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Phase Behavior and ThermodynamicsGas Properties

Sutton Pseudo-Critical Gas Properties Formula

Tpc=169.2+349.5γg74.0γg2T_{pc}=169.2+349.5\gamma_g-74.0\gamma_g^2

Sutton Pseudo-Critical Gas Properties calculates pseudo-critical temperature for gas properties workflows in phase behavior and thermodynamics.

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How engineers use this formula

Use this formula when the listed inputs (gamma_g) are known and the assumptions behind the cited gas 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, T_pc equals 365.11 °R.

gamma_gdimensionless

0.65

Inputs

gamma_g

dimensionless

Gas Specific Gravity Relative to Air

Outputs

T_pc

°R

Pseudo-Critical Temperature

P_pc

psia

Pseudo-Critical Pressure

Source and review

reviewed

Sutton, R.P. 1985. Compressibility Factors for High-Molecular-Weight Reservoir Gases, SPE-14265-MS.

Source

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