GAS HYDRATE SATURATION AND ITS RELATION WITH GRAIN SIZE OF THE HYDRATE-BEARING SEDIMENTS IN THE SHENHU AREA OF NORTHERN SOUTH CHINA SEA
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摘要: 为探讨沉积物粒度与水合物饱和度的关系,对南海神狐海域水合物钻探区2个获取水合物的钻孔岩心沉积物进行了粒度分析及粒度与水合物饱和度对比分析。结果表明,含水合物沉积物具有粉砂含量72%~82%、黏土含量小于30%、砂含量一般小于10%的基本特征,其中粉砂中以8~32和32~63 μm粒级的中细-粗粉砂占优势;该特征与上下不含水合物层位粒度特征没有明显的差异;含水合物层砂、粗粉砂含量高的层位与水合物饱和度高的层位呈良好的对应关系,粗粒沉积物更有利于孔隙的发育和水合物的形成。Abstract: Grain sizes are analyzed for the sediments taken from two drill holes in the Shenhu area of northern South China Sea in order to understand the relationship between the saturations of gas hydrates and the grain-size of the sediments. Results suggest that the silt fraction is the dominant component of gas-hydrate-bearing sediments in the studied area, making up about 72%~82% of the sedimentary grains. The second component is clay, which is usually less than 30%; whereas the sand fraction is less than 10%. The Grain size distribution pattern of the gas-hydrate-bearing sediments is similar to the non-gas-hydrate-bearing sediments above and below. Coarse silt(0.063~0.032 mm) and sand(0.063~0.5 mm) are usually high in gas hydrates saturations, further suggesting that coarse sediments are more favorable for the formation of gas hydrates.
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