基于叠前地震数据的地层Q值估计

Estimation of stratigraphic quality factors on pre-stack seismic data

与叠后地震资料相比,叠前地震资料包含了更加丰富的地层信息。传统的基于叠后地震资料的地层Q值估算方法因叠加平均效应的影响,Q值估算精度较低、适用性差。为此,本文提出了基于叠前地震资料利用时频谱分解技术估算地层Q值的方法。该方法借助于S变换对叠前地震数据做时频分析,逐道求取频谱比斜率,经炮检距归零处理得到零炮检距处的地层Q值。模型数据和实际资料的应用表明,该方法不仅充分考虑了因地层吸收而引起的振幅、频率等信息的变化,而且避免了常规品质因子计算中的平均效应,使估算的品质因子更加准确,适用性更强。

Compared to post-stack seismic data,pre-stack seismic data have more stratigraphic information.Due to the average effect,the quality factor accuracy obtained by traditional methods on post-stack data is low and their applicability is poor.For this reason,we put forward here a method for quality factor estimation on pre-stack seismic data using spectrum decomposition.First we use S-transform on pre-stack seismic data for time-frequency analysis.Then we obtain the slope of the ratio of frequency spectrum trace by trace.Finally we get the quality factors at zero-offset after offset-return-to-zero process.Model and real data examples show that this method not only considers the change of amplitude and frequency caused by stratigraphic absorption,but also avoid the average effect of the absorption coefficient,so it can improve the accuracy of Q estimation and its applicability.