Free Gas in Place
Free gas in place, abbreviated as \(G_f\), is the total volume of natural gas that is present in a reservoir and is not dissolved in oil or water but exists in a free state. This term is used in reservoir engineering and the oil and gas industry, as it represents a measure for evaluating the potential productivity of a gas reservoir.
Key Points about Free Gas in Place
Reservoir Rock - The porous rock in which the gas is stored.
Porosity - The measure of the void spaces in the rock, which can hold the gas.
Gas Saturation - The fraction of the pore space that is filled with free gas.
Reservoir Volume - The total volume of the rock containing the gas.
Free Gas in Place Formula |
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\( G_f \;=\; 7758 \cdot A \cdot h \cdot n \cdot ( 1 - S_{wi} ) \cdot E_{gi} \) (Free Gas in Place) \( A \;=\; \dfrac{ G_f }{ 7758 \cdot h \cdot n \cdot ( 1 - S_{wi} ) \cdot E_{gi} }\) \( h \;=\; \dfrac{ G_f }{ 7758 \cdot A \cdot n \cdot ( 1 - S_{wi} ) \cdot E_{gi} }\) \( n \;=\; \dfrac{ G_f }{ 7758 \cdot A \cdot h \cdot ( 1 - S_{wi} ) \cdot E_{gi} }\) \( S_{wi} \;=\; 1 - \dfrac{ G_f }{ 7758 \cdot A \cdot h \cdot n \cdot E_{gi} }\) \( E_{gi} \;=\; \dfrac{ G_f }{ 7758 \cdot A \cdot h \cdot n \cdot ( 1 - S_{wi} ) }\) |
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| Symbol | English | Metric |
| \( G_f \) = Free Gas in Place | \(ft^3\) | - |
| \( A \) = Drainage Area | \(ft^2\) | - |
| \( h \) = Thickness | \(ft\) | |
| \( n \) = Porosity | \(dimensionless\) | - |
| \( S_{wi} \) = Initial Water Saturation | \(dimensionless\) | - |
| \( E_{gi} \) = initial gas Expansion Factor | \(ft^3 \;/\; bbl\) | - |
