The Study Of Wave Equation Prestack Depth Migration With Optimum Split-step Fourier Method

It shows that, from the production practice of oil and gas exploration, the geological conditions of petroleum in China are complicated, the oil or gas is buried deeply and concealed strongly. Oil exploration is facing more difficulty problems with the continuous improvement of the degree of the gas (or oil ) exploration and development. More and more detailed,accurate information is need for the seismic exploration. Complex structure imaging which has a high practical value and significance for improving the success rate of gas exploration and reducing the exploration risk has been the critical problem in seismic exploration, so that it is a problem which is needed to be solved as soon as quickly to study the theory and technology of complex structure imaging.The imaging technology of pre-stack depth migration based on the wave equation is an effective way to solve the problem of complex geology imaging when the lateral velocity changes strongly. In this paper, more in-depth theoretical analysis and the study of theoretical model have been done for wave equation depth migration with optimum split-step Fourier method. In addition, some common migration methods based on wave equation and the Kirchhoff integral migration method based on the ray theory have been studied in this paper.Migration operator with optimum split-step Fourier is derived in theory in this paper which verified the accuracy of this operator and the migration operator based on the wave equation. It is proved that there is a higher precision for migration operator with optimum split-step Fourier which can achieve the correct imaging of steep structure with less computation by means of the test of migration pulse response and complex structure Marmousi model data. There is an apparent advantage in keeping the dynamics and kinematics characteristics of wave field for wave equation depth migration with optimum split-step Fourier which can accurately describe the Marmousi model structure changes. It is more suited to the wave field imaging of complex structure for migration operation with optimum split-step Fourier.According to the velocity analysis capability of Kirchhoff integral migration and the high-precision imaging quality of wave equation depth migration with optimum split-step Fourier, both of them can be combined in the actual seismic processing. In this paper the interval velocity-depth model is built by Kirchhoff integral, then it is processed by wave equation depth migration with optimum split-step Fourier which also is used in the seismic data processing of some work areas, such as DL. According to the actual practice it is shows that wave equation depth migration with optimum split-step Fourier is an effective way to solve the problem of complex geology imaging when the lateral velocity changes strongly.