Multi-wave Joint Inversion Of Anisotropic Media And Shale Gas Reservoir Prediction

Shale reservoirs usually exhibit strong anisotropy characteristics.In simple cases,they can be approximated as VTI media.Anisotropic parameters have a great influence on wave propagation velocity and amplitude,which can’t be ignored.Prestack synchronous inversion technology,as an important means to obtain the physical parameters of transverse rock in the strata,has been widely used in shale gas exploration and development in recent years.Therefore,in this paper,the multi-wave synchronous joint inversion research and application of VTI media is carried out for the purpose of obtaining more accurate reservoir elastic parameters and anisotropic parameters.Based on the multi-wave reflection theory,this paper analyzes the reflection amplitude response characteristics of longitudinal wave,PS converted wave and pure shear wave in VTI media,and discusses the influence of anisotropy on AVO for different types of waves.An improved approximation formula for reflection coefficient of converted wave in VTI media is proposed.Compared with the existing formula,the formula has higher precision.On this basis,the Bayesian framework is used to develop a multi-wave joint inversion method for VTI media.This method can simultaneously invert five parameters and has obvious advantages over conventional longitudinal wave inversion in terms of accuracy and stability.The above inversion method is applied to the prediction of shale gas reservoirs in southern Sichuan.Work on well seismic calibration and horizon matching for actual multi-wave data was done.On this basis,the application of the new method was carried out.Finally,the inversion algorithm is used to transplant the Geo East software module.