Total skin in partially depleted wells for a buildup test
Input(s)
\(r_{e w}\): Dimensionless Parameter in terms of Perforated Length and Wellbore Radius (dimensionless)
\(\emptyset\) : Porosity (fraction)
\(\mu\) : Viscosity \((\mathrm{cP})\)
\(c_{t}\): Total Compressibility \((1 / \mathrm{psi})\)
k: Permeability \((\mathrm{mD})\)
\(p_{s}\): Shut-in Pressure at any Shut-in Time (psi)
\(p_{w}\) : Well Flowing Pressure at the Instant of Shut-in (psi)
\(\Delta t\): Shut-in Time (day)
\(\mathrm{m}\) : Slope of Cartesian Pressure Build-up Plot (psi/cycle)
Output(s)
S: Skin (dimensionless)
Formula(s)
\[
S=34.7 * r_{e w} *\left(\left(\left(\emptyset * \mu * \frac{c_{t}}{k}\right)\right)^{0.5}\right) *\left(\left(\frac{p_{s}-p_{w}}{m}\right)+\left(\frac{1}{(\Delta t)^{0.5}}\right)\right)-1
\]
Reference(s)
Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 1, Page: 81 .