Gas formation volume factor, abbreviated as \(G_f\), is the ratio of the volume of a given quantity of natural gas at reservoir conditions of pressure and temperature to the volume occupied by the same quantity of gas at standard surface conditions. Standard conditions are established as 14.7 psia (or occasionally 14.65 psia) and 60°F, representing typical surface reporting conditions for gas production volumes in standard cubic feet (scf). This parameter directly quantifies how much reservoir space the gas occupies compared to the expanded volume it would have once brought to the surface, where lower pressure allows the gas to occupy more space.
Gas Formation Volume Factor Formula |
||
|
\( G_f \;=\; \dfrac{ 0.02827 \cdot z \cdot T }{ p }\) (Gas Formation Volume Factor) \( z \;=\; \dfrac{ G_f \cdot p }{ 0.02827 \cdot T }\) \( T \;=\; \dfrac{ G_f \cdot p }{ 0.02827 \cdot z }\) \( p \;=\; \dfrac{ 0.02827 \cdot z \cdot T }{ G_f }\) |
||
| Symbol | English | Metric |
| \( G_f \) = Gas Formation Volume Factor | \(RB \;/\; SCF\) | - |
| \( z \) = Gas Deviation Factor | \(dimensionless\) | - |
| \( T \) = Temperature | \(^\circ R\) | - |
| \( p \) = Pressure (psi) | \(lbf \;/\; in^2\) | - |
These conversion factors used in the calculations of the \(G_f\) when 0.005032 is expressed in reservoir cubic feet per standard cubic foot (RCF/SCF) and when 0.02827 is expressed in reservoir barrels per standard cubic foot (RB/SCF).
Gas Formation Volume Factor Formula |
||
|
\( G_f \;=\; \dfrac{ 0.005032 \cdot z \cdot T }{ p }\) (Gas Formation Volume Factor) \( z \;=\; \dfrac{ G_f \cdot p }{ 0.005032 \cdot T }\) \( T \;=\; \dfrac{ G_f \cdot p }{ 0.005032 \cdot z }\) \( p \;=\; \dfrac{ 0.005032 \cdot z \cdot T }{ G_f }\) |
||
| Symbol | English | Metric |
| \( G_f \) = Gas Formation Volume Factor | \(RCF \;/\; SCF\) | - |
| \( z \) = Gas Deviation Factor | \(dimensionless\) | - |
| \( T \) = Temperature | \(^\circ R\) | - |
| \( p \) = Pressure (psi) | \(lbf \;/\; in^2\) | - |