Abstract: Yuqi block is an important oil & gas exploration target of Tahe oilfield in Akekule arch, Tarim Basin. The research results indicate that the oil & gas in Yuqi block are from Cambrian to lower Ordovician source rocks in the south of the Akekule arch. Halahatang Formation in Yuqi block has definite exploration potential. The crude oil density of Halahatang Formation is low, the content of sulfur is also low, and the content of wax is high, the gas in Halahatang Formation belong to typical mixed gas. The trap types are mostly tectonicly controlled, which are low scope, the oil & gas distribution is mostly faultbounded. There are at least three episodes of oil/gas charges, i.e., Jurassic-Cretaceous, late Palaeocene-Eocene and early Oligocene-Miocene. The oil & gas accumulation model in Yuqi block is outward source-bidirectional expulsion of hydrocarbon-multistage accumulation or hydrocarbon sourced from the old rocks and preserved in the young rocks-bidirectional expulsion of hydrocarbon-multistage accumulation. and its evolution has two stages.

Key words: hydrocarbon source conditions, hydrocarbon reservoirs types, accumulation model, Halahatang Formation, Akekule arch, northern Tarim Basin