4,231
edits
Changes
Jump to navigation
Jump to search
Line 19:
Line 19: + + + + + + + + + +
→Archie and non-Archie rocks
:<math>\mbox{S}_{\rm w} = \left(\frac{1}{\Phi^{\rm m}} \times \frac{\mbox{R}_{\rm w}}{\mbox{R}_{\rm t}}\right)^{\rm 1/n}</math>
:<math>\mbox{S}_{\rm w} = \left(\frac{1}{\Phi^{\rm m}} \times \frac{\mbox{R}_{\rm w}}{\mbox{R}_{\rm t}}\right)^{\rm 1/n}</math>
where:
* S<sub>w</sub> = water saturation of the uninvaded zone
* n = saturation exponent, which varies from 1.8 to 4.0 but normally is 2.0
* R<sub>w</sub> = formation water resistivity at formation temperature
* Φ = [[porosity]]
* m = cementation exponent, which varies from 1.7 to 3.0 but normally is 2.0
* R<sub>t</sub> = true resistivity of the formation, corrected for invasion, borehole, thin bed, and other effects
without modification. To predict water saturation in rocks with non-Archie porosity, we modify the Archie equation.
without modification. To predict water saturation in rocks with non-Archie porosity, we modify the Archie equation.