ABSTRACT
By definition (Chapter 1), petroleum (also called crude oil) is a mixture of gaseous, liquid, and solid hydrocarbon compounds. Petroleum occurs in sedimentary rock deposits throughout the world and also contains small quantities of nitrogen-, oxygen-, and sulfur-containing compounds, as well as trace amounts of metallic constituents (Speight, 2000; Hsu and Robinson, 2006; Ancheyta and Speight, 2007; Gary et al., 2007). Thus, the classification of petroleum as a hydrocarbon mixture should follow from this definition. But some clarification is required.
