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Phase Behavior and ThermodynamicsPVT Properties

Glaso Solution Gas-Oil Ratio from Pressure Formula

Rs=γg(pbAPI0.989T0.172)1/0.816R_s=\gamma_g\left(\frac{p_b^*API^{0.989}}{T^{0.172}}\right)^{1/0.816}

Glaso Solution Gas-Oil Ratio from Pressure calculates solution gas-oil ratio for pvt properties workflows in phase behavior and thermodynamics.

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How engineers use this formula

Use this formula when the listed inputs (p, gamma_g, API, T) are known and the assumptions behind the cited pvt properties relationship match the engineering case being checked.

Assumptions

  • Input values are representative for the well, reservoir, fluid, or equipment case being evaluated.
  • The declared units match the field-unit constants used in the formula.
  • The cited formula applies to the selected petroleum engineering workflow.

Limitations

  • The calculation does not replace a full engineering model or operating procedure.
  • Accuracy depends on the source correlation, assumptions, input quality, and unit consistency.

Common mistakes

  • Mixing unit systems without converting the inputs.
  • Using default example values as field recommendations.
  • Applying the formula outside the source assumptions.

Default example

Using the default inputs, R_s equals 545.728847 SCF/STB.

ppsi

2500

gamma_gfraction

0.8

APIAPI

35

Tdeg F

180

Inputs

p

psi

Pressure

gamma_g

fraction

Gas Specific Gravity

API

API

Oil API Gravity

T

deg F

Reservoir Temperature

Outputs

R_s

SCF/STB

Solution Gas-Oil Ratio

x_glaso_pb

dimensionless

Glaso Bubble Point Quadratic Root

p_b_star

dimensionless

Glaso Bubble Point Correlating Parameter

p

psi

Pressure

Source and review

reviewed

Oil Correlations - Glaso (North Sea Oil), Glaso, O., IHS Harmony

Glaso, O. 1980. Generalized Pressure-Volume-Temperature Correlations, Journal of Petroleum Technology, SPE-8016-PA; IHS Harmony oil correlations.

Source

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