Page 36: of Marine Technology Magazine (October 2014)

ous Transfer of Rights Agreement, between Petrobras and the Union (Brazilian Government). BroadSeis Technology CGG?s BroadSeis technology is based on a marine broad- band seismic data acquisition system, combining the use of sensitive low-noise Sercel Sentinel streamers con gured to optimally curved, variable-depth, streaming pro les, with an average depth of over 40 m, and 3D de-ghosting. The com- bined use of the optimized Sentinel streamers and very deep and stable towing has delivered an excellent signal-to-noise ratio at the lowest frequencies (down to 2.5 Hz). The devel- opment of this unique broadband seismic data acquisition system, has been a key factor in enhance deep, pre-salt imag- ing, and also to highlight layering and facies variations. ?The optimally curved streamer pro le provides excellent receiver ghost notch diversity, for de-ghosting the data and accessing the widest bandwidth possible. This results in a clean, sharp seismic wavelet, with minimal sidelobes. This, along with Reverse Time Migration imaging technology has greatly im- proved the resolution of events and allowed geologists to more easily recognize and interpret the geological features that iden-tify the location of potential hydrocarbon reservoirs. After the discovery of Lula, subsequent discoveries con rmed that the Lower Cretaceous carbonate reservoirs have been established within the upper synrift and post-rift layers, singling out these layers as the most probable locations of any pre-salt reservoirs in the Santos Basin,? said Luiz Braga, while explaining how BroadSeis worked. Another CGG seismic asset is StagSeis, which is a full-azimuth, ultra-long offset broadband solution to provide the best images beneath complex overburdens, such as found in the pre-salt, to reduce exploration risk. Variable depth streamer BroadSeis frequencies in colorOctober 201436 MTRMTR #8 (34-49).indd 36MTR #8 (34-49).indd 3610/10/2014 11:13:49 AM10/10/2014 11:13:49 AM