Tectonic Evolution and Geological Characteristics of Hydrocarbon Reservoirs in Marine Mesozoic-Paleozoic Strata in the South Yellow Sea Basin

The South Yellow Sea Basin is the main body of the lower Yangtze area in which marine Mesozoic-Paleozoic strata are widely distributed. The latest geophysical data were used to overcome the limitation of previous poor-quality deep data. Meanwhile, the geological characteristics of hydrocarbon reservoirs in the marine Mesozoic-Paleozoic strata in the South Yellow Sea Basin were analyzed by comparing the source rocks and the reservoir and utilizing drilling and outcrop data. It is believed that the South Yellow Sea Basin roughly underwent six evolutionary stages: plate spreading, plate convergence, stable platform development, foreland basin development, faulted basin development, and depression basin development. The South Yellow Sea Basin has characteristics of a composite platform-fault depression geological structure, with a half-graben geological structure and with a 'sandwich structure' in the vertical direction. Four sets of hydrocarbon source rocks developed-the upper Permian Longtan-Dalong formation, the lower Permian Qixia formation, the lower Silurian Gaojiabian formation, and the lower Cambrian Hetang formation/Mufushan formation, giving the South Yellow Sea Basin relatively good hydrocarbon potential. The carbonate is the main reservoir rock type in the South Yellow Sea area, and there are four carbonate reservoir types: porous dolomitic, reef-bank, weathered crust, and fractured. There are reservoir-forming horizons similar to the typical hydrocarbon reservoirs in the Yangtze land area developed in the South Yellow Sea, and there are three sets of complete source-reservoir-cap rock assemblages developed in the marine strata, with very good hydrocarbon potential.