Page 58 - Formulas and Calculations for Petroleum Engineering

Reservoir engineering formulas and calculations Chapter 1 51

1.115 Relative permeability—Corey exponents

Input(s)
k roe : Permeability at end point (mD)
S w : Saturation of Water (fraction)
S or : Residual Water Saturation (fraction)
S wi : Initial Water Saturation (fraction)
N o : Corey Coefficient (fraction)

Output(s)

k ro : Relative Permeability at given Saturation (mD)

Formula(s)

N o
1 S S or
w
k ¼ k
ro roe
1 S S
wi or
Reference: Dandekar, A. Y. 2006. Petroleum Reservoir Rock and Fluid Properties. Boca Raton, FL: CRC Press Taylor &
Francis Group, Chapter: 9, Page: 233.

1.116 Remaining gas in place in coalbed methane reservoirs

Input(s)
A: Drainage Area (acres)
Ø: Porosity (fraction)
h: Thickness (ft)
B w : Water Formation Volume Factor (bbl/STB)
W p : Cumulative Water Produced (bbl)
S wi : Water Saturation (fraction)
P i : Initial Pressure (psi)
P: Current Reservoir Pressure (psi)
c f : Formation Compressibility (1/psi)
c w : Water Compressibility (1/psi)
E g : Gas Expansion Factor (SCF/bbl)

Output(s)

G R : Remaining Gas at Reservoir Pressure (SCF)

Formula(s)

B W
0 1
w p
ð
ð
+1 S Þ P Pð i Þ c +c S Þ
w
f
wi
wi
7758 A h Ø
B C
G ¼ 7758 A h Ø E B C
R
1 P Pð Þ c A
g @
i f
Reference: Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 3,
Page: 227.