O contexto estratigráfico da porção oeste da Bacia do Solimões, na zona limítrofe entre Brasil, Peru e Colômbia, foi elaborado com base em dados de 9 logs de sondagem (P1 a P9) do Projeto Carvão no Alto Solimões. Com os dados geológicos (testemunhos) e geofísicos (Raios Gama, Resistividade e Potencial Espontâneo) foi elaborada a seção geológica A-A’, de direção geral SW-NE, com cerca de 400 km de extensão, onde foram definidas as espessuras e limites das formações Solimões (Mioceno-Plioceno) e Içá (Plioceno-Pleistoceno) e Depósitos Quaternários. A Formação Solimões exibe continuidade lateral nas sondagens P1 a P9 e espessura em torno de 332 metros, sendo constituída por intercalações de pelitos e arenitos, com calcários, linhitos e conglomerados subordinados, que exibem padrões de adelgaçamento, espessamento e interdigitação. A Formação Içá ocorre principalmente na porção leste da seção, sendo predominantemente arenosa, com raras intercalações de pelitos e linhitos e espessura variando entre 30 a 55m, recoberta por delgados depósitos Quaternários, compostos de areia e lama (silte e argila), com espessura de até 16 metros. Perfis geofísicos proporcionaram padrões de eletrofácies e em conjunto com dados litológicos permitiram a individualização dos limites estratigráficos e das litofácies internas, que foram correlacionados nos perfis analisados.

Objective: this work presents the results obtained in the development of a seismic velocity inversion mo­del. The reference times recorded on the surface are taken and using the inversion model to obtain the initial reference model (hypocenters and velocities), starting from an unknown model. Methodology: A hypothetical reference model is pro­posed containing 64 blocks with interval velocity, 16 recording stations on the surface, and 64 earth­quakes in the center of each block. With this model, the reference arrival times are generated for each ear­thquake registered in each station. The inversion mo­del is made up of two parts: the direct model, which allows calculating the arrival times of the signal regis­tered on the surface according to the hypo-central lo­cation of the earthquake and the velocity of the P and S wave of the medium; and the inverse model, which estimates a model of the velocity of the environment and hypo-central locations of the earthquakes that are the input variables of the direct model. The direct model was developed with the wave equation, while the inverse model was developed by modifying the generalized inverse matrix by introducing a factor called “damping.” Results: The discretization model is based on the finite difference method.. When estimating the values of velocity and hypo-central location with the inverse algorithm, the propagation of the wave is simulated with the direct model, and they are compared with the data of reference times measured on the surface. Depending on the value of the mean square error, we proceed to modify the mean velocities and hypo­centers of the earthquakes. This process is repeated iteratively until the calculated error is less than a to­lerance of 2x10-3s2. Conclusions: It was found that the estimated values of velocity and hypo central locations coincide well for regions closer to the surface, while for deep regions the error is greater compared to the hypothetical re­ference model.

The reliable prediction of pore pressure is essential for petroleum engineering in its different stages, with the Eaton and Bowers' methods being the most used for this purpose. However, their application in carbonate rocks still needs to be improved because carbonates do not compact uniformly with depth, as shale does. This research calculated the pore pressure using the Eaton, Bowers, and Weakley methods and well logs of a carbonate formation and found that the Weakley's approach predicts pressure more accurately. The method presented uses an acoustic impedance equation derived from the Bowers' method, whose parameters were calibrated with the Weakley's pore pressure profile. The pore pressure estimated near the borehole, via the acoustic impedance provided by the pre-stack inversion, is very close to that observed during drilling, which indicates a reliable prediction. The method was applied to a seismic line and well logs in the Middle Magdalena Valley Basin—Colombia, where the overpressured well Lizama 158 caused a significant environmental disaster in 2018. The obtained subsurface pore pressure distribution is reliable, matches overpressure in calcareous rocks near the well, and estimates anomalous pressure in zones distant from the well.

Fields of sandy paleodunes have been identified in Brazil, Colombia, Venezuela, and Guyana north of the South American continent. In this study, geochronological data obtained by optically stimulated luminescence (OSL) for paleodunes in the Middle Rio Negro region (Brazil) allowed the identification of two stages of dune deposition: the older from 169.74 ± 1.01 ka to 124.38 ± 0.91 ka and the younger from 18.89 ± 0.88 ka to 14.75 ± 0.77 ka. The older interval is the first reported in the Amazon; no correlated sediment has been documented. In contrast, the more recent depositional interval correlates to the interval of paleodune fields of the region called “dry corridor” in the Late Pleistocene–Holocene. In this study, we associated the genesis of paleodunes with the reworking of alluvial deposits from the Negro and Demini rivers, driven by river seasonality during the Pleistocene–Holocene, as evidenced by characteristic microtextural data.