Saturation from Resistivity Log

Specific electrical resistivity  $//<![CDATA[ \begin{array}{l}R_t\end{array} //]]>$ or specific electrical conductivity   $//<![CDATA[ \begin{array}{l}\sigma_t = \frac{1}{R_t}\end{array} //]]>$ of formations is defined by mineralization of the rock matrix and saturating fluids which depend on water-saturated shaliness  $//<![CDATA[ \begin{array}{l}V_{sh}\end{array} //]]>$ , formation porosity $//<![CDATA[ \begin{array}{l}\phi_e\end{array} //]]>$ and water saturation volumetric share  $//<![CDATA[ \begin{array}{l}s_w\end{array} //]]>$.