Study of Sequence Stratigraphy Framework of Dongying Formation in Area Z of Liaoxi Depression

Liaoxi depression is located in the southwest of Liaodong Bay, with Suizhong 36-1 oil field discovered in Paleogene of the southern Liaoxi depression (SLXD), which has hundred million tons of original oil in place (OOIP), indicating a great hydrocarbon potential in this area. Dongying Formation (Paleogene) is the main exploration targets in area Z of the southern Liaoxi depression. On the basis of the paleontological data, core, logging and seismic data, three sequences have been distinguished in Dongying Forma-tion from bottom to top, including SQd3, SQd2 and SQd1, of which SQd3 & SQd2 can be divided further into lacustrine-expanded systems tract and highstand system tract. Various sequence interfaces are different in the characteristics of paleontology, lithology, log responses and seismic reflection. The stratigraphic sequences and sedimentary systems are controlled obviously by the structures and paleogeomorphy. At the upland of slope and the uplifted area, Dongying Formation overlays on the basement rock, and trunca-tion occurred between Dongying Formation and the overlying Guantao Formation. Within order III sequence of Dongying formation, transgressive to regressive sedimentary cycles deposited, with obvious different lithology, log responses and seismic reflection char-acteristics.