Waveform inversion based on adaptive source wavelet extraction and correction for Rayleigh waves
SHAO Guangzhou1, DU Ting1, WU Hua2
1. School of Geological Engineering and Geomatics, Chang'an University, Xi'an, Shaanxi 710054, China; 2. School of Science, Chang'an University, Xi'an, Shaanxi 710064, China
Abstract：Full waveform inversion (FWI) based on Rayleigh waves has made significant advances in recent years. If the receiver coverage is adequate,FWI offers a high resolution in laterally heterogeneous complex media. Source wavelet is one of the key factors affecting the accuracy of waveform inversion. However,the seismic wavelet for field seismic record is unknown,and an improper source wavelet is bound to have a negative effect on inversion results. The conventional solution is extracting and correcting a wavelet with synthesized data. However,wavelet correction is time-consuming because it requires repeated iterations. To solve this problem,this paper proposes a windowed adaptive wavelet extraction method to extract a source wavelet that is in line with the actual situation from the observation records,use it as the initial wavelet for wavelet correction,and thereby achieve the purpose of further optimizing inversion results. Inversion tests on a fault model constructed are conducted with five wavelets,including the actual wavelet,a wrong wavelet,a wrong wavelet combined with wavelet correction,an extracted wavelet,and an extracted wavelet combined with wavelet correction,respectively. The test results show that the wavelet obtained by the proposed method corresponds to the best inversion result,while the wrong wavelet corresponds to the worst one. Although a favorable inversion effect can also be achieved with the extracted wavelet alone,combining wavelet extraction with wavelet correction can save computation time and further improve the accuracy of Rayleigh waveform inversion. More-over,field data application further verifies this conclusion.
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