Evanescent wave suppression in full-wave-equation wavefield depth extrapolation
Evanescent wave suppression presents a special challenge to full-wave-equation wavefield depth-extrapolation and related depth migration methods.This is because,in contrast to classic one-way depth migration,more challenges in both imaging quality and computational cost are involved in full-wave-equation wavefield depth migration.To address this challenge,we propose two new methods for evanescent wave suppression.Method I is an extension of the classic one-way frequency-wavenumber domain method,named generalized low-pass filter;Method Ⅱ is the energy norm method by using the energy conservation law to identify and eliminate energy explosion of evanescent waves.Impulse responses in a gradient velocity prove that our proposed two methods are stable and enable to achieve the similar wavefield extrapolation accuracy as the finite different method.When imaging the standard Salt model,with the same hardware configuration and parallelization implementation,the new methods solve the weakness of using the conventional low-pass filter in suppressing evanescent waves and achieve the similar imaging quality as that of full-wave-equation depth migration by using the spectral projector in suppressing evanescent waves,but with much less computational cost.The proposed methods provide two numerical algorithms to efficiently suppress evanescent waves in performing full-wave-equation wavefield depth extrapolation and migration.
Full acoustic equationDepth-extrapolationEvanescent waveNumerical simulation
NETL
NSTL
万方数据
维普
