Seismic inversion and prediction based on PSV wave reflection coefficients in HTI media

The inversion of fracture parameters has important theoretical significance for identifying fractured reservoir types. Based on the relationship between anisotropic parameters and fracture parameters, an approximate formula of PSV wave reflection coefficient for HTI medium with upper isotropic medium and lower vertical fracture under weak anisotropic condition is derived. By comparing the response characteristics of PSV wave and PP wave reflection coefficient in identifying water-bearing sandstone and gas-bearing sandstone, it is concluded that PSV wave has more advantages in identifying water-bearing sandstone and gas-bearing sandstone. Based on the derived reflection coefficient approximation formula, the inversion objective function of fracture parameters is established, and the advantages of particle swarm optimization algorithm and differential evolution algorithm are combined to form PSO-DE algorithm, which effectively overcomes the premature convergence problem of single algorithm and improves the global optimization performance. Gauss random noise with different signal-to-noise ratio is added to the theoretical model to test the noise immunity of the inversion method. The results show that the inversion error is small, the convergence speed is fast and the noise immunity is good. The velocity, density and fracture parameter profiles are obtained by inversion of the improved Marmousi2 model, and the fluid factor prediction is realized. The inversion and prediction results are consistent with the theoretical model, which verifies the effectiveness of the method. The research results will provide technical support for improving the inversion accuracy and reliability of seismic data.