The Study On Geochemical Exploration Technology And Resource Potential Of Gas Hydrate In Hanhai

Based on the gas hydrate geological accumulation theory and the gas hydrategeochemistry of the ODP（Ocean Drilling Program）/IODP（Integrated Ocean DrillingProgram） and Nanhai, we classify the exploration methods by studying thegeochemical technology and their effects. Then the geochemical optimal index arechoosed and the evaluation standard of the index are established.The indication ofthe authigenic carbonate and isotope to gas hydrate are also studyed. According tothe above, three classes of gas hydrate foreground are plotted out: the first is the areaof Xisha Trough, Dongsha sea-area, Shenghu, North Slope and Taixinan, the secondis the area of Qiong Dongnan Basin and Nansha Trough, and the third is the area ofWest Slope and Centric Sea Basin.The study point out that, the best geochemical index include the acidolysis andHS method in soil geochemistry, the reducing of Cl^-and high δ¹⁸O, high Cl^-in theshallow, shallow SMI bound（<50m）, high SO₄^2-in the fluid geochemistry andauthigenic carbonate. Also the optimal index in judging the hydrocarbon genesis areby the δ¹³C, δD and C₁/（C₂+C₃）.The data include: the adsorbed hydrocarbon and isotope data of the samples weapplied from ODP/IODP and corresponding free gas site tested, the adsorbedhydrocarbon data of the geochemistry in Qiong dongnan-Xisha Trough, and thedomestic and overseas geochemical index data collected.The paper aims at providing reference and scientific basis of the gas hyadrategeochemistry for the following exploration in Naihai.