Study Of 3d VSP Modeling And Migration Method Based On Wave Equation

VSP is excited in the near-surface, a seismic observation techniques with wells received. Compared with the surface seismic, in VSP, their receivers placed in the well, so VSP data have high signal to noise ratio and high resolution, and VSP can be more close to the target layer. So VSP is an apromising method of seismic exploration wells. In order to effectively solve the complex evaluation of structure and lithology and fluid prediction of reservoir space issues, three-dimensional VSP exploration is getting more and more attention. Because of the specific characteristic of three-dimensional VSP observation method, conventional surface seismic data processing methods can not meet the needs of three-dimensional VSP exploration, therefore, it is necessary to study the three-dimensional VSP data processing method, in which three-dimensional forward modeling and the VSP is to focus on migration one of the elements.This paper first past the reviewed and the introduction of conventional VSP data forward modeling and migration, analyzed the difficulty and weaknesses of the problems. According to these two aspects, proposed the overall paper research contents and research ideas of this paper, and obtain the corresponding results.One of the results:Based on three-dimensional one-way wave equation, this paper described the basic principles of one-way wave equation decomposition and prolongation, introduced several commonly used introduced three-dimensional one-way wave continuation operator, and on this basis to further the introduction of plus interpolation based on orthogonal directions (ADIPI) Fourier finite difference (FFD) operator, achieved high-precision three-dimensional wave field prolongation, and overcame the error caused by two-way three-dimensional orthogonal operator splitting anisotropy. It could not only ensure simulation accuracy, but also help to improve computational efficiency. At the same time, Huygens principle-based one-way wave forward modeling methods and anti-period expansion of the boundary method solved the border shooting and Fourier pseudo-periodic wave field problems, at last achieved the three-dimensional wave VSP forward modeling. This method overcomes the traditional two-way wave equation prolongation based on the wave field in both up and down wave and direct wave is difficult to avoid the direct waves with the multiples, according to the actual need for a separate analog upgoing or downgoing wave, without further information on the VSP the wave field separation processing, this method greatly facilitated the subsequent analysis and processing.Results of the two:based on the method of forward modeling, aimed at the feature of the three-dimensional VSP observation system, which have less receiver points and more shot points, this paper studyed the three-dimensional set of common receiving VSP wave equation migration method, it could not only greatly improved three-dimensional VSP migration computational efficiency, but also more adapt for lateral velocity variation in the complex structure models. Finally, theoretical models and real data validation, verify the correctness and validity.