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Petroleum Processing

Summary and Final Tasks


Lesson 2 Summary

Selected properties of crude oil provide information on its quality and the conditions for optimum operation of a petroleum refinery for processing the crude oil to produce the desired fuels. Readily measurable physical properties of crude oil (such as density, boiling point, and viscosity) not only help predict the physical behavior of crude oil during refining but also give insight into the chemical composition of the oil. Therefore, physical properties can be used in developing characterization factors that relate to the chemical behavior of crude oil and the characteristics of the resulting refinery products. In addition to using characterization factors, crude oils are classified using ternary diagrams reflecting the hydrocarbon composition in terms of paraffins, naphthenes, and aromatics.

Learning Outcomes

By the end of this lesson, you should be able to:

  • define the significant properties of crude oil, including density, viscosity, average boiling point, sulfur, and salt content;
  • understand the significance of crude oil properties in terms of refinery objectives, and describe crude oil assay;
  • define and interpret the classification factors (Watson, UOP, VGC, and BMCI) as they relate to the hydrocarbon composition of crude oils;
  • calculate average boiling points for crude oils using different averaging techniques, and differentiate Watson and UOP characterization factors;
  • analyze the elemental composition of crude oils and outline ternary classification of crude oils with respect to hydrocarbon composition, i.e., aromatics, paraffins, and naphthenes;
  • assess the use of ternary classification of crude oils to estimate the refinery product yields.

Reminder - Complete all of the Lesson 2 tasks!

You have reached the end of Lesson 2! Double-check the to-do list below to make sure you have completed all of the activities listed there before you begin Lesson 3. Please refer to the Course Syllabus for specific time frames and due dates. Specific directions for the assignment below can be found within this lesson.

This table contains the reading and assignments for Lesson 2.
Readings J. H. Gary, G. E. Handwerk, Mark J. Kaiser, Chapter 3, pp. 57-61, 65-70 and the course material from this site
Assignments Exercise 1 - Submit to the Exercise 1 Assignment in the Lesson 2 Module.
  • Calculation of API gravity of crude oil blends
  • Calculation of Watson and UOP characterization factors for hydrocarbons and crude oil fractions
Quiz 1: Assessment of learning outcomes in Lessons 1 and 2. Quiz 1 is found in the Lesson 2 module.


If you have any questions, please post them to our Help Discussion Forum (not email), located in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.