Methodology And Research On Improving Seismic Resolution In Viscoelastic Media

As known to all, the attenuation effect by earth absorption causes the high-frequency lossof seismic wave, thus damaging seismic resolution. The paper stepped out from the viscoelsticwave equation which characterized attenuation by earth absorption, and worked over theabsorption compensation method by inverse scattering imaging theory and wavelet transform.In chapter one, firstly a classified introduction of some concepts and formulas aboutseismic resolution was given, and some opinions and discussion were followed as well. Thensome processing methods used in practice for improving resolution of seismic data wereintroduced, and the perfect inverse scattering imaging method based on elastic wave equationwas reviewed. However, this method has no consideration of attenuation by earth absorption,thus restricting its imaging resolution. Finally some mathematic models which characterizeattenuation by earth absorption were introduced, and the Kelvin-Voigt solid model was selectedfor the research in following chapters on inverse scattering imaging in viscoelastic media. Forthe need of theory deduction, wavelet transform and some of its mathematic properties wereintroduced in chapter two.Making use of inverse scattering imaging theory and wavelet transform, formulas forinverse scattering imaging in 1-D and 3-D viscoelastic media were deduced respectively inchapter three and four, and also the corresponding computing processes were given.In the last chapter, firstly a theoretic geological model based on practical attenuation byearth absorption in Songliao basin was built, and seismic forward modeling by wave equationwas carried out respectively in two situations, one considered attenuation by earth absorptionand the other not. The propagation laws seismic wave obeys and the characters of attenuationby earth absorption were shown up by comparing snapshots of wave field and syntheticseismograms obtained in the two situations. Then the synthetic seismogram was processed byinverse scattering imaging formulas to improve its resolution, by comparing the result with thatobtained by spectrum whitening and predictive deconvolution, the theory and method wereproved to be right and effective. Finally this method was applied to real data processing, andquite good outcome was obtained.