| (1) | RQI=0.0314 \sqrt \frac{k}{\phi_e} |
where
k | absolute permeability to air |
\phi_e | 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