Water saturation from neutron tools

Input(s)

$\Sigma_{l o g}$: Measured Capture Cross Section of Formation (dimensionless)

$\Sigma_{m a}$: Capture Cross Section of Matrix (dimensionless) $\Sigma_{w}$: Capture Cross Section of Water (dimensionless)

$\Sigma_{h}$: Capture Cross Section of Hydrocarbon (dimensionless)

$\Phi$: Porosity (fraction)

Output(s)

$S_{w}$: Water Saturation (fraction)

Formula(s)

$$ \mathrm{S}_{\mathrm{w}}=\frac{\left(\Sigma_{\log }-\Sigma_{\mathrm{ma}}\right)-\Phi *\left(\Sigma_{\mathrm{h}}-\Sigma_{\mathrm{ma}}\right)}{\Phi *\left(\Sigma_{\mathrm{w}}-\Sigma_{\mathrm{h}}\right)} $$

Reference(s)

Bassiouni, Z., 1994, Theory, Measurement, and Interpretation of Well Logs. SPE Textbook Series Vol. 4. Chapter 9, Page: 181 .