# Pseudo skin factor due to partial penetration (Brons and Marting method)

## Input(s)

\(h_{p}\): Perforation interval \((\mathrm{ft})\)

\(\mathrm{h}\) : Total pay thickness (ft)

kh: Vertical permeability \((\mathrm{mD})\)

\(\mathrm{kv}\) : Horizontal permeability \((\mathrm{mD})\)

rw: Wellbore diameter (ft)

## Output(s)

\(h_{d}\) : Dimensionless Payzone Thickness (dimensionless)

b: Penetration Ratio (dimensionless)

\(\mathrm{Gb}\) : Function for penetration ratio (dimensionless)

\(s_{p}\) : Skin due to partial penetration (dimensionless)

## Formula(s)

\[
\begin{gathered}
h_{d}=\frac{h_{p}}{h} \\
b=\frac{h}{r w} *\left(\frac{k h}{k v}\right)^{0.5} \\
G b=2.948-7.363 * b+11.45 * b^{2}-4.675 * b^{3} \\
s_{p}=\left(\frac{1}{b}-1\right) *\left(\ln \left(h_{d}\right)-G b\right)
\end{gathered}
\]

## Reference(s)

Horizontal Well Technology, Joshi, Page: 493.