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复杂近地表条件通常制约着常规地震勘探的成像精度,而虚源法可以通过逆时重构消除近地表的影响,实现前提为检波器放置于复杂近地表之下,其优点是在处理阶段不需要建立复杂的近地表速度模型.本文首先通过逆时原理和扰动理论对虚源法的理论基础进行了研究,通过对虚源法的实现方法进行对比,得出结论:上下行波分离与加时窗结合的实现方法可以有效压制有限震源孔径造成的成像假象.验证了利用边缘道衰减压制互相关道集边界效应的有效性.
Complicated near-surface conditions usually constrain the imaging accuracy of conventional seismic exploration, while the virtual source method can eliminate the influence of near-surface by reverse-time reconstruction, and the precondition is that the detector is placed under complex near-surface. The advantage of this method is that during the processing stage We need to establish a complex near-surface velocity model.In this paper, the theoretical basis of the virtual source method is firstly studied by the inverse time principle and the perturbation theory. By comparing the implementation methods of the virtual source method, we conclude that the separation and addition The time-window combination method can effectively suppress imaging artifacts caused by limited source aperture, and verify the effectiveness of using boundary channel attenuation to suppress the boundary effect of cross-correlation gathers.