With the rapid development of my country's social economy, the demand for oil and gas resources is increasing day by day, and its dependence on foreign countries is also increasing year by year. Oil and gas resources in the South China Sea account for about 1/3 of my country's total oil and gas resources, 70% of which are contained in deep-water areas. Accelerating deep-water oil and gas exploration in the South China Sea is of great significance to ensuring my country's energy security. Affected by water depth, deepwater oil and gas exploration is highly risky and costly. Accurately finding large-scale high-quality reservoirs is the key to improving exploration success rates and reducing costs. It is also a major technical problem facing global deepwater oil and gas exploration. Relying on projects such as the National Natural Science Foundation of China and CNOOC Joint Research, the team carried out research on a series of key issues such as the identification technology and resource potential of large-scale oil and gas reservoirs in the deepwater area of the northern South China Sea, and achieved breakthrough results, guiding the discovery of a number of large and medium-sized gas fields., the application prospects in future deepwater oil and gas exploration are very broad. Expert appraisal: ldquo; The results of this project are a model for the combination of source and sink comparative research and oil and gas exploration in the South China Sea, and have a leading role. The overall project has reached the international advanced level, among which the results of evolution and reconstruction of ancient rivers in the northern South China Sea have reached the international leading level rdquo;. 1. Innovative application of U-Pb age pedigree and rare earth comprehensive tracing technology confirmed three major source and sink systems, including the Kunyingqiong ancient river in the northern South China Sea, for the first time, and discovered the Kunyingqiong large ancient water system in the deep water area for the first time. The spatio-temporal distribution of these three sets of source-sink sedimentary systems in the deepwater basin was accurately predicted, and it was innovatively proposed that the deepwater basin develops three types of large-scale high-quality reservoir masses: ancient channel type, shelf margin delta type and deepwater fan, pointing out the exploration breakthrough direction of deepwater basin., successfully guided 8 deepwater commercial oil and gas discoveries, with a cumulative proven natural gas geological reserves reaching 245.627 billion cubic meters;2. Innovatively using the method of combining zircon dating with lithofacies and palaeogeography to clarify the intrinsic relationship between transgression and the sedimentary environment and types of source rocks. It is pointed out for the first time that there are three sets of oil and gas source rocks in the deep water area: lacustrine facies, land-land transitional facies and marine hydrocarbon source rocks are superimposed and produced, co-controlled by source and heat, replacing hydrocarbons, which directly confirms the huge oil and gas resource potential in the deep water area; reveal the basement nature and basin development background of the Cenozoic basin in the northern South China Sea, and provide a theoretical basis for basin type classification.; Identify the transgression process gradually advancing from east to west and from south to north in the South China Sea; systematically reveal the existence and temporal and spatial distribution of marine oil and gas source rocks, providing a theoretical basis for the evaluation of oil and gas resources in deepwater areas; 3. The innovative use of seismic tomography and comprehensive identification technology of microfacies-element geochemistry revealed for the first time that the continental shelf slope break zone in the northern South China Sea migrated rapidly from the south side to the north side of the Baiyun Depression from the Oligocene to the Miocene, resulting in large-scale oil and gas reservoirs. The sudden change in the composition and type of the reservoirs has developed two large reservoirs: Oligocene shelf marginal delta and Miocene deepwater fan, with high-quality oil and gas reservoir forming conditions. This achievement not only effectively guided four commercial oil and gas discoveries such as Liuhua 34-2 on the north slope of Baiyun, but also pointed out the exploration direction of ultra-deep water areas south of Baiyun Depression. The economic benefits were very outstanding. Only Baiyun deep water area increased its output value in 2018. 6.5486 billion yuan. The results of this project accurately predicted the spatio-temporal distribution of source rocks and reservoir bodies, the two most important elements in deepwater oil and gas accumulation in the northern South China Sea, pointed out that they have huge oil and gas resource potential, and guided the discovery of the first deepwater 100 billion tons gas field, making important contributions to ensuring my country's energy security. The project published 115 papers (94 SCI/EI papers), 3 monographs, and obtained 1 invention patent. Another 1 invention patent passed the actual review stage. Searching for new large-scale strategic bases for oil and gas resources in the deepwater areas of the South China Sea is an important measure to implement the Party Central Committee's proposal to enhance exploration and development efforts and ensure the security of the national energy strategy. The results of this project point out favorable exploration directions for deep-water and ultra-deep water basins in the lower stage of the South China Sea, and also have important reference value for oil and gas exploration and development in the East China Sea Basin.