Formation resistivity and porosity relations for carbonate rocks

Input(s)

a: Constant (Range of 2.2 to 2.5 ) (dimensionless)

$\Phi$ : Porosity (dimensionless)

$F_{c}$ : Formation Resistivity Factor for Chalky Rocks (dimensionless)

$F_{c} O$ : Formation Resistivity Factor for Compact Rocks (dimensionless)

$F_{l}$ : Formation Resistivity Factor for Low Porosity and non-fractured Carbonates, Shell Equation (dimensionless)

\begin{gathered} F_{c}=\frac{1}{(\Phi)^{2}} \\ F_{c} O=\frac{1}{(\Phi)^{a}} \\ F_{l}=\frac{1}{(\Phi)^{1.87+\left(\frac{0.019}{\Phi}\right)}} \end{gathered}

Bassiouni, Z., 1994, Theory, Measurement, and Interpretation of Well Logs. SPE Textbook Series Vol. 4. Chapter 1, Page: 10.