Dimensionless Time for Semi-Steady-State Coalbed Methane Flow Formula
Dimensionless Time for Semi-Steady-State Coalbed Methane Flow calculates dimensionless time for unconventional reservoirs workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (k_g, t, phi, mu_gi, c_ti, A) are known and the assumptions behind the cited unconventional reservoirs 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 0.118665 dimensionless.
0.1
720
0.04
0.02
0.0002
1000000
Inputs
k_g
mDEffective Gas Permeability
t
hElapsed Time
phi
fractionPorosity
mu_gi
cPGas Viscosity at Initial Pressure
c_ti
1/psiTotal Compressibility at Initial Pressure
A
ft^2Drainage Area
Outputs
t_DA
Dimensionless Time
k_g
Effective Gas Permeability
t
Elapsed Time
phi
Porosity
mu_gi
Gas Viscosity at Initial Pressure
c_ti
Total Compressibility at Initial Pressure
A
Drainage Area
Source and review
reviewedAhmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter 3, Page 221.
Source