Abstract: This paper analyzes the special sedimentary environment and petroleum geologic conditions in Taibei sag in Tuha basin. For oil-gas accumulation pattern with source bed in lower formations and reservoir bed in upper formations, the good assemblage among source fault, paloestructual setting and lithologic trap is the key for hydrocarbon accumulation. In lithologic oil-gas reservoir exploration in Taibei sag, the lithologic trap is not only focused on, but also study of the source fault development feature, paleostructural setting of trap and related condition and process of oil-gas accumulation should be paid more attention to. Based on analysis of oil-gas accumulation characteristics, this paper proposes the thought, studied focal point and explorative direction in this area.

Key words: Tuha basin, lithologic reservoir, lower source and upper reservoir, exploration