SUMMARY
Residual moveout based wave-equation migration velocity analysis uses residual moveout to characterize the kinematic error caused by the inaccurate velocity model, and computes velocity updates using wave-equation tomographic operators. However, the per iteration cost of this method is even more expensive than that of full waveform inversion because of the construction and back-projection of offset/angle domain common-image gathers. In order to speed up the residual moveout based migration velocity analysis, we examined its work flow, and proposed the following acceleration scheme: 1) by using compressed-sensing technique, we can very well reconstruct the angle domain common image gathers from a fraction of the subsurface offset common image gathers, therefore saving significant cost for common image gathers computation; 2) after we extract the residual moveout information from the reconstructed angle domain common image gathers, we reduce the cost of back-projection by synthesizing an approximation of the original image perturbation which can be back-projected with much cheaper cost and can yield a velocity gradient with the same behavior.
