Tomograph With Fresnel Volume Under Complex Near-surface Conditons

In all kinds of oil and gas exploration method, seismic exploration has been one of the most important techniques in modern petroleum exploration, and plays an important role. As it has been deeply used in the plain area, seismic exploration for oil and gas exploration and development has shifted it's main battlefield to northwest and southwest areas, where the main surface are mountain,desert and loess plateau. Static correction, pre-stack denoise and migration imaging are key and most difficult seismic data processing problems to be solved in these complicated surface areas. Static correction is especially the first and most important seismic data processing task because the effect of static correction will not only affect the following processing task and may affect the final imaging.Aiming at the main and deficullt problems at these complex surface model, this paper studied the theory of first arrival wave and used to tomographic inversion model reversing method, and applied to the practical data tomographic inversion and static correction, obtained good effect.Based on the research of the analysis of tomographic inversion theory, method and technology from home and abroad, the paper has studied the traditional ray tracing methods of 2D and 3D space, and has improved LTI method to increase the precition of ray tracing. Proposed and implemented a rapid sieve method to calculate Fresnel volume, then improved the BPT method and applied it to the tomographic inversion based on Fresnel volume, got a high computational efficiency while ensuring the accuracy. The forward and inverse methods proposed by the paper have been proved to be correct and effective by the typical 2D and 3D theoretical models, and have got some good effect when applying to actual seismic data.In summary, this paper realized the forwarding and inversion methods of the velocity model based on Fresnel volume, and is able to perform tomographic inversion and static correction to complex surface seismic data. The methods have good application prospect.