“…However, this model can be used in a much wider range of reservoir and gas conditions.2: The proposed GEP model follows the actual physical trends perfectly and fits the experimental data points very well. Thus, it can be effectively employed in prediction of the viscosity of pure hydrocarbons and natural gas and it can be employed in any reservoir simulator.3: Lucas[15] correlation overestimates the gas viscosity value, while Carr et al[8], Sutton[17], Jossi et al[10], Dean and Stiel[11], Sanjari et al[6] and Heidarian B[19] correlations underestimate this value.4:The results of sensitivity analysis show that gas molecular weight has the biggest impact on gas viscosity, while pressure has the smallest impact on this value.…”