Research On The Pre-stack Seismic Probabilistic Inversion Method For Fractured Reservoirs Driven By Petrophysics

With the deepening of oil and gas exploration,the study of fractured reservoirs has now become the focus of oil and gas exploration in the world.However,in the actual process,the structure of fractured reservoirs is very complex,so the modeling research work on fractured reservoirs is very important.Nowadays,fractured reservoirs are the hotspot of current research.For the research content,how to establish a more suitable The petrophysical model of fractured reservoir is very important.The closer the petrophysical model of fractured reservoir is to the actual strata,the more favorable it will be for the subsequent inversion work.Modeling and inversion of fractured reservoirs are based on actual seismic data.Reservoir parameter information estimation and reservoir qualitative evaluation are the focus of this study.For reservoirs,strong velocity dispersion and attenuation will occur when seismic waves pass through formations where fluid exists.If the velocity dispersion and attenuation of fluid rocks can be accurately explained and predicted,it will be useful for fluid detection and reservoir quantification.The analysis is of great significance.Based on the above analysis,this thesis studies the experimentally driven AVAF dispersion velocity inversion method.At the same time,in the inversion process,it is considered that the velocity dispersion increases with the increase of frequency,so adding rock physics constraints.This paper presents the Chapman(2003)fracture rock physics model.Through the study of this model,the dispersion characteristics and attenuation information are analyzed.Compared with other fracture models,this model has more advantages..At the same time,the influence of the changes of several fracture parameters on the dispersion and attenuation in the model is analyzed through this model,and it is found that the changes of different fracture parameters have different effects on the dispersion and attenuation,which provides a basis for the subsequent inversion work.and the fracture parameters are inverted according to the MCMC inversion method,which provides a new research method for fracture parameter inversion.According to the weakly anisotropic reflection coefficient derived by Shaw(2004),the objective function of elastic parameters(modulus of compression and shear waves,density)and maximum P-wave attenuation for inversion of fractured reservoirs is deduced.The ill-posedness,the objective function is re-derived in combination with the Bayesian formula.Due to the different prior information in the Bayesian inversion,the final result may be different,so on this basis,three more By comparing the objective function derivation and inversion results under different prior distribution information,it is found that the results may be different under different prior distributions.The method has good results and certain noise resistance,and provides a new method for inversion of fractured reservoir parameters.