Abstract: Shawan Formation is a set of favorable oil-bearing series in Chepaizi area in the west of Junggar Basin, which is classified into three oil-bearing strata vertically with different sedimentary characteristics and hydrocarbon accumulation conditions. The first member of Shawan Formation is a progradational braided-river delta deposition, of which paleo-provenance system and ancient landform play an important role in the development of its sedimentary distribution and physical properties. The second member of Shawan Formation is beach-bar sandbodies deposition, of which the deposition, filling, modification, and selectivity are greatly influenced by paleogeographic environment such as paleowave and paleodepositional base-level. The third member of Shawan Formation is a set of stable mudstone deposition. It can be used as a regional seal, and protect hydrocarbon accumulation for the first member and the second member well. Major control factors include hydrocarbon source rock condition, migration pathways, preservation conditions, and accumulation models. Based on above research, this paper comprehensively predicted the favorable oil distribution areas by analyzing the variation of seismic attributes restricted by geological conditions. It has proved thin oil reserves of 1500 × 104t, heavy oil reserves of 5128 × 104t by drilling, and built 82 × 104t annual production capacity.

Key words: Shawan Formation, braided-river, delta, beach-bar sandbody, deposition, accumulation