Abstract: The reservoir characteristics of Triassic between Shanshen structure belt in Taibei sag and Lukeqin structural belt in Tainan sag as well as their controlling factors are analyzed. The differential mechanism in hydrocarbon accumulation is due to their different structural settings in late Indosinian movement, late Y anshan movement till Late Himalayan movement. The paleo-uplift structural belt (i.e. Shanshan arcuate zone) in Taibei sag is adjacent to the source rocks, but for diagenesis and tectonic variation, the differential reservoir quality and trap shape timing behind hydrocarbon generation and expulsion periods occur; while the relatively shallow deposits of Early Jurassic in Tainan sag have better reservoir quality for its weak diagenesis and compaction. A lso, since Late Indosinian movement, the structures in the southeastern Tainan sag commence stable and continuous tilting, thus being the long- term directional domain. Therefore, the petroleum exploration of Triassic in Tuha basin should pay more attention to the southern area with relatively stable structures,hydrocarbon supply and better reservoir quality.

Key words: Tuha basin, Taibei sag, Tainan sag, Triassic, petroleum exploration