Page 18 - Formulas and Calculations for Petroleum Engineering

Reservoir engineering formulas and calculations Chapter 1 11

1.20 Cumulative oil production—Undersaturated oil reservoirs

Input(s)
N: Initial Oil-in Place (STB)
c e : Effective Compressibility (1/psi)
B o : Oil Formation Volume Factor at the Assumed Reservoir Pressure (bbl/STB)
B oi : Oil Formation Volume Factor at Initial Reservoir Pressure (bbl/STB)
DP: Pressure Differential (psi)

Output(s)
N p : Cumulative Oil Production (STB)

Formula(s)

B o
N ¼ N c DP
p e
B
oi
Reference: Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 5,
Page: 333.

1.21 Deliverability equation for shallow gas reservoirs

Input(s)
k: Permeability (mD)
h: Thickness (ft)
T: Temperature (°R)
m: Viscosity (cP)
z: Compressibility Factor (dimensionless)
r e : Radius of Drainage Area (ft)
r w : Wellbore Radius (ft)

Output(s)

C: Performance Coefficient (dimensionless)

Formula(s)

k h
C ¼
r e
1422 T m Z ln 0:5
g
r
w
Reference: Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 3,
Page: 287.

1.22 Dimensionless pressure—Kamal and Brigham

Input(s)
Q: Flow Rate (STB/day)
k: Average Permeability (mD)
h: Thickness (ft)