Interpretation of the meaning of gas/oil ratio in oilfield engineering
Oil and natural gas in most cases are found in reservoirs in the form of a single mixture, i.e. a single fluid commonly called hydrocarbons, this is a condition in which we will not find only oil reservoirs or dry gas reservoirs, when talking about a mixture of oil + natural gas we have to introduce a new concept known as gas / oil ratio.
When the hydrocarbon is already produced through the various wells and reaches the surface with surface temperatures and pressures, it is normal that some natural gas escapes from this gas + oil solution due to the intrinsic properties of the gases, so it is necessary not only to conceptualize about the gas / oil ratio, but it is also necessary to calculate the relationship between the volume of gas that comes out of the gas + oil mixture and the volume of oil at surface pressure and temperature conditions.
There are disciplines within petroleum engineering such as reservoir simulation that express the gas/oil ratio as Rs.
It is important to be aware at the time when we are going to measure the volume of oil, since the volume of oil remaining after gas separation will be less.
The GOR (gas/oil ratio) is a ratio that is dimensionless, since the numerator measures the volume of gas that escapes from the gas+oil mixture, all divided by the volume of oil remaining after separation, so that unit of volume between unit of volume cancels out and a dimensionless ratio value remains.
However, in field units this ratio can be measured in cubic feet of gas per barrel of oil, i.e. it is measured in volume units of different units.
The importance of measuring the gas/oil ratio is to be able to estimate the potential with which the oil field can continue producing, since the higher the gas/oil ratio is, the less oil will be obtained at the surface under pressure and temperature conditions.
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