P-88 Increasing Resolution with a New Method for Efficient Broadband Marine Acquisition and Processing E. Kragh (Schlumberger Cambridge Research), M. Svendsen (WesternGeco), D. Kapadia (WesternGeco), G. Busanello* (WesternGeco), R. Goto (WesternGeco), G. Morgan (WesternGeco), E. Muyzert (Schlumberger Cambridge Research) & T. Curtis (WesternGeco) Summary We present a new method for broadband marine acquisition and processing. A 3D shallow towedstreamer spread is deployed, designed to optimize the mid- and high-frequency parts of the bandwidth. In addition, data are simultaneously acquired from a small number of deeper towed streamers. The depth of these deeper streamers is optimized for the low frequencies such that the combined overall bandwidth is enhanced. Because the deep streamers only provide the low-frequency part of the bandwidth, we can more sparsely sample these data enabling efficient acquisition scenarios as fewer streamers are required. A 3D case study using this new acquisition method was acquired off the NW Shelf of Australia. The streamer spread consisted of six shallow streamers towed at a depth of 6 m and two deeper streamers (below shallow streamers 2 and 5) towed at a depth of 20 m. The resulting data exhibit both high resolution and deep penetration for subsalt and sub-basalt imaging, for example. In addition, inversion for acoustic impedance, imaging, and velocity model building, also benefit from the broadband result. Data acquired in this way are more robust to poor weather conditions than conventionally acquired data. Introduction We present a new method for broadband marine acquisition and processing. A 3D shallow towedstreamer spread is deployed, designed to optimize the mid- and high- frequency parts of the bandwidth. In addition, data are simultaneously acquired from a small number of deeper towed streamers. The depth of these deeper streamers is optimized for the low frequencies such that the combined overall bandwidth is enhanced. Because the deep streamers are only going to provide the low-frequency part of the bandwidth, we can more sparsely sample these data enabling efficient acquisition scenarios as fewer streamers are required. The data are combined in processing, optimizing the signal-to-noise ratio over the entire bandwidth. The resulting data exhibit both high resolution and deep penetration, for subsalt and sub-basalt imaging, for example. In addition, inversion for acoustic impedance, imaging, and velocity model building, also benefit from the broadband result. Data acquired in this way are also more robust to poor weather conditions than conventionally acquired data. Data for a 3D case study using this new acquisition method were acquired off the NW Shelf of Australia. The streamer spread consisted of six shallow streamers towed at a depth of 6 m and two deeper streamers (below shallow streamers 2 and 5) towed at a depth of 20 m. A novel over/under source design was also used to bias source output toward low frequencies and further enhance the low-frequency signal-to-noise ratio of the acquired data. Method The effect of the free-surface ghost in marine seismic acquisition is well understood. Shallow towing favours the higher frequencies at the expense of attenuating the low frequencies, while deeper towing favours the lower frequencies, at the expense of attenuating frequencies within the seismic bandwidth. Compensating for the ghost effect has been the subject of geophysical research for many years and two successful solutions have been developed on the receiver side. These are over/under acquisition, where streamers are towed as vertically aligned pairs (Hill et al., 2006) and the use of additional velocity measurements in the streamer, where pressure and velocity measurements are combined to achieve the deghosting step (Long et al., 2008). The over/under method requires twice