Evaluation of Predictive Models for High-Pressure Natural Gas Viscosity

Accurate knowledge and prediction of natural gas thermo-physical properties, such as density and viscosity, is requisite to appropriate, reliable, and economical design of natural gas related production, transmission, and processing.  Of increasing importance are accurate predictions at higher pressures and temperatures due to, among other things, deeper drilling, higher wellhead pressures, and discovery of new reservoirs with such conditions.  Historically, viscosity data in this range of pressures and temperatures has been limited.  Towards addressing this need, viscosity data for 5 synthetic natural gas mixtures over a temperature range of 250 to 450 K and pressure range of 10 to 65 MPa was recently obtained and reported.  These previously reported results are utilized to investigate and compare the predictive ability of several viscosity models (PFCT, LBC, CLS, and NBS) and the PR and SRK Equations of State.  ProMax simulations are utilized to facilitate evaluation of PR and SRK. The effect of sample composition is also discussed.