A 3D full waveform inversion method based on reconstructed source wavelet with wave equation
(2.Research Institute of Geophysics, Shengli Oilfield Branch Co., SINOPEC, Dongying, Shandong, China 257022)
【Abstract】We propose in this paper a 3D full waveform inversion method based on reconstructed source wavelet with wave equation. We resolve the wave equation with the direct waves at near offsets of prestack shot gathers as boundary conditions and take the time series at the source point as source wavelet. This method uses the principle of source wavefield reconstruction to simulate the inverse process of the wave propagation along the surface, and extracts direct waves at near offsets, which avoids the interference from the waves such as refraction wave, reflection wave and diving wave. So the method has less dependence on the initial model. For tests, we select the 3D SEG/EAGE overthrust model and field data to analyze the phase difference of 3D seismic wavelet based on the source wavefield reconstruction theory of wave equation. The test results show that there is only phase difference between the reconstructed wavelet and the input wavelet. After the phase adjustment, the reconstructed wavelet is used for the 3D full waveform inversion; the inversion velocity is close to the real one. The results are more reliable at channels. The waveform and phase between the observed records and simulated records have also good correspondence, which validates the feasibility and applicability of the proposed method.
【Keywords】 seismic wavelet; full waveform inversion; source wavefield reconstruction; wave equation; SEG/EAGE overthrust model;
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