturing and massive increase in permeability deviating from exponential.