The Relative volume based on the pressure, is the relationship between the volume biphase (Oil and Gas) to an initial pressure below the pressure of bubble and the volume to the pressure of a bubble. Denoted as Vr.

Vr: relative volume V: Volume biphase Vb: Volume to bubble pressure

RELATIVE VOLUME

SOLUBILITY RATIO

The solubility of the gas in the oil, is defined as the quantity of gas measured to surface conditions, which is dissolved in a barrel of oil, also measured to surface conditions, this is:

Rs = dissolved gas volume @ sc (m3) / oil volume@ sc (m3)

The solubility of natural gas in a oil depends on the pressure, temperature and the density of the oil, that is to say:

- As the pressure Increases , Increases the Rs

- As temperature increases, decreases Rs

- By increasing the density °API, increases the RS

- To increase the specific gravity of the gas increases the RS

BEHAVIOR OF RS IN FUNCTION OF THE PRESSURE

The typical curve of the solubility of the gas as a function of pressure. Note that as pressure decreases until the pressure of saturation (Pb), does not release the oil gas and consequently solubility ratio is kept constant to the maximum value Rsb. Below the saturation pressure, solution gas is released and the value of Rs tends to decrease with pressure

CORRELATIONS

The physical properties of the oil must be determined by an analysis PVT. However, on many occasions and for different reasons it is not possible to have a study PVT. Under these circumstances, it is resorting to the use of empirical correlations, among the most widely used are: -- - Correlation of Standing- Correlation of Vasquez-Beggs - Correlation of Glaso

Correlation of Standing

Standing, he developed a correlation to determine the relative solubility of the gas, Rs, based on the pressure, specific gravity of the gas, the °API and the temperature.

- Rs solubility ratio of de gas P ≤ Pb in (p3/bl)

- P Pressure reservoir of interest in lb / pg2

- T Reservoir Temperature in °F

- Specific gravity of gas (air =1)

- °API Oil Density in °API

Correlation of Vasquez-Beggs

- Rs solubility ratio of de gas P ≤ Pb in (p3/bl)

- P Pressure reservoir of interest in lb / pg2

- T Reservoir Temperature in °F

- Specific gravity of gas (air =1)

- °API Oil Density in °API

CORRELATION OF GLASO

- Rs solubility ratio of de gas P ≤ Pb in (p3/bl)

- P Pressure reservoir of interest in lb / pg2

- T Reservoir Temperature in °F

- Specific gravity of gas (air =1)

- °API Oil Density in °API