PetrophysicsResistivity Logs
Humble Formation Factor from Porosity Formula
Humble Formation Factor from Porosity calculates formation resistivity factor for resistivity logs workflows in petrophysics.
How engineers use this formula
Use this formula when the listed inputs (phi) are known and the assumptions behind the cited resistivity logs relationship match the engineering case being checked.
Assumptions
- Input values are representative for the well, reservoir, fluid, or equipment case being evaluated.
- The declared units match the field-unit constants used in the formula.
- The cited formula applies to the selected petroleum engineering workflow.
Limitations
- The calculation does not replace a full engineering model or operating procedure.
- Accuracy depends on the source correlation, assumptions, input quality, and unit consistency.
Common mistakes
- Mixing unit systems without converting the inputs.
- Using default example values as field recommendations.
- Applying the formula outside the source assumptions.
Default example
Using the default inputs, F equals 19.732277 dimensionless.
phifraction
0.2
Inputs
phi
fractionPorosity
Outputs
F
dimensionless
Formation Resistivity Factor
phi
fraction
Porosity
Source and review
reviewedBassiouni, Z. 1994. Theory, Measurement, and Interpretation of Well Logs, SPE Textbook Series Vol. 4, Chapter 1, Page 8.
Source