Skin during infinite-acting pseudoradial flow for vertical wells

Input(s)

$p_{i}$: Initial Pressure $(\mathrm{psi})$

$p_{1 h r}$: Pressure After 1 Hour (psi)

$\mathrm{m}$: Slope $(\mathrm{psi} / \mathrm{h})$

k: Permeability $(\mathrm{mD})$

$\emptyset$: Porosity (fraction)

$\mu_{\text {Total }}$: Viscosity $(\mathrm{cP})$

$c_{t}$: Total Compressibility (1/psi)

$r_{w}$: Wellbore Radius (ft)

Output(s)

S: Skin (dimensionless)

Formula(s)

$$ S=1.151 *\left(\left(\frac{p_{i}-p_{1 h r}}{m}\right)-\log \left(\frac{k}{\emptyset * \mu_{\text {Total }} * c_{t} * r_{w}^{2}}\right)+3.23\right) $$

Reference(s)

Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 1, Page: 99