Gas oil ratio
 | This article does not cite any references or sources. (December 2009) |
When oil is brought to surface conditions it is usual for some natural gas to come out of solution. The gas/oil ratio (GOR) is the ratio of the volume of gas that comes out of solution, to the volume of oil at standard conditions.
A point to check is whether the volume of oil is measured before or after the gas comes out of solution, since the oil volume will shrink when the gas comes out.
In fact gas dissolution and oil volume shrinkage will happen at many stages during the path of the hydrocarbon stream from reservoir through the wellbore and processing plant to export. For light oils and rich gas condensates the ultimate GOR of export streams is strongly influenced by the efficiency with which the processing plant strips liquids from the gas phase. Reported GORs may be calculated from export volumes which may not be at standard conditions.
The GOR is usually measured in cubic feet of gas per barrel of oil or condensate.
If the GOR is greater than 10,000 cf/bbl, then the field is usually described as a gas well. If less than 10,000, then the field is generally described as an oil well.
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