Page 77 - Formulas and Calculations for Petroleum Engineering

70 Formulas and calculations for petroleum engineering

1.161 Water two-phase formation volume factor

Input(s)
B w : Water Formation Volume Factor (one phase) (rb/STB)
B g : Gas Formation Volume Factor (MSCF/STB)
R s : Gas Oil ratio (rb/MSCF)
R i : Initial Gas Oil Ratio (rb/MSCF)

Output(s)

B t : Water Formation Factor (rb/STB)

Formula(s)

B ¼ B + B R R
t w g s i
Reference: Ahmed, T. & McKinney, P. Advanced reservoir Engineering, Gulf Publishing House, Burlington, MA, 2015.

1.162 Waxman and Smits model—Clean sands
Input(s)

F: Shaly-Sand Formation Resistivity Factor (dimensionless)
Øe: Effective Porosity (fraction)
C cl : Clay Exchange Cation Conductivity (1/O m)
C w : Formation Water Conductivity (1/O m)

Output(s)
C o : Brine Saturated Rock Conductivity (1/O m)

Formula(s)

1
C ¼ C +Cð cl w Þ
o
F
Reference: Bassiouni, Z., 1994, Theory, Measurement, and Interpretation of Well Logs. SPE Textbook Series Vol. 4.
Chapter 1, Page: 17.

1.163 Welge extension—Fractional flow

Input(s)
f o : Fractional Flow of Oil Obtained (fraction)
m w : Viscosity of Water (cP)
m o : Viscosity of Oil (cP)

Output(s)
relpr: Relative Permeability Ratio of Water to Oil (fraction)

Formula(s)

1 f
m w o
relpr ¼
f
m o o
Reference: Dandekar, A. Y. 2006. Petroleum Reservoir Rock and Fluid Properties. Boca Raton, FL: CRC Press Taylor &
Francis Group, Chapter: 9, Page: 215.