The Study Of AVF Inversion

With the development of oil and gas exploration,formation absorption and attenuation parameter as a seismic attribute,is playing an increasingly important role in the medium reservoir prediction and the inversion of physical properties.The quality factor Q as a most commonly used parameter to indicate the nature of the medium attenuation,not only in the seismic data processing,is an important basis for estimation and compensation subsurface seismic wave energy abso rption,but also in the prediction of lithology,indicating the location and extent of oil and gas reservoirs is playing an increasingly important role.Therefore,the quality factor Q of the strike is important in dealing with the interpretation of seismic data.The accurate estimate of quality factor Q is the key to process pre-stack or stack seismic data and AVO analysis.Theoretical analysis and forward modeling indicate that a contrast in the absorptive properties of two media will cause a frequency dependent reflection coefficient(Amplitude Versus Frequency,AVF).Using its linear approximation formula can be accurately obtained quality factor Q by AVF inversion.AVF inversion method provides a new way of obtaining the Q value,and with different to the traditional values of Q extraction,this method mainly considers the impact on the reflection attenuation coefficient and obtains the target layer Q value by reflection coefficient.AVF inversion is performed in the frequency domain,so the study of time-frequency analysis method is necessary.Short-time Fourier transform,wavelet transform,S transfor m and generalized S transform are relatively mature time-frequency analysis method,but ha ve corresponding disadvantage,too.This paper introduces the basic principles of fast S transform and shares the advantages compared with the other frequency analysis methods.Because the use of the reflection coefficient by AVF inversion only considers a simple reflex reflector interface,how to eliminate the impact caused by other reflection is one of the keys to the success of AVF inversion.This reflex response of the target layer and reach an accurate estimate of the time when the window width is closely linked.Based on S-transform-based fast The paper first discusses the impact of the reflection coefficient extraction which include the truncate frequency,the closeness of adjacent reflection coefficient and noise,analysis the impact of sub-waves at last,laying the groundwork for the next step.AVF inversion process utilizes the least squares method to obtain a stable and accurate quality factor Q.