Brooks-Corey Nonwetting Permeability Calculator
Calculate Brooks-Corey nonwetting relative permeability from effective wetting saturation and pore-size index. Check which phase the input represents.
Calculate Brooks-Corey nonwetting relative permeability from effective wetting saturation and pore-size index. Check which phase the input represents.
Published by PetroCalcHub Team. Linked workflow tools and revision log.
Calculation context and source notes
Evaluate normalized nonwetting-phase relative permeability from effective wetting saturation and the Brooks-Corey pore-size distribution index. The nested saturation factor makes this relationship distinct from a single Corey oil or gas power law.
Use a positive distribution index and the same effective wetting-saturation convention as the fitted two-phase model. The input deliberately describes the wetting phase, while the output describes the other phase; zero wetting saturation gives the normalized nonwetting endpoint of one.
Solves for
k_rn (fraction)
Best next page
Formula, variables, and sourceCheck the input phase before evaluating
With effective wetting saturation 0.5 and lambda = 2, the exponent 1 + 2/lambda is two. The result is (1 - 0.5) squared times (1 - 0.5 squared), or 0.1875. Increasing wetting saturation reduces nonwetting relative permeability; zero and full wetting saturation give one and zero respectively.
The INL source function takes the nonwetting phase's own effective saturation s_n. Its expression is s_n squared times [1 - (1 - s_n)^(1 + 2/lambda)]. Substituting s_n = 1 - S_e gives this page's wetting-input convention. The regression suite checks that transformation explicitly rather than copying the source variable name.
| Effective WETTING saturation | Normalized k_rn, lambda = 2 |
|---|---|
| 0 | 1 |
| 0.5 | 0.1875 |
| 1 | 0 |
Distinguish the two Brooks-Corey branches
The corresponding wetting expression is S_e^(3 + 2/lambda), which the existing parameterized Corey wetting family can already represent by choosing its exponent. That power was not added as another duplicate calculator. The nonwetting nested relation here cannot generally be reduced to one Corey power over the full saturation range.
The capillary-pressure curve uses the same named distribution index within the model, but sharing a symbol does not establish that independently fitted curves are consistent. Compare residual endpoints, drainage or imbibition history and endpoint scaling before transferring parameters between measurements. The output is a dimensionless curve point, not a multiphase flow forecast.
Related source-backed guides
Formula, variables, and default calculation
Reproducible default result
With the default values shown below, the calculation returns k_rn = 0.1875 fraction. Defaults demonstrate the implementation; they are not recommended field values.
0.5
2
Input definitions
S_e
fractionEffective WETTING Saturation
lambda
dimensionlessPositive Pore-Size Distribution Index
Output definitions
k_rn
Normalized Nonwetting Relative Permeability
Engineering use, assumptions, and limits
Use a positive distribution index and the same effective wetting-saturation convention as the fitted two-phase model. The input deliberately describes the wetting phase, while the output describes the other phase; zero wetting saturation gives the normalized nonwetting endpoint of one.
Assumptions
- Two-phase normalized saturation is consistent with the calibrated curve's residual endpoints.
- The pore-size index is positive, the nonwetting endpoint multiplier is one, and no hysteresis is modeled.
Limitations
- This normalized evaluator does not fit lambda, add an endpoint multiplier or predict three-phase relative permeability.
- The nonwetting phase is defined by wettability, not automatically by the name oil or gas in every fluid-rock system.
Common mistakes
- Entering effective nonwetting saturation directly even though this interface requires effective wetting saturation.
- Replacing the nested factor with a single Corey exponent, or assuming normalized relative permeability is absolute permeability.
Frequently asked questions
What inputs does the Brooks-Corey Nonwetting Relative Permeability calculator need?
The calculation uses Effective WETTING Saturation (S_e), Positive Pore-Size Distribution Index (lambda). Enter values on the units shown beside each field.
What result does this calculator return?
The primary result is normalized nonwetting relative permeability in fraction. The formula section shows the declared relationship, variables, and a reproducible default calculation.
What should I check before using the result?
Confirm the unit basis, source applicability, and input quality. This normalized evaluator does not fit lambda, add an endpoint multiplier or predict three-phase relative permeability. Entering effective nonwetting saturation directly even though this interface requires effective wetting saturation.
Source and record status
Source metadata identifies the relationship implemented by the calculator. Check the cited edition, unit basis, and scope against the engineering case before operational use.
PorousFlowBrooksCorey.h: relativePermeabilityNonwetting, Idaho National Laboratory MOOSE contributors
Idaho National Laboratory MOOSE PorousFlowBrooksCorey::relativePermeabilityNonwetting, pinned revision 6b1f253f8541e0b6eddc30616dbd2068b0b4edc2. The source takes effective NONWETTING saturation; this calculator substitutes s_n = 1 - S_e to use effective WETTING saturation consistently.
Open source reference