起伏地表最小二乘傅里叶有限差分偏移方法及应用

The theory and application of least-squares Fourier finite-difference migration from topography

随着我国西部勘探开发的深入,起伏地表情形下的保幅成像逐渐成为研究热点。在线性Born近似的基础上,推导了最小二乘偏移基本公式,利用傅里叶有限差分传播算子设计了对应的偏移算子和反偏移算子,结合"逐步延拓-累加"的波场传播模式,给出了起伏地表最小二乘傅里叶有限差分偏移方法。利用加拿大逆掩断层模型对方法进行了测试,结果表明,该方法能够较好地实现地下构造成像,明显改善中深部成像的保幅性和振幅横向均衡性。将该方法应用于陆上某探区实际资料的偏移成像试处理,结果较常规偏移方法在成像精度和中深层保幅性等方面都有一定程度的改善,说明该方法对起伏地表陆上资料具有一定的实用性。

As the development of the seismic exploration in Western China,the preserved-amplitude migration methods from topography have become more and more popular.Due to the difficulty for the preserved-amplitude migration from topography,we propose a new least-squares Fourier finite-difference migration method by deducing the migration and demigration operators based on Born modeling approximation as well as the＂accumulating wavefields step by step＂strategy to continue the wavefield.After implementing the program,the migration results on the synthetic Canadian overthrust fault model suggest that the new method is good enough to recover the theoretic input reflectivity model,especially the obvious preservedamplitude improvement at the deeper layer of the model as well as a better amplitude balance along the horizontal event.The migration results on the field data show that our method has a good flexibility on the field land data and from topography.