Reservoir Imaging Ltd (RIL), the 4-D seismic software services consultancy based in Edinburgh, Scotland has been working on the planning and QC of wide-azimuth surveys, the emerging marine seismic data acquisition technique being employed to image complex geologies such as the subsalt of the Gulf of Mexico.

RIL is drawing on its established expertise in ensuring the accuracy of 4-D repeat seismic reservoir monitoring surveys to provide optimal positioning and QC for the large towed streamer spreads being deployed in wide-azimuth surveys. In particular, wide azimuth surveys have source lines shot multiple times by source vessels: these have to be accurately plotted in the same way as the repeat lines in a 4-D seismic survey. A further challenge is the need for feather-matching, a process which ensures that the varying degrees of ocean turbulence affecting the seismic recording cables on each line recorded can be accurately accounted for in the seismic data acquired.

Last year RIL launched its Osprey suite of QC technologies for 4-D survey positioning accuracy and repeatability, which has been adapted and enhanced to deal with the complexities of wide-azimuth acquisition. RIL personnel in the field perform the data quality control with all outputs loaded into a GIS database.  The QC system incorporates mapping, repeatability, coverage, and documentation. Results are made available via a Web-based GIS server which enables all the stakeholders to be involved in the decision-making process regarding the survey’s progress.