The Study Of Frequency-dependent Petro-physical Properties Pre-stack Seismic Inversion

Seismic dispersion is one of the research hotspots in exploration of geophysics and oil exploration.It is often believed that it is directly related to reservoir fluid and reservoir lithology.With the progress of rock physics theory and experimental technology,the cognition of the attenuation and dispersion of seismic waves is constantly improved.The seismic dispersion attribute is extracted from seismic data,so as to realize fluid identification of underground reservoirs,predict lithologic properties and distribution rules of oil and gas.In this paper,an inversion method for identifying reservoir fluid based on seismic dispersion attributes is proposed considering viscoelasticity of medium.It is helpful to understand the distribution of underground reservoir,improve the success rate of exploration and reduce the cost.Compared with traditional frequency inversion,the attenuation and dispersion of seismic waves caused by inelastic media are neglected.In this paper,based on the viscoelastic medium,a pre-stack seismic inversion method of frequency-dependent viscoelastic fluid factor and a pre-stack seismic inversion method of frequency-dependent solid-liquid decoupling fluid factor are proposed.The frequency dependent indicator factor is constructed by using the elastic modulus of rock.On the basis of this,the reflection characteristic equation is derived.In order to increase the inversion stability,the reflection characteristic equation is further rewritten as a frequency dependent elastic impedance equation.At the same time,the frequency division processing of seismic data is realized,and the multi angle frequency variable elastic impedance data in the frequency division segment is obtained under the framework of Bayesian theory,which provides the data basis for the inversion method,and finally the extraction of indicator factors is realized.Inversion of reservoir physical properties plays an important role in comprehensive evaluation of reservoirs.On the basis study of the prior dispersion properties,this paper further explores the inversion method of extracting the physical parameters of the reservoir by applying the amplitude and frequency information of seismic data.On the basis of reservoir petrophysics,the relationship between elastic parameters related to frequency and physical parameters is studied,and the elastic parameters obtained by frequency inversion are used as data basis to predict the physical parameters of reservoir.This method,on the basis of Bayesian theory,Monte Carlo random sampling technique and EM algorithm,joint statistical petrophysical model to predict reservoir physical property parameters.