基于Shearlet系数空间相关性的地震数据去噪研究

    A seismic data denoising method based on the spatial correlation of Shearlet coefficients

    • 摘要: Shearlet变换作为被广泛应用于地震数据随机噪声压制的工具之一, 其传统硬阈值去噪方法在压制噪声时容易过度抑制有效信号, 尤其是弱信号易出现损失; 同时, 该方法也忽略了Shearlet系数在空间分布上的相关性特征。针对上述问题, 提出一种基于Shearlet系数空间相关性的自适应阈值地震噪声压制方法, 该方法在尺度维度构建方向子带间的邻域相关性模型, 在空间维度建立跨尺度的系数映射关系, 通过相关性约束构建具有物理意义的自适应阈值矩阵。理论推导与实验验证表明, 相较于传统硬阈值方法, 本文提出的自适应阈值算法在压制随机噪声过程中可最大程度地保留有效信号, 对弱同相轴信号的振幅保幅性表现出色, 验证了该方法在提升地震数据质量方面的优越性。

       

      Abstract: Shearlet transform serves as a tool extensively applied for random noise attenuation in seismic data. However, it faces critical drawbacks: (1) the over-attenuation tendency of valid signals due to its traditional hard-threshold denoising method, especially the loss of weak signals, and (2) ignoring the spatial correlation of Shearlet coefficients. To address these issues, this paper proposed an adaptive-threshold denoising method for seismic data based on the spatial correlation of shearlet coefficients. Specifically, this method constructed a neighborhood correlation model between directional sub-bands in the scale dimension and established a cross-scale coefficient mapping relationship in the spatial dimension. Based on the correlation constraints, an adaptive threshold matrix with physical significance was derived. Theoretical calculation and experimental validation demonstrate the superiority of the proposed adaptive-threshold algorithm in enhancing the quality of seismic data over traditional hard-threshold methods. Specifically, it retained effective signals to the maximum extent during random noise attenuation and significantly improved the amplitude preservation of weak seismic events.

       

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