Comparison of correlations based on API gravity for predicting viscosity of crude oils

Correlations for the prediction of dynamic viscosity of crude oils as a function of the absolute temperature and API gravity are compared. Twelve crude oils with wide range of API gravity (12.4-43 degrees API) are used for comparison of correlations. It was identified the need of an accurate correlation for calculating viscosity of heavy crude oils. Thus, a new correlation is proposed, which was validated using viscosity values different to those used to derive it. Comparison of results using literature information and own set of data indicated better predictability over other correlations previously reported. High accuracy was observed with the developed correlation for crude oils with low API gravity (<= 21.1 degrees API), so that it resulted to be more accurate for calculating viscosity of heavy crude oils. (C) 2014 Elsevier Ltd. All rights reserved.