南海北部陆坡天然气水合物存在的地球物理和地球化学特征

Geophysical and Geochemical Characters of Natural Gas Hydrate Occurence in Northern Continental Slope of South China Sea

南海北部陆坡海域具有十分有利的水合物生成和赋存的构造、沉积等条件,从地球物理勘探和地球化学勘探2个方面对近期南海北部陆坡的水合物勘探工作和成果进行了综述。南海北部陆坡水合物存在的地球物理证据主要包括:地震剖面出现BSR、阻抗空白带、速度及振幅结构(VAMP)异常等;地球化学证据有:沉积物孔隙水氢氧同位素、孔隙水离子浓度、酸解烃、自生矿物及碳硫同位素等地球化学指标的异常。这些证据显示南海北部陆坡的西沙、东沙和台西南等海域具有较好的水合物勘探前景。

Since there are very favorable geological structure and sediment conditions for formation and conservation of natural gas hydrates in northern continental slope of South China Sea, it is important for research of energy source and environment to explore natural gas hydrates in this sea area. Recent works of gas hydrate exploration on the northern continental slope were summarized from aspects of geophysical and geochemical characters in this paper. In this sea area, geophysical evidences include BSR, Blank Zone, and VAMP, etc, in seismic data profiles, and geochemical abnormity evidences include ion concentration in pore water, isotope of hydrogen and oxygen of pore water, adsorbed hydrocarbon, top gas, authigenic minerals and their carbon or sulfur isotope, etc. These geophysical and geochemical characters indicate a bright prospect of gas hydrate exploration. It is advised that different methods should be combined to enhance the progress of gas hydrate exploration in the area.