The Study And Application Of Complex Near Surface Tomography Inversion Method

Near surface problem is the key to success of seimic exploration.This thesis discusses the high-precision high efficiency ray tracing algorithm based on multi-retracing and full travel course constraints tomographic inversion algorithm based on the priori information comes from short-refraction and Micro logging and so on,by thoroughly studied the theory of ray tracing and tomographic inversion,after comprehensively contrasted and analyzed advantages and disadvantages and adaptabilities of the traditional ray tracing methods and tomographic inversion numerical algorithm.Also advanced a series of technologies,which can improve the accuracy and efficiency in forward modeling.All these techniques are used in practical seismic exploration and give excerlant results.This thesis put some effort on dynamic range of velocity restriction,multi-retracing ray tracing algorithm,HASH query to obtain accurate ray route,and slowness correction,internal iterations constraint,relaxation factor adjusting convergence speed to make sure the correctness of nonlinear results,and priori information constraint and double grid constraints can both guarantee the tomographic calculation accuracy also improve iteration efficiency.To make the tomographic inversion results closer to authentic seismic data,put forward the velocity extrapolating and smoothing technologies based on layer constraints in graphic display.Meanwhile this paper obtained research results in 3D ray tracing and tomographic inversion technology.Using MPI and OpenMP united parallel computing technology,realized the 3D ray tracing and tomographic inversion method paralleled,and advanced parallel management,parallel quality control and nodes management methods.Aiming the technical difficulties of high-capacity memory space required and great computing time consumption,advanced the large sparse matrix compress and storage technology,and solved the difficulties efficiently.Aiming the difficulties of limited reliable information,advanced priori information full travel course constraint and virtual receiver technology.The post constraint optimized and improved 3D inversion algorithm,could more accurately inverse the location of the formation interface,velocity information of each layers and the underground geological structure form.In addition,an advanced 3D tomographic inversion near surface velocity model processing flow is established,the methods and techniques of the research results is coded,user visual interface of modeling accuracy control modules is programmed,near surface inversion modeling software is finally formed,which was verified and analyzed by multi theoretical models and actual data,and the theoretical models trials and actual data inversion results proved the correctness of this topic theoretical methods.