Study of the Prestack Elastic Parameter Inversion Based on Immune Genetic Algorithm

In order to efficiently invert seismic amplitudes for elastic parameters, the Zoeppritz equations are simplified with only four independent elastic property contrasts across the interface. A novel immune genetic algorithm (IGA) is presented for geophysical P-wave amplitude variation with offset (AVO) inversion. The details of an IGA approach are described and implemented. The elitism method increases the probability of finding the global optimum. The mechanism of antibody suppression and the adaptive probabilities of crossover and mutation adoption greatly improve the effectiveness of IGA. Applying the IGA to typical earth interface models for P-wave AVO inversion, four rock property contrasts are better extracted. The precision of the inverted P-wave velocity and bulk density contrast is high.