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逆时偏移是基于双程波动理论,没有倾角和横向变速限制,能够解决复杂地质构造成像问题.在逆时偏移成像实现过程中,需要对源波场进行正推和对接收波场进行逆推,由于这两个波场外推方向不一致,需要对其中一个波场(源波场或接收波场)进行存储,这部分存储量很大,是制约逆时偏移成像应用的瓶颈.本文探讨了一种有效的边界存储方法,即先让源波场正推到最大记录时间,在研究区域边界存储所有时刻波场记录,同时记录最大时刻该区域全波场.然后将边界存储波场和最大时刻全波场分别作为边界条件和初始条件,进行波场逆推来重构源波场,这样就解决了源波场与接收波场外推方向不一致的问题,从而可以克服逆时偏移成像存储瓶颈,并将该方法应用到逆时偏移成像.通过简单层状模型和复杂逆掩断层模型试验,并和直接存储方法进行了对比,证明了该方法的有效性.
The inverse time migration is based on the two-way wave theory, and there is no inclination and lateral speed change limitation to solve the problem of complex geological structure imaging. In the process of inverse time migration imaging, the source wavefield needs to be normalized and the received wavefield Backward, due to the extrapolation directions of these two wavefields, one of the wavefields (source wavefield or receiving wavefield) needs to be stored. This part of storage is very large, which is the bottleneck restricting inverse time migration imaging applications. In this paper, an effective method of boundary storage is discussed, that is, the source wavefield is first pushed to the maximum recording time, and the wavefield records of all the time are stored at the boundary of the study area and the full wave field of the region at the maximum moment is recorded. Field and the maximum moment of the full-wave field as the boundary conditions and initial conditions, respectively, to reverse the wave field to reconstruct the source wave field, thus solving the source wave field and receiving wave field is not consistent with the direction of extrapolation, which can overcome the inverse time Migration imaging storage bottleneck, and apply the method to inverse time migration imaging.Through simple layered model and complex inverse fault model test, and compared with the direct storage method, the method is proved to be effective Sex.