Page 198 - Formulas and Calculations for Petroleum Engineering

Well test analysis formulas and calculations Chapter 3 191

3.35 Dimensionless wellbore storage coefficient (compressible fluids for pressure
build-up test)

Input(s)
C: Well Bore Storage Coefficient (bbl/psi)
ø: Porosity (fraction)
c f : Formation Compressibility (1/psi)
h: Pay zone Thickness (ft)
r w : Well Bore Radius (ft)

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

Formula(s)
0:8936 C
C ¼
d 2
ø c h r
f w
Reference: Lee, J., Rollins, J. B., & Spivey, J. P. (2003). Pressure Transient Testing (Vol. 9). Richardson, Texas: Society of
Petroleum Engineers, Page: 105.

3.36 Flow period duration (hydraulically fractured wells)

Input(s)
ø: Porosity (fraction)
c t : Total Compressibility (1/psi)
m: Viscosity (cP)
L f : Fracture Length (ft)
t LfD : Time of End of Linear or Start Pseudo Radial Flow from Plot (dimensionless)
k: Permeability (mD)

Output(s)
t: Duration of Flow Periods (h)

Formula(s)

ø m c L 2 f t LfD
t
t ¼
0:0002637 k
Reference: Lee, J., Rollins, J. B., & Spivey, J. P. (2003). Pressure Transient Testing (Vol. 9). Richardson, Texas: Society of
Petroleum Engineers, Page: 115.

3.37 Fracture conductivity (bilinear-flow regime in gas wells)

Input(s)

q: Flow Rate (bbl/d)
ø: Porosity (fraction)
m: Viscosity (cP)
B: Formation Volume Factor (BBL/STB)