USBM Wettability Index Formula
USBM Wettability Index calculates usbm wettability index for rock properties workflows in petrophysics.
How engineers use this formula
Use this formula when the listed inputs (A_1, A_2) are known and the assumptions behind the cited rock properties 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, I_U equals 0.60206 dimensionless.
8
2
Inputs
A_1
dimensionlessArea Ratio of Oil Displacing Water
A_2
dimensionlessArea Ratio of Water Displacing Oil
Outputs
I_U
USBM Wettability Index
A_1
Area Ratio of Oil Displacing Water
A_2
Area Ratio of Water Displacing Oil
Source and review
reviewedWettability Profile of a Thick Carbonate Reservoir by the New Rise in Core Wettability Characterization Method, Ghedan, S. G., Canbaz, C. H., Boyd, D. A., Mani, G. M., Haggag, M. K. (2010)
Ghedan, S. G., Canbaz, C. H., Boyd, D. A., Mani, G. M., and Haggag, M. K. 2010. Wettability Profile of a Thick Carbonate Reservoir by the New Rise in Core Wettability Characterization Method. ADIPEC. SPE, Page 3.