中尺度涡影响下目的层地震成像的畸变与影响因素分析

将PE方法与地震数值模拟方法相结合研究了中尺度涡影响下目标地层成像的畸变.模拟了不同声源频率、不同水深条件下的地震波场.计算结果发现,中尺度涡的存在使得真实地形结构无法在地震成像中反映,而且地震成像畸变随着海水深度、震源频率的增加而增大.机理分析表明,中尺度涡所带来的水体温度梯度变化是产生地震成像畸变的主要因素.为了便于工程应用,本文还推导了有效涡强度、温度差与地形畸变率的关系式.本文的研究结果将对提高深海地震成像精度有一定的指导意义.

The distortion of seismic imaging in the presence of mesoscale eddies and analysis of influencing factors

Combined with seismic simulation methods, the parabolic equation method is used to investigate the distortion of seismic imaging of the target stratum caused by mesoscale eddies. Seismic wave fields for different frequencies and water depth are simulated. It is found that the seismic imaging of the target stratum, due to the perturbation of eddies, does not agree with the original stratum and the distortions increase with the water depth and the frequency. Analyzing the mechanism of distortions, we have concluded that the perturbation of temperature gradient caused by eddies is one of the most important reasons. For the sake of ingineering application, we deduce a relationship among the maximum distorted rate of seismic imaging, the temperature difference and the effective intensity of eddies. The results of this paper could be used to improve the quality of seismic imaging in deep sea.