Abstract: The complex faulting system and abnormally active volcanic process make the middle segment of Dongbu sag in Liaohebasin possess unique hydrocarbon accumulation model.Establishment of such a model is based on relationship between the vol-canic process and hydrocarbons in it and the analysis of reservoir rocks and spatial distribution.Study shows that Sha-3 layer of Oulituoz area is rich in petroleum due to premiere assemblages among enough oil sources, fair transport system and fine energyconfiguration. The petroleum accumulation model is characterized by vertical migration assisted with lateral short-distance migration.But in Tiejianglu area, petroleum migration and accumulation are different from those in Oilituoz area,its channel media forpetroleum migration are dominated by interconnected sands with little vertical migration along the faults,thus resulting in petroleum distribution primarily in the middle-lower section of Sha-3 layer.

Key words: Liaohe basin, volcanic rock, petroleum accumulation model, migration, accumulation