Abstract
Brine from Niigata natural gas field has the abnormal characteristics in the chemical composition of dissolved material and in the isotopic composition of hydrogen of water molecule.
Na/Cl of Niigata brine has extraordinarily smaller value than that of sea water and other brines. The deuterium content determined by T. Chitani and Y. Horibe has abnormally decome impoverished in Niigata brine. The ordinary brines have a deuterium content that is comparable to that of sea water.
These facts mean that original Niigata brine has been contaminated by much choride- and much protium-bearing water during geological ages.
