POST MIGRATION PROCESSING FOR AVA INVERSION

摘要

The goal of this paper is to present a processing flow applied to prestack depth-migrated common image gathers, before the amplitude versus angle inversion (AVA). We developed a technique to detect and follow the amplitude variations along the offset or incidence angle axis in the main events, within the common image gathers. The inversion is then performed along these events, the so-called trajectories. We first start with an automatic detection of the incidence angle range, to predict and detect the amplitude variation to the farthest available angle, through two inversion steps. The advantage of this technique is that the robustness of the inversion is increased by taking into account long-offset or wide-angle contributions. We present an application to synthetic data, to demonstrate that the trajectory-based technique also reduces the impact of offset or angle-dependent stretch, compared to the conventional amplitude balancing method. Also, the resolution of the AVA inversion after prestack depth migration in case of thin beds is increased.