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Wave Impedance Inversion By Wavelet Transform

Posted on:2004-08-03Degree:MasterType:Thesis
Country:ChinaCandidate:J S WangFull Text:PDF
GTID:2120360092980872Subject:Earth Exploration and Information Technology
Abstract/Summary:PDF Full Text Request
In this paper, wave impedance inversion and wavelet transform were studied and applied. The. accurate inversion for seismic lithological parameters, especially for velocity or impedance, has been being the main objective on which geophysicists make their efforts for long time. By using GLI's (Generalized Linear Inversion) algorithmic advantages, with the consideration that noise can't be defined in single trace, this paper applied the wavelet transform theory and dividing-frequence idea to multi-traces impedance inversion, the signal/noise ratio of inverse impedance was improved to some degree.In this paper, the necessity and significance for carrying this thesis was discussed firstly, after summarizing various methods in impedance inversion area, the paper analyzed the advantages and disadvantages of each method. Then the paper researched the active theory in neoteric geophysics, wavelet transform, especially with its "focus" characteristic and dividing-time & dividing-frequence idea, furthermore, the error doesn't carry when inversing impedance by GLI algorithm, accordingly multi-traces wavelet impedance inversion method was developed lastly.Seismic data in different frequency bands have different signal/noise ratios, and there is good correlation between waveforms or energies of corresponding useful reflection on adjacent traces. In view of above fact, simultaneous multi-traces wave impedance inversion is achieved by using wavelet transform characteristics. To speak in detail, in iteration process, we finish reasonable wavelet decomposition of residual traces resulting from real and synthetic seismograms to form the frequency-division wavelet section of residual traces; then, with the use of K-L transform, the coherent contents of frequency-division section are taken to estimate wave impedance variations, thus preventing noise from joining in the estimation of wave impedance variations, and so noise can be removed while impedance inversion being performed.Theoretical model and real data inversion shows that the method is robust with which we can obtain reliable results.
Keywords/Search Tags:Wavelet impedance, Generalized Linear Inversion, Noise Removal with multi-traces, Frequency-division by wavelet transform, K-L transform
PDF Full Text Request
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