One of the saturation from resistivity models with specific electrical resistivity
R_t is defined as:
R_w
A dimensionless constant, characterizing the rock matrix contribution to the total electrical resistivity 0.5 ÷ 1, default value is 1 for sandstones and 0.9 for limestones
m
n 1.5 ÷ 2.5, default value is 2 Archie model is usually used in:
(1)
\frac{1}{R_t} = \frac{\phi_e^m \, s_w^n }{A R_w} \quad \Rightarrow \quad s_w = \Big ( \frac{A}{\phi_e^m} \; \frac{R_w}{R_t} \Big) ^{1/n}
wherespecific electrical resistivity of formation water formation matrix cementation exponent 1.5 ÷ 2.5, default value is 2 formation matrix water-saturation exponent