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Phase Behavior and ThermodynamicsPVT Properties

Benedict-Webb-Rubin PVT Equation Formula

P=RTρ+(BRTACT2)ρ2+(bRTa)ρ3+aαρ6+cρ3T2(1+γρ2)eγρ2P=RT\rho+\left(BRT-A-\frac{C}{T^2}\right)\rho^2+(bRT-a)\rho^3+a\alpha\rho^6+\frac{c\rho^3}{T^2}(1+\gamma\rho^2)e^{-\gamma\rho^2}

Benedict-Webb-Rubin PVT Equation calculates pressure for pvt properties workflows in phase behavior and thermodynamics.

Calculate

How engineers use this formula

Use this formula when the listed inputs (R, T, rho, A, B, C, a, b, c, alpha, gamma) 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, P equals 129.03687 psi.

Rconsistent EOS units

10.7316

TR

600

rholbmol/ft3

0.02

Aconsistent EOS units

1

Bconsistent EOS units

0.1

Cconsistent EOS units

10

aconsistent EOS units

0.5

bconsistent EOS units

0.01

cconsistent EOS units

1

alphaconsistent EOS units

0.001

gammaconsistent EOS units

0.1

Inputs

R

consistent EOS units

Gas Constant

T

R

Absolute Temperature

rho

lbmol/ft3

Molar Density

A

consistent EOS units

BWR A Coefficient

B

consistent EOS units

BWR B Coefficient

C

consistent EOS units

BWR C Coefficient

a

consistent EOS units

BWR a Coefficient

b

consistent EOS units

BWR b Coefficient

c

consistent EOS units

BWR c Coefficient

alpha

consistent EOS units

BWR Alpha Coefficient

gamma

consistent EOS units

BWR Gamma Coefficient

Outputs

P

psi

Pressure

R

consistent EOS units

Gas Constant

Source and review

reviewed

Gas Conditioning and Processing, Campbell, J. M. (1992)

John M. Campbell. 1992. Gas Conditioning and Processing, Campbell Petroleum Series, Vol. 1, Page 48.

Source

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