Damaged/undamaged zone productivity comparison (acidizing)

Input(s)

$F_{k}$: Permeability Ratio (dimensionless)

$r_{e}$: Drainage Radius (in.)

$r_{w}$: Wellbore Radius (in.)

$r_{s}$ : Damaged Zone Radius (in.)

Output(s)

$J_{s}$: Damaged or Stimulated Formation Productivity Index (STB/day/psi)

$J_{o}$ : Undamaged Formation Productivity Index (STB/day/psi)

Formula(s)

$$ \frac{J_{s}}{J_{o}}=\frac{F_{k} \log r_{e} / r_{w}}{\log r_{s} / r_{w}+F_{k} \log r_{e} / r_{s}} $$

Reference(s)

Williams, B. B., Gidley, J. L., \& Schechter, R. S. (1979). Acidizing fundamentals. Henry L. Doherty Memorial Fund of AIME, Society of Petroleum Engineers of AIME, Page: 6.