中文摘要：

赛汉塔拉凹陷是二连盆地主要的油气富集凹陷之一，面积2300km^2，探明石油地质储量1458万吨。论文应用层序地层学的基本理论，根据钻井和三维地震资料，在下白垩统中识别出5个层序界面，以此将该套地层划分为4个三级层序和12个体系域，建立了赛汉塔拉凹陷下白垩统层序地层格架。通过层序内部沉积体系及其演化的研究，对层序格架内的烃源岩条件、储集层条件等成藏要素进行了综合分析，确定了3套生储盖组合。综合分析表明，阿尔善组中下部、腾一段中部的近岸水下扇和浊积扇砂体，垂向上与烃源岩直接连通，可形成有效的生储盖组合，在凹陷生油中心附近易形成有效的岩性圈闭，成为凹陷最有利的油气聚集带，是下一步的重点勘探目标。

英文摘要：

The Saihantala Sag is one of the main hydrocarbon enrichment sags in Erlian Basin, with an area of 2300 km2 and proved geological reserves of 14580 000 tons. According to the basic theories of sequence stratigraphy, 5 sequence stratigraphic boundaries were recognized by seismic profile and drilling data, and as a result, the Lower Cretaceous of Saihantala Sag was classified into 4 third-order sequences.The systems tracts were subdivided with first flooding surfaces and maximum flooding surfaces within each stratigraphic sequence and thus the sequence stratigraphic framework was established for the Lower Cretaceous of Saihantala Sag. Reservoir-forming factors in different sequences, such as hydrocarbon source and reservoir condition, and so on, were comprehensively analyzed by studies of depositional systems and their evolution, and 3 sets of source-reservoir-cap rock assemblages were established in the Lower Cretaceous of Saihantala Sag. The sandbodies of sublacustrine fan and turbidite fan of the Lower-Middle A＇ershan Formation and middle part of Member 1 of the Tengge＇er Formation, which were connected with source rocks in vertical direction, are able to form effective lithologic traps around the oil generating center of Saihantala Sag. Thus they are the most favourable hydrocarbon accumulation zones and the main exploration targets of the Saihantala Sag.