Abstract: Applying biomarks of m/z191 terpane-hopane series and sterane series, the authors analyzed the oil sources and suggested that the oil and gas of K₁y₁ came from the overlaid K₁n₁.The oil and gas generated in K₁n₁ migrated to the Putaohua oil layer of K₁y₁ through faults. The oil layer was of an assemblage type of upper source rocks and lower reservoirs. Faults were the main controlling elements. The main accumulation model of reservoirs was structuralstratigraphic trap and the Putaohua oil layer should be the main target layer for prospecting in the Heidimiao area in the future. The detailed research on the faults in K₁y and the relationship between low-amplitude structures and sand deposits will be the key for oil and gas prospecting in future.

Key words: correlation of oil sources, source-reservoir-cap rock assemblage, structural-stratigraphic trap, accumulation model of reservoirs, southern Songliao Basin