Viscosity Prediction for Natural Gas Mixtures

The viscosity of multicomponent natural gas-mixtures containing hydrocarbons (C1 through C7) is predicted by modifying a previously published dilute-gas viscosity model and extending its applicability to a wide range of temperature and pressure conditions including liquid and gas states. Nitrogen, oxygen, carbon dioxide, and helium are also included among components of mixtures for which published viscosity data are available. The approach takes advantage of currently available formulations and models for the density and viscosity of pure fluid constituents of natural gases. The predicted viscosity is compared with available data in both gas and liquid regions. Comparisons of calculated values to the available measurements of viscosity of natural gas mixtures and of binary, ternary, and quaternary mixtures of constituent fluids are summarized to illustrate the accuracy of the predicted values.