Page 17 - Formulas and Calculations for Petroleum Engineering

10 Formulas and calculations for petroleum engineering

Formula(s)
N pcf N pncf
CI ¼
N N pncf
pu

Reference: Willhite, G.P. 1986. Waterflooding, Vol. 3. Richardson, Texas: Textbook Series, SPE, Chapter: 2, Page: 166.

1.18 Cumulative effective compressibility—Fetkovich
Input(s)

S wi : Initial Water Saturation (fraction)
c : Cumulative Total Water Compressibility (1/psi)
w
M: Dimensionless Volume Ratio (dimensionless)
–1
c : Total PV (Formation) Compressibility (psi )
f
Output(s)

c : Effective Compressibility (1/psi)
e

Formula(s)

S c + M c + c + c
wi w f w f
c ¼
e
1 S
wi
Reference: Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 3,
Page: 215,216.

1.19 Cumulative gas production—Tarner’s method

Input(s)

N: Initial Oil-in Place (STB)
R s : Gas Solubility (SCF/STB)
R si : Initial Gas Solubility (SCF/STB)
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)
B g : Gas Formation Volume Factor at the Assumed Reservoir Pressure (bbl/SCF)
N p : Cumulative Oil Production (STB)

Output(s)
G p : Cumulative Gas Production (SCF)

Formula(s)
" !# " #
B B B
oi o o
G ¼ N R R N R
p si s p s
B B
g g
Reference: Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 5,
Page: 340.