Dimensionless Time for Radial Flow Constant-Rate Production Formula
Dimensionless Time for Radial Flow Constant-Rate Production calculates dimensionless time based on wellbore radius for pressure transient analysis workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (k, t, phi, mu, c_t, r_w) 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, t_D equals 5,860 dimensionless.
50
0.1
0.18
2
0.00001
0.25
Inputs
k
mDPermeability
t
hProduction Time
phi
fractionPorosity
mu
cPOil Viscosity
c_t
1/psiTotal Compressibility
r_w
ftWellbore Radius
Outputs
t_D
Dimensionless Time Based on Wellbore Radius
k
Permeability
t
Production Time
phi
Porosity
mu
Oil Viscosity
c_t
Total Compressibility
r_w
Wellbore Radius
Source and review
reviewedLee, J., Rollins, J. B., and Spivey, J. P. Pressure Transient Testing, SPE Textbook Series Vol. 9, Page 8.
Source