Page 40 - Formulas and Calculations for Petroleum Engineering

Reservoir engineering formulas and calculations Chapter 1 33

Output(s)

G: Gas Initially in Place (MSCF)

Formula(s)

G B W W B
p g e p w
G ¼
B B
g gi
Reference: Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 3,
Page: 207.

1.73 Injectivity index
Input(s)

q: Flow Rate of injection Well (STB/day)
p: Reservoir Pressure (psi)
p wf : Well Flow Pressure (psi)

Output(s)

I: Injectivity Index (STB/day/psi)

Formula(s)

q
I ¼
pwf p

Reference: Horizontal Well Technology, Joshi, Page: 10.

1.74 Instantaneous gas-oil ratio

Input(s)

R s : Gas Solubility (SCF/STB)
k rg : Relative Gas Permeability (dimensionless)
k ro : Relative Oil Permeability (dimensionless)
m o : Viscosity of Oil (cP)
m g : Viscosity of Gas (cP)
B o : Oil Formation Volume Factor (bbl/STB)
B g : Gas Formation Volume Factor (bbl/SCF)

Output(s)
GOR: Gas Oil Ratio (SCF/bbl)

Formula(s)

k m B o
rg
o
GOR ¼ R +
s
k m B
ro g g
Reference: Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 1,
Page: 16.