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Produced Gas-Oil Ratio

 

Produced Gas-Oil Ratio Formula

  • A standard cubic foot (scf) is a unit representing the amount of gas (such as natural gas) contained in a volume of one cubic foot at reference temperature and pressure conditions.
  • When referring to liquid volumes at stock tank conditions, use the units of Stock Tank Barrels (STB).

\( R_{go} \;=\; \dfrac{ G_p }{ O_p }\)     (Produced Gas-Oil Ratio)

\( G_p \;=\;  R_{go} \cdot O_p \)

\( O_p \;=\; \dfrac{ G_p }{ R_{go} }\)
Symbol English Metric
\( R_{go} \) = Produced Gas-Oil Ratio (SCF/STB) \(ft^3 \;/\; bbl\) -
\( G_p \) = Cumulative Gas Production (SCF) \(ft^3\) -
\( O_p \) = Cumulative Oil Production (STB) \(bbl\) -

Produced gas-oil ratio, abbreviated as GOR, is the volume of natural gas produced alongside a unit volume of crude oil at standard temperature and pressure conditions.  It's the ratio of the gas liberated from the oil as it travels from the reservoir to the surface to the remaining volume of oil after this separation.  The produced GOR provides valuable insights into reservoir performance, the characteristics of the hydrocarbon fluids, and the efficiency of production operations.  Changes in the GOR over time can indicate shifts in reservoir pressure, the influx of a gas cap, or the effectiveness of enhanced oil recovery techniques.

Produced Gas-Oil Ratio Types

  •  Solution Gas-Oil Ratio (Rs)  -  The volume of gas that is dissolved in the oil at a specific reservoir pressure and temperature.  It's an inherent property of the crude oil system and decreases as pressure declines below the bubble point, causing gas to come out of solution.  While not a "produced" GOR type, it dictates the initial gas that will be produced with the oil.
  • Instantaneous Gas-Oil Ratio (GOR)  -  This is the ratio of the volume of gas being produced at a specific point in time to the volume of oil being produced at that same instant.  It can change throughout the production life of a well as reservoir pressure declines and the gas-oil relative permeability changes.
  • Cumulative Gas-Oil Ratio (Rp)  -  This is the total volume of gas produced from a well or reservoir up to a certain point in time divided by the total volume of oil produced during the same period.  It represents the average gas production per unit of oil produced over the entire production history.

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