Abstract: The mid-western Tabei uplift in Tarim basin is in good prospects for petroleum exploration, but has complex petroleum geological features. The regional geologic data analysis indicates that the mid-section of south Tianshan oceanic basin was formed in Late Ordovician-Early Silurian, and Tabei slope was good geological background for oil-gas enrichment in this area. It is indicated from Yingshan formation source rock samples of Ha-6 Well that the organic carbon content in its dolomitic limestone with thickness of 130 m is higher than 0.5%, showing the Lower Ordovician in this area belongs to commercial source rocks, which could broaden the depth and domain of exploration here. Study shows that the mid-western Tabei uplift is of conditions of complex paleo-karst system, along the unconformity and adjacent pinch-out are favorable areas for large-scale paleo-karst oil-gas reservoirs; the Cambrian fold in western Yingmaili swell is of premium conditions of petroleum accumulation and preservation, being a new and potential domain for petroleum exploration. Also, the buried hill area in Yingmaili swell is still of some explorative potential due to its partial and favorable control factors on petroleum accumulation.

Key words: Tarim basin, Tabei uplift, petroleum reservoir, exploration domain