Repeatability Of 3-D Ocean Bottom Cable Seismic Surveys

The repeatability of seismic data acquisition and processing has become an important question in determining<br>the role of conventional land, marine, and transition zone systems in seismic monitoring of reservoirs. In this<br>paper we examine a case study involving two repeated 3-D seismic surveys acquired using an ocean bottom<br>cable (OBC) system. Although not originally acquired as part of a monitoring project, the survey design and<br>preplanned source and receiver patterns were identical over a significant area. We found, not surprisingly, that<br>since the two had some differences in acquisition and processing, “off-the-shelf” final migrated data volumes<br>showed significant differences. However, by careful reprocessing of the prestack data with a sequence<br>designed to maximize repeatability of the signal, the differences were reduced dramatically. The level of<br>repeatability required for a given monitoring project depends on the specifics of the reservoir and the<br>monitoring goals; however, in this case, repeatability achieved between the two data volumes indicates that<br>OBC data would likely be suitable for analysis of reservoir fluid movement.