Abstract: Wu-Xia fault belt is a large-scale overthrust belt developed from Late Carboniferous to Triassic and faults mostly develop below the Triassic. The structure overlying the Jurassic occurs mainly in monocline. Oil-gas reservoirs have been found in the Permian, the Triassic and the Jurassic, of which the oil-bearing horizons of Jurassic are mainly found in its Badaowan formation, dominated by stratigraphic and lithologic oil-gas reservoirs, with strong secondary reconstruction of crude oil. The dissection of the Jurassic typical reservoirs in this area indicates that the oil and gas migrated along the faults to the basal unconformity of Jurassic followed by starting lateral migration, and accumulation in the basal conglomerate or the transgressed sand bodies due to meeting barrier beds of updip heavy oils. Such an idea has been examined from exploration and practices.

Key words: Junggar basin, Wuerhe-Xiazijie fault belt, unconformity, heavy oil, control factor, hydrocarbon accumulation