Formation Volume Factor

on . Posted in Reservoir Engineering

 

Oil Formation Volume Factor Formula

  • Oil formation volume factor, abbrevated as \( B_o \), is the volume of oil in the reservoir (at reservoir conditions of temperature and pressure) required to produce one unit volume of oil at surface conditions.  It accounts for the shrinkage of oil when brought to the surface due to gas coming out of solution and temperature and pressure changes.
  • The volume of oil in reservoir barrels (RB) needed to produce one stock tank barrel (STB) of oil at the surface.
\( B_o \;=\; \dfrac{  V_{res}  }{ V_{surf}  } \)
Symbol English Metric
\( B_o \) = Oil Formation Volume Factor \(RB\;/\;STB\) \(RB\;/\;STB\)
\( V_{res} \) = Volume of Oil at Reservoir Conditions \(bbl\) \(bbl\)
\( V_{surf} \) = Volume of Oil at Surface Conditions \(bbl\) \(bbl\)

Formation volume factor, abbreviated as FVF, commonly denoted as B, is used in reservoir engineering and petroleum production.  It is used to relate the volume of oil and gas in the reservoir to the volume at surface conditions.  There are different formation volume factors for oil and gas, but the concept is similar for both.

Importance in Reservoir Engineering

The formation volume factors are critical for several calculations, including:

  • Estimating the initial volumes of hydrocarbons in place.
  • Forecasting production rates.
  • Designing production facilities and equipment.
  • Conducting material balance calculations.

The formation volume factor varies with pressure and temperature and is influenced by the composition of the reservoir fluids.  Accurate determination of \( B_o \) and \( B_g \) is essential for reliable reservoir management and production optimization.

Gas Formation Volume Factor Formula

  • Gas formation volume factor, abbrevated as \( B_g \), is the volume of gas at reservoir conditions required to produce one unit volume of gas at surface conditions.  It reflects the expansion of gas as it is brought to the surface.
  • The volume of gas in reservoir cubic feet (RCF) or reservoir cubic meters (Rm³) needed to produce one standard cubic foot (SCF) or standard cubic meter (Sm³) of gas at the surface.
\( B_g \;=\; \dfrac{ V_{res}  }{ V_{surf}  } \)
Symbol English Metric
\( B_g \) = Gas Formation Volume Factor \(RCF\;/\;SCF\) \(Rm^3\;/\;Sm^3\)
\( V_{res} \) = Volume of Gas at Reservoir Conditions \(ft^3\) \(m^3\)
\( V_{surf} \) = Volume of Gas at Surface Conditions \(ft^3\) \(m^3\)

 

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Tags: Reservoir