Datadomain wave equation reflection traveltime to

Authors: Bo Feng Huazhong Wang

Publish Date: 2015/07/25

Volume: 26, Issue: 4, Pages: 487-494

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Abstract

Estimation of an accurate macro velocity model plays an important role in seismic imaging and model parameter inversion Full waveform inversion FWI is the classical datadomain inversion method However the misfit function of FWI is highly nonlinear and the local optimization cannot prevent convergence of the misfit function toward local minima To converge to the global minimum FWI needs a good initial model or reliable low frequency component and long offset data In this article we present a waveequationbased reflection traveltime tomography WERTT method which can provide a good background model initial model for FWI and leastsquare prestack depth migration LSPSDM First the velocity model is decomposed into a lowwavenumber component background velocity and a highwavenumber component reflectivity Second the primary reflection wave is predicted by waveequation demigration and the reflection traveltime is calculated by an automatic picking method Finally the misfit function of the l2norm of the reflection traveltime residuals is minimized by a gradientbased method Numerical tests show that the proposed method can invert a good background model which can be used as an initial model for LSPSDM or FWI

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