RQI=0.0314  \sqrt  \frac{k}{\phi_e}

where 

absolute permeability to air

effective porosity


This value accounts for monotonous growth of permeability on porosity and the square root decreases the variability thus increasing linearity of correlation between RQI and porosity


See also


Petroleum Industry / Upstream / Subsurface E&P Disciplines / Petrophysics