Processamento de dados sísmicos marinhos de alta resolução usando sistema sparker monocanal: (plataforma da Bahia, Brasil)

Abstract

Single-channel seismic data are still a challenge to apply fundamental processing techniques such as deconvolution and migration. This study proposes a workflow processing for high-resolution seismic-reflection data regarding problems of wavelet phase, low signal/noise ratio of raw data, random noise, transmission loss, static variations, and multiples, which restrict the geological information of shallow marine strata. The data were acquired using an Applied Acoustics Squid2000 sparker system, operating up to 2500J, with a frequency range of 100-1200Hz. The survey was carried out in the inner shelf of Bahia in front of the Jequitinhonha delta and aimed to investigate Quaternary deposits and stratigraphic structures. The processing explores fundamentally predictive deconvolution and Kirchhoff migration, and then applies techniques of static correction, band-pass frequency, gain, and average filters as secondary techniques. Deconvolution removed random and high-frequency noises and broadened the frequency spectrum of the data. Kirchhoff migration collapsed the diffraction hyperbolas, enhanced coherency, and continuity of reflectors along with the data, and repositioned dip reflectors close to their real position. Application of static correction combined with bandpass fitter and average filters smoothed the undulating seabed reflector and subsurface reflectors. The results confirmed the efficiency of the processing workflow proposed here by removing random and high-frequency noises, correcting static variations, slightly attenuating the seabed multiple, moving reflectors to their real position, and providing a high signal/noise ratio image that better represents the subsurface of the southern Bahia continental shelf.