Abstract: The Toutunhe formation of Shinan field in hinterland of Junggar basin is dominated by braided fluvial deposits with grey-brown lithic sandstone, brown-red and grey-yellow mudstone, and sand depositional thickness of 7~26 m, being a reservoir of medium-low porosity and low permeability. The reservoir is laterally screened by mud and contolled by oil-water interface at low position of the structure. The study shows that the faults and unconformities are dominant in petroleum migration and accumulation of top Jurassic and Cretaceous. The two-stage uncon-formities between the Cretaceous and Jurassic and between Toutunhe and Xishanyao formations of Jurassic are major channels for petroleum migration, whereas the local normal faults play roles in connecting the oil sources to the reservoirs.

Key words: Junggar basin, Jurassin, lithologic trap, exploration