f Evaluation of 3D coverage specs - a case study

It is common practice in 3-D seismic surveying to specify criteria for CMP coverage in terms of minimum acceptance levels fór different parts of the streamers . In case these minimum levels are not met, infill seismic data are acquired in addition to the socalled primary seismic data . Depending on sea currents the infill percentage is often between 10 and 25 percent . The need for infill is also depending on the extent of flexible binning which is considered acceptable . For different levels of infill in combination with fixed and flexible binning the seismic results of a 3-D seismic survey have been analysed, in order to assess the relevante of these infill specifications . The main results of this analysis are presented in this paper . It comprises full 3-D seismic processing including 3-D migration of the primary dataset with and without the infill dataset . For this processing botte fixed binning and flexible overlapping binning has been used . In addition the effects on seismic data quality of less accurate navigation by omitting the acoustic network, has been investigated .