Study On Seismic Inversion Of AVO In Depth Domain

The technology of seismic exploration is changing with each passing day,and with the rapid development and popularization of pre-stack depth migration technology,the processing method of depth domain seismic data has become more and more important.However,the current depth domain seismic inversion still applied in time domain only,which means we use the "depth-time-depth" process to transfer imaging data from depth domain to time domain,then carry out relatively mature inversion in time domain,and finally transfer inversion results to depth domain.but this repeated conversion not only waste time but also result in accuracy loss caused by resampling.Since pre-stack seismic data has sufficient underground information,such as amplitude,travel time,shear waves and other related information.More information can be botain by making full use of pre-stack seismic data for seismic inversion.The AVO technology is the basis of pre-stack inversion.Therefore,in order to eliminate the errors caused by many unnecessary transformations and realize the direct AVO pre-stack inversion in the depth domain,it is of great significance to the development of the depth domain inversion.At present,the depth domain seismic prestack inversion still has considerable shortcomings.This article will study the direct depth domain prestack parameter inversion method.First,the analysis illustrates the correlation and difference between the seismic wavelet in the time domain and the depth domain,explains that the "depth-time-depth" conversion will cause certain errors,the necessity and feasibility of seismic prestack inversion in depth domain are proved.Then,using the time domain synthetic seismogram method,combined with the"depth-time-depth" relationship and unsteady convolution,the expression of the synthetic seismic record in the depth domain is obtained.Then the Bayesian theory is used to introduce prior information,which greatly improves the stability of the AVO three-parameter inversion.Different types of prior information distribution rules affect the final inversion results,and prior information is generally obtained based on geological data and logging information.The accuracy of the initial model will directly affect the results of the inversion method.And then realized the Bayes-based depth domain AVO inversion.In addition,the simulated annealing algorithm is used to realize the depth domain pre-stack inversion,and its principle and parameter settings are explained in detail,and the seismic pre-stack inversion based on the simulated annealing algorithm is realized.Finally,the inversion of the two methods were compared in various aspects,describes applicability,advantages and disadvantages of the two methods.Through the above theoretical analysis and models testing,the depth-domain AVO inversion method based on Bayesian theory and the depth-domain seismic pre-stack seismic inversion method based on simulated annealing are realized.Successfully solved various difficulties in depth domain inversion.According to the test results of the two methods,the depth-domain pre-stack seismic inversion method studied in this paper can avoid various problems such as errors caused by the "depth-time-depth" conversion,and can fully integrate prior information to obtain better inversion results,it provides theories and methods for the study of depth-domain pre-stack inversion methods,and has broad application prospects.