Reservoir EngineeringPVT Properties
Gas Expansion Factor from Formation Volume Factor Formula
Gas Expansion Factor from Formation Volume Factor calculates gas expansion factor for pvt properties workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (P, z, T) are known and the assumptions behind the cited pvt properties 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 208.058824 SCF/ft³.
Ppsia
3000
zdimensionless
0.85
T°R
600
Inputs
P
psiaReservoir Pressure
z
dimensionlessGas Compressibility Factor
T
°RReservoir Temperature
Outputs
E_g
SCF/ft³
Gas Expansion Factor
P
psia
Reservoir Pressure
z
dimensionless
Gas Compressibility Factor
T
°R
Reservoir Temperature
Source and review
reviewedAhmed, T. 2007. Equations of State and PVT Analysis, Natural Gas Properties, Equations 3-52 through 3-54.
Source