Abstract:

Yanqi Basin is stituated between Tarim Basin and Tarpan-Harmi Basin.Its petrolenm system underwent the formation and destruction during Jurassic-Cretaceous, the activation and reconstruction during Tertiary-Quaternary. The petroleum system of the basin formed in the end of Badaowan Formation depositional stage,and was destroyed by a large scale of thrust uplift and denudation of the Jurassic System in mid-late Yenshan stage,and the oil generation process was stoped. In Himalaya period,the basin was compressed.As Tertiary deposits increased,Jurassic source rocks started secondary hydrocarbon generation, thus resulting in the activation and reconstruction of the petroleum system. The inhomogeneous structurral evolution resulted in the charactoristics of early stage pool forming,serious pool destruction, small range of secondary oil generation, and poorly developed sand bodies and lower hydrocarbon enrichnrent of the south sag of the basin. Things are opposite for the north sag. These characteristics should be taken into account in hydrocarbon exploration.

Key words: petroleum system, secondary hydrocarbon generating, activation, Yanqi Basin