Reverse time migration has become a standard imaging tool of complex structure such as salt model , strongly steep reflector and nappe structure, for their high precision, adapting to strong velocity variation and being free of reflector angle. The imaging condition requires the source wavefield and receiver wavefield could be obtained simultaneously, which could result in storage shortage and tremendous I/O time when large-scale data is faced. The imaging condition could also arouse low frequency artifacts in wave propagation path. Thus, a RTM scheme is proposed. To the storage and I/O problem, we use source wavefield reconstruction to ensure that the source wavefield and receiver wavefield can be available simultaneously. It means that in the forward modeling of source wavefield, we only need to store the wavefield around the imaging region and that of the last two time slices as boundary condition and initial condition of reconstruction. This strategy could decrease storage and I/O requirements greatly. We also combine up-down, left-right going wavefield decomposition imaging condition with Laplace filter to remove the artifacts of RTM. This method works well in testing. The significance of this scheme is that it could improve the method of removing artifacts in RTM, which could help to deal with the complex geological structure and give a high-quality image, and with the use of source wavefield reconstruction, it can decrease the storage and I/O time of RTM greatly.%逆时偏移以其高精度、适于强变速地质体和不受反射层倾角限制的特点,已经成为处理盐丘、高陡倾角反射层和推覆构造等复杂地质体的标准成像手段.然而,其成像条件需要具有同一时间上的源波场与检波点波场,这在大规模数据上会导致存储的不足与I/O时间过长.这种成像条件也会在波场传播路径上产生假象.鉴于此,提出了一套可以有效解决这些问题的逆时偏移方案.对于存储与L/O问题,用源波场重建技术来使源波场与检波点波场在时间上同步,即在源波场正演过程中,仅需存储成像区域边界的波场和最后两层时间的波场作为源波场重建的边界条件和初始条件,从而大幅度节约存储与I/O.对于假象问题,利用上下左右行波分解成像条件与Laplace滤波技术结合,以达到去除假象的目的.经测试,该方案取得较好的成像效果.其意义在于改进了逆时偏移去假象的方案,使其可以有效地对复杂地质情况进行高质量的成像,并通过源波场重建技术来减少实现逆时偏移所需要的存储与I/O时间.
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