Page 55 - Formulas and Calculations for Petroleum Engineering

48 Formulas and calculations for petroleum engineering

1.110 Productivity index for a gas well

Input(s)
k: Permeability (mD)
h: Thickness (ft)
T: Temperature (°R)
2
A: Drainage Area (ft ))
C A : Shape Factor (dimensionless)
r w : Wellbore Radius (ft)
S: Skin (dimensionless)

Output(s)
2
J: Productivity Index (MSCF/day/psi /cP)

Formula(s)

k h
J ¼
4 A
1422 T 0:5 ln +S
1:781 C r 2
A w
Reference: Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 3,
Page: 188.

1.111 Pseudo-steady state productivity of horizontal Wells—Method 1

Input(s)
2
A: Drainage Area (ft )
s: Skin Factor (dimensionless)
D: Turbulence Coefficient (1/BOPD for oil and 1/MSCFD for gas)
C: Shape Factor Conversion Constant ¼ 1.386 (dimensionless)
s CAh : Shape-Related Skin Factor (dimensionless)
h: Thickness of Reservoir (ft)
k v : Vertical Permeability (mD)
k h : Horizontal Permeability (mD)
k: Permeability (mD)
q: Flow Rate (BOPD for oil and MSCFD for gas)
L: Fracture Length (ft)
r w : Radius of Wellbore (ft)
m o : Viscosity of Oil (cP)
B o : Oil Formation Volume Factor (RB/STB)

Output(s)

r e : Effective Radius of Drainage Area (ft)
s m : Mechanical Skin Factor (dimensionless)
s f : Skin Factor of an Infinite-conductivity, Fully Penetrating Fracture of Length L (dimensionless)
J h : Pseudo-steady State Productivity of a Horizontal Well (bbl/day/psi)