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Phase Behavior and ThermodynamicsFluid Properties

McCain Pure-Water Solution Gas-Water Ratio Formula

Rswp=A+BP+CP2R_{swp}=A+BP+CP^2

McCain Pure-Water Solution Gas-Water Ratio calculates solution gas-water ratio for pure water for fluid properties workflows in phase behavior and thermodynamics.

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How engineers use this formula

Use this formula when the listed inputs (P, T) are known and the assumptions behind the cited fluid 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_swp equals 14.881375 scf/STB.

Ppsia

3000

Tdeg F

180

Inputs

P

psia

Pressure

T

deg F

Temperature

Outputs

R_swp

scf/STB

Solution Gas-Water Ratio for Pure Water

A_mccain_rsw

scf/STB

McCain Pure-Water Rsw Coefficient A

B_mccain_rsw

scf/STB/psi

McCain Pure-Water Rsw Coefficient B

C_mccain_rsw

scf/STB/psi^2

McCain Pure-Water Rsw Coefficient C

P

psia

Pressure

Source and review

reviewed

Formation Water PVT Properties, McCain, W.D. Jr., Petroleum Office, AAPG Wiki

McCain, W.D. Jr. 1991. Reservoir-Fluid Property Correlations-State of the Art; Petroleum Office Formation Water PVT Properties.

Source

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