The modern practices of petroleum engineering is in the need of accurate predictions of reservoir phase behaviour properties in order to simulate and optimize other operations mostly production and processing operations. Among these reservoir fluid properties, viscosity is one of the most important properties especially during the design of pipelines, production and processing equipment, well testing, and also reservoir simulation. Using the direct measurement method to obtain the viscosity of the reservoir fluid requires a representative reservoir fluid sampling that is high in cost and it is often unavailable. In that case, the common procedure that is been using in the industry is using developed correlations as the main objective is to predict the viscosity of the crudes. However, the major problems with these developed correlations are focused in their extremely simplistic or complex nature that made their applicability decreases. Futhermore, in the case of heavy oil, they contain a large proportion of asphaltenes, waxes, and also other heavy components and so far, there are no prediction scheme has been capable of dealing with the mixtures successfully. Other than that, the commonly used correlations in predicting the viscosity, in the industry, were developed based on the data from a special regions or certain regions of the world only that limit their applications as a universal approach for viscosity estimation or prediction
