In addition to RKCMurphy's message, the elemental composition wt-% ranges for almost all crude oils -as published quite a time ago- is:
Carbon 83.9-86.8
Hydrogen 11.0-14.0
Sulphur 0.06-8.00
Nitrogen 0.02-1.70
Oxygen 0.08-1.82
Metals 0.00-0.14
Evidently in lighter crude oils the hydrogen content would tend toward its higher limit.
Some 70 years ago the US Bureau of Mines established a general scheme for the classification of crudes based on the specific gravity of two fractions (key fractions) from a standardized method of fractionation of the crude. From the specific gravity (or API gravity) of these two fractions, the crude is assigned to one of nine classes ranging from Paraffinic to Naphthenic.
When total analysis of fractions is practicable two groups of characterization (not too accurate) methods are applicable.
One group uses sets of physical constants to describe, by means of factors or indices, the predominant chemical character of a fraction.
The other group, based on structural group analysis, describes the character of a fraction in terms of the elements making up an imaginary average molecule with chemical or physical properties of the sum of the individual components, according to their concentration.