# PVT

PVT is calculated at various phases of the ProdX modeling flow to establish relevant properties at pressures and temperatures of interest. Input properties for the PVT model can have significant impacts on downstream calculations, like multiphase flow correlations during a bottomhole pressure traverse. As such, it's important to define these as accurately as possible for each well.

The black oil model is used to calculate PVT properties of fluids. The input requirements for creating a black oil PVT model are described as follows and are imported in the Wellbore Formation table:

Oil specific gravity at formation conditions, in degrees API

Ratio between hydrocarbon gas density and air density at standard conditions, unitless

Salinity content of reservoir water, in parts per million

Initial solution gas oil ratio at reservoir conditions, scf/STB

Impurity content of reservoir gas, in molar fraction

Initial reservoir pressure (psia) and temperature (degF) are used to both establish initial conditions for saturation pressure and establish a linear geothermal gradient in the absence of more granular data.

Gas correlations are calculated for the following properties, and the available options in ProdX are noted

Gas pseudo-critical pressure and temperature are the weighted average of critical properties of pure components in a gas mixture. Available correlations:

- Sutton
- Standing

The gas z-factor is the** **ratio of the gas volume at input pressure and temperature to the volume that an ideal gas would occupy at the same pressure and temperature. Available correlations:

- Dranchuk Aboukassem
- Hall Yarborough

Gas compressibility is the measure of volume change in response to a pressure change. Available correlations:

- Hall Yarborough
- Mattar

Gas formation volume factor is the ratio of volume of gas at a specified temperature and pressure to standard conditions. Available correlations:

- Xecta (Internal)

Gas density is its mass divided by its volume at a specific pressure and temperature. Available correlations:

- Xecta (Internal)

Gas viscosity is a measure of its resistance to flow. Available correlations:

- Lee
- Carr

Oil correlations are calculated for the following properties, and the available options in ProdX are noted

Oil saturation pressure is the pressure at which the gas phase evolves out of solution, also known as the bubble point. Available correlations:

- Standing
- Vazquez Beggs
- Lasater
- Glaso
- Glaso Corrected
- Glaso Volatile
- Glaso Volatile Corrected

Solution gas-oil ratio is the ratio of gas volume that will dissolve in a volume of oil at a given pressure and temperature. Available correlations:

- Standing
- Vazquez Beggs
- Lasater
- Glaso
- Glaso Corrected
- Glaso Volatile
- Glaso Volatile Corrected

Oil compressibility is the measure of volume change in response to a pressure change. Available correlations:

- Vazquez Beggs

Oil density is its mass divided by its volume at a specific pressure and temperature. Available correlations:

- Xecta (Internal)

Oil formation volume factor is the ratio of volume of oil at a specified temperature and pressure to standard conditions. Available correlations:

- Standing
- Vazquez Beggs
- Glaso

Oil viscosity is a measure of its resistance to flow. Available correlations:

- Beggs Robinson
- Beal

Water correlations are calculated for the following properties, and the available options in ProdX are noted

Water compressibility is the measure of volume change in response to a pressure change. Available correlations:

- Dodson Standing
- Osif

Water density is its mass divided by its volume at a specific pressure and temperature. Available correlations:

- Xecta (Internal)
- McCain

Water formation volume factor is the ratio of volume of water at a specified temperature and pressure to standard conditions. Available correlations:

- McCain
- McCoy

Water viscosity is a measure of its resistance to flow. Available correlations:

- Matthews Russel
- McCain
- McCoy
- Van Wingen

Solution gas-water ratio is the ratio of gas volume that will dissolve in a volume of water at a given pressure and temperature. Available correlations:

- Mccoy
- Culberson McKetta

Interfacial tension correlations are calculated for the following properties, and the available options in ProdX are noted.

Surface tension between the gas and oil phases. Available correlations:

- Abdul Majeed
- Baker Swerdloff

Surface tension between the gas and water phases. Available correlations:

- Firoozabadi Ramey
- Jennings Newman

Surface tension between the oil and water phases. Available correlations:

- Firoozabadi Ramey