Flushed-Zone Apparent Formation Factor from Apparent Saturation Formula
Flushed-Zone Apparent Formation Factor from Apparent Saturation calculates apparent flushed-zone formation factor for resistivity logs workflows in petrophysics.
How engineers use this formula
Use this formula when the listed inputs (F_s, S_xo) 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_xo equals 31.25 dimensionless.
20
0.8
Inputs
F_s
dimensionlessFormation Resistivity Factor from Sonic or Density Porosity
S_xo
fractionApparent Saturation in Flushed Zone
Outputs
F_xo
Apparent Flushed-Zone Formation Factor
F_s
Formation Resistivity Factor from Sonic or Density Porosity
S_xo
Apparent Saturation in Flushed Zone
Source and review
reviewedTheory, Measurement, and Interpretation of Well Logs, Bassiouni, Z. (1994)
Bassiouni, Z. 1994. Theory, Measurement, and Interpretation of Well Logs. SPE Textbook Series Vol. 4, Chapter 12, Page 250.
Source