Original Gas in Place - Volumetric Method Calculator
Enter the required inputs, confirm the units, and run the calculator to solve G. Review the formula source and assumptions before using the result in engineering work.
Calculation context and source notes
Original Gas in Place - Volumetric Method calculates original gas in place for reservoir volumetrics 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_gi) are known and the assumptions behind the cited reservoir volumetrics relationship match the engineering case being checked.
Solves for
G (SCF)
Best next page
Formula, variables, and sourceFormula, variables, and default calculation
Reproducible default result
With the default values shown below, the calculation returns G = 7,840,800,000 SCF. Defaults demonstrate the implementation; they are not recommended field values.
160
50
0.15
0.25
0.005
Input definitions
A
acresReservoir Area
h
ftAverage Reservoir Thickness
phi
fractionPorosity
S_wi
fractionInitial Water Saturation
B_gi
ft³/SCFInitial Gas Formation Volume Factor
Output definitions
G
Original Gas in Place
A
Reservoir Area
h
Average Reservoir Thickness
phi
Porosity
S_wi
Initial Water Saturation
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_gi) are known and the assumptions behind the cited reservoir volumetrics 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 Original Gas in Place - Volumetric Method calculator need?
The calculation uses Reservoir Area (A), Average Reservoir Thickness (h), Porosity (phi), Initial Water Saturation (S_wi), 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 original gas in place 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.
Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter 3, Page 202.
Open source reference