南海北部陆坡热流与天然气水合物赋藏研究

A STUDY ON GEOTHERMICS AND OCCURRENCE OF GAS HYDRATES IN THE NORTHERN SLOPE OF THE SOUTH CHINA SEA

天然气水合物逐渐成为科学界研究焦点,内容包括能源、温室效应以及灾害预防等课题。我国的南海沉积盆地富含有机质烃源岩,气源条件和海底物理条件有利于水合物的生成,尤其2007年在南海发现了样品实物进一步证明了其广阔前景。通过南海北部陆坡获取的127个地热数据,采用静态模式研究其赋存状况。特征指标为天然气水合物的稳定带厚度,主要受控于地温梯度、相变曲线及气源中重烃的组成比例等参数,同时依据南海北部陆坡3种可能气源组成情况计算稳定带厚度分布,对上述参数变化因素影响气水合物量值关系做出解析及数值解释。计算结果表明地热是重要的天然气水合物控制因素,地热数据是天然气水合物重要的寻矿指标。

The research on gas hydrates focuses potential new energy sources, greenhouse gases effects, and seafloor instabilities. The South China Sea sediment basins containing a lot of hydrocarbon source rock were a possible carbon reservior because of its tectonics and geophysics conditions suitable for the formation of gas hydrates especially with the latest news that gas hydrates samples were acquired there in 2007. This paper presents research showing the occurrence of gas hydrates in the Northern Slope of the South China Sea using the static mode after analyzing 127 thermal data packages. The significant in- dex is the thickness of hydrate stability zone which is controlled by geothermal gradient, phase equilibri- um and ratio of methane contents. The maps of the thickness distribution with three possible combina- tions are displayed. Based on two assumptions, influences on thickness induced by the parameter chan- ges are discussed through numerical analysis. The calculation indicates that geothermics can influence the occurrence of gas hydrates and the geothermal data is one of the most important tools in the gas hy- drates explorations.