Abstract:

Pool-forming conditions in Qingdong Sag is discussed on the basis of analysis on structure，formation and deposition.Structural framework in Qingdong Sag is fault subsidence in the east and overlap in the west，and depression alternates with uplift because of the effect of Yi-Shu fault belt activity and Dongying movement.Resource abundance in Qingdong Sag is high owing to high organic content of oil source rock.Source material type is kerogenⅠ-Ⅱ1 and in low mature to mature stage.Paleogene Shahejie formation is interstratified between sandstone and mudstone，“self-generation，self- reservoir and self- seal” pool-forming types are common.Sideway and short distance hydrocarbon migration in Qingdong Sag is main with strong structural segmentation，major fault activity was weak in late period and hydrocarbon generation and expulsion is late.So the traps being close to deep depressions and associated with fault are the most favorable targets for prospecting.

Key words: Qingdong Sag, Shahejie Formation, Pool-forming conditions, short-distance migration, prospecting target