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 permeability-porosity models

The most generic approach to permeability modelling is based on the concepts of Flow Zone Indicator  $//<![CDATA[ \begin{array}{l}FZI\end{array} //]]>$, Rock Quality Index (RQI)  $//<![CDATA[ \begin{array}{l}RQI\end{array} //]]>$ and normalised porosity  $//<![CDATA[ \begin{array}{l}\phi_r\end{array} //]]>$:

In case  $//<![CDATA[ \begin{array}{l}FZI = \rm const\end{array} //]]>$ for each lithofacies the model  (4) transforms into conventional Cozeny-Karman permeability @model

In general case, the Flow Zone Indicato depends on shaliness and effective porosity  $//<![CDATA[ \begin{array}{l}FZI(V_{sh}, \, \phi)\end{array} //]]>$, but not as strong as permeability which makes it easier to identify the correlation.