Study On The Analysis Method Of Frequency Variable AVO Attribute Based On Chapman Frequency Dispersion Medium

In geophysical exploration,with the greater complexity of underground media,the more unstable the propagation process of seismic waves in the ground.For non-stationary seismic signals,because the time-frequency analysis method can depict the essential characteristics of the signal in the time-frequency domain at the same time,it is widely used to study the instantaneous frequency of seismic signals.In recent years,the level of oil and gas exploration has been improving,and its exploration degree is becoming more and more large,and the target of seismic exploration has gradually changed from conventional shallow tectonic oil and gas reservoirs to lithologic reservoirs.Seismic exploration is becoming more and more difficult because of its deep burial,thin reservoir,complex relationship between water and gas and strong non-mean value of lithologic reservoirs.In view of this situation,we are required to use more accurate time-frequency analysis and seismic data inversion methods for seismic data processing and interpretation.The traditional AVO seismic analysis method is based on the Zoeppritz equation,the premise of which is to assume that the underground medium is elastic of the same sex.However,current research shows that frequency attenuation often occurs when seismic waves are transmitted underground,which is caused by the fact that in strata,rock mass is usually heterosexual and has viscoelastic properties.Based on the theory of Chapman frequency dispersion medium,this paper studies the method of extracting the dispersion attribute of the frequency dispersion medium model and the Aki-Richards approximation equation,and deduces the variable AVO approximation of the longitudinal wave transverse wave velocity with the frequency change which is in accordance with the actual situation,The method is applied to the analysis and processing of seismic data in the actual work workspace,and good results are obtained.Firstly,the paper summarizes the velocity dispersion and attenuation of seismic signal when it is transmitted in underground medium by means of wave-induced dispersion theory,and illustrates it by frequency dependent jet model,and then under the Chapman frequency dispersion medium model,the soft porosity,soft pore aspect ratio,porosity and The variation of parameters such as fluid viscosity and dispersion attributes are studied respectively,and the rationality of distinguishing gas water by using the dispersion attribute of reflection coefficient is used to illustrate the theoretical basis for the study of the analysis of the following frequency variable AVO attributes.Secondly,by comparing and analyzing the existing time-frequency analysismethods,based on their respective advantages and disadvantages,the generalized S transform with relatively good effect is selected to process the seismic data,and then,from the Zoeppritz equation,Based on the approximate equation of Aki-Richards and the approximate equations of Smith and Gidlow,we study and deduce the method of extracting the dispersion attribute based on Gray reflection coefficient and the theory of the extraction of the dispersion AVO attribute based on Aki-Richards AVO approximation.Combining the generalized S transform and the theory method of frequency dispersion AVO attribute extraction based on Aki-Richards AVO approximation,the inversion optimization and model trial calculation are carried out,and the logging data can be used to show that the method can achieve better application effect for the actual working work.