General form of the Archie equation-Water saturation from resistivity logs

Input(s)

m: Cementation Factor (dimensionless)

a: Tortuosity Factor (dimensionless)

$\Phi$: Porosity (fraction)

$R_{w}$: Resistivity of Water (ohm m)

$R_{t}$: True Resistivity (ohm m)

$\mathrm{n}$: Saturation Exponent (dimensionless)

Output(s)

$S_{w}$: Water Saturation (fraction)

Formula(s)

$$ S_{w}=\left(\left(\frac{a}{\Phi^{m}}\right) *\left(\frac{R_{w}}{R_{t}}\right)\right)^{\frac{1}{n}} $$

Reference(s)

Core Laboratories. 2005. Formation Evaluation and Petrophysics, Page: 45.