Diffraction separation by variational mode decomposition

Abstract

Diffracted wavefields with superior illumination encode key geologic information about small‐scale geologic discontinuities or inhomogeneities in the subsurface and thus possess great potential for high‐resolution imaging. However, the weak diffracted wavefield is easily masked by the dominant reflected data. Diffraction separation from specular reflected data still plays an important role and plays a major role in diffraction imaging implementation. To solve this problem, a new diffraction‐separation method is proposed that uses variational mode decomposition to suppress reflected data and separate diffracted wavefields in the common‐offset or poststack domains. The variational mode decomposition algorithm targets reflected wavefield by decomposing seismic data into an ensemble of band‐limited intrinsic mode functions representing linear and strong reflected data. This method is based on the principle of energy sparsity and can utilize the kinematic and dynamic differences between reflected and diffracted wavefields to effectively predict linear reflected data. Synthetic and field data examples using complex body geometries demonstrate the effectiveness and performance of the proposed method in enhancing diffracted wavefield and attenuating reflected data as well as increasing the signal‐to‐noise ratio, which helps to clearly image small‐scale subwavelength geologic structures.

Research on Bi–ISAR Sparse Aperture High Resolution Imaging Algorithm under Low SNR

“…Among the IMFs obtained from signal decomposition, some IMFs mainly consist of effective signals, called signal components, and some IMFs mainly consist of noise, called noise components. In this paper, the separation of these two components is achieved by the energy criterion [34,35].…”

Diffraction separation and imaging using ensemble empirical mode decomposition and multichannel singular spectrum analysis

“…Thus, the diffracted wavefield, which represents an obvious response to small‐scale discontinuities, carries critical geological information about these structures (Landa, 2012). As the diffracted wavefield follows Huygens' principle and radiate uniformly (Lin et al., 2021), it can be utilized for their high‐resolution imaging (Khaidukov et al., 2004; Zhao et al., 2019). However, weak diffracted wavefield is difficult to identify in seismic wavefields because it is typically masked by the dominant high‐amplitude reflection (Harlan et al., 1984; Klem‐Musatov, 1994; Klokov et al., 2010).…”