Page 51 - Formulas and Calculations for Petroleum Engineering

44 Formulas and calculations for petroleum engineering

1.100 Oil saturation at any depletion state below the bubble point pressure

Input(s)
S wi : Initial Water Saturation (fraction)
N p : Cumulative Oil Production (STB)
N: Oil in Place (STB)
B oi : Initial Oil Formation Volume Factor (bbl/STB)
B o : Oil Formation Volume Factor (bbl/STB)

Output(s)
S o : Oil Saturation (fraction)

Formula(s)

N B

p o
S ¼ 1 S Þ 1
ð
o wi
N B
oi
Reference: Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 4,
Page: 312.
1.101 Original gas in place

Input(s)
A: Area of Reservoir (acres)
h: Average Reservoir Thickness (ft)
Ø: Porosity (fraction)
S wi : Initial Water Saturation (fraction)
B gi : Gas Formation Volume Factor at Initial Pressure (ft3/SCF)

Output(s)
G: Gas-in-Place (SCF)

Formula(s)

ð
43560 A h Ø 1 S Þ
wi
G ¼
B
gi
Reference: Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 3,
Page: 202.

1.102 Payne method for intercompartmental flow in tight gas reservoirs
Input(s)

k: Permeability (mD)
T: Temperature (°R)
2
A: Cross-Sectional Area (ft )
L: Distance between the Center of the Two Compartments (ft)
2
m(P 1 ): Gas Pseudo pressure in Compartment (Tank) 1 (psi /cP)
2
m(P 2 ): Gas Pseudo pressure in Compartment (Tank) (psi /cP)