Abstract:

Researches on gas hydrates are based upon geophysics, geochemistry and geology, and so on. By geochemical prospecting approach, as one of these researches, we could obtain some geochemical marker of gas hydrate from sediment undersea, and then establish the anomaly area of gas hydrate. Recently many geophysical and geochemical evidences have been discovered, which indicate that the northeast of the South China Sea is one of the most prospective gas hydrate bearing areas in China. In 2005, 93 sites at the geochemical work area for gas hydrate in Qiong-dongnan Basin of the South China Sea have been detected on-site. According to the acidolysis hydrocarbon test of the sediment from this detection and the isotopic analysis, the distribution of gaseous hydrocarbon anomaly and its causes have been studied in this paper. The prospect of gas hydrate in this work area has been estimated here on the ground of the geological condition for gas hydrate accumulation and the detective study over the Xisha Trough. The results will show an outstanding geochemical marker for gas hydrate prospecting in this work area.

Key words: gas hydrate, geochemical prospecting, Qiong-dongnan Basin, the north of the South China Sea, prospective area of gas hydrate bearing