This is a summary of the results obtained by the authors during the past 20 years from their studies in combining the geochemistry of natural gases with that of noble gases. The book focuses on the gas constitution of the noble gases helium and argon, their isotopic composition in oil/gas reservoirs in the major oil-gas-bearing basins in China, and their geochemical implications, as well as the geochemical characteristics of noble gases and natural gases as the high-quality energy resources in China's oil-bas-bearing regions.