天然气水合物地热场分布特征

GEOTHERMAL FIELD CHARACTERISTICS IN THE AREAS OF GAS HYDRATES DISTRIBUTION

天然气水合物广泛分布于海底和永久冻土带。通过统计世界上已发现水合物或水合物标志的地区的热参数值 ,发现水合物分布区具有低热流的特征 ;由于水合物本身的低热导率特性 ,导致水合物分布区的热导率值较低 ;含水合物的沉积物由于水合物的分解 ,岩心温度也较低。通过研究南海的热场特征 ,发现南海的吕宋海槽、西沙海槽附近、湄公盆地和台西南盆地几个地区热流较低 。

Gas hydrates are located widely in marine sediments and permafrost. Through generalizing the geothermal field characteristics in the areas of gas hydrates distribution where gas hydrates sample of indications were found, we could conclude that the heat flow value was relatively lower in the areas. The thermal conductivity of sediments containing gas hydrates was lower because of the lower thermal conductivity of gas hydrates, and the temperature of core containing gas hydrates was usually lower because of the decomposition of gas hydrates. Therefore, the area with lower heat flow values usually was favourable for gas hydrates. The lower thermal conductivity and temperature of core might indicate the exist of gas hydrates. From geothermal field aspect, gas hydrates might have a better perspective in the Luzon Trough, the Xisha Trough area, the Meigong basin and the Southwest Taiwan Basin in the South China Sea for the lower heat flow values. From the measured results in the South China Sea, we could conclude that there were not gas hydrates in the site 1143, site 1144, site 1146 and site 1148.