Presalt reservoirs of the Santos Basin accounted for more than 50% of Brazilian hydrocarbon production in the first two months of 2019. Its most important reservoirs are found in the Barra Velha Formation; thus understanding its genesis and geologic history is essential. This formation is composed of carbonates deposited in an alkaline lacustrine environment with a multiplicity of facies from boundstones and grainstones to mudstones. We have performed a sedimentary analysis based on the integration of sidewall core (SWC) samples and well logs from two wells coupled with seismic patterns discrimination to characterize the tectonic and depositional evolution of the Barra Velha Formation in a sector of the Outer High of the Santos Basin in this study. Our method initially consisted of the evaluation of well logs, aiming to identify shallowing and flooding upward cycles of the second and third orders for the paleoenvironmental conceptualization upper rift and sag phases. Then, we defined electrofacies through the integration of SWCs, gamma ray, and acoustic impedance logs using the crossplot approach. Finally, we described seismic patterns throughout the study area and correlated with results from well data analysis. Therefore, the Barra Velha Formation was subdivided into three zones: the lower, intermediate, and upper zones. Well 1 has a facies association characteristic of a proximal and stable environment during deposition, whereas well 2 initially presents in a distal environment sedimentation that evolves to a more proximal setting. This fact evidenced differences with respect to base-level variations indicating compartmentalization within the lacustrine environment of the upper rift and sag phase that corroborated with the detailed seismic pattern interpretation of the study area.

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This paper discusses the generation of synthetic 3D seismic data for training neural networks to solve a variety of seismic processing, interpretation, and inversion tasks. Using synthetic data is a way to address the shortage of seismic data, which are required for solving problems with machine learning techniques. Synthetic data are built via a simulation process that is based on a mathematical representation of the physics of the problem. In other words, using synthetic data is an indirect way to teach neural networks about the physics of the problem. An important incentive for using synthetic data to solve problems with artificial intelligence methods is that with real seismic data the ground truth is always unknown. When generating synthetic seismic data, we first build the model and then calculate the data, so the answer (model) is always known and always exact. We describe a methodology for generating on-the-fly simulated postmigration (1D modeling) synthetic data in 3D, which are high resolution and look similar to real data. A wide range of models is covered by generating an unlimited number of data examples. The synthetic data are built from impedance models that are constructed through geostatistical simulation of real well logs. With geostatistical simulation, we can describe various geologic variance models in 3D and obtain realistic images. To cover a broad range of scenarios, we need to generalize the seismic data story by randomly perturbing many parameters including structures, conformity styles, dip-strike directions, variograms, measured input logs, frequencies, phase spectra, etc.

ABSTRACT. Studies on evaporitic rocks are of great importance for the oil and gas industry as they can create traps and seals for the hydrocarbon accumulations. Also, salt high ductility allows the formation of complex structures associated with halokinesis posing thus major challenges for imaging the rocks at their flanks and below the structures. This paper discusses the effects of salt tectonics on post-salt layers and the difficulties in interpreting the top salt surface in a particularly complex area of the Santos Basin. The available seismic and migration velocity model data are from an area located in the distal portion of the Santos Basin where the existing salt structures had a profound effect on the post-salt layers. Complex salt structures were formed in this area due to the intrinsic characteristics of salt rocks as it flew away from the terrigenous depocenters, pushed in the Atlantic Ocean realms. Structures such as overhangs are common and sometimes difficult to be mapped. Their geometry generates multiple points with the same latitude and longitude, but at different depths as they are interpreted and thus represent a challenge for current surface interpolation algorithms. A workflow is proposed to optimize multi-z surfaces generation from the top of the salt layer from the interpretation this surface in conjunction with the analysis of the migration velocity model. Finally, a zonation map of the salt walls, mini-basins, salt domes, overhang and salt window in the region is presented.Keywords: halocynesis, seismic interpretation, salt structures zonation, top of the salt layer.RESUMO. Estudos sobre rochas evaporíticas são de grande importância para a indústria de petróleo e gás, pois podem criar armadilhas e selos para o acúmulo de hidrocarbonetos. Além disso, a alta ductilidade do sal permite a formação de estruturas complexas associadas à halocinese, representando assim grandes desafios para a visualização das rochas em seus flancos e abaixo das estruturas salinas. Este artigo discute os efeitos da tectônica de sal nas camadas do pós-sal e as dificuldades em interpretar a superfície do topo do sal em uma área particularmente complexa da Bacia de Santos. Os dados sísmicos e de poços utilizados são de uma área localizada na porção distal da Bacia de Santos, onde as estruturas de sal existentes tiveram um grande efeito nas camadas do pós-sal. Estruturas complexas de sal foram formadas nesta área devido às características intrínsecas das rochas salinas à medida que se distanciaram dos depocentros terrígenas, empurradas para o domínio do Oceano Atlântico. Estruturas como overhangs são comuns e às vezes difíceis de serem mapeadas. Sua geometria gera múltiplos pontos com a mesma latitude e longitude, mas em profundidades diferentes conforme são interpretadas e, portanto, representam um desafio para os algoritmos existentes de interpolação de superfície. Um fluxo de trabalho é proposto para otimizar a geração de superfícies multi-z do topo da camada de sal a partir da interpretação sísmica desta superfície em conjunto com a análise do modelo de velocidade de migração. Por fim, é apresentada um zoneamento das muralhas de sal, mini-bacias, domos de sal e janela de sal na área de estudo.Palavras-chave: halocinese, interpretação sísmica, zoneamento das estruturas do sal, topo da camada do sal.