Abstract: The Silurian system in Tarim basin is an important domain for exploration of big oil-gas field for its large area and enriched oil-gas shows. With the increase of exploration extent, stratigraphic-lithologic hydrocarbon reservoirs have already become leading aspect for finding oilfield of it. At present, the commercial producing horizons mainly focus on the upper member of Kepingtag formation. The effective reservoir rock is sandstone with quartz content of over 65% formed in tide-flat, shore and delta environment. The study shows that multiple transgression and regression cycles caused by the fluctuating changes of sea level are favorable to formation of multi-set reservoir-cap rock assemblages and stratigraphic-lithologic traps; well preservable primary paleo-oil reservoir may exist in the sag hinterland; recharging of hydrocarbon during Yanshan-Hilalayan movement forms the non-structural reservoirs of unconformity barrier in Tabei area and stratigraphic overlap in Tazhong area, indicating its broad exploration prospect.

Key words: Tarim basin, Silurian, hydrocarbon accumulation, geologic condition, non-structural reservoir, exploration prospect