| Popis: |
Computation efficiency is one of the most important factors restricting application of prestack depth migration. Sparse depth-step size of wavefield-continuation is able to reduce computational cost. However imaging-result quality will be affected. General linear interpolation cannot solve the problem because of its inability to follow wavefieldcontinuation characteristics. In this paper, we derive oneway wavefield continuation operators in true-amplitude wave-equation migration and obtain imaging results with a large depth-step by using the time-shift imaging condition as an interpolator in shot-domain, true-amplitude migration. This method can greatly improve computation efficiency, and output imaging results are comparable to those of normal depth-step migration. The same principle applies to extracting true-amplitude, angle-domain, common-image gathers (ADCIGs), which can effectively reduce time of extraction, and can be used to accelerate amplitude and velocity analysis. Marmousi Numerical Model test shows evidence of its correctness and effectiveness. |
