ABSTRACT
In the area of petroleum science, asphaltenes are the most studied yet the least understood components of crude oils. An extensive book review of asphaltenes and asphalts was published (Chilingarian and Yen, 2000). The term asphaltenes is used to describe the insoluble content precipitated from petroleum oils using paraffinic solvents. Crude oils are usually characterized by API gravity, distillation range, pour point, sulfur content, metals, salt content, and carbon residue. The definition of ‘‘heavy oil’’ is usually based on the API gravity of <20. Very heavy crude oils and tar sand bitumens have an API <10. Usually, the higher the density, or lower the API gravity of the crude oil, the higher the sulfur content. The total sulfur in the crude oil can vary from 0.04 wt% in a light paraffin oil to 5 wt% in a heavy crude oil. Heavy crude oils contain a higher content of heteroatom content, metals, and asphaltenes and have a higher carbon residue. The carbon residue is roughly related to the asphalt content of the crude oil and the quantity of the lubricating oil fraction that can be recovered (Gary and Handwerk, 2001). Only some crude oils are suitable to produce lube oil base stocks. The literature reported that correlations have been developed to characterize the crude oils in terms of typical assay parameters and their effect on increased processing cost related to desalting and corrosion formation (Van den Berg et al., 2003). The effect of crude oil properties and composition on their processing is shown in Table 4.1.
