The crude oils of Chang 20 belong to typical immature oil which have odd even predominance and lower ratios of sterane and terpane maturity index.

长20井的原油既具有正烷烃奇偶优势，又具有甾萜烷构体比，典型的熟原油。

Biological marks of the crude oil contain long lateral chain of tricyclic terpane, and the content of gammacerane is low.

原油生物标志化合物分布,见长侧链三环萜烷,但γ-蜡烷丰度。