Fractional Gas Recovery Below the Critical Desorption Pressure in Coal Bed Methane Reservoirs Formula
Fractional Gas Recovery Below the Critical Desorption Pressure in Coal Bed Methane Reservoirs calculates fractional gas recovery for unconventional reservoirs workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (V_m, G_c, b, P, 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, RF equals 0.056867 fraction.
800
600
0.005
500
1.2
Inputs
V_m
scf/tonLangmuir Volume Constant
G_c
scf/tonGas Content at Critical Desorption Pressure
b
psi⁻¹Langmuir Pressure Constant
P
psiReservoir Pressure
a
dimensionlessRecovery Exponent
Outputs
RF
Fractional Gas Recovery
V_m
Langmuir Volume Constant (not symbolically solvable)
G_c
Gas Content at Critical Desorption Pressure (not symbolically solvable)
b
Langmuir Pressure Constant (not symbolically solvable)
P
Reservoir Pressure (not symbolically solvable)
a
Recovery Exponent (not symbolically solvable)
Source and review
reviewedAhmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 3, Page: 223.
Source