Abstract: Petroleum geochemistry parameters and indexes exert great effect on the study of petroleum system. The study mainly consists of six decisions on hydrocarbon kitchen, critical moment, migration pathway, boundary of hydrocarbon migration-and-accumulation units (HAMU), resources potential, target potential and level. Based on the discussion of the six aspects mentioned above, this paper presents the practical application of petroleum geochemistry in petroleum system study. It is considered that petroleum geochemistry can be applied from the beginning to the end of the study. Emphasis needs to be laid on the close combination between geochemistry experiment and petroleum system study.

Key words: petroleum geochemistry, petroleum system, hydrocarbon source rock, critical moment, effect