流体渗透扩散对三峡库区浅层介质物性及地震活动影响研究

Fluid infiltration and diffusion in shallow crust and its influences on seismic activity are the unresolved difficulties in induced earthquake field. Cyclic water loading and unloading, and frequent seismic activities in Three Gorges area provide a good opportunity for furthering the knowledge of the problem. Based on it, we will conduct the studies from the following aspects. Firstly, we will make full use of complete seismic monitoring data before and after water impoundment to do 3D seismic velocity and attenuation structure tomography in Three Gorges area. Thereby, the influences of fluid on the physical properties of shallow crustal media can be retrieved. Then, we will take earthquake-prone active Fairy mount fault with direct hydralic connection with reservoir as an example to understand the mechanism of fluid affecting shallow crustal media. To achieve this goal, fault internal structure and permeability structure of the given Fairy mount fault should be built with compound means, including mineralogical, chemical analysis and so on. Thirdly, we will carry out numerical simulation with the above results to learn the fluid infiltration and diffusion under the different water levels. To better analyze the relationship between the cyclic water loading and unloading with seismic activity, Felicity effects in acoustic emission theory will be adopted. Finally, a regular model related water loading and infiltration with seismic activity can be established, which is good for deepening our knowledge of effects of fluid infiltration and diffusion on shallow crust media, and can provide help to earthquake trend analysis in Three Gorges area. In addition, the research can offer reference to geological fields, such as nuclear waste storage, underground oil and gas exploration drilling, etc, as well.

流体在地下介质中的渗透扩散及其对地震活动的影响机制一直是诱发地震研究未解决的难题，而三峡水库周期性蓄排水及库区频发的地震活动为认识该难题提供了契机。基于此，本申请拟开展以下几方面工作：1）充分利用三峡水库蓄水前后地震资料完备的优势，分时段进行库区三维地震波速度和衰减结构成像，获取流体对库区浅层介质物性的影响；2）选取库区地震频发且与库水有直接水力联系的仙女山断裂，首次融合多手段构建该断裂带渗透结构模型，研究流体对介质物性影响的机制；3）基于流体对库区介质影响及特定断层与流体的关系，进行不同库水位条件下流体渗透扩散数值模拟；4）采用声发射理论的Felicity效应分析库水周期性加卸载与地震活动的关系，最终建立三峡水库库水荷载渗透与地震活动规律模型，为深化流体对浅层介质及地震活动影响的认识及三峡后续地震趋势分析提供帮助，同时也为地学其它领域(如核废液地下贮藏、石油\天然气勘探开采等)提供参考。

流体在地下介质中的渗透扩散及其对地震活动的影响机制一直是诱发地震研究未解决的难题，而三峡水库周期性蓄排水及库区频发的地震活动为认识该难题提供了契机。基于此，本申请拟开展以下几方面工作：1）充分利用三峡水库蓄水前后地震资料完备的优势，分时段进行库区三维地震波速度和衰减结构成像，获取流体对库区浅层介质物性的影响；2）选取库区地震频发且与库水有直接水力联系的仙女山断裂，首次融合多手段构建该断裂带渗透结构模型，研究流体对介质物性影响的机制；3）基于流体对库区介质影响及特定断层与流体的关系，进行不同库水位条件下流体渗透扩散数值模拟；4）采用声发射理论的Felicity效应分析库水周期性加卸载与地震活动的关系，最终建立三峡水库库水荷载渗透与地震活动规律模型，为深化流体对浅层介质及地震活动影响的认识及三峡后续地震趋势分析提供帮助，同时也为地学其它领域(如核废液地下贮藏、石油\天然气勘探开采等)提供参考。