Page 207 - Formulas and Calculations for Petroleum Engineering

200 Formulas and calculations for petroleum engineering

3.54 Slope of Horner plot in pressure buildup test

Input(s)
Q o : Stabilized Well Flow Rate before Shut-in (STB/day)
m o : Oil Viscosity (cP)
B o : Oil Formation Volume Factor (bbl/STB)
k: Permeability (mD)
h: Thickness (ft)

Output(s)
m: Slope (psi/cycle)

Formula(s)

162:6 Q m B o
o
o
m ¼
k h
Reference: Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 1,
Page: 54.

3.55 Slope of pseudo-steady state flow in pressure buildup test

Input(s)
Q: Flow Rate (STB/day)
B: Formation Volume Factor (bbl/STB)
c t : Total Compressibility (1/psi)
2
A: Drainage Area (ft )
ø: Porosity (fraction)
h: Thickness (ft)

Output(s)
m pss : Slope (psi/h)

Formula(s)

0:23396 Q B
m ¼
pss
c A h ø
t
Reference: Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 1,
Page: 33.

3.56 Time to pseudo-steady state (single well-circular reservoir)

Input(s)
Ø: Porosity (fraction)
m: Viscosity (cP)
c t : Compressibility (/psi)
r e : Radius of reservoir (ft)
k: Permeability (mD)