利用速度滤波改善平面波分解与偏移

Using velocity filtering to improve decomposition of plane wave and migration

平面波叠前深度偏移是高效率的深度偏移技术,精确的平面波分解是平面波精确成像的前提。双曲速度滤波方法能有效地去除CMP道集τ-p变换产生的假频与噪声。本文提出了一种利用快速双曲速度滤波技术改善平面波分解与偏移质量的方法:首先对CMP域的τ-p变换进行Mitchell等的快速双曲速度滤波,然后将炮检距平面波拟合成炮域平面波,最后对拟合的平面波进行傅里叶有限差分深度偏移,从而通过改进平面波品质实现提高平面波偏移的精度。实际资料处理结果表明:速度滤波能够有效地滤除倾斜叠加产生的噪声,反射能量显著增强,同相轴更加连续,偏移成像剖面断点更加清晰,断层更加清楚。

Prestack depth migration of plane wave is high effective depth migration technique and precious decomposition of plane wave is precondition of precious imaging of plane wave. Hyperbolic velocity filtering approach can effectively eliminate the alias and noise produced by τ-p transform of CMP gather. The paper presented an approach using fast hyperbolic velocity filtering technique to improve the decomposition of plane wave and quality of migration: firstly, Mitchell fast hyperbolic filtering is carried out for CMP gather after τ-p transform; then,the offset plane wave is fitted into plane wave in shot domain; finally, the Fourier finite-differ-ence depth migration is carried out for fitted plane wave, raising the precision of migration of plane wave by improving the quality of plane wave. Practical data processing showed the velocity filtering can effectively filter the noise produced by dip stack, significantly increase reflection energy and make events more continuous, the fault position more identified on the migrated imaging section.