| Shengli Oilfield is one of the oldest oilfields in east China. The exploration degree of the major structural belts and the middle- and shallow exploring targets is very higher. The important task is now how to find new hydrocarbon traps so that the productive of oil-gas can be remained stable. The Jiyang depression is the major exploring area of the Shengli oilfield, in which develops many large-scale buried hills consisting of Archean, Paleozoic and Mesozoic. The buried-hill type reservoir is an important oil-gas reservoir type. Therefore, we focus our research on the attractive buried hills.This paper describes regional and basement structural features, using gravity and magnetic anomalies, logging and seismic profiles, in order to clear the distribution rule of the buried hills in plane view and the vertical architectures in the inner buried hills. At last, combined with the response to regional structural evolution of the Jiyang depression, the paper discusses the development, evolution and distribution of the buried hills and the rules of hydrocarbon generation and accumulation in term of dynamics.Until now, more than 20 buried hill-type hydrocarbon reservoirs have been found, which are mainly located at the Zhenhua, Chezhen and Dongying depressions and underwent multi-stage deformations. The Indosinian structural style is very similar to that of the Luxi uplift, of which features are gentle strata, no large-scale and intensive folds rather than near EW-trending open folds except for local overturned folds such as at Wuhaozhuang area. In addition, a set of near EW striking reverse faults develops, accompanying with two sets of NE- and NW-striking secondary faults which resulted in the zigzag shape of the large-scale reverse fault. All of them led the basement of the Jiyang depression to the framework of near EW-oriented blocks and controlled the structural style at the later structural stages. The Yanshanian structural pattern is a key factor constraining the development and evolution of Neozoic buried hills, which ischaracterized by NE-striking thrust faults and folds. Neozoic faulted grabens at the Jiyang depression is produced by block extrusion under the pure compression, controlled by NWW- and near EW-striking, spatially interlocked, basement-involved faults at the border of the Meso-Neozoic basin. The NW- and near EW-striking faults are depression-controlled faults with large amount of extension and listric fault planes. However, the NE-striking faults appeared some strike-slip or transfer faults with large dip angle and little extensional displacement. The Jiyang depression appears present-day the architecture of the overlapping at the south and the faulting at the north, which and north- or northwest-dipping monocline mountains composed a pattern of basin and range.By comparison to the Yanshanian and Neozoic deformations in the same depression, it is found that many earlier structures are enhanced and reformed in the later evolutionary stages. However, the strikes of the old and new structures are characterized by the inheritage. But their fault property has been changed. For example, The Yanshanian reverse faults in the Jiyang depression have been changed into the tranfer faults playing a role of accomadation of strain. Obviously the basement structure controlled that of the Neozoic sedimentary cover, and controlled the paleogeographic pattern of the sedimentary cover and the migration direction of hydrocarbon. Therefore, the study on the basement structure and its reformation is benefit and important to finding "Neozoic-generated and Paleozoic-accumulated " and "Paleozoic-generated and accumulated" types of hydrocarbon reservoirs.The research results suggest that the covers of the buried hills in the Jiyang depression have multi-eras (including Paleozoic, Mezozoic and Neozoic) and multi-types (mainly including mudstone) of stable and widely-distributed trapping sedimentary series. The limestone and dolomite of lower Plaeozoic are good coverage. The regional coverage includes Carboniferious and Permian such as gray shale and mudstone, purple iron-bearing shale and aluminothermics of the Benxi Formation, half lacustrine-lacustrine dark mudstone of the Shasan Member. The local coverages include Ordovician marine carbonites, Middle- and lower-Jurassic coal and gray mudstone, purple-gray green mudstone of the Shasi Member and Kongdian Formation. Because ofthe intensive weathering and tectonic activity, the reservoir types and properties are very good. The carbonites have large number of secondary hole, structural fracture and eroded cave and hole. The accumulated space is characterized by the multiple types, complex textures and un-homogeneous distribution. The debritris of the lower Shihezi Formation is composed of good fracture, inter-grained hole, intra-grained hole and others. The buried-hill type of traps formed later, from Ed-stage in the south and Nm-stage in the north of the Jiyang depression to Ed-Nm-stage in the Bozhong depression. This paper also proposes three buried hill types, i.e. the rise-type, gentle-slope-type and scarp-type based on the structural sites. The oil sources of Paleozoic and Neozoic mainly focus on the Dongying, Zhanghua, Chezhen and Huimin sags, in which the thickness of lower Tertiary is summed up to more than 3000 meters. They underwent multiple-stage histories of oil generation. The later Early Permian to the end of middle Triassic is the first gas-generating stage. The middle- and late Jurassic is the second gas-generating stage. The third oil-generating stage is Neozoic. The oil mainly trends to migrate into the south gentle slope and rise. The synthetic assessment suggests that the rise in the depression or the uplift near the sags and the slope or the buried hills on the slope with reverse dip direction to the direction of strata are favorable targets of the buried hill-type reservoirs. Especially it is important that the exploration is focused on the south gentle slope in the Jiyang depression.
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