Source-independent elastic waveform inversion using a logarithmic wavefield
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
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AbstractThe logarithmic waveform inversion has been widely developed and applied to some synthetic and real data. In most logarithmic waveform inversion algorithms, the subsurface velocities are updated along with the source estimation. To avoid estimating the source wavelet in the logarithmic waveform inversion, we developed a source-independent logarithmic waveform inversion algorithm. In this inversion algorithm, we first normalize the wavefields with the reference wavefield to remove the source wavelet, and then take the logarithm of the normalized wavefields. Based on the properties of the logarithm, we define three types of misfit functions using the following methods: combination of amplitude and phase, amplitude-only, and phase-only. In the inversion, the gradient is computed using the back-propagation formula without directly calculating the Jacobian matrix. We apply our algorithm to noise-free and noise-added synthetic data generated for the modified version of elastic Marmousi2 model, and compare the results with those of the source-estimation logarithmic waveform inversion. For the noise-free data, the source-independent algorithms yield velocity models close to true velocity models. For random-noise data, the source-estimation logarithmic waveform inversion yields better results than the source-independent method, whereas for coherent-noise data, the results are reversed. Numerical results show that the source-independent and source-estimation logarithmic waveform inversion methods have their own merits for random- and coherent-noise data. © 2011.
SponsorsThis work was financially supported by "Development of Technology for CO2 Marine Geological Storage" program of the Ministry of Land, Transport and Maritime Affairs (MLTM), and the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2010-0006155), and the Energy Efficiency & Resources of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No. 2010T100200133). The first author would like to thank Tariq A. Alkhalifah for his helpful review and discussion. The first author would also like to thank the King Abdullah University of Science and Technology for financial assistance in this research. The authors thank Christos Saragiotis for English editing.
JournalJournal of Applied Geophysics