Milestones in OBC Data Processing

Abstract OBC technology reveals more and more potentials in PZ imaging. It shows a better image in comparison with the conventional streamer result. In the following paper, we will describe the methodology for processing OBC data. We will focus on the key points that could explain the effectiveness of this technology. After a description of OBC data, we will see that many issues are specific to this technology due to the fact that it is half way from land and marine acquisition. We will show how we deal with different issues such as reorientation, coupling, noise and water-layer multiples attenuation through our new methodology for PZ summation. Receiver ghost elimination, high fold and wide azimuth coverage are the main points that differentiate the OBC from the conventional streamer and contribute to the improvement of the results. We will show how these features contribute to the building of a good structural image. Moreover, processing the data with respect to the azimuth is important to fully take into account 3D heterogeneities and possible azimuthal anisotropy by tracking velocity variations. For that purpose we settled an effective methodology that allows us to check these variations through adequate and accurate QCs. All these topics will be illustrated on several real datasets. Introduction In the past, ocean bottom cable (OBC) technology was mainly used in transition zones where neither onshore nor offshore conventional seismic could be shot. In the nineties, OBC moved to offshore showing a high potential for imaging areas where platforms obstruct the navigation of streamer boats. In the meantime, cables were enriched with new horizontal sensors making it possible to record converted PS waves and image through gas clouds where conventional P wave imaging failed due to very strong wave attenuation [1]. OBC technology has now been deployed in many areas of the world. It has been intensively shot in the North Sea where streamer data is available.