With the rapid development of China's socio-economy, the demand for oil and gas resources is increasing day by day, and our country's dependence on imports is also growing year by year. The South China Sea region accounts for about one-third of China's total oil and gas resources, with 70% of them buried in deep waters. Accelerating the exploration of deepwater oil and gas in the South China Sea is of great significance for ensuring China's energy security. Influenced by water depth, deepwater oil and gas exploration carries high risks and large costs. Accurately identifying large-scale high-quality reservoirs is key to improving exploration success rates and reducing costs, and it is also a major technical challenge faced by global deepwater oil and gas exploration. Relying on projects such as National Natural Science Foundation and joint researches with China National Offshore Oil Corporation (CNOOC), the team has focused on solving a series of key issues related to the identification technology of large-scale oil and gas reservoirs in the northern deep waters of the South China Sea and their resource potential. They have achieved breakthrough results, guiding the discovery of a number of medium and large-sized gas fields, which have very broad application prospects in future deepwater oil and gas exploration. Experts' appraisal: "The project's achievements are a model of the integration of comparative research on the South China Sea source and sink with oil and gas exploration, serving as a leading example. The overall project has reached an international advanced level, with the reconstruction of the evolution of ancient rivers in the northern South China Sea reaching an international leading level." 1. Innovative application of U-Pb age chronology and rare earth element comprehensive tracing techniques confirmed for the first time the three major source and sink systems in the northern South China Sea: Kunying-Qiong, and discovered the large ancient river system in the deep water area of Kunying-Qiong. Accurately predicted the spatiotemporal distribution of these three sets of source-sink sedimentary systems in the deep-water basin, innovatively proposed three types of large high-quality reservoirs in deep-water basins: ancient waterway type, continental shelf edge delta type, and deep-water fan type, pointed out the direction of exploration breakthroughs in deep-water basins, successfully guided eight commercial oil and gas discoveries in deep waters, accumulating proven geological reserves of natural gas up to 245.627 billion cubic meters; 2. The innovative use of zircon dating combined with lithofacies paleogeography has elucidated the intrinsic connection between transgression and hydrocarbon source rock depositional environments and types, pointing out for the first time that there are three sets of oil and gas hydrocarbon source rocks in deep waters: lacustrine, continental margin transition, and marine hydrocarbon source rocks superimposed on each other, controlled by common sources and thermal energy, succeeding in hydrocarbon generation, directly confirming the huge potential of oil and gas resources in deep waters; it reveals the nature of the Cenozoic basin basement and the developmental background of the basins in the northern South China Sea, providing a theoretical basis for basin classification; it identifies the progressive transgression process from east to west and from south to north in the South China Sea; systematically reveals the existence and spatiotemporal distribution patterns of marine hydrocarbon source rocks, providing a theoretical basis for the evaluation of oil and gas resources in deep waters; 3. The innovative use of seismic tomography imaging combined with microfacies-element geochemical comprehensive identification technology has for the first time revealed that from the late Eocene to the middle Miocene, the slope break zone on the northern continental shelf of the South China Sea rapidly migrated from the south side of the Baiyun Depression to the north side. This has led to mutations in the composition and types of large hydrocarbon reservoirs, developing two major reservoir groups: the Eocene shelf margin delta and the Miocene deepwater fan, which have excellent conditions for oil and gas accumulation. The results not only effectively guided four commercial oil and gas discoveries such as the Baiyun North Slope Liuhua 34-2 but also pointed out the exploration direction for the ultra-deep waters south of the Baiyun Depression, with very significant economic benefits. In 2018 alone, the deepwater area of Baiyun added a new value of 6.5486 billion yuan. The project's achievements accurately predicted the spatiotemporal distribution of the two most important elements for deepwater hydrocarbon accumulation in the northern South China Sea: source rocks and reservoirs, indicating their tremendous potential for oil and gas resources. This guidance led to the discovery of the first deepwater trillion cubic meter gas field, making an important contribution to ensuring China's energy security. The project published 115 papers (including 94 SCI/EI papers), three monographs, obtained one invention patent, Another invention patent has passed the substantive examination stage. Searching for new large-scale oil and gas resources strategic bases in the deep waters of the South China Sea is an important measure to implement the Central Committee's proposal of 'enhancing exploration and development efforts to ensure national energy strategy security'. The achievements of this project have pointed out the favorable exploration directions for the next phase of deep-water and ultra-deep-water basins in the South China Sea; it also has important reference value for the oil and gas exploration and development of the East China Sea basin.