Abstract: Based on the geological interpretation of more than ten thousand seismic profiles of 1000 meters in Sanhu region of Qaidam Basin, this paper shows that two strike-slip faults developed in the basin, among which one in the south of the basin and another in the middle of the basin, while the latter one has played an important role in the formation of the structure of the region. Three en-echelon anticline belts, i.e., the faulted anticline belt and the slope anticline belt with low amplitude as well as the central anticline belt with low amplitude developed in the region in Early Pleistocene owing to the right-lateral strike-slip and inversion thrust of the fault in the middle of the basin under E-W compression. Fold intensity gradually decreases from the belt in middle Qaidam to the south. This paper finally reveals that the Quaternary biogas reservoir is mainly controlled by structural background, regional slope belts, gas generation intensity, and cap rock, based on structural conditions, preservation conditions, and the relationship between essential gas-generating regions and known gas fields. It suggests that the central anticline belt with low amplitude in the south of the basin is favorable for discovering structure conglomerate gas reservoirs in the future.

Key words: Qaidam Basin, Sanhu region, structural characteristic, gas reservoir