Phase Behavior and ThermodynamicsGas Properties

Real Gas Pseudopressure Difference for Constant Mu-Z Formula

\Delta m=\frac{p_2^2-p_1^2}{\mu_g z}

Real Gas Pseudopressure Difference for Constant Mu-Z calculates real gas pseudopressure difference for gas properties workflows in phase behavior and thermodynamics.

Calculate

How engineers use this formula

Use this formula when the listed inputs (p_1, p_2, mu_g, z) 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, Delta_m equals 470,588,235.294118 psi^2/cp.

p_1psia

1000

p_2psia

3000

mu_gcp

0.02

zdimensionless

0.85

Inputs

p_1

psia

Lower Pressure

p_2

psia

Upper Pressure

mu_g

Gas Viscosity

z

dimensionless

Gas Compressibility Factor

Outputs

Delta_m

psi^2/cp

Real Gas Pseudopressure Difference

p_2

psia

Upper Pressure

p_1

psia

Lower Pressure

mu_g

Gas Viscosity

z

dimensionless

Gas Compressibility Factor

Source and review

reviewed

Gas permeability measurements from pressure pulse decay laboratory data using pseudo-pressure and pseudo-time transformations, Abdelmalek, B. et al.

Abdelmalek et al. 2017. Gas permeability measurements from pressure pulse decay laboratory data using pseudo-pressure and pseudo-time transformations.

Source