密度波形反演的滤波特性分析与全波数模型构建OA

Based on the born weak scattering approximation,the essence of full waveform inversion is a process to construct the full wavenumber spectrum of the perturbation model.The low-medium-high wavenumber(as we known as tomography+migration)reconstruction successful is the key to the full waveform inversion.Density inversion is a big challenge for full waveform inversion,the high coupling of density and velocity make a big problem to density inversion that has not be solved well.However,density inversion has another major problem:under the velocity-density parameterization,the density inversion results has the migration effect,and the low wavenumber information in the model cannot be constructed.In this paper,under the condition of ignoring the coupling of velocity-density parameterization,we focus on solving the migration characteristics.Firstly,the chain-rules is used to derive the sensitive kernel functions under the velocity-density parameterization mode,and with the far-field plane wave approximation,the relationship between amplitude,wavenumber and scattering angle in the new velocity-density gradient is derived to explain the migration effect of density inversion.Then the new density gradient with Laplace filtering form is derived,and we establish a new objective function based on integration for the density.So that a new density gradient is derived to suppress the filtering effect and implement a full wavenumber model inversion by releasing the low wavenumber information.Finally,the contribution of the new and old method to tomography+migration parts in density gradient is analyzed by the two-layer model.The accuracy and effectiveness of the density full-wavenumber residual model spectrum reconstruction is verified by the Marmousi model with density single-parameter and velocity-density two-parameter simultaneous inversion test.