When

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturated ...

is produced to surface temperature and pressure it is usual for some

natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...

to come out of solution. The gas/oil ratio (GOR) is the ratio of the volume of gas ("scf") that comes out of solution to the volume of oil — at standard conditions. In

reservoir simulation Reservoir simulation is an area of reservoir engineering in which computer models are used to predict the flow of fluids (typically, oil, water, and gas) through porous media. The creation of models of oil fields and the implementation of ca ...

gas/oil ratio is usually abbreviated

R_s

. A point to check is whether the volume of oil is measured before or after the gas comes out of solution, since the remaining oil volume will decrease 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 A borehole is a narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water ( drilled water well and tube well), other liquids (such as petrole ...

and processing plant to export. For light oils and rich

gas condensate Natural-gas condensate, also called natural gas liquids, is a low-density mixture of hydrocarbon liquids that are present as gaseous components in the raw natural gas produced from many natural gas fields. Some gas species within the raw natur ...

s 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 a dimensionless ratio (volume per volume) in metric units, but in field units, it is usually measured in cubic feet of gas per barrel of oil or condensate. 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. The state of New Mexico also designates a gas well as having over 100 MCFG per barrel. The

Oklahoma Geological Survey The Oklahoma Geological Survey is a state agency chartered in the Constitution of Oklahoma responsible for collecting and disseminating information about Oklahoma's natural resources, geological formations, and earthquakes. Shortly after Oklahoma b ...

in 2015 published a map that displays ''gas wells'' with greater than 20 MCFG per barrel of oil. They go on to display ''oil wells'' with GOR of less than 5 MCFG/BBL and ''oil and gas wells'' between these limits. The EPA's 2016 Information Collection Request for Oil and Gas Facilities (EPA ICR No. 2548.01, OMB Control No. 2060-NEW) divided well types into five categories: 1. Heavy Oil (GOR ≤ 300 scf/bbl) 2. Light Oil (GOR 300 < GOR ≤ 100,000 scf/bbl) 3. Wet Gas (100,000 < GOR ≤1,000,000 scf/bbl) 4. Dry Gas (GOR > 1,000,000 scf/bbl) 5. Coal Bed Methane.

References

Bibliography

* {{DEFAULTSORT:Gas Oil Ratio Ratios Petroleum production Petroleum economics Natural gas