Calculate producing GOR, solution GOR, and free gas volume from production data
Total gas production measured at surface (separator + stock tank gas). Standard conditions: 14.696 psia and 60°F.
Mscf/day
Stock tank oil production rate at standard conditions (60°F, 14.696 psia).
STB/day
Solution gas-oil ratio at current reservoir pressure from PVT data. This is the gas dissolved in oil at reservoir conditions. Use Vasquez-Beggs or Standing correlation if lab data unavailable.
scf/STB
Ratio of gas volume at reservoir conditions to standard conditions. Bg = 0.0283(zT/P). Typical range 0.002-0.02 rb/scf.
rb/scf
Ratio of oil volume at reservoir conditions to stock tank volume. Typical range 1.05-1.80 rb/STB.
rb/STB
Results
Producing GOR-scf/STB
Free Gas at Surface-scf/STB
Free Gas Volume (Reservoir)-rb/day
Total Reservoir Voidage-rb/day
Gas as % of Total (BOE basis)-%
References & Formulas:
Producing GOR = Total Gas Rate / Oil Rate
Free Gas = Producing GOR − Rs
Free Gas Volume (res) = (GOR − Rs) × Qo × Bg
Total Voidage = Qo × Bo + Free Gas Vol(res)
BOE conversion: 5,800 scf = 1 BOE