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 .