项目名称: 微观孔隙结构对含水合物沉积物渗透率影响规律研究
项目编号: No.41506082
项目类型: 青年科学基金项目
立项/批准年度: 2016
项目学科: 天文学、地球科学
项目作者: 李承峰
作者单位: 青岛海洋地质研究所
项目金额: 20万元
中文摘要: 含水合物沉积物渗透率是水合物开采方案设计与产量预测的基础参数,而微观孔隙结构是影响渗透率大小的一个直接因素。水合物在沉积物孔隙中的生长或分解会明显地改变微观孔隙结构特征,由于缺乏有效的直接观测技术,目前国内外研究多采用理想化的微观孔隙结构来建立渗透率评价模型,与实际情况往往有较大偏差。本项研究拟采用微观模拟实验与模型分析相结合的方法开展含水合物沉积物微观孔隙和渗透率研究。分别在天然海砂和南海海底沉积物体系中进行水合物生长和分解模拟实验,利用高精度X-CT技术实时观测水合物赋存模式和沉积物孔隙微观分布状态,并根据灰度图像反演水合物饱和度;通过三维数字化建模确定微观孔隙结构参数,并结合分形几何理论的渗透率模型计算含水合物沉积物的渗透率;系统分析水合物赋存模式、饱和度对微观孔隙结构参数的影响规律,进而探讨南海沉积物渗透率的微观控制机理,为南海水合物的开采提高有价值的参考。
中文关键词: 天然气水合物;微观孔隙结构;渗透率;X射线计算机断层扫描;南海沉积物
英文摘要: The permeability of gas hydrate bearing sediment is the basic parameter of design and production prediction for gas hydrate exploitation. The micro-pores structure is one of the immediate factors influencing the permeability. Hydrate formation or decomposition will significantly change the microscopic pores structure characteristics. Due to lacking of high resolution of microscopic direct observation technology, most researchers established the permeability parameter models with ideal micro-pores structure, which existed large deviation with the actual situation. In this study, we will research on the permeability of gas hydrate bearing sediment, combining the methods of micro-experiments and model analysis. We will use the natural sea sands and seabed sediment from South China Sea for gas hydrate formation and dissociation. The hydrate and pores microstructure can be directly observed using X-ray computed tomography. The saturation of hydrate will be inversed by the gray images. Secondly, pores structure parameters will be determined by 3D digital modeling and the permeability at different hydrate saturations can be calculated on the base of fractal geometric theory. By revealing the respond characteristics of micro-pores structure on the factors such as hydrate saturation and distribution modes, we seek to explore the micro control mechanism of permeability. These results will provide basic support for South China Sea gas hydrate exploitation.
英文关键词: natural gas hydrate;micro-pores structure;permeability;X-ray computer tomography;South China Sea sediment