Phase Behavior and ThermodynamicsPVT Properties
Vasquez-Beggs Undersaturated Oil Compressibility Formula
Vasquez-Beggs Undersaturated Oil Compressibility calculates undersaturated oil compressibility for pvt properties workflows in phase behavior and thermodynamics.
How engineers use this formula
Use this formula when the listed inputs (R_sb, T, gamma_g, API, p) 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, c_o equals 0.000013 1/psi.
R_sbSCF/STB
569.1641063395102
T°F
180
gamma_gfraction
0.8
APIAPI
35
ppsi
3000
Inputs
R_sb
SCF/STBSolution Gas-Oil Ratio at Bubble Point
T
°FReservoir Temperature
gamma_g
fractionGas Specific Gravity
API
APIOil API Gravity
p
psiPressure Above Bubble Point
Outputs
c_o
1/psi
Undersaturated Oil Compressibility
p
psi
Pressure Above Bubble Point
Source and review
reviewedVasquez and Beggs 1980 undersaturated oil compressibility, summarized by Petroleum Office and IHS oil-correlation documentation.
Source