FREQUENCY-DOMAIN FINITE-ELEMENT INVERSION OF ELASTIC-WAVE VELOCITY USING THE GEOLOGICAL REGULAR-BLOCKY-MODEL METHOD
利用地质规则块体建模方法的频率域有限元弹性波速度反演

In order to obtain the elastic velocity of subsurface media directly, this paper derives a frequency-domain elastic-wave finite-element least-squares inversion method according to the criterion of minimizing the misfit function (the l 2-norm of the data residuals between observational data and modeling data) on the basis of the frequency-domain elastic-wave finite-element modeling equation. This inversion method includes the matrix compressional storage and LU decomposition techniques to save and solve the large sparse complex-valued coefficient matrix in frequency-domain modeling equation. Then the Levenberg-Marquard technique with an adjustable damping term is used to solve the inverse equation group. To sufficiently exploit subsurface geologic distribution features to decrease the number of inverse unknowns, this paper introduces the regular-blocky-model method into the inversion. Being verified by numerical models, this inversion method can obtain satisfied results using the shot profile contaminated with great random noise even up to 50% or the initial model parameters that have much difference from the original model parameters, which proves the inversion is noise-resistable and 'robust'.