一种基于相似系数谱约束的多次波自适应减去方法

多次波压制主要分预测和减去两个环节，提出了一种基于相似系数谱约束的多次波自适应减去方法，可以有效地实现多次波的自适应减去。首先通过Radon谱约束的最小二乘反演来实现局部τ-p变换,以获得更高的分辨率,同时压制随机噪声；在局部τ-p域,利用预测多次波模型的相似系数谱来指示原始记录中多次波存在的位置;根据预测多次波模型相似系数谱的约束设计滤波器,将多次波模型和原始记录中的多次波进行振幅、相位和旅行时匹配,实现多次波的自适应减去。与常规基于L2范数的多次波减去方法相比,当一次波和多次波非正交时,局部τ-p域多次波减去方法可以在减去多次波的同时,更有效地保存一次波。相似系数谱的约束为振幅匹配提供了一种更有效、更稳定的方式,在振幅匹配的同时进行相位和旅行时匹配,可以弱化子波对匹配过程的影响。模型数据和实际地震资料的试验结果证明了这种多次波自适应减去方法的有效性。

Multiple prediction and subtraction are two key steps for multiple suppression in seismic.Multiple adaptive suppression in local τ-p domain based on semblance spectrum can adaptively subtract the multiple successfully.The local τ-p transform is realized in the least-square sense with Radon spectrum constraints,which offers higher resolution than the conventional local τ-p transform,and suppresses the random noise at the same time.Based on the assumption that the traveltime of multiple can be predicted accurately,the semblance spectrum of the multiple model can be utilized to indicate the locations of multiple.With the constraints of semblance spectrum,we can subtract the multiple from the original dataset adaptively.Compared with the conventional methods for multiple subtraction based on L2-norm,the new method in the local τ-p domain can preserve the primary better when the multiple and primary are not orthogonal to each other.The introduction of semblance spectrum,not only provides a more effective and robust way for matching amplitude,but weakens the effects of wavelets during the process of subtraction.The results of numerical tests and actual seismic data prove the effectiveness of the new method.