Gas Drive Index in Gas Reservoirs Formula
Gas Drive Index in Gas Reservoirs calculates gas drive index for material balance workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (G, G_p, B_gi, B_g) are known and the assumptions behind the cited material balance 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, GDI equals 0.8 fraction.
2000000000
500000000
0.004
0.005
Inputs
G
SCFOriginal Gas In Place
G_p
SCFCumulative Gas Production
B_gi
bbl/SCFInitial Gas Formation Volume Factor
B_g
bbl/SCFGas Formation Volume Factor at Current Pressure
Outputs
GDI
Gas Drive Index
G
Original Gas In Place
G_p
Cumulative Gas Production
B_gi
Initial Gas Formation Volume Factor
B_g
Gas Formation Volume Factor at Current Pressure
Source and review
reviewedAhmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Chapter 3, Page 211; ScienceDirect gas-reservoir drive-index summary.
Source