Reservoir EngineeringWaterflooding and EOR
Welge Extension Fractional Flow Relative Permeability Ratio Formula
Welge Extension Fractional Flow Relative Permeability Ratio calculates relative permeability ratio of water to oil for waterflooding and eor workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (f_o, mu_w, mu_o) are known and the assumptions behind the cited waterflooding and eor 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, relpr equals 0.085714 dimensionless.
f_ofraction
0.7
mu_wcP
1
mu_ocP
5
Inputs
f_o
fractionFractional Flow of Oil
mu_w
cPWater Viscosity
mu_o
cPOil Viscosity
Outputs
relpr
dimensionless
Relative Permeability Ratio of Water to Oil
f_o
fraction
Fractional Flow of Oil
mu_w
cP
Water Viscosity
mu_o
cP
Oil Viscosity
Source and review
reviewedDandekar, A. Y. Petroleum Reservoir Rock and Fluid Properties, CRC Press Taylor and Francis Group, Chapter 9, Page 215.
Source