Strengthening exploration and development of oil and gas is crucial for mitigating China’s reliance on oil and gas supply from foreign countries and ensuring national energy security. Since the 11th Five-Year period, fundamental research on the deep-wate area of the northern South China Sea has been strengthened, along with the acceleration of technological innovation and increase in exploration investment. As a result, a series of major exploration discoveries were found. This paper presents five major learnings regarding the theories of exploration geology and two achievements in the innovation of exploration technology. It also discusses the new challenges and coping strategies for oil and gas exploration in deep-water areas, and prospects the exploration potentials of three major exploration fields—medium-deep layers, buried hills, and lithologic traps—in the deep-water area of the northern South China Sea. Our research shows that the detachment of the continental margin in the deep-water area of northern South China Sea controls the formation of large sags in the Pearl River Estuary Basin and the Qiongdongnan Basin. Three sets of large-scale source rocks were developed from lacustrine, terrestrial-marine transitional, and marine sedimentary facies. High yet variable subsurface temperature controls the rapid hydrocarbon generation from the source rocks in the sags. In addition, three different hydrocarbon accumulation modes were established: accumulation mode of large axial canyon channel in the deep-water area of the Qiongdongnan Basin, late natural gas accumulation mode of deep-water fan in the deep-water area of Baiyun Sag, and differential hydrocarbon accumulation mode jointly controlled by fault and ridge. Meanwhile, the broadband seismic acquisition and processing technology for threedimensional source triggering and plow-like cable receiving was independently developed. Guided by several geological theories and innovative technologies, a series of large- and medium-sized gas fields represented by “Deep Sea No. 1” (LS 17-2) were discovered, which are of great significance to ensuring the energy supply of the Guangdong ‒ Hong Kong ‒ Macao Greater Bay Area, facilitating the green development of energy in the Hainan Free Trade Zone (Port), and promoting the increase of oil and gas reserves and
production in China.