Time-domain adaptive focused beam migration for viscous and VTI media
GAO Xue1,2, HUANG Jianping1,2, LI Zhenchun1,2, LYU Qingda3, LI Shengya1,2, WANG Zhaozhong4
1. School of Geosciences, China University of Petroleum(East China), Qingdao, Shandong 266580, China; 2. Pilot National Laboratory for Marine Science and Technology(Qingdao), Qingdao, Shandong 266580, China; 3. SINOPEC Geophysical Research Institute, Nanjing, Jiangsu 211103, China; 4. Institute of Geology and Mineral Resourcess Shandong Province, Jinan, Shandong 250014, China
Abstract:The adaptive focused beam operator relies on the dynamic initial beam parameters and focuses adaptively based on the velocity drive in the process of ray tracing. The operator has great fle-xibility, which is suitable for the region with drastic changes in velocity. Therefore, the idea of adaptive focused beam migration was extended to viscous and VTI media. By modifying the beam ray tracing equation and correcting the travel time information, we derived the viscous Green's function represented by adaptive focused beams and proposed a new beam migration method suitable for both viscous and VTI media. Beam migration in the frequency domain follows the single-trace input mode of Kirchhoff migration, with low efficiency. This paper introduced Fourier transform and Hilbert transform to reduce the migration integral dimension and changed the calculation in the frequency domain to that in the time domain, realizing the fast time-domain adaptive focused beam migration for viscous and VTI media. Comparing the processing results of viscous VTI sag model, viscous VTI SEG/Hess model and actual data based on the procedural method, we find that 1) when the viscosity and anisotropy cannot be ignored, this method can concurrently deal with the influence of both of them, thereby improving the image quality significantly; 2) compared with the frequency-domain adaptive focused beam migration, the proposed method has higher computational efficiency while ensuring the imaging accuracy; 3) the new method can improve the results of actual data processing.
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