According to the structural group theory, the chemical composition of petroleum fractions can be classified as structural groups as aromatics, naphthene, olefin and non-hydrocarbon elements etc.

• 按照结构基团理论，将石油馏分的化学组成划分为芳烃、环烷烃、烯烃和非烃元素等结构基因，其中芳烃和环烷烃还按照其环分布划分为若干个亚族基因。