Gamma ray log shale index

Input(s)

$G R_{c l}$: Log Response in Clean Beds (API)

$G R_{s h}$: Log Response in Shale Beds (API)

GR: Log Response in Zone of Interest (API)

Output(s)

$I_{G R}$: Gamma Ray Shale Index (fraction)

Formula(s)

$$ I_{G R}=\frac{G R-G R_{c l}}{G R_{s h}-G R_{c l}} $$

Reference(s)

Core Laboratories. 2015. Formation Evaluation and Petrophysics, Page: 63.