Dimensionless Buildup Time Formula
Dimensionless Buildup Time calculates dimensionless buildup time for pressure transient analysis workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (k_D, t, phi, mu, c_t_metric, r_w_m) 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 8,898.765432 dimensionless.
0.005
10
0.18
1.2
0.00015
0.25
Inputs
k_D
DEffective Permeability of Flowing Phase
t
hElapsed Buildup Time
phi
fractionPorosity
mu
cPViscosity of Flowing Fluid
c_t_metric
(kg/cm^2)^-1Total System Effective Isothermal Compressibility
r_w_m
mWell Radius
Outputs
t_D
Dimensionless Buildup Time
k_D
Effective Permeability of Flowing Phase
t
Elapsed Buildup Time
phi
Porosity
mu
Viscosity of Flowing Fluid
c_t_metric
Total System Effective Isothermal Compressibility
r_w_m
Well Radius
Source and review
reviewedReservoir Engineering Assessment of Geothermal Systems, Ramey Jr., H.J. (1981)
Ramey Jr., H.J. 1981. Reservoir Engineering Assessment of Geothermal Systems, Department of Petroleum Engineering, Stanford University, Page 5.7.