Seismic exploration is a remote-sensing tool applied in a great many projects for engineering and resource-exploration purposes. Random noise suppression is one of the key steps in seismic-signal processing, especially those with important details and features. The threshold-shrinkage method based on Shearlet transform has been effectively applied in seismic-signal denoising. However, the method usually introduces the boundary effect, which influences the imaging quality. The denoising method of total generalized variation (TGV) is easy to produce 'oil painting' effect, but it can effectively suppress the boundary effect. This paper proposes a denoising method based on Shearlet threshold-shrinkage and TGV for making full use of their characteristics, which can recover both edges and fine details much better than the existing regularization methods. First, we use the Shearlet threshold-shrinkage result as the input of TGV to obtain the primary denoising result and the residual profile. Second, we use the interactive iteration of Shearlet threshold-shrinkage and TGV to extract the signals efficiently from the residual profile and perform the effective signals stack continuously. During the processing, the adaptive-weight factor is combined for estimating the optimal denoising result. Last, the final estimated denoising result is obtained when the stopping criterion is met or the maximum number of iterations is reached. The synthetic and field results show that the proposed method can effectively suppress random noise. In addition, it can also remove the boundary effect and 'oil painting' effect, which further improves the signal-to-noise ratio (SNR).
Theoretical and simulation studies are carried out to study the propagation characteristics of Scholte waves in non-horizontal underwater interface of shallow sea. The dispersion and polarization characteristics of Scholte waves in horizontal layered underwater interface are analyzed by using wave theory and staggered grid finite difference method. The effectiveness of the method used in this paper is proved from the perspective of theory and simulation. The propagation characteristics and polarization characteristics of Scholte waves in non-horizontal underwater interface are also analyzed. At the wedge-shaped underwater interface, the particle trajectory of Scholte wave is related to the angle between the propagation direction and the underwater interface, and with the increase of the angle, the deflection angle of the particle trajectory increases. At the bulged underwater interface, the particle trajectory of seismic wave has nothing to do with the propagation direction and the bulged underwater interface, but the bulged underwater interface has a great influence on the amplitude of seismic wave. The research results are of great significance to underwater target detection and geological exploration.
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