Petrosky-Farshad Saturated Oil Formation Volume Factor Formula
Petrosky-Farshad Saturated Oil Formation Volume Factor calculates saturated oil formation volume factor for pvt properties workflows in phase behavior and thermodynamics.
How engineers use this formula
Use this formula when the listed inputs (R_s, gamma_g, gamma_o, 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, B_ob equals 1.347215 RB/STB.
600
0.8
0.85
180
Inputs
R_s
SCF/STBSolution Gas-Oil Ratio
gamma_g
fractionGas Specific Gravity
gamma_o
fractionStock-Tank Oil Specific Gravity
T
°FReservoir Temperature
Outputs
B_ob
Saturated Oil Formation Volume Factor
F_petrosky_fvf
Petrosky-Farshad Formation Volume Factor Correlating Parameter
R_s
Solution Gas-Oil Ratio
Source and review
reviewedPetrosky, G.E. Jr. and Farshad, F.F. 1993. Pressure-Volume-Temperature Correlations for Gulf of Mexico Crude Oils, SPE 26644.
Source