Abstract: The third member of Shahejie formation in Dongying sag consists of sequences of lacustrine transgression system tract (TST) and regression system tract (RST), of which the TST is the main control factor in tectonic subsidence, resulting in increase of accommodation space in the faulted lake basin and shape of dark shale source rocks from under-compensation deposits; the RST is the main factor in sedimentary material supply, as a result of forming accommodation transformation zone in central ramp and central sdeep slope, decreased accommondation space at outer side and increased accommondation space at inner side of the zone. In plane, the formation and distribution of petroleum reservoirs are closely related to the distribution of accommondation space, indicating that the accommondation transformation zone is the most favorable area for hydrocarbon accumulation, especially, the centralized distribution area for lithologic reservoirs, while the accommondation decreasing zone is the main area for structural-fault block reservoirs, the accommondation increasing zone will become oil reservoirs formed by slump turbidite sand bodies.

Key words: continental faulted lake basin, accommodation transformation, hydrocarbon accumulation, Shahejie formation, Dongying sag