Oil Gas Solubility (Rs)

The gas solubility (Rs) is defined as the number of standard cubic feet of gas which will dissolve in one stock-tank barrel of crude oil at certain pressure and temperature. This value is constant at pressures above the bubble point as above the bubble point there is no free gas in the reservoir. The typical Oilfield unit of Rs is standard cubic feet of gas per stock tank barrel of oil (scf/stb).

The solubility of a natural gas in a crude oil is a strong function of the pressure (P), temperature (T), oil gravity (API) and gas specific gravity (γg).

Reference: Reservoir Engineering Handbook, Tarek Ahmed


  • 1-Standing
  • 2-Glaso
  • 3-Marhoun
  • 4-Petrosky Farshad
  • 5-Velarde et al
  • 6-De Ghetto et al
  • 7-Vasquez and Beggs
  • 8-Material Balance

Input Parameters

NameInput Value - UnitConverted ValueValidity CheckLink to Calculation Page




Stock Tank Oil Specific Gravity (ɣo) More Details

deg API

Solution Gas Specific Gravity (ɣg) Weighted average of separated gas specific gravities from each separation stage
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Solution Gas Specific Gravity (ɣg)
Bubble Point Pressure (Pb) Saturation pressure at reservoir temperature
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Bubble Point Pressure (Pb)
Separator Pressure Actual separator pressure (first stage separator pressure at two stage separation)
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Separator Temperature Actual separator temperature (first stage temperature pressure at two stage separation)
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Oil Density (ρo) More Details

lb/ft³ - pcf

Saturated Oil Density (ρo,s)
Oil Formation Volume Factor (Bo) Experimentally measured Bo @ desired pressure
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Solution Gas/Oil Ratio @ Pb (Rs,b)




CorrelationCalculated ValueWarningsRemarks
1-Standingscf/STBCalifornia crude oils and natural gases
2-Glasoscf/STBNorth Sea crude oil- Rs range is 90 to 2639 scf/STB
3-Marhounscf/STBMiddle Eastern crude oil systems- Rs range is 26 to 1602 scf/STB
4-Petrosky Farshadscf/STBGulf of Mexico crude oil system- Rs range is 217 to 1406 scf/STB
5-Velarde et alscf/STBRs range is 100 to 1800 scf/STB
6-De Ghetto et alscf/STBRs range is 17 to 640 scf/STB
7-Vasquez and Beggsscf/STBRs range is 0 to 2199 scf/STB
8-Material Balancescf/STB