Three Dimensional Pre-stack Depth Migration Based On The Wave Equation

With the development of exploration and exploitation in the oil area, the seismic survey focused on the accurate imaging of complex geological structure. The production indicates that the post-stack time migration can't product accurate image of the reflect wave, while the pre-stack depth migration has the substitute function. In the paper, the pre-stack depth migration based on wave equation and velocity methods were studied.At the present, Kirchhoff integral migration based on the radial theory is applied broadly in the industrialation production. The method has the advantages as follow: capability suitable to seismic data collected in any irregular survey and migration velocity analysis, flexible target oriented imaging, the higher efficiency in computation and the acceptable imaging results. All of that lead it to be an indispensable kind of migration algorithm. Low precision of data imaging is its most disadvantages, which is caused by aliasing, amplitude infidelity, difficulty in choosing migration aperture and multi-arrivals of travel-time.The solution of wave equation pre-stack depth migration, being high precision and embodying the dynamic characteristics of seismic wave field, has attached importance and indicates the trend of imaging techniques. The efficiency in computation is the problem.It is a uniform process between the pre-stack depth migration and velocity model building. Velocity is the core of wave pre-stack depth migration, while migration is the tool to testing the accuracy of velocity.Considering the velocity analysis capability of Kirchhoff migration and the higher precision imaging results of wave pre-stack depth migration, both of them were applied in the practical seismic processing. In the paper, interval velocity—depth model was built by Kirchhoff integral migration, and then method of Optimum Split-step Fourier was applied to the DL seismic data. The result indicates that the wave pre-stack depth migration is an effective method of seismic imaging and has prospect development.