Water-Drive Index for Gas Reservoirs Formula
Water-Drive Index for Gas Reservoirs calculates water-drive index for material balance workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (W_e, W_p, B_w, G_p, 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, WDI equals 0.2 fraction.
1302000
100000
1.02
1000000000
0.006
Inputs
W_e
bblCumulative Water Influx
W_p
STBCumulative Water Production
B_w
bbl/STBWater Formation Volume Factor
G_p
SCFCumulative Gas Production
B_g
bbl/SCFGas Formation Volume Factor at Current Pressure
Outputs
WDI
Water-Drive Index
W_e
Cumulative Water Influx
W_p
Cumulative Water Production
B_w
Water Formation Volume Factor
G_p
Cumulative Gas Production
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