The Study Of Frequency-dependent AVO Based On Broad-band Experimental Measurement

Rock physics as a bridge between seismic attributes(Amplitude and phase et al)and Reservoir properties(rock physical parameters ans fluid properties et al),has been paid more and more attention in the trend of increasing difficulty of exploration.According to the theory of rock physics,when the seismic wave propagates in the porous rock saturated fluid,the movement of the pore fluid relative to the solid(wave-induced flow)caused by the wave propagation will result in the frequency-dependent velocity dispersion and attenuation phenomenon in seismic wave,and dispersion and attenuation will change with different fluid properties,which is also the theoretical basis of identifying the pore fluid with different properties based on the seismic data.Cross frequency experiment can measure the velocity dispersion and attenuation of rock in rock physics experiment,However,there is a big gap between the theoretical calculation results and the experimental measurement results,which makes it difficult for the application of rock frequency-dependent properties in fluid prediction by seismic.Therefore,a theory that can accurately interpret and predict the velocity dispersion and attenuation characteristics of rock is particularly important.In frequency-dependent seismic attribute extraction and seismic inversion based on rock physics,many scholars have developed many methods to realize the qualitative identification of reservoir fluid.However,most methods are based on time-frequency decomposition technology and driven by data,lack of rigorous forward theory to support,and these methods are unable to extract the velocity of different frequencies from seismic data,so we can't compare the rock physical experiment or theoretical data with inversed data to predict the fluid information more precisely.For the above problems,the purpose of this paper is to accurately predict the reservoir fluid by frequency-dependent AVO inversion method combined with the rock physics experiment and theory.The main work is as follows:(1)the dispersion velocity of the core saturated fluid at the actual reservoir location is accurately obtained by stress-strain cross-band measurement system;(2)based on the dispersion law of cross band measurement,analyzed the seismic response caused by the change of dispersion properties of rock saturated fluid by the seismic forward and data-driven frequencydependent inversion method,it is found that the inversion is susceptible to the influence of time-frequency resolution and reservoir thickness;(3)study the inversion of seismic velocity in different frequency based on the pre-stack inversion method driven by model,and the inversion results can be directly compared with the corresponding cross frequency measurement results of core,which makes it possible to quantitatively predict reservoir physical parameters and fluid properties by cross band measurement or dispersion theoretical model.