e Barreirinhas Basin is located in northeast Brazil and is part of the Brazilian Equatorial Margin, a new exploration frontier with complex geology. is basin is characterized by a rugose water bottom, a fast carbonate platform, shallow gas pockets, and a complex channel network. All of these elements represent a signi cant challenge for velocity model building and imaging of the depositional system. From preprocessing to nal imaging, high-end technologies were required to meet the processing objectives. e 3D designature and 3D deghosting were crucial to remove bubble energy and ghosts related to canyon di ractions. e velocity model building exploited o set-dependent dip information in the nonlinear slope tomography-i.e., dip-constrained tomography (DCT)-to deal with small-scale lateral velocity variations. e full-waveform inversion, up to 20 Hz, was able to e ciently capture small velocity anomalies and resolve highspatial-resolution variations that DCT could not totally solve. Even with a detailed velocity model, some dim zones and amplitude variations were still observable in the depth-migrated image. Gas pockets, responsible for the absorption and phase distortion of the seismic signal (commonly denoted by the quality factor of attenuation, Q), were detected and delineated using volumetric Q tomography. e resultant interval Q model was consistent with the geology, and its use was bene cial in a Q-compensating Kirchho prestack depth migration.

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