References provide data tables and methods for obtaining the compressibility factor at base conditions, such as GPA 2145, although these data generally are only true for one of most used base ...

Compressibility Factor: A dimensionless quantity that indicates the deviation of a real gas from ideal gas behaviour under specific conditions of pressure and temperature.

The compressibility factor (z-factor) quantifies the deviation of natural gas from ideal gas behaviour under varying pressures, temperatures, and compositions.