This calculator enable you to estimate gas density, specific gravity, compressibility and viscosity. The input required is reservoir pressure and temperature. Molecular weight for natural gas range from 17-20 g/mol, and this calculator uses 19.5 g/mol for natural gas. Methane molecular weight of 16.043 g/mol is also used.
The gas compresibility factor Z, is computed using the CNGA (California Natural Gas Association) correlation, which is suitable for pressures above 100 psig (below 100 psig, the compressibility factor is 1).
Gas viscosity calculation is based on the Lee, Gonzalez and Eakin correlation, which only requires the pressure, temperature and molecular weight of the natural gas.
You can run this calculator for gas properties as input to the NMR calculator for gas T1, D and Tw estimation for pre logging planing.