基于变分模态分解和曲波变换的海洋地震随机噪声衰减应用研究

    Application of marine seismic random noise attenuation based on variational mode decomposition and curvelet transform

    • 摘要: 曲波变换可以实现地震记录中常见曲线的稀疏表达,根据频率域内有效信号和噪声系数稀疏性特征,通过能量阈值筛选实现对地震资料中噪声的衰减,但由于实际地震数据波场复杂,噪声能量分布满足非高斯随机噪声的鲁棒性不足,仅凭该方法进行去噪很难达到理想效果。本文基于变分模态分解算法(VMD)对信号多尺度的分解特性,结合曲波变换稀疏性特征,提出一种适用于地震随机噪声压制的联合方法。首先通过VMD算法对地震信号进行多尺度分解,获得1组具有更好稀疏性的固有模态函数(IMF),信噪比分析筛选出含有随机噪声的噪音模态;随后利用频率域曲波变换对噪声的良好识别性,对提取的含噪IMF剖面进行自适应阈值处理;最后利用处理后的IMF分量和有效IMF分量重构信号得到去噪后的剖面。本文从模型地震数据和实际地震数据出发,通过对比传统的曲波变换去噪结果,验证了联合方法对地震随机噪声的衰减有更佳的压制效果。

       

      Abstract: Curvelet transform can achieve sparse representation of common curves in seismic records. Based on the characteristics of the sparsity of effective signals and noise coefficients in the frequency domain, noise attenuation in seismic data can be realized through energy threshold screening. However, due to the complex wave field of actual seismic data and the insufficient robustness of non-Gaussian random noise in terms of noise energy distribution, it is difficult to achieve an ideal denoising effect merely by this method. Based on the characteristics of multi-scale decomposition of signals of the variational mode decomposition (VMD) algorithm, combined with those of the sparsity in the curvelet transform, we proposed a joint method suitable for suppressing random noise in seismic data. First, the seismic signal is decomposed on multiple scales by the VMD algorithm to obtain a set of intrinsic mode functions (IMF) with better sparsity, and the noise-dominant IMF containing random noise are screened out through signal-to-noise ratio analysis. Then, taking advantages of the good recognition of noise by curvelet transform in frequency domain, the extracted noisy IMF profile is processed via adaptive thresholding. Finally, the denoised profile is obtained by reconstructing the signal with the processed IMF components and the effective IMF components. By comparing the denoising results of the proposed joint method with those of the traditional curvelet transform on both synthetic and real seismic data, it is demonstrated that our method can achieve a superior suppression on seismic random noise.

       

    /

    返回文章
    返回