Conclusions and upcoming work

The stationary-phase approximation used to derive the CAM algorithm yields constraints in the downward-continuation process that limit accuracy in imaging, even in 1-D v(z) media. However, those errors only become apparent for really steep reflectors (about $60^\circ$)with an important cross-line component. CAM is also a more reliable approximation of the 5-D phase-shift operator than the offset plane-wave algorithm. An even more robust approximation of the 5-D operator can be the narrow-azimuth migration algorithm, presently in progress. Eventually, 1-D media only allow us to estimate errors due to varying azimuth in downward-continuation. We will address issues related to multipathing and lateral velocity variations using the SEG/EAGE salt dome dataset.