Total Skin in Partially Depleted Wells for a Buildup Test Formula
Total Skin in Partially Depleted Wells for a Buildup Test calculates total skin factor for well performance workflows in production engineering.
How engineers use this formula
Use this formula when the listed inputs (r_ew, phi, mu, c_t, k, p_s, p_w, Delta_t, m) are known and the assumptions behind the cited well performance 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 1.586067 dimensionless.
100
0.18
1.5
0.00001
50
3000
2500
2
200
Inputs
r_ew
dimensionlessDimensionless Radius Parameter Based on Perforated Length and Wellbore Radius
phi
fractionPorosity
mu
cPFluid Viscosity
c_t
1/psiTotal Compressibility
k
mDPermeability
p_s
psiShut-In Pressure at Selected Shut-In Time
p_w
psiFlowing Pressure at the Instant of Shut-In
Delta_t
dayShut-In Time
m
psi/cycleCartesian Pressure Buildup Plot Slope
Outputs
S
Total Skin Factor
Source and review
reviewedAdvanced Reservoir Engineering, Ahmed, T., McKinney, P.D. (2005)
Ahmed, T. and McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing/Elsevier, Chapter 1, Page 81.
Source