Formation Volume Factor (FVF) for gas:
| (1) | B_g(p,T) = \frac{\rho_g^{\circ}}{\rho_g} = \frac{V_g}{V_{Gg}^{\circ}} = \frac{q_g}{q_{Gg}} |
where
\rho_g^{\circ} | fluid density at reference conditions | V_m^{\circ} | molar volume at reference conditions |
\rho_g | fluid density at reservoir conditions | V_m | molar volume at reservoir conditions |
The reference conditions may vary from case to case but most popular choice are: Separator, Stock Tank and SPE STP.
It can be expressed through the Z-factor as:
| (2) | B_g(p,T) = \frac{Z(p, T)}{Z^{\circ}} \cdot \frac{T/T^{\circ}}{p/p^{\circ}} |
where
p | reservoir pressure | p^{\circ} | reference pressure |
T | reservoir temperature | T^{\circ} | reference temperature |
Z^{\circ} = Z(T^{\circ}, \, p^{\circ}) | Z-factor at reference conditions |
If reference conditions are set at SPE STP then equation (2) takes explicit from as:
| (3) | B_g(p,T) = 0.3470 \cdot Z(p, T) \cdot \frac{T}{p} |
where
B_g | Gas formation volume factor in frac = m3/m3 |
p | reservoir pressure in [kPa ] |
T | reservoir temperature in [K] |
See Also
Petroleum Industry / Upstream / Subsurface E&P Disciplines / Fluid (PVT) Analysis / Dynamic fluid properties
[ Formation Volume Factor (FVF) ][ Oil formation volume factor (Bo) ][ Water formation volume factor (Bw) ]