Method Study Of Deep And Complex Structure Imaging

The problem which will be met in the future exploration is how to solve the imaging of complex geological structure, especially in deep layers. Wave-equation pre-stack migration is an important method used to realize the imaging of complex geological structure. It can not only solve the problem of steep dip layers imaging, but also handle the wave propagation and imaging problems that arise from laterally varying. Moreover, due to the absorption of underground media, the reflection amplitude of deep layers attenuated seriously. However, the wave-equation pre-stack depth migration methods that widely used can only guarantee the correctness of phase in the wave field continuation while neglecting the effect on the reflection amplitude arise from wave propagation. So it is of great significance to do some research on the theory and method of amplitude-preserved migration for imaging deep and complex structure. First, in the common-shot gathers, the shot and record wavefield are continued separately by using single square-root operator equations, then the entire imaging profile is obtained using cross-correlation imaging condition. The trial results for the deep and complex model and the real seismic data confirm the practicability of wave-equation pre-stack depth migration in deep and complex structure. Secondly, based on the wave equation in 3D heterogeneous medium, amplitude-preserved one-way wave equation is derived by decomposing the operator and corresponding SSF,FFD and kxFD methods are presented. Then by modifying boundary condition and imaging condition, amplitude affected by geometric spreading loss and transmission effect is compensated. The trial results for the theoretical model data and the real seismic data indicate that the method would not only compensate the reflection energy in deep layers effectively and improve the imaging accuracy, but also can output the amplitude information which reflects the correct subsurface reflection coefficients. So the method can provide more reliable lithologic parameters and reservoir information.