Exploration targets in southern Yellow Sea through analysis of tectono-depositional evolution and hydrocarbon accumulation of marine basin in Yangtze area

The Southern Yellow Sea Basin locates in the eastern extension region of the Yangtze area, where marine Mesozoic-Paleozoic strata with great thickness developed. In order to investigate the petroleum geologic conditions and exploration direction of these marine Mesozoic-Paleozoic strata, and based on the evolution of marine Mesozoic-Paleozoic basin prototype and the regional development characteristics of main source rocks, the paper indicates that four main source rocks developed in the marine Mesozoic-Paleozoic strata in the Southern Yellow Sea Basin, similar with four source rocks (∈₁, O₃-S₁, P₁, P₂) in the Yangtze area. The later three main source rocks which were widely developed in the inner Yangtze area need to be paid more attention. Meanwhile, according to the analysis of the reformation characteristics of all previous Cenozoic-Mesozoic tectonic declensions to the marine Mesozoic-Paleozoic strata in Yangtze area as well as the main petroleum formation types in the Yangtze area and the structural features of the Southern Yellow Sea Basin, it is suggested that the middle uplift and the southern depression area are the favorable exploration areas of marine Mesozoic-Paleozoic primary petroleum reservoirs. The marine Mesozoic-Paleozoic source rocks are in great conditions in these areas, completely preserved, and shallowly buried, and most important is that the structure was relatively stable with weak reformation in the later period. There could be some residual marine Mesozoic-Paleozoic primary petroleum reservoirs similar as those in the Huangqiao area in the northern Jiangsu. The northern depression of this basin was closely adjoining to the Sulu orogenic belt, therefore, the marine Mesozoic-Paleozoic strata was undergoing great deformation and even deflection. Similar to the Jurong area in the southern Jiangsu, the deformation petroleum reservoir could be developed in the later fault depression area. The Wunansha uplift was in the Cenozoic-Mesozoic intense fold-uplift belt for a long time, and mainly destructive primary petroleum reservoirs were developed in the marine Mesozoic-Paleozoic strata.