The Study Of Multiwave Amplitude Equation And Inversion Method In Transverse Isotropic Medium

AVA analysis plays an important role in the multiwave seismic data processing. The anisotropy, however, has an important influence on the AVA.Therefore, the multiwave amplitude characteristic equation of the anisotropic media should be established and then the AVA analysis and parameter inversion could be realized.The amplitude characteristic equations of P wave and S wave in transverse isotropic media have been deduced by using the method of Aki and Richards, that is use the border conditions in elastic interface to solve the elastic wave equation and to decide the energy distribution of different types of wave. The comparing between amplitude characteristic equations deduced in this paper and the existed approximate expressions of the reflection and transmission coefficient in TI media and AVA modeling has been done for different synthetic data and different theory model. The AVA inversion equation of multiwave in TI media has been set up on the basis of amplitude characteristic equations. The velocity, density and especially the anisotropic parameter which is important to the study of fractured formation can be achieved by the generalized linear inversion based on the AVA inversion equations.According to the non-linear nature of geophysics problems, the multiwave AVA inversion by use of genetic algorithms was discussed in this paper. There are some improvement during encode and mutation process in order to improve the efficiency.The software development for the studied methods is completed in the FORTRAN and C language. After applying these new methods to the real data inversion, the better geology effect was obtained. It shows that the inversion based on the amplitude characteristic equation has better utility and wide development prospects.This research is to belong to multiwave prospecting of national 863 project.