Low-Pressure Non-Circular Gas Flow Rate Formula
Low-Pressure Non-Circular Gas Flow Rate calculates gas flow rate for well performance workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (k, h, P_r, P_wf, mu_gavg, Z_avg, A, C_A, r_w, S, T) are known and the assumptions behind the cited well performance 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, Q_g equals 9,007.910402 MSCF/day.
50
40
1200
800
0.018
0.9
4356000
31.6
0.328
5
620
Inputs
k
mDPermeability
h
ftFormation Thickness
P_r
psiAverage Reservoir Pressure
P_wf
psiBottomhole Flowing Pressure
mu_gavg
cPAverage Gas Viscosity
Z_avg
dimensionlessAverage Gas Compressibility Factor
A
ft^2Drainage Area
C_A
dimensionlessShape Factor
r_w
ftWellbore Radius
S
dimensionlessSkin Factor
T
degRReservoir Temperature
Outputs
Q_g
Gas Flow Rate
P_r
Average Reservoir Pressure
P_wf
Bottomhole Flowing Pressure
k
Permeability
h
Formation Thickness
Source and review
reviewedAdvanced Reservoir Engineering, Ahmed, T., McKinney, P. D. (2005)
Ahmed, T. and McKinney, P. D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter 3, Page 189.
Source