Multiple attenuation techniques on OBC survey in Campos basin

Multiple attenuation is one of the biggest challenges in the seismic signal processing workflow in Campos basin. This comes from the seafloor depth variability and multiple reservoir target levels, in both pre-salt and post-salt zones. In this scenario, the main multiples interfere with the primaries, preventing a good reservoir image. The industry standard approach for multiple prediction is the 3D surface related multiple elimination (SRME) with many good implementations on towed streamer data. In Ocean Bottom Seismic (OBS) acquisition, sources are near the surface while the receivers are deployed at the seafloor, giving two different datums in the process. This dual datum poses a problem to the use of this technique direct from the OBS data. To overcome this, the traces necessary to the prediction with SRME in the OBS data are obtained from a towed streamer data in the same area. Another effective demultiple technique is the one based on the source-side wavefield propagation of the water layer to model the related multiples as described by Kostov et al. (2015) with the Generalized Deterministic Water bottom Demultiple (GDWD). Here we show a case study in Campos Basin, offshore Brazil, where towed streamer complements ocean bottom cable (OBC) data to generate a 3D SRME multiple model and then combined with water-layer wavefield propagation model to produce an improved multiple attenuation from shallow to deep water. We look at the models and its adaptive subtraction results. The streamer-OBC 3D SRME shows a reliable multiple model where the towed streamer data coverage matches the OBC’s. Meanwhile, the GDWD produces a complementary model covering most of the previous’ weaknesses resulting in a robust combined model.