AVF反演Q值方法研究

The study of AVF inversion for Q value extraction

品质因子Q的准确估计是叠前、叠后地震数据处理及AVO分析的关键环节.理论分析和正演模拟表明界面处单纯Q值的变化也会引起反射,该反射系数随频率变化而变化(Amplitude Versus Frequency,AVF).利用其线性近似公式,通过AVF反演可以准确地获得品质因子Q.AVF反演方法为Q值的求取提供了新的思路,与传统Q值求取方法不同,该方法主要考虑衰减对反射系数的影响,通过反射系数获得目的层的Q值.将上覆层为弹性介质的假设扩展到非弹性介质,构建新的近似公式,该近似公式应用更具普遍性与适应性,并利用时频分析方法获得多层模型介质的Q值;测试结果显示AVF反演的Q值准确、稳定.

The accurate estimation of the quality factor Q is the key of pre-stack,post-stack seismic data processing and the AVO analysis. Theoretical analysis and forward modeling indicate that the only difference of Q value in the interface can cause reflection which changes with frequency.Based on the linear approximation formula,we can accurately obtain the quality factor Q by AVF inversion.AVF inversion provides a new idea about Q extraction. Unlike the traditional Q extraction which mainly considers the attenuation effect on the propagation wavelet, AVF inversion mainly considers the attenuation effect on the reflection coefficient,and gets the Q value of target by it.This method assumes the overlying layer elastic medium extending to non-elastic media and builds a new approximate formula.This new formula applies more universal and adaptable;besides that we get the Q value of multi-layers using the time-frequency analysis method. AVF inversion model tests show that the extraction of Q value is accurate and stable.