Abstract: The Saihantala Sag of Erlian Basin features in medium amplitude sedimentation and relative inheritance development in the Early Cretaceous Epoch. Guided by theories of basin evolution and hydrocarbon generation and accumulation of overlapped sags in syngenetic fault depressions, this paper conducts organic geochemistry analysis on the shale and evaluates all kinds of geochemical indexes comprehensively, and predicts the oil & gas resources potentialities in Dubei Sag of Zhongyuan Block, based on such technology as sedimentary facies analysis, effective hydrocarbon source rock evaluation, erosion thickness restoration, and reformed basin modeling, etc. The Lower Cretaceous Bayanhua Group has a set of inland fluvial-lacustrine clastic rocks in Saihantala Sag, and the black mud shale here belongs to high quality hydrocarbon source rock. Based on the discoveries in exploration of oil and gas fields in Erlian Basin, this paper puts forward the oil and gas accumulation law of Dubei Sag. This is of realistic significance to select the target in Erlian Basin.

Key words: organic matter abundance, low maturity, burial depth, resources, hydrocarbon expulsion, Saihantala Sag