Page 60 - Petroleum and Gas Field Processing

2

Composition and Characteristics of
Crude Petroleum

A Brief Review

2.1 GENERAL

Crude oils are complex mixtures of a vast number of hydrocarbon
compounds. Properties of crude petroleum vary appreciably and depend
mainly on the origin. In this chapter, the chemical composition of the crude
oils is viewed, including the hydrocarbon series as well as the
nonhydrocarbon compounds. Physical methods generally used for indentify-
ing types of crude oils are described next. Characterization and classification
of crude oils based on correlation indexes and crude assays are presented,
followed by a comparison between some of the well-known types of oil.

2.2 CRUDE OIL COMPOSITION
The raw material that we deal with—referred to as crude petroleum—is,
by definition, the naturally occurring rock oil produced as was explained
in Chapter 1. In general, composition of crude oil may be studied by two
methods:
1. Chemical approach
2. Physical methods
Chemical composition describes and identifies the individual
chemical compounds isolated from crude oils over the years. Physical
representation, on the other hand, involves considering the crude oil and
its products as mixtures of hydrocarbons and describing physical
laboratory tests or methods for characterizing their quality.

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.