Trapped Gas Volume in Water-Invaded Zones Formula
Trapped Gas Volume in Water-Invaded Zones calculates trapped gas volume 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, S_wi, S_grw) 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, TG equals 144,727.272727 MSCF.
500000
100000
1.02
0.25
0.2
Inputs
W_e
bblCumulative Water Influx
W_p
STBCumulative Water Production
B_w
bbl/STBWater Formation Volume Factor
S_wi
fractionInitial Water Saturation
S_grw
fractionResidual Gas Saturation in Water-Invaded Zone
Outputs
TG
Trapped Gas Volume
W_e
Cumulative Water Influx
W_p
Cumulative Water Production
B_w
Water Formation Volume Factor
S_wi
Initial Water Saturation
S_grw
Residual Gas Saturation in Water-Invaded Zone
Source and review
reviewedAhmed, T. and McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter 3, Page 208.
Source