Since RTM angle gathers based on wavefield decomposition or extended imaging condition are too computationally expensive to put into practice, the Poynting vector is very attractive for RTM angle gathers. However, it always suffer from instability and imprecision. One important reason for this is that the Poynting vector is composed by the time derivative and the space derivative. Both the two kinds of derivatives would be very low when the values of wavefield are large. So Poynting vectors of the dominant wavefield that do most contribution to the final image, are closing to zero, which means not stable and precise. In this paper, a scheme called time-lapse Poynting vector is proposed to improve the stability and precision of Poynting vectors. Poynting vectors are not computed simultaneously with the wavefield they describe, but several time steps later, when the derivatives get their first peak or nearby region. The method has been proved better than conventional scheme. Moreover, source wavefield reconstruction is used to reconstruct Poynting vectors for avoiding the immense storage and I/O time caused by RTM imaging condition.


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