基于改进广义S变换二次时频谱反褶积在南海工区的应用

The application of quadratic time spectral deconvolution based on improved generalized S transform in south China sea area

传统的时频域反褶积模型虽然吻合地震子波在粘弹性介质传播过程中的衰减特征,但受拟合函数和时频分析窗函数的影响,使得其算法缺乏稳定性和准确性。为了避免这一问题,推导出一种基于改进广义S变换二次时频谱反褶积方法。利用改进广义S变换的灵活性来获取非平稳地震记录时频谱,再对其傅里叶变换得到二次时频谱,从而以一种低通滤波的方式提取子波时频谱,实现二次时频谱反褶积。经理论模型论证和实际数据处理结果表明,利用二次时频谱提取子波具有较高的准确性,同时能够有效地分辨薄层,在不用考虑Q值的条件下直接恢复地震波被地层吸收所引起的衰减。

Although the traditional time-frequency domain deconvolution model is consistent with the attenuation characteristics of the seismic wavelet in the viscoelastic medium propagation process,the influence of the fitting function and the time-frequency analysis window function makes the algorithm lack stability and accuracy.In order to avoid this problem,a quadratic time-frequency deconvolution method based on improved generalized S-transform is proposed.Utilize the flexibility of improving generalized S transform to obtain the time-frequency spectrum of non-stationary seismic records,and then the fourier transform to obtain the quadratic time-frequency spectrum and the wavelet time-frequency spectrum is extracted by a low-pass filter,so as to realize quadratic time-frequency spectrum deconvolution.Theoretical model and practical data processing results show that using the quadratic time-frequency spectrum to extract the wavelet has high accuracy,which can effectively distinguish the thin layer and directly restore the attenuation caused by the absorption of stratigraphy without considering the value of Q.