This crossplot is used to graphically determine a saturation exponent (n) value for a set of core data representing a particular rock type.
Resistivity index (RI) is measured in the lab and is equal to the ratio of the true resistivity of the rock to the resistivity of 100% water saturated rock. Resistivity index can also be determined with the equation RI=1/Sw^n, where the slope equals saturation exponent (n).
Start by inputting Sw-RI data series, (green, blue and orange cells). Each data series allows an unlimited number of rows, and cut and paste functionality is available. Next, adjust the saturation exponent value until the line fits the desired data series.