Common Angle Image Gather - a Strategy for Imaging Complex Media

Common image panels are commonly used for migration based velocity analysis and for migration based AVO analysis. The advantages of common offset image gather with respect to common shot image gathers are now well established [4] but also their poor quality in case of complex models [3]. The reasons of this failure may appear when the problem is analyzed in the frame of the asymptotic linearized inverse theory [7, 6]. We propose here an analysis of the relevance of common image gather analysis in case of velocity models with triplicated ray fields. We show that individual common shot or common offset may provide inconsistent images of the subsurface, and we propose a strategy for common anale imaging avoiding the former artefacts. Comparisons of common shot, common offset and common angle image gathers are presented for 2D complex Marmousi dataset.