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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 used in the petroleum industry to measure the volume of gas produced in relation to the volume of oil produced from a reservoir.  The GOR is used for understanding the behavior of a reservoir and for making decisions regarding production strategies and reservoir management.

Produced Gas-Oil Ratio Types

  • Solution GOR  -   The gas that is dissolved in the oil under reservoir conditions and comes out of solution as pressure decreases.
  • Producing GOR  -  The actual ratio measured at the surface during production.

Importance

Reservoir Characterization  -  Helps in understanding the nature of the reservoir fluid.  High GOR can indicate a gas cap above the oil column or the depletion of oil and breakthrough of gas.
Production Strategy  -  Affects decisions regarding well completion, production facilities, and artificial lift requirements.
Economic Analysis  -  Impacts the economic viability of a reservoir.  Gas can be a valuable byproduct or a challenge if there is no market for it or if handling is expensive.

Factors Influencing GOR

Reservoir Pressure  -  As pressure decreases, more gas comes out of solution, increasing GOR.
Production Rate  -  High production rates can lead to higher GOR due to greater pressure drops.
Reservoir Characteristics  -  Heterogeneity, permeability, and fluid properties also impact GOR.

Applications of Gas-oil Ratio

Well Testing  -  Helps in evaluating the performance of a well and predicting future production.
Reservoir Simulation  -  Used in models to simulate reservoir behavior and predict future production scenarios.
Enhanced Oil Recovery  -  Decisions on gas injection or other EOR techniques can be influenced by the GOR.

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