ABSTRACT
The two most important properties of crude oils are its density and sulfur content, because the weight of crude oil provides an indication of product composition and sulfur content indicates the degree of processing required. Color is the first and most obvious indicator of crude quality. Heteroatoms in crude oil refers to any elements that are not hydrogen or carbon. All crude oils consist of three groups of components: Saturated hydrocarbons, Aromatic hydrocarbons, and Resins and asphaltenes. Crude is classified according to API gravity, but different organizations apply different thresholds and there is no standard universal definition. Refiners also blend crude oils to feed a more constant diet to the process units, increasing operational efficiency, and sometimes may blend crudes to achieve specific product qualities. Historically, crude blends of nonadditive properties were combined using a blending index of the property, which linearized the mixing rule.
