FSC 432
Petroleum Processing

Lesson 2 Overview


Lesson 2 Overview

Video: FSC 432 Lesson 2 (2:27)

Lesson 2 Breakdown
Click here for transcript

In lesson two, we will talk about the properties and classifications of crude oil. Because of the extreme complexity of crude oil, it is impossible to get the molecular analysis, or the molecular composition. Because of this reason, people, even in the very early days of refinery, they developed some techniques to use easily measurable physical properties, such as density or viscosity, to make inferences about the molecular composition of crude oils.

This information is very important for refiners to adjust operating conditions in many units that are all integrated in the whole refinery. So to get these properties is really critical. And that can be easily measured in the laboratory.

What is important and fascinating to see that some classification parameters or characterization factors use these easily measurable properties to make inferences on the chemical constitution, chemical composition, of the oil. From physical properties to chemical composition.

You know that crude oil contains, essentially, hydrocarbons that are paraffinic or naphthenic and aromatic. So, using these characterization factors could classify the crude oils into these three subcategories. But beyond that, if you do have information on the hydrocarbon composition, you could use a more sophisticated classification system to divide crude oils into six classes.

Again, these are very important in terms of informing the refiners what to expect from this crude oil, how they can adjust the operating parameters so that they can produce the products that they would like and the properties of these products, the quality of the products-- to make these adjustments, to reach these refinery goals and objectives, in general. So see you in class after this.

Credit: Dutton Institute © Penn State is licensed under CC BY-NC-SA 4.0


Physical properties and composition of crude oil provide critical information for the optimum operation of a petroleum refinery. This information does not only help predict the physical behavior of crude oil in refinery units, but also gives insight into its chemical composition. Therefore, the physical properties can be related to chemical properties of crude oil and its fractions and the characteristics of the resulting refinery products. The most important properties of crude include density, viscosity, boiling point distribution, pour point, and the concentration of various contaminants.

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.

What is due for Lesson 2?

This lesson will take us one week to complete. Please refer to the Course Syllabus for specific time frames and due dates. Specific directions for the assignments below can be found on the Assignments page within the 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 folder.


If you have any questions, please post them to our Help Discussion (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.