Skin During Infinite-Acting Pseudoradial Flow Formula
Skin During Infinite-Acting Pseudoradial Flow calculates skin factor for pressure transient analysis workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (p_i, p_1hr, m, k, phi, mu_total, c_t, r_w) are known and the assumptions behind the cited pressure transient analysis 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, S equals 4.980273 dimensionless.
4000
3500
50
100
0.2
1
0.00001
0.25
Inputs
p_i
psiInitial Pressure
p_1hr
psiPressure After One Hour
m
psi/cycleSemilog Slope
k
mDPermeability
phi
fractionPorosity
mu_total
cPTotal Fluid Viscosity
c_t
1/psiTotal Compressibility
r_w
ftWellbore Radius
Outputs
S
Skin Factor
p_i
Initial Pressure
p_1hr
Pressure After One Hour
m
Semilog Slope
k
Permeability
Source and review
reviewedAdvanced Reservoir Engineering, Ahmed, T., McKinney, P. D. (2005)
Ahmed, T. and McKinney, P. D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter 1, Page 99.
Source