Gas in place, abbreviated as GIP, is the total quantity of natural gas contained in a subsurface reservoir. It includes all the gas within the rock formations of the reservoir, regardless of whether it is technically or economically recoverable. Understanding and accurately estimating the reservoir gas in place is vital for efficient reservoir management and the planning of gas field development.
The amount of gas in place is estimated using geological and engineering data such as: reservoir volume, porosity, gas saturation, p;ressure and temperature, gas formation volume factor.
Key Points about Gas in Place
Gas in Place Formula
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\( OGIP \;=\; \dfrac{43560 \; A \cdot h \cdot n \cdot (1 - W_s )}{B_g }\) (Gas in Place) \( A \;=\; \dfrac{ OGIP \cdot B_g }{ 43560 \; h \cdot n \cdot (1 - W_s )} \) \( h \;=\; \dfrac{ OGIP cdot B_g }{ 43560 \; A \cdot n \cdot (1 - W_s )} \) \( n \;=\; \dfrac{ OGIP \cdot B_g }{ 43560 \; A \cdot h \cdot (1 - W_s )} \) \( W_s \;=\; 1 - \dfrac{ OGIP \cdot B_g }{ 43560 \; A \cdot h \cdot n } \) \( B_g \;=\; \dfrac{43560 \; A \cdot h \cdot n \; (1 - W_s ) }{ OGIP } \) |
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| Symbol | English | Metric |
| \( GIP \) = Gas in Place | \(bbl\) | - |
| \( A \) = Reservoir Area, acres from map data | \(acre\) | - |
| \( h \) = Reservoir Thickness | \(ft\) | - |
| \( n \) = Porosity | \(dimensionless\) | - |
| \( W_s \) = Water Saturation | \(dimensionless\) | - |
| \( B_g \) = Gas Formation Volume Factor (cubic feet of gas at standard conditions per cubic foot of gas at reservoir conditions) | \(bbl\;/\;ft^3\) | - |
Gas in Place formulas |
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\( OGIP \;=\; A \cdot h \cdot n \cdot S_g \cdot \frac{ 1 }{ B_g } \) (Gas in Place) \( A \;=\; \dfrac{ OGIP \cdot B_g }{ h \cdot n \cdot S_g }\) \( h \;=\; \dfrac{ OGIP \cdot B_g }{ A \cdot n \cdot S_g }\) \( n \;=\; \dfrac{ OGIP \cdot B_g }{ A \cdot h \cdot S_g }\) \( S_g \;=\; \dfrac{ OGIP \cdot B_g }{ A \cdot h \cdot n }\) \( B_g \;=\; \dfrac{ A \cdot h \cdot n \cdot S_g }{ OGIP } \) |
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| Symbol | English | Metric |
| \( OGIP \) = Gas in Place | \(bbl\) | - |
| \( A \) = Reservoir Area, acres from map data | \( acre \) | - |
| \( h \) = Reservoir Thickness | \( ft \) | - |
| \( n \) = Porosity | \(dimensionless\) | - |
| \( G_s \) = Gas Saturation | \(dimensionless\) | - |
| \( B_g \) = Gas Formation Volume Factor (cubic feet of gas at standard conditions per cubic foot of gas at reservoir conditions) | \(bbl\;/\;ft^3\) | - |
