Frequency-Dependent AVO Analysis Based On S Transforms

Traditional AVO is presented basing on Zoeppritz equation,which does not consider attenuation and frequency dispersion which caused by elastic waves' propagation in the stratum.In order to simulate the reality of elastic waves' propagation in the stratum,this paper bases on Chapman frequency dispersion media theory,establishing water-saturated sandstone model,studying the attenuation and frequency dispersion of P wave and S wave during the propagation in the stratum,and discussing how the model parameters,including time scale and fracture density,influence P wave's attenuation and frequency dispersion.Establishing numerical model of three common AVO and introducing frequency in it to study the relationship between reflection coefficient and frequency of each type,getting the energy's moving direction of three AVO types.For choosing time-frequency analysis method of high “price/performance ratio”,synthesizing seismic record single-trace model and seismic record including noises,using common time-frequency analysis methods,including STFT,WVD,S-transform and generalized S transform,to analyze its time-frequency spectrum.Deciding to choose S transform as this paper's time-frequency analysis method,design and manufacture low-velocity water saturated artificial sandstone physical model,using S transform to analyze physical model's data,getting its iso-frequency section,so as to detect fluids.Finally,basing on Smith&Gidlow formula,this paper elicits frequency-dependent AVO inversion formula,combining S transform and AVO analysis to analyze the two-layer and three-layer numerical model which have Class ? AVO characteristic,getting the frequency-dispersive attribute curve of frequency-dispersive condition and elastic condition which can reflect the frequency-dispersive degree,the results show that frequency-dependent AVO inversion can commendably distinguish elastic media and frequency-dispersive media.