PetrophysicsResistivity Logs
Mud Cake Resistivity from Mud and Filtrate Resistivity Formula
Mud Cake Resistivity from Mud and Filtrate Resistivity calculates mud cake resistivity for resistivity logs workflows in petrophysics.
How engineers use this formula
Use this formula when the listed inputs (R_m, R_mf) 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, R_mc equals 0.161652 ohm m.
R_mohm m
0.12
R_mfohm m
0.08
Inputs
R_m
ohm mMud Resistivity
R_mf
ohm mMud Filtrate Resistivity
Outputs
R_mc
ohm m
Mud Cake Resistivity
R_m
ohm m
Mud Resistivity
Source and review
reviewedBassiouni, Z. 1994. Theory, Measurement, and Interpretation of Well Logs. SPE Textbook Series Vol. 4, Chapter 4, Page 67.
Source