Research On Waveform Contrast Method In Seismic Waveform Inversion

With the continuous advancement of method innovation and technology development,the role of seismic inversion in exploration is becoming more and more important.The inversion method based on the convolution model has the advantages of easy implementation,simple and efficient,and strong robustness,and is widely used in actual production.With the increasing accuracy requirements of reservoir prediction,these inversion methods are gradually being replaced by Full Waveform Inversion(FWI)based on wave equation theory.Waveform inversion method,with its firm theoretical foundation and advantages,has become a hot topic in the research of inversion methods.In particular,the(full)waveform inversion method for oil and gas reservoir prediction and seismic data interpretation has attracted more and more researchers' attention.Based on the technical requirements for improving seismic inversion accuracy in the project “Research and Application of Favorable Reservoir Prediction Methods for Bohai Sea Buried Hill Exploration”,this paper mainly studies the accuracy of numerical calculation based on wave equation forward and how to realize the full matching of waveforms in the realization of(full)waveform inversion.And some theoretical methods of seismic waveform inversion are discussed to further promote the improvement and practicability of full waveform inversion in the prediction and interpretation of oil and gas reservoirs.Because the nonlinearity of the full waveform inversion is extremely high,the optimal solution of the problem is very difficult,which directly affects the accuracy of the waveform inversion and the application effect of these methods in seismic reservoir prediction.Through this research,the deeper understanding of the basic theoretical system of(full)waveform inversion is obtained.The full waveform inversion framework is implemented by Python language programming and the model test is carried out to verify the role of full waveform inversion of various parameters.The waveform contrast method in waveform inversion has been studied in detail,and a solution for joint inversion using different waveform contrast methods is proposed.In this paper,the joint waveform inversion method of which the initial model provided by waveform envelope contrast is realized,the joint waveform inversion method of which the initial model provided by waveform phase contrast is proposed,and the waveform inversion method for the full matching of waveform segment contrast is implemented.Envelope error functional,phase error functional,and waveform segment contrast error functional are derived.The effects of three contrast methods are tested by using model data.The envelope contrast promotes the coupling of the low frequency information with the initial model,the phase contrast has high stability and mitigation of nonlinearity and the waveform segment contrast achieves waveform full-matching,which can improve the stability and accuracy of full waveform inversion.