This package contains custom activities to calculate PVT properties for oil, gas and water.
Usage
Run the workflows from this package to perform the calculations. The schedules may be adapted to use different contexts.
Details
Oil Correlations
Oil Bubble Point Pressure
The bubble point pressure is calculated according to the correlation of Vasquez and Beggs (1980) from the solution gas-oil ratio at the bubble point, the specific gravity of gas and the specific gravity of oil.
Solution Gas-Oil Ratio
If the pressure is below or equal to the bubble point pressure, the solution gas-oil ratio is calculated according to the correlation of Vasquez and Beggs. For pressures above or equal to the bubble point pressure, the solution oil-gas ratio is constant and the solution gas-oil ratio at bubble point is returned.
Formation Volume Factor Oil
If the pressure is below or equal to the bubble point pressure, the formation volume factor is calculated according to the correlation of Vasquez and Beggs (1980). For pressures above or equal to the bubble point pressure, the correlation of Levitan and Murtha (1999) is returned.
Oil Viscosity
If the pressure is below or equal to the bubble point pressure, the viscosity is calculated according to the correlation of Beggs and Robinson. For pressures above or equal to the bubble point pressure, the correlation of Vasquez and Beggs is returned.
Additionally, the following inputs must be within the specified data range for the script to execute successfully:
- 0 < pressure [psi] < 5250
- 70 <= temperature [°F] <= 295
- 16 < api gravity oil [°API] < 58
- 20 < solution gas oil ratio at bubble point [SCF/STB] < 2070
Oil Compressibility Coefficient
If the pressure is below the bubble point pressure, the compressibility is calculated according to the correlation of McCain. For pressures above or equal to the bubble point pressure, the correlation of Vasquez and Beggs is returned.
Oil Density
The oil density is calculated from the specific oil and gas gravities, the solution gas-oil ration and the formation volume factor of oil.
Data Requirements (Oil Correlations)
The following data is required to perform the calculations:
solution gas oil ratio at bubble point
gas specific gravity
api gravity oil
Gas Correlations
Gas Z Factor
The gas deviation factor (Z-factor) is calculated according to the correlation of Papay (1985).
Gas Density
The gas density is calculated using the real gas law from the gas deviation factor and the specific gas gravity.
Formation Volume Factor Gas
The gas formation volume factor is calculated from the gas Z factor assuming that the standard conditions are represented by a pressure of 14.7 psi and a temperature of 520 °R.
Gas Compressibility Coefficient
The gas compressibility coefficient is calculated according to the technique presented by Mattar, Brar, and Aziz (1975), with a validity range:
- 100 <= temperature [°F] < 300
- 154 < pressure [psi] < 7026
- 0.57 < gas specific gravity [ ] < 1.68
- CO2 content < 0.544
-
H2S content < 0.738
Gas Viscosity
The gas viscosity is calculated according to the method developed by Lee, Gonzales, and Eakin (1966).
Data Requirements (Gas Correlations)
The following data is required to perform the calculations:
gas specific gravity
H2S content
CO2 content
Water Correlations
Water Bubble Point Pressure
The bubble point pressure is calculated according to the correlation of Antoine (1888).
Formation Volume Factor Water
The formation volume factor is calculated according to the correlation of McCain.
Water Viscosity
The viscosity is calculated according to the correlation of McCain.
Water Compressibility Coefficient
If the pressure is below the bubble point pressure, the compressibility is calculated according to the correlation of Osif. For pressures above or equal to the bubble point pressure, the correlation of McCain is returned.
Data Requirements (Water Correlations)
The following data is required to perform the calculations:
water salinity
Further comments
Each activity requires setting a temperature and pressure range, as well as suitable increments. If a temperature or pressure is outside of a correlation's validity, no value is returned for this pressure / temperature.
References
[1] Ahmed, T. (2013). Equations of state and PVT analysis. Elsevier.