UNDERGROUND IMAGING METHOD BASED ON A COMPLEX FREQUENCY GROUP FOR IMPROVED EFFICIENCY AND STABILITY BY USING WAVEFORM INVERSION IN THE LAPLACE-FOURIER REGION WHICH CALCULATES A GRADIENT OF AN OBJECTIVE FUNCTION BY COMPLEX FREQUENCY GROUP

摘要

PURPOSE: An underground imaging method based on a complex frequency group is provided to perform a strategic waveform inversion by effectively adjusting the size and the space of frequencies and attenuation integers of complex frequencies in a group.;CONSTITUTION: A gradient of an objective function on the difference between modeling data, which is a value of a wave equation with the coefficient matrix obtaining from modeling parameters in the Laplace-Fourier region, and measured data is calculated by multiple complex frequencies in a complex frequency group(40). A representative gradient value is calculated from the calculated gradient values(80). The velocity model and the transmission source of the wave equation are updated from the calculated representative gradient value. The objective function calculation stage or the updating stage is repeated in multiple groups of complex frequencies until the objective function meets the completion standard, and a final speed model is outputted as imaging data of medium(110).;COPYRIGHT KIPO 2013;[Reference numerals] (10) Converting measurement data into a Laplace-Fourier region; (100) Satisfying a termination condition?; (110) Outputting the final modeling parameter; (20) Setting an initial value of a coefficient matrix and a transmission source model; (30) Calculating modeling data by solving a wave equation; (40) Calculating an objective function; (50) Calculating the gradient of the objective function; (60) Finishing the calculation in a group?; (70) Changing complex frequencies in the group; (80) Calculating a representative gradient value; (90) Updating the modeling parameter