In elastic-wave reverse-time migration(ERTM),the reverse-time reconstruction of source wavefield takes advantage of the computing power of GPU,avoids its disadvantages in disk-access efficiency and reading and writing of temporary files,and real-izes the synchronous extrapolation of source and receiver wavefields.Among the existing source wavefield reverse-time reconstruc-tion algorithms,the random boundary algorithm has been widely used in three-dimensional(3D)ERTM because it requires the least storage of temporary files and low-frequency disk access during reverse-time migration.However,the existing random boundary algorithm cannot completely destroy the coherence of the artificial boundary reflected wavefield.This random boundary reflected wavefield with a strong coherence would be enhanced in the cross-correlation image processing of reverse-time migration,resulting in noise and fictitious image in the migration results,which will reduce the signal-to-noise ratio and resolution of the migration sec-tion near the boundary.To overcome the above issues,we present an ERTM random boundary-noise suppression method based on generative adversarial networks.First,we use the Resnet network to construct the generator of CycleGAN,and the discriminator is constructed by using the PatchGAN network.Then,we use the gradient descent methods to train the network.We fix some parame-ters,update the other parameters,and iterate,alternate,and continuously optimize the generator and discriminator to achieve the Nash equilibrium state and obtain the best network structure.Finally,we apply this network to the process of reverse-time migration.The snapshot of noisy wavefield is regarded as a 2D matrix data picture,which is used for training,testing,noise suppression,and imaging.This method can identify the reflected signal in the wavefield,suppress the noise generated by the random boundary,and achieve denoising.Numerical examples show that the proposed method can significantly improve the imaging quality of ERTM.

Key Laboratory of the Ministry of Education for Seafloor Science and Detection Technology,Ocean University of China,Qingdao 266100,China;Functional Laboratory of Marine Mineral Resources Evaluation and Exploration Technology,Qingdao National Laboratory of Marine Science and Technology,Qingdao 266100,China

[1]XU Guohao;HE Bingshou-.Elastic-Wave Reverse Time Migration Random Boundary-Noise Suppression Based on CycleGAN)[J].中国海洋大学学报（自然科学英文版）,2022(04):849-860

ERTM,wavefields,iterate

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