二氧化碳地质封存工程防灾监测中瑞雷波敏感性初步分析

瑞雷波勘察技术常用于地震场地土评价,且长波微动观测可以获得深部地层的信息,但其在CO2地质封存工程防灾监测中应用的可行性探讨还未见深入研究报道。基于一典型CO2封存场地地层模型,通过数值模拟的方式,分析了瑞雷波波速对储层弹性参数改变的敏感性。模拟分析表明,CO2储层弹性参数变化对瑞雷波波速的影响随频厚积变化而变化;研究发现CO2储层横波波速改变相对于层厚、纵波或密度的改变对面波波速影响较大;研究还发现当CO2储层薄且埋深大时,面波频散特性对储层弹性参数改变不敏感。研究初步认为,当前常规的瑞雷波勘察技术用于深部CO2封存工程防灾监测具有一定的技术难度。

Sensitivity study of the Rayleigh wave velocity for CO2 geological storage monitoring

The surface wave analysis method has been widely used for earthquake microzoning surveys and long wave microtremors have been confirmed to contain deep underground geological information.Feasibility discussions about using the surface wave analysis for CO2 geological storage monitoring are restrictive in literatures.A numerical study was implemented in this paper to investigate the sensitivity of the Rayleigh wave velocity to the elastic parameter changes of the CO2 storage layer in a typical reservoir.It is observed that the influence of parameter variations on the Rayleigh wave velocity is associated with the frequency thickness products.The study results also indicate that the Rayleigh wave velocity is more sensitive to the change of the shear wave velocity than those of the thickness,the compression wave velocity and the density of the CO2 storage layer.The variation of the Rayleigh wave velocity is difficult to be detected by using the typical surface wave engineering survey strategy if a thin CO2 storage layer is located deeply underground within a geological reservoir.