Formation Volume Factor (FVF) for gas:
B_g(p,T) = \frac{\mathring{\rho}_g}{\rho_g} = \frac{V_g}{\mathring{V}_{Gg}} = \frac{q_g}{q_{Gg}} |
where
| fluid density at reference conditions | molar volume at reference conditions | ||
| fluid density at reservoir conditions | 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:
B_g(p,T) = \frac{Z(p, T)}{Z^{\circ}} \cdot \frac{T/T^{\circ}}{p/p^{\circ}} |
where
| reservoir pressure | reference pressure | ||
| reservoir temperature | reference temperature | ||
| Z-factor at reference conditions |
If reference conditions are set at SPE STP then reference Z-factor is close to 1 for all natural gases and equation
takes explicit form as:
B_g(p,T) = 0.3470 \cdot Z(p, T) \cdot \frac{T}{p} |
where
| Gas formation volume factor in frac = m3/m3 | |
| reservoir pressure in [kPa ] | |
| 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) ]