Vasquez-Beggs Solution Gas-Oil Ratio from Pressure Formula
Vasquez-Beggs Solution Gas-Oil Ratio from Pressure calculates solution gas-oil ratio for pvt properties workflows in phase behavior and thermodynamics.
How engineers use this formula
Use this formula when the listed inputs (p, T, API, gamma_g, C_rs1, C_rs2, C_rs3) 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, R_s equals 569.164106 SCF/STB.
2500
180
35
0.8
0.0178
1.187
23.931
Inputs
p
psiPressure
T
°FReservoir Temperature
API
APIOil API Gravity
gamma_g
fractionGas Specific Gravity
C_rs1
dimensionlessVasquez-Beggs C1 Coefficient (0.0178 if API > 30; 0.0362 if API <= 30)
C_rs2
dimensionlessVasquez-Beggs C2 Coefficient (1.1870 if API > 30; 1.0937 if API <= 30)
C_rs3
dimensionlessVasquez-Beggs C3 Coefficient (23.931 if API > 30; 25.724 if API <= 30)
Outputs
R_s
Solution Gas-Oil Ratio
p
Pressure
gamma_g
Gas Specific Gravity
Source and review
reviewedVasquez and Beggs 1980 oil PVT correlations, as summarized in IHS Harmony / WellTest documentation and PIPESIM fluid-property documentation.
Source