Dimensionless Time for Linear Flow Constant Rate General Case Formula
Dimensionless Time for Linear Flow Constant Rate General Case calculates dimensionless time based on drainage area 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, A) 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_DA equals 1.465 dimensionless.
50
24
0.18
1.2
0.00001
100000
Inputs
k
mDEffective Permeability
t
hrElapsed Flow Time
phi
fractionPorosity
mu
cPFluid Viscosity
c_t
1/psiTotal Compressibility
A
ft^2Drainage Area
Outputs
t_DA
Dimensionless Time Based on Drainage Area
k
Effective Permeability
t
Elapsed Flow Time
phi
Porosity
mu
Fluid Viscosity
c_t
Total Compressibility
A
Drainage Area
Source and review
reviewedLee, Rollins and Spivey, Pressure Transient Testing, SPE Textbook Series Vol. 9, linear-flow constant-rate dimensionless variables.
Source