Abstract: Haian depression in the Subei Basin is a half graben-like faulted depression which is developed in the Late Cretaceous, and its early exploration mainly focuses on Paleogene Taizhou Formation. It has been deemed for a long period that Funing Formation is thick in the cover and thin inside with limited resources. As the exploration idea is innovatively transformed, three hydrocarbon bearing zones including Zhangjiaduo, Qutang and Xiangyang-Huji are discovered successively in Funing Formation in the south of Haian depression, and their submitted cumulative proved reserves during the 12th Five-Year Plan are 1353×10⁴t. The following cognitions are obtained based on the practical exploration of lithological oil reservoirs in the south of Haian depression. First, there is a "compartment" source-reservoir system with hydrocarbon generation and accumulation in the late stage in the south of Haian depression and it is characterized by effcient hydrocarbon expulsion and accumulation. The amount of resources in Qutang sub-depression of Haian depression is recalculated and it is up to 9000×10⁴t. Second, the sedimentary model of beach-bar sand in the south of Haian depression is established. The beach-bar sand is developed in Qutang sub-depression. Bar sand is distributed in the shape of EW band and it is mainly concentrated in the area of Zhangjiaduo-Qutang in the north while beach sand is mainly distributed in the south. Third, the hydrocarbon generation and expulsion periods in the south of Haian depression are well matched with the formation period of Ef₃ (Fu 3 Member) trap in time and space, and it is favorable for the formation of lithological oil reservoir of Ef3 beach bar sand. And fourth, the oil reservoirs are areally distributed around the hydrocarbon generating sags and they are controlled by sedimentary microfacies. The vertical distribution of lithological oil reservoirs are dominated by the main source-reservoircaprock assemblages. The long-term active faults are conducting faults which control the accumulation of hydrocarbon.

Key words: Subei Basin, Haian depression, lithological oil reservoir, exploration achievement, abnormal pressure, beach-bar sand