Abstract: On the basis of the sequence stratigraphy and sedimentology, the sequence stratigraphic framework and sedimentary facies of Shahezi Formation in Qikeshu oilfield, Songliao Basin were established, and the distribution characteristics of sandstone and the rules of hydrocarbon accumulation within the sequence stratigraphic framework were analyzed, then the type and distribution of lithologic reservoir were predicted. The results show that Shahezi Formation is a third-order sequence and can be subdivided into two fourth-order sequences, experiencing an evolution process from rapid regression to slow transgression. The development of sand bodies is controlled by the tectonic effect, lake-level change and sediment supply, and the sand bodies mainly grow in the descending base-level cycles of the fourth-order sequence, which are favorable exploration zones for lithologic reservoirs.

Key words: sequence stratigraphic framework, Shahezi Formation, Qikeshu oilfield