Specular Imaging of Converted Wave Data and its AVO Impact

In principle, high quality pre-stack converted wave (PS) data can provide valuable complementary information to conventional P wave (PP) data to highlight seismic amplitude anomalies in areas with complex imaging problems such as steeply dipping structures and obscured areas. However, in practice, we often find that PS images are noisier than the corresponding PP images. In addition, the amplitude versus offset (AVO) behaviour of PS gathers is generally poor and joint PP-PS AVO analysis is a struggle. In this paper, we propose to employ specular imaging for converted waves. Benefits of specular imaging with dip-angle migration have been widely shown both for 3D imaging and 4D monitoring of P wave data. Here we apply the specular imaging method to an ocean-bottom cable (OBC) dataset from the North Sea to enhance the PS images. We show that, by selection of specular energy in the dip-angle domain, PS images are significantly less noisy and migration artefacts are reduced. As a result, the AVO compliance of specular migrated gathers is significantly enhanced.