Gas/oil ratio

When oil is produced to surface temperature and pressure it is usual for some natural gas to come out of solution.

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.

The GOR is a dimensionless ratio (volume per volume) in metric units, but in field units, it is usually quoted in cubic feet of gas (at standard conditions: 0°C, 100 kPa) per barrel of oil or condensate, scf/bbl.

In the states of Texas and Pennsylvania, the statutory definition of a gas well is one where the GOR is greater than 100,000 ft3/bbl or 100 Kcf/bbl.

[1] The Oklahoma Geological Survey in 2015 published a map that displays gas wells with greater than 20 MCFG per barrel of oil.