Seismic Inversion Of Anisotropic Parameters Of TTI Media Based On Genetic Algorithm

Inversion is the process of imaging the structure and rock properties of underground media by using seismic data collected from the surface and using known geological,drilling and logging data as constraints,so as to achieve the purpose of reservoir parameter prediction,reserve estimation and work area description,and provide reliable basic data for geological exploration.As is known to all,the actual underground medium is very complex,but the spread of seismic wave research was originally based on infinite uniform,perfectly elastic and isotropic three under the condition of basic hypothesis,the seismic exploration precision and reliability very big impact,therefore,from the traditional simple homogeneous medium development to closer to the actual complex anisotropic medium inversion,wave impedance of underground rock stratum anisotropic related physical parameters,is cognitive earth medium,the development trend of the study of seismology,and solve problems in geological exploration and development needs.Paper based on the basic theory of anisotropic medium,the choice can more truly reflect the formation of geological characteristics of the geological model is established for TTI media research,AVO forward modeling by anisotropic medium PP wave reflection coefficient formula of accuracy verification,and further reflection sequences with wavelet convolution synthetic corresponding seismic records,and analyses the influence of anisotropy parameters TTI medium PP wave reflection coefficient curve influencing factors and anisotropic medium interface AVO seismic response characteristics of the different model and its anisotropy parameters to reflect the influence of the PP wave amplitude.Aiming at the anisotropic TTI medium inversion,the objective function composed of longitudinal wave,shear wave velocity and density and anisotropic parameters was constructed,and the genetic algorithm of efficient global optimization search was introduced to realize the seismic inversion method of TTI medium anisotropic parameters based on genetic algorithm.The numerical model,1-D logging model,2-D Marmousi2 model and the stability analysis of inversion results are used to test and verify the inversion method in this paper,and the feasibility and stability of the inversion method are shown.On this basis,according to the characterization formula of anisotropic parameters of the definition of Thomsen Hudson fissure equivalent theory,through the inclined crack the p-wave reflection coefficient of equivalent TTI medium RPP approximate formula of fracture properties using prestack AVO inversion information parameter prediction,Realize effective prediction of fracture physical parameters such as fracture density,fracture symmetry axis inclination angle,and fracture filling state,the research results for fracture type reservoir prediction and analysis of complex medium of seismic wave propagation law,has important theoretical significance.