Synonyms: Compressibility factor = Z-factor
Disclaimer: Not to be confused with Compressibility
c.
Dimensionless multiplier describing the deviation of a fluid density from ideal gas estimate under the same pressure & temperature conditions:
(1) | Z = \frac{p \, V_m}{R \, T} = \frac{p}{\rho} \cdot \frac{M}{R \, T} |
where
p | fluid pressure | V_m = V/\nu | fluid molar volume |
T | fluid temperature | V | fluid volume |
\rho | fluid density | \nu | |
R | gas constant | M | molar mass of a fluid |
Z-factor is related to fluid density \rho and Formation Volume Factor (FVF) B as:
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Z-factor is related to fluid compressibility c as:
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The Z-factor value is trending towards unit value (
Z \rightarrow 1) for incompressible fluids and linear pressure dependence (
Z \rightarrow a \cdot p) for strongly compressible Fluids.
Modelling Z-factor Z(T,p) as a function of fluid pressure p and temperature T is based on Equation of State.
There is also a good number of explicit Z-factor Correlations @models.
See also
Natural Science / Physics / Thermodynamics / Equation of State
[ Compressibility ][ Fluid Compressibility ][ Gas compressibility ]