Page 237 - Formulas and Calculations for Petroleum Engineering

230 Formulas and calculations for petroleum engineering

4.61 Pore growth function (acidizing)

Input(s)
2
r ave : Average Wall Reaction Rate taken over the entire Reactive Surface Area (mol/cm s)
β: Acid gravimetric dissolving power (mass rock/mass acid)
3
ρ ma : Formation Matrix Density (g/cm )
Γ: Perimeter of the Pore (μm)
2
A: Cross-sectional Area of Pore (cm )
l: Length of Pore (μm)
t: time (s)

Output(s)
2
ψ: Pore Growth Function (cm /s)

Formula(s)

r ave βΓ
ψ ¼
ρ ma

or
dA
ρ l ¼ r βΓl
ma ave
dt
Reference: 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: 69.

4.62 Pressure drop across perforations in gas wells

Input(s)
q g : Gas Flow Rate through Perforation (bbl/d)
n: Number of Perforations (dimensionless)
μ g : Gas Viscosity (cP)
Z: Gas Supercompressibility Factor (dimensionless)
T: Formation Temperature (R°)
L p : Perforation Length (ft)
k pd : Perforation Damaged Zone Permeability (mD)
r p : Perforation Radius (ft)
r pd : Perforation Damaged Zone Radius (ft)
γ g : Gas Specific Gravity (air ¼ 1.0)

Output(s)

p sf : Pressure at the Sandface (psi)
p wb : Pressure in the Wellbore (psi)
β pd : Velocity Coefficient of Turbulence Factor (1/ft)