There is a statistical correlation between absolute permeability  $//<![CDATA[ \begin{array}{l}k_a\end{array} //]]>$ and effective porosity  $//<![CDATA[ \begin{array}{l}\phi = \phi_e\end{array} //]]>$ which can be approximated by various empirical models based on PORO-PERM correlations.

The most generic approach to permeability modelling is based on the concepts of Flow Zone Indicator  $//<![CDATA[ \begin{array}{l}FZI\end{array} //]]>$:

In case  $//<![CDATA[ \begin{array}{l}FZI = \rm const\end{array} //]]>$ for each lithofacies the model  (1) represents conventional Cozeny-Karman permeability @model

In a more general case, the Flow Zone Indicator keeps dependance on variation of shaliness and effective porosity within a given lithofacies:

but not as strong as permeability and with a better separation between lithofacies which makes it easier to pick up the correlation.

Below is the list of popular permeability-porosity models also called PORO-PERM correlations: