P-to-S converted waves (or C-waves) have been successfully used to image beneath gas clouds in many areas. However, C-waves often suffer from severe diodic effects due to the gas clouds; that is, the C-wave amplitude and traveltime may be different in the forward and reverse shooting directions, giving rise to different C-wave stacking velocities (diodicVC) and velocity ratios (diodic γeff). In some cases, whether a horizon (a geologic target) beneath a gas cloud can be undershot also depends on the shooting directions (diodic illumination). These effects,...

First Page Preview

First page PDF preview
You do not currently have access to this article.