Page 21 - Formulas and Calculations for Petroleum Engineering

14 Formulas and calculations for petroleum engineering

Ø: Porosity (fraction)
c t : Total Compressibility (1/psi)
r w : Wellbore Radius (ft)

Output(s)
C d : Dimensionless Wellbore-Storage Coefficient (dimensionless)

Formula(s)
0:8936 C
C ¼
d 2
Ø c h r
t w
Reference: Lee, J., Rollins, J. B., & Spivey, J. P. (2003). Pressure Transient Testing (Vol. 9). Richardson, Texas: Society of
Petroleum Engineer, Page: 8.

1.28 Effective compressibility in undersaturated oil reservoirs—Hawkins

Input(s)
S oi : Initial Oil Saturation (fraction)
S wi : Initial Water Saturation (fraction)
c o : Oil Compressibility (1/psi)
c w : Water Compressibility (1/psi)
c f : Formation Compressibility (1/psi)

Output(s)
c e : Effective Compressibility (1/psi)

Formula(s)
S c +S c +c f
oi
o
w
wi
c ¼
e
1 S
wi
Reference: Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 5,
Page: 334.
1.29 Effective wellbore radius of a horizontal well—Method 1—Anisotropic reservoirs
Input(s)
L: Horizontal Well Length (ft)
h: Pay Zone Thickness (ft)
r w : Wellbore Radius (ft)
k h : Horizontal Permeability (mD)
k v : Vertical Permeability (mD)
A: Drainage Area (acre)

Output(s)

r eh : Effective Drainage Radius (ft)
a: Horizontal wellbore variable from Joshi (dimensionless)
b: Permeability Ratio constant (dimensionless)
r wd : Effective Wellbore Radius (ft)