Gas Expansion Calculator - Produced Gas Volume
Calculate gas produced by expansion from initial gas in place and the change in gas formation volume factor. Confirm both volume factors use the same basis.
Calculation context and source notes
Gas Produced by Gas Expansion calculates gas produced by gas expansion for material balance and production workflows in reservoir engineering. The page keeps the declared variables, units, source relationship, and output definition visible for technical review.
Use this formula when the listed inputs (A, h, phi, S_wi, B_g, B_gi) are known and the assumptions behind the cited material balance and production relationship match the engineering case being checked.
Solves for
G_p (SCF)
Best next page
Formula, variables, and sourceRelated source-backed guides
Formula, variables, and default calculation
Reproducible default result
With the default values shown below, the calculation returns G_p = 2,613,600,000 SCF. Defaults demonstrate the implementation; they are not recommended field values.
160
50
0.2
0.25
0.005
0.004
Input definitions
A
acreDrainage Area
h
ftReservoir Thickness
phi
fractionPorosity
S_wi
fractionInitial Water Saturation
B_g
ft3/SCFCurrent Gas Formation Volume Factor
B_gi
ft3/SCFInitial Gas Formation Volume Factor
Output definitions
G_p
Gas Produced by Gas Expansion
A
Drainage Area
h
Reservoir Thickness
phi
Porosity
S_wi
Initial Water Saturation
B_g
Current Gas Formation Volume Factor
B_gi
Initial Gas Formation Volume Factor
Engineering use, assumptions, and limits
Use this formula when the listed inputs (A, h, phi, S_wi, B_g, B_gi) are known and the assumptions behind the cited material balance and production 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.
Frequently asked questions
What inputs does the Gas Produced by Gas Expansion calculator need?
The calculation uses Drainage Area (A), Reservoir Thickness (h), Porosity (phi), Initial Water Saturation (S_wi), Current Gas Formation Volume Factor (B_g), Initial Gas Formation Volume Factor (B_gi). Enter values on the units shown beside each field.
What result does this calculator return?
The primary result is gas produced by gas expansion in SCF. The formula section shows the declared relationship, variables, and a reproducible default calculation.
What should I check before using the result?
Confirm the unit basis, source applicability, and input quality. The calculation does not replace a full engineering model or operating procedure. Mixing unit systems without converting the inputs.
Source and record status
Source metadata identifies the relationship implemented by the calculator. Check the cited edition, unit basis, and scope against the engineering case before operational use.
Advanced 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 202.
Open source reference