Viscosity model based on equations of state for hydrocarbon liquids and gases

Based on the similarity between P-v-T and T-μ-P relationships, viscosity (μ) models for pure hydrocarbons (mainly for n-alkanes) have been developed from the three-parameter Patel-Teja (PT) and two-parameter Peng-Robinson (PR) cubic equations of state. The EOS-based viscosity models are applicable to both liquid and gas phases, and have been successfully extended to hydrocarbon mixtures containing defined components as well as undefined C7+-fraction. Compared to the typical viscosity correlations widely used in the petroleum industry, significant improvement in prediction accuracy was achieved. Since the P-v-T, V-L-E and viscosity calculations can be performed by using a single equation of state, the thermodynamic consistency of reservoir simulation and process simulation calculations is improved.