时变地震子波提取研究方法综述

受地下介质非均匀性、非完全弹性等因素影响,实际地震资料中的地震子波具有时变特征,即子波在传播过程中是不断变化的。传统的地震子波提取方法大多基于时不变的假设,往往不能满足勘探所需的精度要求,如何从非平稳地震记录中准确提取时变子波成为近年的研究热点之一。概括总结了时变子波提取方法的研究进展,认为对非平稳地震记录进行衰减补偿和分段处理以及分别估计子波振幅谱和相位谱后再进行匹配融合是实现时变子波提取的两类主要方法。进一步的分析发现衰减补偿和分段处理难以真实反映地震记录的非平稳性,而子波振幅谱和相位谱的估计精度仍需提高。因此,下一步的研究方向应充分考虑地下复杂衰减和噪声干扰的影响,采用先进的智能信息处理技术,研发适用范围更广、准确度更高的时变子波提取方法,并应用于叠前全波形反演与深层复杂构造的成像,从而有效提高地震资料的处理精度。

A review on time-varying seismic wavelet extraction

Because of the heterogeneity and viscoelasticity of the underground medium,the high frequency component of seismic wavelets attenuates during propagation,generating temporal variation in the seismic wavelets.Traditional seismic wavelet extraction methods are mostly based on the time-invariant assumption,which decreases the accuracy of exploration.Therefore,extracting time-varying wavelets from non-stationary seismic records has become a research hotspot in recent years.In this review,mainstream methods are summarized into two types:in the first one,the attenuation of the seismogram is compensated,then the seismogram is decomposed into several segments;in the second one,time-varying seismic wavelets are extracted by estimating their amplitude and phase spectra from the non-stationary seismogram.Further analysis showed that models of the first type can hardly truly reflect the non-stationarity of actual seismic records,while those of the second type still need improvement in terms of extraction accuracy of wavelet amplitude and phase spectra.Therefore,considering the influence of complex attenuation effects and noise interference,advanced techniques of intelligent information processing are introduced in this work,so as to develop novel time-varying wavelet extraction methods that would offer a wider application range and higher accuracy.These methods could be applied in pre-stack full waveform inversion and migration imaging,thereby effectively improving the processing and interpretation accuracy of seismic data.