Relation between Porosity and permeability

Many investigators have attempted to correlate permeability to porosity, grain size and shape, and packing. The most frequently used relation was developed by Kozeny as follows:

k = Φ³/ (5×Sv× (1-Φ)²)

k = permeability, cm² (= 1.013 x 10⁸ Darcies)
Φ = effective porosity
Sv = total grain surface/unit volume of reservoir, cm²/cm³

The following images show the relationship of grain size and sorting & to porosity and permeability.

porosity, permeability and grain size. Porosity is not affected by grain size but permeability increases with increase in grain size.

Porosity and permeability are affected by sorting, both increases with better sorting.