A 1000 cu ft tank contains 85 STB of crude and 20,000 SCF of gas, all at 120°F. When equilibrium is established, (i.e., when as much gas has dissolved in the oil as will), the pressure in the tank is 500 psia. If the solubility of the gas in the crude is 0.25 SCF/STB/psi and the deviation factor

Question

A 1000 cu ft tank contains 85 STB of crude and 20,000 SCF of gas, all at 120°F. When equilibrium is established, (i.e., when as much gas has dissolved in the oil as will), the pressure in the tank is 500 psia. If the solubility of the gas in the crude is 0.25 SCF/STB/psi and the deviation factor for the gas at 500 psia and 120°F is 0.90, find the liquid formation volume factor at 500 psia and 120°F.

Accepted Answer

[latex]{ R }_{ s }=0.25(500)=125\frac { scf }{ sTB }[/latex]

solution gas at surface =85(125)=10625scf

free gas at surface =2000-10625=9375scf

[latex]{ B }_{ g }=0.02829\frac { ZT }{ P } =0.02829\frac { (0.9)(580) }{ 500 } =0.0295\frac { { ft }^{ 3 } }{ scf }[/latex]

free gas at reservoir condition=9375(0.0295)=276.56[latex]{ ft }^{ 3 }[/latex]

solution gas at reservior condition + oil volume=[latex]\frac { 1000-276.56 }{ 5.615 } =128.8bb1[/latex]

[latex]{ B }_{ 0 }=\frac { 128.8 }{ 85 } =1.515\frac { bb1 }{ sTB }[/latex]

Question : A 1000 cu ft tank contains 85 STB of crude and 20,000 SCF of...

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