Research Of Multi-Waves Jointed Inversion Method Based On The Zoeppritz Equation

AVA inversion using pre-stack seismic gather data has become a commonly used technical method for reservoir prediction and fluid detection.Especially for the exploration and development of complicate oil and gas reservoirs such as the tight reservoirs,the unconventional shale reservoirs,and the carbonate reservoirs with complex pore structures,AVA inversion based on pre-stack seismic data is a research hotspot for obtaining geophysical "dessert" parameters in reservoir prediction and fluid detection,and it is also a difficult point in current method and technology research.The commonly used AVA inversion method mainly adopts the linearized approximation of the Zoeppritz equation,and mainly uses the compressional wave data of pre-stack gathers,so the stability of the inversion method and the accuracy of the three-parameter inversion will be affected.This paper mainly studies the joint inversion of compressional and converted waves based on the exact Zoeppritz equation,and forms a stable joint inversion method.The application of the synthetic data and actual data verify the effectiveness of the method and the applicability of the actual data.The pre-stack inversion method is to invert the three elastic parameters by adding information in one angle dimension.In order to improve the stability of inversion,a direct inversion method based on the analytical expression of the exact Zoeppritz equation is formed.Taking the exact Zoeppritz equation as the forward calculation model of the inversion process,the objective function of the compressional and converted wave data is iteratively solved from the initial model,and the three elastic parameters results are obtained by joint inversion of the compressional and converted waves.In the inversion algorithm,a nonlinear inversion algorithm solved by Iteratively Regularized Levenberg-Marquardt(IRLM)method is formed to solve the unstable characterization of the strong nonlinearity of the joint inversion of compressional and converted waves and the low signal-to-noise ratio of actual data.Meanwhile,due to the different time domains of compressional and converted waves of actual seismic data,the time domain matching processing of compressional and converted wave data is carried out in the application.By combining compressional and converted wave data for pre-stack inversion,one more data information can be added to improve the stability of pre-stack inversion.Besides,the pre-stack inversion method and algorithm based on the exact Zoeppritz equation can improve the accuracy of the inversion.Through the application of synthetic data and actual data,the inversion results verify the applicability of the paper method,the method improves the accuracy of the inversion results and has strong anti-noise and can be applied to the actual data.