Gas Compressibility Factor (Z-Factor)

The compressibility factor (Z) corrects for deviation from the ideal gas law. The compressibility factor is calculated using an equation of state or industry correlation.

For an ideal gas, the value of Z is 1 at all states. For real gases, Z is a function of the state.

Reference: Natural Gas Measurement Handbook, James E. Gallagher

Correlations

  • 1-Papay
  • 2-HALL-YARBOROUGH
  • 3-Dranchuk-Abu Kassem
  • 4-Heidaryan
  • 5-Brill-Beggs

Input Parameters

NameInput Value - UnitConverted ValueValidityLink to Calculation Page
Temperature

619.67

°R

Pressure

3500

psi

Average Surface Gas Specific Gravity

0.7

SG

Pseudo Properties Calculation Method

2

Pseudo Critical Properties Correction Method

2

N2 Content

0

%

CO2 Content

5

%

H2S Content

10

%

CALCULATE

Results

CorrelationCalculated ValueWarningsRemarks
1-Papay0.843-This is a direct method to calculate Z-Factor
2-HALL-YARBOROUGH0.832-For pseudo critical pressure (Ppr) range from 0.2 to 25 For pseudo critical temperature (Tpr) range from 1.0 to 3
3-Dranchuk-Abu Kassem0.833-For pseudo critical pressure (Ppr) range from 0.2 to 15 For pseudo critical temperature (Tpr) range from 1.0 to 3
4-Heidaryan0.852-This is a direct method to calculate Z-Factor For pseudo critical pressure (Ppr) range from 0.2 to 15 For pseudo critical temperature (Tpr) range from 1.2 to 3
5-Brill-Beggs0.825-