Migration in the angle domain: Theory and practical aspects

Kirchhoff prestack depth migration in the angle domain helps in the reduction of acquisition footprints, in true amplitude migration, in Amplitute Versus Offset or Angle analysis and in migration velocity analysis. Scattering angles replace surface related acquisition coordinates in the Kirchhoff summation. The regularization of illumination is performed with respect to scattering angles and illumination dip angles. At each depth point, the coverage in the angular domain is equalized by an explicit regularization through binning and hit counting. After a review of migration in the angle domain, we examine some practical aspects of implementation, namely those that mostly impact performances and effectiveness: memory, poor illumination and sampling of integration domain. The most critical factor is memory. We suggest a strategy, based on the computation of an off-line, coarse sampled, hit-count panel, to face the increase in memory requirement. We successfully limit noise amplification by using a damping factor.