Abstract: In Turpan-Hami basin, multi-source rocks are developed in Xiaocaohu secondary sag,and show good source conditions, abundant petroleum resources and bright prospects for exploration. Three reservoir-cap assemblages developed in Middle Jurassic formed reservoir ty pes in the sag which are structural-lithology oil-gas pools in Sanjianfang formation and Qiketai formation along with deep basinal gas pools in Xishanyao formation of Jurassic. The late Yanshan movement is a major stage for hydrocarbon accumulation in Xiaocaohu secondary sag. The primary controlled factors for its hydrocarbon accumulation is due to its palaeo-structures, tectonic setting and traps with structural-lithology feature. The exploratory efforts has good effectiveness based on these main controlled factors for evaluation and optimization of its favorable zones.

Key words: Xiaocaohu secondary sag, complex trap, dominant factor, hydrocarbon reservoir