Page 91 - Environmental Control in Petroleum Engineering

78 Environmental Control in Petroleum Engineering

3.2.1 Hydrocarbon Families

Crude oil contains thousands of different kinds of hydrocarbon
molecules, making it very difficult to characterize. Crude oil can also
contain significant quantities of other elements, like sulfur, nitrogen,
oxygen, and heavy metals, further complicating its characterization.
Crude oil is typically composed of between 50% and 98% hydro-
carbons. Other important components can be sulfur (0-10%), nitrogen
(0-1%) and oxygen (0-5%). Heavy metals can be found in the parts-
per-million level (National Research Council, 1985).
The molecules in crude oil, however, can be grouped into a few
families having similar properties. These families are distinguished
primarily by how the carbon atoms bond to each other and by the
presence of elements other than carbon and hydrogen. Table 3-3
summarizes most of the families of hydrocarbons found in crude oil.
These families are discussed below.

Table 3-3
Families of Hydrocarbons
Family Name Examples Formula

Alkanes Methane CH 4
Ethane C 2H 6
Propane C 3H 8
Alkenes (olefins) Methene C 2H 4
Propene
Alkynes (acetylenes) Ethyne C 2H 2
Propyne C 3H 4
Cyclic Alkanes (naphthenes, Cyclopropane C 3H 6
cycloparaffins) Cyclobutane C 4H 8
Aromatics Benzene C 6H 6
Toluene C 6H 5CH
ft r>
Polyaromatics Naphthelene C 10H 8
Tetralin C !0H 12
Alcohols Methanol CH 3OH
Ethanol C 2H 5OH
Acids Acetic acid C 2H 4OH
Amines Methyoamine CH 3NH 2