Abstract: The development and origin of faults in Dongpu sag are studied. The effects of the faulted structures on the petroleum accumulation in this area are discussed. It is pointed out that these faults with different classes and different phases are characterized by long-term inherited development, which not only control the formation and development of Dongpu sag basin, but also control the source sub-sag's formation and distribution as well as the sedimentations of source rocks and reservoir rocks, followed by controlling the shape, distribution and enrichment of every oil-gas trap in this basin.

Key words: Dongpu sag, fault, hydrocarbon accumulation, enrichment