We successfully attenuated water bottom multiples from seismic data obtained from offshore Niger Delta by deriving a special parabolic Radon filter and applying it to the input. However, [ 21 ] opine that applying a proper bulk shift to the CMP gathers and picking NMO velocities for flattening the gathers prior to the parabolic radon transform could remove the drawback of the method in complex areas. Veiw figure View current figure in a new window View previous figure. This was done in the domain; of approximately ms was obtained and the value was fairly constant for all the multiples in the data, measured at different locations in the area. To optimally transform the data in the Radon space where the primaries are well separated from the multiples, an optimum range of moveout values is necessary, and the challenge is how to choose the maximum and minimum value of. Multiples from the water bottom the interface of the base of water and the rock or sediment beneath itas illustrated here, and the air-water interface are common in marine seismic data, but they can be suppressed by seismic processing. It is therefore easy to separate the multiple model from the primaries by picking a mute in the Radon space as shown in Figure 5.
As a result, in our approach to the multiple elimination, we output the modeled radon gathers and transformed back to the domain where we did a subtraction of the multiple model from the primaries by application of the mute.
If the acoustic impedance contrasts generating multiples are higher than the contrasts generating primary reflectors, for a given time, the spurious events will be stronger on the seismic section. We observed that as the increment increases, more detail and resolution is seen in the Radon space, but beyond a particular sampling, no significant improvement is seem in the multiple model generated. Fig ure 1 a: As a result, in our approach to the multiple elimination, we output the modeled radon gathers and transformed back to the domain where we did a subtraction of the multiple model from the primaries by application of the mute. In the present work, we used the approach of parabolic Radon transform to successfully model and attenuate water bottom multiples from seismic data acquired in offshore Niger Delta and by this process, improved the seismic data quality. Direct primary arrivals and different sets of multiples are shown. Their presence on a recorded section is due to the fact that an acoustic impedance contrast between two adjacent layers, reflects down-going waves up as well as down.