Gas to Oil Ratio (GOR) - EnggCyclopedia

Gas to Oil Ratio (GOR) is a commonly used term in the crude oil exploration and production industry. GOR is the ratio of volumetric flow of produced gas to the volumetric flow of crude oil for crude oil and gas mixture sample.

For any hydrocarbon mixture produced from an oil production well, the proportion of liquid and vapor phases in the mixture changes with changing temperature and pressure conditions. In order to compare the GOR from different oil and gas samples, the oil and gas flowrates must be considered at same temperature and pressure conditions. Hence the GOR is always specified at standard temperature and pressure conditions. The liquid and vapor volumetric flow rates are calculated at standard temperature and pressure conditions, expressed in sm³/hr.{adinserter 1}

Sometimes only the gas volume is expressed at standard conditions and liquid volume is expressed in barrels. Then the GOR is expressed in sm³/bbl. But it is still important to calculate the gas and liquid volume at standards conditions, even if later they are converted to other units only for reporting purpose. If a hydrocarbon producing well produces high GOR mixture, it is identified as a gas well. If GOR is low, it is identified to be an oil well.

GOR Calculation

To calculate the GOR, you will need to know the volume of gas and oil produced by the well, as well as the time period over which the production was measured. For example, if the well produced 100 barrels of oil and 5,000 cubic meter of gas over a period of one month, the GOR would be 50 sm³/bbl (5,000 cubic feet of gas / 100 barrels of oil).

Gas to Oil Ratio (GOR) = Volume of gas produced over a time period / Volume of oil produced in the same time period

It is important to note that the GOR can vary significantly from one well to another, and it can also change over time as the well is produced. As such, it is important to continuously monitor and measure the GOR to ensure that the well is producing at its optimal efficiency.