南海富含有孔虫沉积物中水合物形成及其声学响应机理研究

项目名称： 南海富含有孔虫沉积物中水合物形成及其声学响应机理研究

项目编号： No.41474119

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 天文学、地球科学

项目作者： 胡高伟

作者单位： 青岛海洋地质研究所

项目金额： 90万元

中文摘要： 有孔虫是促进南海神狐海域高饱和度水合物富集的重要因素之一，了解有孔虫对水合物形成的时空分布及其声学响应影响特征，是应用地质、地球物理手段对有孔虫型水合物进行勘探和资源评价的基础。国内外与水合物相关的有孔虫研究多用于指示环境，鲜有从物性角度揭示其对水合物储层物性异常影响的研究工作。本研究拟结合国际先进的高精度X-CT技术和声学与时域反射联合探测技术，采用模拟实验的方法直接观测原始南海沉积物、剔除有孔虫后的沉积物和纯有孔虫中水合物的微观形成过程和声学参数变化情况，结合南海水合物赋存的沉积物地质年代与有孔虫分布的宏观关系，从宏、微观角度探讨有孔虫对南海水合物形成的时空分布影响机理；通过建立水合物饱和度、微观分布和声学特性三者之间的关系，阐明有孔虫对水合物形成的声学响应影响机理，并提出有孔虫型水合物声学模型，为南海水合物的富集规律研究和资源勘探与评价提供理论支撑。

中文关键词： 天然气水合物；有孔虫；南海；微观分布模式；声学特性

英文摘要： Foraminifera has been validated to relate with high-saturation gas hydrate distribution from Shenhu Area, South China Sea (SCS). Understanding the impacts of foraminifera on hydrate formation and its acoustic response on the host sediments are significant for Foraminifera-Type gas hydrate prospecting and subsequent resource evaluation. However, hydrate-related foraminifera research was mainly focused on reconstruction of gas-seepage evironment, the physical property changes by foraminifera were rarely reported. Here, we proposed a combination of the high-resolution X-ray Computed Tomography (X-CT) and the joint acoustical -TDR (Time Domain Reflectometry) technique to reveal micro processes and acoustic parameter changes in the hose sediments during hydrate formation in foraminifera-rich sediments from SCS, foraminifera-free SCS sediments and pure foraminifera in laboratory. Combining the above results with an investigation of the macro relationship between foraminifera and the ages of hydrate host sediment from SCS, the impacts of foraminifera on macro- and micro- timescale and spatial distribution of SCS hydrate accumulation will be discussed. With the experimental data, a relation among hydrate saturation, hydrate microscopic distribution and acoustic properties of the host sediments will also be got, with which we will try to demonstrate the acoustic mechanism of hydrate formation in foraminifera-rich sediments and to propose an effective Foraminifera-Type hydrate-velocity model. These results will provide basic information for studying SCS gas hydrate accumulation mechanism, as well as giving important approaches for hydrate prospecting and resource evaluation in SCS.

英文关键词： Gas hydrate;foraminifera;South China Sea;microscopic distribution model;acoustic property