From inorganic geochemistry, the study results in this paper show that, the information water in the studied interval becomes fresh and its acidity becomes a little strong from the lower to the upper.

Also, the geochemistry of light oil of Neogene in Bohai Bay basin is particularly researched in order to attain the geochemical evidences of inorganic sources.

Deep source gas refers to inorganic genetic gas or abiogenic gas which comes from deep crust or upper mantle, and has apparent geology and geochemistry characteristics.