Reservoir EngineeringMaterial Balance
Gas Expansion Term in Gas Reservoirs Formula
Gas Expansion Term in Gas Reservoirs calculates gas expansion term for material balance workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (B_g, B_gi) 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, E_g equals 0.002 ft³/SCF.
B_gft³/SCF
0.006
B_gift³/SCF
0.004
Inputs
B_g
ft³/SCFGas Formation Volume Factor
B_gi
ft³/SCFInitial Gas Formation Volume Factor
Outputs
E_g
ft³/SCF
Gas Expansion Term
B_g
ft³/SCF
Gas Formation Volume Factor
B_gi
ft³/SCF
Initial Gas Formation Volume Factor
Source and review
reviewedAhmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter 3, Page 209.
Source