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Calculate the properties of petroleum reservoir fluids with a reliable, simple PVT calculator. Use the Vazquez-Beggs oil formation volume factor calculator.

Oil Formation Volume Factor

Vazquez-Beggs (1980)

First-stage separator gas specific gravity
Stock-tank oil specific gravity
Solution gas-oil ratio at bubble point pressure

N.B. At pressures less than bubble point pressure, the Vazquez-Beggs (1980) correlations are used to calculate the solution gas-oil ratio and the saturated oil formation volume factor. At pressures greater than bubble point pressure, the Vazquez-Beggs (1980) correlation for the under-saturated oil compressibility is used to calculate the under-saturated oil formation volume factor.

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Fluid Property Behavior

Oil Formation Volume Factor

In this section, I would like to make sure that you can easily describe the behavior of your oil formation volume factor at any reservoir pressure. Therefore, I will give you brief technical notes by answering three questions.
Why the oil formation volume factor is maximum at bubble point pressure?
When the pressure decreases above the bubble point pressure, the solution gas-oil ratio remains constant. As a result, the single-phase oil starts expanding until the pressure reaches the bubble point pressure. On the other hand, when the pressure decreases below the bubble point pressure, more gas is liberating from the liquid phase, making the oil shrink rapidly. Actually, almost all the black oil properties respond differently to the decrease in reservoir pressure.
What are the black oil PVT properties that are affecting the value estimated for the oil formation volume factor?
The oil formation volume factor is strongly dependent on the values estimated for both the bubble point pressure and the solution gas-oil ratio.
What are the black oil PVT properties that depend on the value estimated for the oil formation volume factor?
Both the oil density and the oil compressibility are strongly dependent on the value estimated for the oil formation volume factor.

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