Reservoir EngineeringUnconventional Reservoirs
Adsorbed Gas in Place from Langmuir Isotherm Formula
Adsorbed Gas in Place from Langmuir Isotherm calculates adsorbed gas in place for unconventional reservoirs workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (A, h, rho_b, V_L, P, P_L) 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, G_a equals 13,923,328,000 SCF.
Aacres
640
hft
20
rho_bg/cc
1.4
V_LSCF/ton
800
Ppsi
500
P_Lpsi
200
Inputs
A
acresCoalbed Area
h
ftCoal Seam Thickness
rho_b
g/ccCoal Bulk Density
V_L
SCF/tonLangmuir Volume
P
psiReservoir Pressure
P_L
psiLangmuir Pressure
Outputs
G_a
SCF
Adsorbed Gas in Place
A
acres
Coalbed Area
h
ft
Coal Seam Thickness
rho_b
g/cc
Coal Bulk Density
V_L
SCF/ton
Langmuir Volume
P
psi
Reservoir Pressure
P_L
psi
Langmuir Pressure
Source and review
reviewedDerived from Ahmed and McKinney's coalbed methane adsorbed-gas-in-place and Langmuir adsorption relationships.
Source