Line-Source Pressure Beyond the Wellbore Formula
Line-Source Pressure Beyond the Wellbore calculates pressure at radius r for pressure transient analysis workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (P_i, t, k, B, phi, c_t, h, mu, r, q) are known and the assumptions behind the cited pressure transient analysis relationship match the engineering case being checked.
Assumptions
- Input values are representative for the well, reservoir, fluid, or equipment case being evaluated.
- The declared units match the field-unit constants used in the formula.
- The cited formula applies to the selected petroleum engineering workflow.
Limitations
- The calculation does not replace a full engineering model or operating procedure.
- Accuracy depends on the source correlation, assumptions, input quality, and unit consistency.
Common mistakes
- Mixing unit systems without converting the inputs.
- Using default example values as field recommendations.
- Applying the formula outside the source assumptions.
Default example
Using the default inputs, P equals 3,873.755305 psi.
4000
10
100
1.2
0.2
0.00001
50
1
10
500
Inputs
P_i
psiInitial Pressure
t
hProduction Time
k
mDPermeability
B
RB/STBFormation Volume Factor
phi
fractionPorosity
c_t
1/psiTotal Compressibility
h
ftReservoir Thickness
mu
cPOil Viscosity
r
ftRadial Distance from Wellbore
q
STB/dayFlow Rate
Outputs
P
Pressure at Radius r
P_i
Initial Pressure
q
Flow Rate
B
Formation Volume Factor
h
Reservoir Thickness
Source and review
reviewedPressure Transient Testing, Lee, J., Rollins, J. B., Spivey, J. P. (2003)
Lee, J., Rollins, J. B., and Spivey, J. P. 2003. Pressure Transient Testing, SPE Textbook Series Vol. 9, Page 11.
Source