Two-phase Formation Volume Factor

Two-phase formation volume factor (FVF) describes the relationship between the volume of a hydrocarbon fluid at reservoir conditions and the volume it occupies at surface conditions.  It helps in understanding how much of the reservoir's hydrocarbon can be produced.  It is used for calculating the reserves of gas and oil in the reservoir and for designing production facilities.

The Two-phase FVF, is the ratio of the volume of a gas-liquid mixture at reservoir conditions (high pressure and temperature) to the volume of the same mixture at standard surface conditions (usually atmospheric pressure and a temperature of 60°F or 15.6°C).  The Two-phase FVF can be estimated using empirical correlations or calculated from reservoir fluid properties, including pressure, temperature, and the composition of the fluids present.  It is used in the design of production systems, determining the flow rates, and in the simulation of reservoir behavior.  It assists in understanding phase behavior, especially when oil and gas are produced simultaneously.

The Two-phase FVF is particularly important in reservoirs where both oil and gas are present, as it can vary significantly depending on the pressure and temperature of the reservoir, the composition of the fluids, and the presence of other components like water.

 

Two-phase Formation Volume Factor formula
\( B_r \;=\; B_o + ( B_g \; ( R_{ogi} - R_{og} ) \;)  \)
Symbol	English	Metric
\( B_r \) = Oil Formation Factor	\(dimensionless\)	-
\( B_o \) = Oil Formation Volume Factor	\(dimensionless\)	-
\( B_g \) = Gas Formation Volume Factor	\(dimensionless\)	-
\( R_{ogi} \) = Initial Solution Oil Gas Ratio	\(dimensionless\)	-
\( R_{og} \) = Solution Oil Gas Ratio	\(dimensionless\)	-