Seismic Wave-field Numerical Modeling And Migration For The Random Medium And Thrust Belt

It is important and difficult to study wave-field characteristic for the random medium and thrust belt in recent decades. The dissertation analyzes and sums up the previous related research results, and combine random medium and actual nappe structure of the geological models to further make more systematic study wave-field characteristic of the complex structure from creating the model of complex structures, pre-stack the finite difference method forward simulation, post-stack forward and migration, based on wavelet transform of time-frequency representation.Main research contents and conclusions in the article are following:First, in summary and systematic analysis of establishment the complex structure models, if there are not actual measured information such as geology, logging, layer to control to establish geological models, conceptual geological model is described the complex two-dimensional geological structure. Statistical method is described the complex non-uniform medium. Summed up the autocorrelation functions such as gauss, exponential, Von Karman, which construct random medium models, of characteristics and its adaptabilities respective, and the programming of the 2-D model of random medium.Second, through solving acoustic wave equation by finite-difference method to achieve pre-stack forward modeling. The main is to analyze the absorbing boundary conditions ,which impact on simulation accuracy and can significantly improve the accuracy of the numerical simulation. Compared the accuracy of algorithms between split-step migration and phase-shift plus interpolation migration that phase-shift plus interpolation migration can adapt vertical and horizontal velocity of change.Third, through solving acoustic wave equation to achieve pre-stack and post-stack forward modeling and post-stack migration in the random medium models. To calculate the constructed the large number of random medium models showed that seismic records are complex and have many small and short events and the scattered wave. Especially, slit holes caused by the seismic response has been totally submerged, through migration, can be reflected. Using time-frequency representation to comparatively analyze wave field characteristics of isotropic media and random medium models in the same structure, through quantitative analysis of its amplitude and frequency characteristics to indicate amplitude greater attenuate and frequency widen in the random medium.Fourth, based on numerical simulation and migration, summed up the wave field characteristics of nappe-tectonic seismic response, to distinguish micro-structure nappe that has provided the theoretical support.