Abstract: Baijiahai-W ucaiwan area is in line intersection of multiple source sags in eastern Junggar basin, with multiple hydrocarbon sourcerocks composed of Carboniferous continental-oceanic interaction deposits, Permian Pingdiquan formation and Triassic Xiaoquangou group lakemudstone, and Jurassic coal measure strata. It is characterized by multi-filled oil in the early time and gas in the late time. Commercial gas flowis output from Carboniferous Tamugang formation and Batamayineishan formation, Triassic Shaofanggou formation, and Jurassic Badaowan, San-gonghe and Xishanyao formations. The source rocks in deep of north sag of Dongdaohaizi and Changji sag have been in matured-over maturedstage, which contribute much to gas reservoir in Baijiahai salient; while the source rocks in Carboniferous Dishuiquan and Batamayineishan for-mations in W ucaiwan sag have reached the matured stage. Natural gas in Baijiahai salient is mostly distributed near the gas-generated centerand by way of close distance migration and accumulation, form gas reservoir(s). W ucaiwan sag is dominated by gas reservoirs with both sourceand reservoir in Carboniferous system.

Key words: Junggar basin, source rock, source sag, natural gas, hydrocarbon accumulation