Abstract: With the influences of southern Tianshan and westermn Kunlun orogenic belts, Kashi sag in Tarim basin has special wedge geologic structure style. On time aspect, it shows the diversity of structural framework and sedimentary env ironment in different evolution period. On space aspect, it shows overlapping of prototype basin and structural sequence of different types. Traps here were mostly formed in the Himalayan movement period. There are two sets of source rocks in the sag: Jurassic and Carboniferous-Lower Permian source rocks. With larger thickness and wide distributed area, the Jurassic source rock that is at the peak of hydrocarbon generation is major source rock. In this sag, two sets of fine reservoir-cap assemblages are developed: one is Lower Tertiary-Cretaceous and the other is Miocene of Upper Tertiary. The comprehensive evaluation suggests that Kashi sag is of material conditions for forming large-scale oil-gas fields and will be a favorable area for hydrocarbon prospecting.

Key words: Tarim basin, Kashi sag, structural evolution, source bed, reservoir rock, source-reservoir-cap assemblage, oil and gasexploration