海底甲烷渗漏区孔隙水及矿物组分变化数值模拟

发布时间：2018-11-08 16:23

【摘要】：海底甲烷的渗漏(通常是底部天然气水合物的分解引起的)往往会伴随着浅表层沉积物中一系列的地球化学变化。文章以南海九龙甲烷礁地区为研究区,建立了一维垂直柱状模型,利用数值模拟方法定量分析甲烷渗漏背景下海底沉积层中孔隙水及矿物组分的变化。结果表明:HCO3-和HS-浓度在垂向上随深度的增加先增大后减小,在SMI(sulfate-methane interface)处浓度达到最大值;SMI的深度会随着底部甲烷泄露通量的增大而变浅;SMI界面处AOM-SR(Anaerobic oxidation of methane coupled to sulphate reduction)反应最为强烈,在界面附近生成了方解石和黄铁矿等自生矿物。该研究结果对于研究天然气水合物相关自生矿物的形成特征、海底地球化学异常探测与水合物勘探等具有重要的理论意义。
[Abstract]:Undersea methane leakage (usually caused by the decomposition of natural gas hydrate at the bottom) is often accompanied by a series of geochemical changes in shallow surface sediments. Taking the Jiulong methane reef area in South China Sea as the study area, a one-dimensional vertical columnar model is established, and the variation of pore water and mineral components in the seabed sediments under the background of methane leakage is quantitatively analyzed by numerical simulation. The results show that the concentrations of HCO3- and HS- increase first and then decrease with the increase of depth, and reach the maximum at SMI (sulfate-methane interface), and the depth of SMI becomes shallower with the increase of methane flux at the bottom. The AOM-SR (Anaerobic oxidation of methane coupled to sulphate reduction) reaction at the SMI interface is the strongest, and the authigenic minerals such as calcite and pyrite are formed near the interface. The results are of great theoretical significance for the study of the formation characteristics of natural gas hydrate related autogenic minerals, the exploration of submarine geochemical anomalies and the exploration of gas hydrate.
【作者单位】：吉林大学地下水资源与环境教育部重点实验室;
【基金】：中国博士后科学基金(2012M520673) 国家海洋地质专项工作项目(GZH201100306) 吉林大学研究生创新基金资助项目(2014104)
【分类号】：P744.4

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