一种带限稳定的反Q滤波算法

A band-limited and robust inverse Qfiltering algorithm

反Q滤波是波传播的逆过程,可同时消除吸收和频散效应。Gabor域反Q滤波方法是以Gabor变换谱代替向下延拓的波场,在对二维时频谱进行稳定的反Q滤波处理后,再使用Gabor逆变换重建时间域地震道。相对于反Q滤波方法的分层实现,该算法可应用更精确的连续Q模型,且不需对二维振幅补偿算子进行近似,其计算效率更高,反Q滤波结果更准确。为了改善补偿效果且不放大环境噪声,在Gabor域反Q滤波过程中联合应用时变带通滤波器,该带通滤波器的高截频从某一时间处随旅行时沿双曲线轨迹变化,以适应衰减介质中信号带宽随旅行时的变化。理论数据测试和实际资料应用的结果均表明,联合时变带通滤波器的反Q滤波算法对含噪地震数据是稳健的,可在保持信噪比的同时提高地震资料的分辨率。

Inverse Qfiltering in Gabor domain makes use of Gabor spectrum instead of the downward wavefield.It performs stabilized inverse Qfiltering in 2-D time-frequency spectrum,and reconstructs seismic traces in the time-domain.Compared with the layered implementation of inverse Qfiltering,this algorithm may use a more accurate earth Q model without 2Damplitude compensation operator approximation.So its efficiency and accuracy are much higher.In order to improve the compensation effect without boosting the ambient noise,we perform inverse Qfiltering in Gabor domain by incorporating a time-variant passband filter.The high-cut frequency of this passband filter follows a hyperbolic trajectory of a seismic signal travel time at a specified point as the signal bandwidth varies in media due to the attenuation.Test results on theoretical and real data demonstrate that the inverse Qfiltering algorithm incorporating a time-va-riant passband filter is robust and effective for seismic noisy data,and improves seismic resolution with no S/N degradation.