Least squares migration of stacked supergathers

We show that phase-encoded shot gathers can be stacked together to form supergathers and efficiently migrated using an iterative least squares migration (LSM) method. The major problem of cross-talk can be largely eliminated by iterative stacking of the phase-encoded migrations and a multisource preconditioning factor, where random static shifts are used for the phase encoding function. Empirical results with synthetic seismic data suggests that increasing the number of stacked shot gathers requires an attendant increase in the number of LSM iterations. A key merit of phase-encoded LSM of supergathers is that, under ideal conditions, computational costs, 10, and storage requirements can be reduced by several orders of magnitude compared to conventional LSM.