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海域天然气水合物多富集于渗透性较好的粗粒砂层中,而中国南海神狐海域细粒沉积层中却发现了高饱和度的天然气水合物,其高丰度的有孔虫壳体是重要影响因素之一.本文通过对南海有孔虫壳体进行分析和水合物生成模拟实验,从微观角度研究了有孔虫对南海水合物富集的贡献.分别以南海纯有孔虫壳体和南海沉积物作为介质进行水合物生长模拟实验,通过微焦点X射线计算机断层扫描(CT)和扫描电子显微镜(SEM)观测了典型有孔虫的孔隙结构,并在线观测了水合物在有孔虫壳体中的生长和赋存特征.研究结果表明,有孔虫壳体的存在显著提升了沉积物的有效孔隙度,水合物优先生长于较大颗粒的有孔虫房室中,并且主要以在有孔虫壳体内壁附着的模式生长,而细砂粒或泥质沉积物中则未见明显的水合物富集.研究成果可为南海水合物成藏机理和储层物性参数研究提供依据.
Most of the gas hydrates in the sea area are enriched in the coarsely-graded sand layers with good permeability. However, gas hydrates with high saturation are found in the fine-grained sediments in Shenhu sea area of the South China Sea. The abundant abundance of foraminifera Body is one of the important influencing factors.In this paper, through the analysis of the foraminifera shell in the South China Sea and the simulation experiment of hydrate formation, the contribution of foraminifera to the enrichment of the South China Sea hydrate was studied from the microscopic point of view, The pore structure of typical foraminifera was observed by micro-focus X-ray computed tomography (CT) and scanning electron microscope (SEM). The hydrate formation in the sediments and the South China Sea sediments were measured. The results show that the presence of foraminifera shell significantly enhances the effective porosity of sediments, and the hydrate preferentially grows in the foraminifera chamber of larger particles, And mainly grows in the mode of attachment on the inner wall of foraminifera shell, while no obvious hydrate accumulation is found in the fine sand or muddy sediments.The research results may be the research on the hydrocarbon accumulation mechanism and reservoir physical property parameters of the South China Sea mention in accordance with.