Research Of Three Dimensional Geological Modeling Based On Two Dimensional Sections And Gaussian Beam Forward Modeling

Ray methods play a vital role in seismic exploration. Among all ray methods, Gaussian beam method is a fast method of seismic wave field modeling. The seismic wave field obtained by this method has wave properties in both kinematics and high-frequency dynamic. By merging wave equation with the ray theory, the method obtains ray tracks by the kinematical ray tracing, and obtains distributions of high-frequency by the dynamic ray tracing. As a result, it has the dynamic and geometric characters while costing little calculation time, and shows good precision.Three dimensional forward modeling by ray method needs three dimensional stream modeling and ray tracing. However the three dimensional geological modeling, especially the complex model structure usually is quite difficult. This article proposes a model expression method of three-dimensional geological model based on three-dimensional geological block, and introduces a algorithm which uses two-dimensional geological cross section to construct the three dimensional geological model. The algorithm has effectively solved the complex geological modeling problem. Based on the firsthand information about two-dimensional geological cross section edited by users, the method automatically structures initial model on three-dimension geological blocks, then smoothes the results, to output a polished, exquisite, and the reasonable triangle grid model. The separate triangle grid may describe the complex geologic structure. But, because of containing massive triangles, it causes the beam tracing efficiency quite to be low. Therefore this article introduces a method by using space surrounding box carries on fast ray tracing on the triangular net model. Using this method, it is possible to quickly complete the beam tracing on the complex model, even up to ten thousand strip beams, while costing little calculation time. The method is helpful for three dimensional forward modeling and has the very strong practical value.By the study of three-dimensional geological modeling and Gaussian beam method, this paper designs an architecture of the distributed three-dimensional geological modeling and Gaussian beam seismic wave field modeling software, based on three layers software framework and net database. We have developed the complete autonomic intellectual property software with Qt and OpenGL, the results of a lot of examples testing indicate that this software is stability and effective, and has a bright perspective in practical application.