IHRDC Logo

Discover the IHRDC Energy Glossarybeta

Search or select a letter above to browse the glossary.

Resistivity Index

The ratio of the true resistivity (Rt) to the resistivity of the same rock filled with water (Ro). It is related to water saturation by the saturation exponent n (I = Sw⁻ⁿ), and is a key component of the Archie equation.