Angle Gathers by Reverse-time Migration

One of the ways to compute angle gathers for reverse-time migration (RTM) is through time lags. Algorithm for the transformation of time lags to angles has been proposed previously by other authors. However, the proposed workflow requires a dip field and is increasingly inaccurate in areas with conflicting dips and for dips greater than 60-degrees. In this paper we propose methods to overcome the dip limitation and to do the angle transformation without explicitly using the dip field. The angle gathers thus obtained can be used for migration velocity analysis or to improve the image quality through stack. We use a synthetic 2D model to compare results obtained using our proposed methods and the conventional workflow. Finally, we show RTM angle gathers for SEAM model using our methods.