Petroleum is an extremely complex hydrocarbon. The chemical
components of crude oil, tar, and natural gas are given in the table
below. It seems that no two crude oils are exactly the same. This is due
primary to the source material and the result of its movement from the
source rock to its reservoir.
The hydrocarbons arrange themselves in chains, and depending on the
amount of chains will be dependant on what type of petroleum product is
formed. However, nature only seems to produce crude oil, tar,
and natural gas. All the other products produced by petroleum have to be
created in the laboratory.