Phase Behavior and ThermodynamicsPVT Properties
Petrosky-Farshad Bubble Point Pressure Formula
Petrosky-Farshad Bubble Point Pressure calculates bubble point pressure for pvt properties workflows in phase behavior and thermodynamics.
How engineers use this formula
Use this formula when the listed inputs (R_sb, gamma_g, API, 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, p_b equals 2,690.751705 psi.
R_sbSCF/STB
600
gamma_gfraction
0.8
APIAPI
35
T°F
180
Inputs
R_sb
SCF/STBSolution Gas-Oil Ratio at Bubble Point
gamma_g
fractionGas Specific Gravity
API
APIOil API Gravity
T
°FReservoir Temperature
Outputs
p_b
psi
Bubble Point Pressure
R_sb
SCF/STB
Solution Gas-Oil Ratio at Bubble Point
x_petrosky_bubble
dimensionless
Petrosky-Farshad Bubble Point Temperature and API Exponent
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