Phase Behavior and ThermodynamicsPVT Properties
Van der Waals Equation of State Pressure Formula
Van der Waals Equation of State Pressure calculates pressure for pvt properties workflows in phase behavior and thermodynamics.
How engineers use this formula
Use this formula when the listed inputs (R, T, v_m, a_vdw, b_vdw) 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 627.785263 psi.
Rpsi*ft^3/(lbmol*R)
10.7316
TR
600
v_mft^3/lbmol
10
a_vdwpsi*ft^6/lbmol^2
5000
b_vdwft^3/lbmol
0.5
Inputs
R
psi*ft^3/(lbmol*R)Gas Constant
T
RAbsolute Temperature
v_m
ft^3/lbmolMolar Volume
a_vdw
psi*ft^6/lbmol^2van der Waals Attraction Parameter
b_vdw
ft^3/lbmolvan der Waals Covolume Parameter
Outputs
P
psi
Pressure
T
R
Absolute Temperature
a_vdw
psi*ft^6/lbmol^2
van der Waals Attraction Parameter
b_vdw
ft^3/lbmol
van der Waals Covolume Parameter
Source and review
reviewedEngineering LibreTexts, Phase Relations in Reservoir Engineering, Section 7.04: The van der Waals Equation.
Source