Abstract：Using transversely isotropic model with horizontal axis of symmetry (HTI) to study the fractured oil/gas reservoir, P-wave amplitude variation with offset and azimuth (AVOA) appears strong azimuth anisotropic feature. Based on the P-wave reflection coefficients formula in HTI media model presented by Mr. Ruger, the paper uses the relative differences between the P-wave coefficients of datum line and other two lines crossing over the datum line with 45 and 90 respectively to evaluate the fractured azimuths; meanwhile, introducing niche genetic algorithm to perform inversion of differences of the coefficients between datum line and the line crossing over the datum line with 90, which obtains higher-precision P-wave velocity-to-S-wave velocity ratio and Thomsen anysotopic parameters
