Petrobras is launching a multidisciplinary carbon capture and storage project at the Barra do Furado Fieldlab, onshore Campos Basin, to test geophysical methods for monitoring the CO2 plume in a deep saline aquifer. Planned activities include advanced 3D seismic and electromagnetic data acquisitions. However, gravity measurements are not part of the current strategy. From 2028 to 2031, approximately 0.36 million tonnes (Mt) of supercritical CO2 will be injected into a reservoir with an average thickness of 130 m at a depth of 1200 m. As part of our objectives at the monitoring site, we conducted a feasibility study using flow simulators to model gravity variations during the CO2 injection. Our results indicate that after two years of injection, the gravitational response exceeded the 1 µGal threshold, demonstrating the effectiveness of 4D surface gravity measurements for monitoring subsurface fluid dynamics. Based on these findings, it is recommended that Petrobras incorporate gravimetry into its current data-acquisition plan to enhance data collection and improve CO2 management strategies at the study site. Upon request, Petrobras will provide the academic community with the 4D density model and related data presented in this paper.
The work of riverbank protection understood as a walk that runs parallel to the bank of the Osmore River - Peru, also protecting an adjacent avenue, was severely affected by the fluvial erosion associated with the dynamics of the river, even eroding part of the dual carriageway. To restore the affected areas, an extensive program of fieldwork and data processing was developed. With this objective, the corresponding analyses were carried out, so that the new design of the riverbank protection provides the technical soundness to resist the river´s extreme floods. Initially, a review of geological information and mechanical pits from previous studies was performed. In the second stage, geological-geotechnical research was carried out, where geophysical studies were developed, using seismic refraction tomography to identify geoseismic strata based on the speed of the seismic waves and high- resolution electrical resistivity tomography to identify georesistivity tomography to identify georesistivity strata based on electrical resistivities. The geophysical results, integrated with the other investigations using direct methods, allowed the integral geotechnical understanding of the study area, which led to proposing the ideal solution to the imminent risk from dynamic force of the river, knowing in detail the morphology of differentiated geophysical strata.
Accurately determining the depth of underground voids from microgravity surveys is difficult whenever neighbouring anomalies overlap or regional drift is imperfectly removed. We present a hybrid spectral–geometric workflow that combines three independent observables to stabilise depth: (1) a geometry-stable flank spacing extracted from a pseudo-magnetic field generated via Green’s vector identity; (2) a curvature-related depth scale computed with a normalised spectral operator of Abdelrahman and El-Araby; and (3) a non-linear spherical fit that ties amplitude to depth and radius. A dimensionless correction factor defined as the ratio between flank spacing and depth scale, rescales the raw fit depth and largely cancels amplitude uncertainties. A synthetic benchmark with a buried sphere at 500 m depth shows that the hybrid correction reduces the half-width error from 94 % to 4 %. Applied to the FL06 anomaly in the Braskem salt-mining district (Maceió, Brazil), the method yields zreal = 744 m ± 37 m (95 % Confidence Interval), in close agreement with borehole BH-06 at 766 m. Monte-Carlo analysis attributes 58 % of the residual depth variance to station positioning and only 9 % to density contrast. Computationally, the full pipeline executes in 30 s on a 12-thread laptop for a 0.25 km2 grid, making the approach suitable for rapid urban-risk audits where dense microgravity acquisition is feasible but full 3-D inversion is not.
This article highlights the importance of active methodologies in the teaching of geosciences, emphasizing their multidisciplinary nature and relevance for both students and society as a whole. Through an integrative review using databases such as Google Scholar, SciELO, and the CAPES journal, the study aims to demonstrate how practical approaches, such as applied projects and educational games, are effective in promoting engagement and facilitating the understanding of complex scientific concepts. By integrating environmental issues, such as climate change and energy transition, into the curriculum, students are sensitized to urgent global challenges and prepared to face them in an informed and proactive manner. Furthermore, the success of these approaches relies on a continuous commitment to the professional development of educators, who must adapt their pedagogical resources to meet the specific needs of students. The combination of active methodologies with the teaching of environmental themes in geosciences offers a significant opportunity to make education more technical and engaging, preparing students for conscious involvement in global environmental issues and bridging the gap between basic and higher education.
The Foz do Amazonas, Barreirinhas and Pará-Maranhão basins, located within the Brazilian Equatorial Margin, present significant hydrocarbon exploration potential. This study applies an integrated seismic attribute analysis to identify and characterize turbidite sandstones and carbonate reservoirs. Seismic attributes such as sweetness, trace envelope, and spectral decomposition were applied to 2D and 3D seismic datasets to enhance the interpretation of key geological features, including depositional systems and structural traps. The results reveal three leads in the Barreirinhas Basin and three leads in the Pará-Maranhão Basin, highlighting structural and stratigraphic traps associated with thrust fault systems and carbonate buildups. Spectral decomposition provided a detailed visualization of thin beds and depositional geometries, while sweetness attributes effectively identified hydrocarbon-bearing zones. These results contribute to a refined understanding of the petroleum systems in the Brazilian Equatorial Margin, offering a robust framework for future exploration and risk mitigation.
Detecting 4D anomalies in pre-salt carbonate reservoirs can be a major challenge for seismic interpretation due to low impedance contrasts and complex fluid substitution effects, as those observed in Mero field located at Santos Basin, Brazil. To overcome this task, the applied methodology comprised the use of Generalized Spectral Decomposition (GSD) jointly with a 4D seismic inversion to analyze frequency, phase and the acoustic components of the 4D signal near an injector well, where frequencies (9 Hz, 18 Hz, and 26 Hz) and phase rotations (±180º, ±90º, 0º) were evaluated. The results indicate that, although the individual spectral decomposition components do not highlight gas anomalies in the oil zone, the use of a combined attribute response — involving the specific 18 Hz spectral component rotated by -90 degrees, together with 4D Acoustic Impedance (IP4D) — shows good correlation with the variation in gas saturation observed in the vicinity of the well. This methodology, also enhanced by geobody generation to isolate anomalies, improves the detection of subtle variations associated with water-alternating-gas (WAG) injection cycles in complex carbonate settings, thereby supporting long-term reservoir management.
This article presents a gravity data integration and a regional geophysical overview of the geological framework in the State of Paraná, southern Brazil. For data processing, we used open-source computational tools based on Python libraries from the Fatiando a Terra Project. Data processing included determining theoretical gravity on the physical surface of the Earth, calculating the Gravity Disturbance, modeling topographic masses to obtain the complete Bouguer Disturbance, data gridding using the equivalent source method, and the application of enhancement techniques. The products obtained were compared with previous geological studies, revealing a robust correlation between our results and the main geological characteristics from literature. Some relatively high values of the Bouguer Disturbance indicate important structural features, such as the Paranapanema Block and the Ponta Grossa Arch. Additionally, enhancement techniques highlighted relevant geological structures, in both the Paraná Basin and the Proterozoic orogenic basement. Using the gravity method and open-source tools, this work aims to serve as a reference for future geophysical and geological investigations in the State of Paraná. The gravity maps of the Paraná are a valuable unified database for the scientific community and for future geophysical investigations. These data will be made available in an open repository, facilitating access and encouraging use in subsequent research and practical applications.
Geological faults are typically interpreted in two dimensions, such as surface objects, in seismic data, and are similarly represented in geological models of hydrocarbon reservoirs. However, in reality, faults are complex three-dimensional zones that may represent regions of weakness concentrating fractures and highly deformed rocks. Therefore, the adequate representation of these zones is important for the management and economic evaluation of a hydrocarbon field, especially for carbonate reservoirs such as pre-salt in the Santos Basin, with implications for well drilling locations, completion, strategies for increasing the recovery factor and even on estimating the recoverable reserve. This work aims at the structural modeling of faults, with geometry similar to that observed for the pre-salt reservoir faults, simulating these faults using a Discrete Element Method and forming the seismic image using Reverse Time Migration method. The fault zone model was built based on published and documented datasets from the Arab-D carbonate reservoir of the Ghawar Field, Saudi Arabia. The work also addresses the impacts of the spatial resolution of seismic data on the fault interpretation. The results showed that although the volumetric interpretation of these structures through interpretation methodologies based on seismic attributes is possible, there is a considerable limitation in the spatial resolution of seismic data, as the fault zone tends to be narrow and exhibits small velocity contrasts compared to the surrounding rocks under the expected stress state for deep reservoirs.
Radon is a radioactive gas produced by the spontaneous decay of uranium. Prolonged exposure to the gas increases the likelihood of developing lung cancer. Therefore, monitoring and control are essential for managing public health risks. However, in the Brazilian State of Rio Grande do Sul, there are no radon measurements for residential areas or a map to guide municipalities for investigation. This study aims to develop a geogenic radon potential map for Rio Grande do Sul based on Radiometric Contour Maps and identify priority municipalities for future studies. A geospatial analysis of geogenic radon potential was conducted for a subset of 85 out of 497 municipalities in the State of Rio Grande do Sul, Brazil, using equivalent uranium (eU) as a predictor. Data were obtained from the Radiometric Contour Map of Uranium Concentration produced by the Geological Survey of Brazil. Most municipalities (57; 67.1%) had uranium concentrations within normal levels. However, 28 municipalities (32.9%) had uranium measurements above normal levels, and seven were identified as priority areas for further studies. The highest uranium concentration detected was in the municipality of Encruzilhada do Sul, with 15.0 ppm of eU. All 85 municipalities in Rio Grande do Sul studied showed geogenic radon potential. Municipalities with higher uranium concentrations were prioritized for radon exposure analysis.
We exploit finite-difference method schemes to solve the wave equation within the migrated time-domain, offering a robust alternative to traditional depth-domain imaging method. While this formulation approximates the acoustic wave equation used in depth models, specific kinematic terms differ. By applying kinematic ray tracing principles to evaluate propagation, we analyze the stability and dispersion of centered and staggered grid schemes. This evaluation is crucial for validating numerical parameters in simulating seis-mic phenomena, bridging the gap between depth and time migration frameworks. Our results indicate that this wave-type behaves numerically similarly to depth-domain models, except for amplitude differences. More-over, the staggered grid scheme superiorly minimizes numerical dispersion and noise. Consequently, this study demonstrates that wave propagation based on plane wave theory and traveltime analysis is highly viable in the time-migrated domain, laying the groundwork for advanced imaging and inversion techniques using two-way equations.
Being an important economic and industrial hub, Arequipa is the second most populous city in Peru, with over one million inhabitants. Within its metropolitan area, high-amplitude vibrations are generated by heavy construction machinery as well as by urban and commercial transportation. These vibrations pose a potential risk of damage to both urban and archaeological infrastructures. To assess possible structural impacts, vibration measurements were collected at significant sites and analyzed according to the DIN 4150- 3 standard. Ground vibrations attenuation was evaluated using the Levenberg-Marquardt inversion method. Regression adjustment models were developed, and the analysis of geometric and material damping coefficients was automated with the application of neural network algorithms, in areas with lower data density. The results indicate that vibrations caused by heavy machinery can damage sensitive or residential structures, as the peak particle velocity (PPV) exceeded 20 mm/s in these cases. However, for sources such as vehicular traffic on bridges and railway transport, the PPV only exceeded 10 mm/s. Attenuation analysis revealed that maximum particle velocity decreases with increasing distance from the source, and that the strongest damping occurs in the vertical component. Geometric damping (γ) values ranged from 0.1 to 1.65, and material damping (α) values ranged from 0.001 to 0.03 for the various sources evaluated. In cohesive soils, wave propagation is faster, which reduces tension in the foundations, whereas in sandy-silty soils, slower propagation increases the tension transmitted to the foundations. This research also aims to lay the foundation for the development of Peruvian regulations framework to assess structural damage caused by anthropogenic vibrations, since there are no existing regulations governing these effects on buildings. This study can help propose guidelines for the city of Arequipa.
Most of the information available in frontier exploration areas comes from seismic data, eventually from legacy 2D seismic lines. This is the case of the Pelotas Basin, the southernmost basin along the Atlantic continental margin in Brazil. The basin belongs to the Austral sector of the rift and breakup of the Gondwana Supercon- tinent, in the Early Cretaceous. Significant hydrocarbon discoveries have been reported over the last few years in this sector, along the counterpart African margin, in ultra deep-water, offshore Namibia. This article describes a successfully tested workflow to forecast geomechanical and petroleum system information during seismic reprocessing of outdated 2D data from the Pelotas Basin. A geomechanical-geopressure model was produced from seismic velocities double-checked with both normal move out and image gathers. The model, which was computed with standard equations (eg. Gardner’s and Eaton’s), and conceptual velocity gradients of normal compaction trends, is fully consistent with the mechanical stratigraphy and deformation analysis of the studied area, close to the shelf border in the Central Pelotas Basin. The geomechanical results pertinent to petroleum systems indicated good seal potential and probably hydrocar- bon generation associated with an overpressure regime in the deeper Paleogene and Cretaceous successions of the basin, particularly beyond shelf border and slope. In this way, the Pelotas Basin may share, in deep-water environments, the same promising play found in recent times in Namibia.
Brazilian pre-salt carbonates represent more than 70% of the produced hydrocarbons in Brazil, which makes them of great interest for 4D seismic studies. 4D seismic modeling is crucial to understand how production impacts the 4D seismic response. We propose including rock-fluid interaction on the traditional methodology for 4D petro-elastic modeling (generally considering only variations of pressure and fluid saturation) given the presence of CO2 in the injected fluid. To model the rock-fluid interaction, we consider expressing the dry rock bulk and shear moduli as a function of the porosity for the monitor data. In the modeling, we focus in observing changes in the rock due to dissolution of CaCO3 by the CO2-rich injected fluid. We perform the analysis in the region around the injector wells and the results show that rock-fluid interaction favors the 4D anomalies, considering the reservoir conditions in this study. The higher ∆AI values obtained in petro-elastic modeling with rock-fluid interaction present an optimistic scenario compared to a traditional petro-elastic modeling in 4D feasibility studies and as another hypothesis that supports the interpretation of 4D anomalies.
A common approach to stabilize the ill-posed inverse problem is to apply regularization, which restricts the possible solutions to these problems. Thus, a regularization term is often incorporated into the tomographic objective function to resolve the non-uniqueness of the inverse geophysical problem, restricting the possible solutions to these problems. This work evaluates the effects of regularization and analyzes its impact on the resulting seismic velocities. Grounded in a detailed case study, we investigate Tikhonov's regularization of order 1 and its variants, including order 2, utilizing a tomography program that employs ray tracing, a finite differences scheme with the eikonal equation for first arrivals, and the regularization algorithm. The velocity model is synthetic and based on shallow seabed channel geology. The true model was compared with the tomography results without regularization and with regularization schemes. The results clearly indicate that regularization parameters play a critical role in defining the outcomes of velocity models in tomography inversion. By applying regularization, we significantly reduce structural distortion in tomographic results — this approach proves to be not only effective but essential. Tikhonov’s regularization of order 2 consistently demonstrates faster convergence and notable improvements in the velocity model. Furthermore, our parameter sensitivity tests reveal the extent to which an inappropriate choice can distort geological structures, such as by creating artificial structural highs or lows, underscoring the necessity of careful selection in regularization techniques.
The exhumation and exposure of mantle rocks is a common process that takes place during the tectono-magmatic evolution of a newly created lithosphere along slow- and ultraslow-spreading oceanic ridges, such as the Equatorial Mid-Atlantic Ridge. A geophysical survey conducted in 2012 and 2013 between the Bogdanov (7º 10’ N) to the St. Paul (0º 50’ N) fracture zones revealed lower crust and upper mantle rocks exposures through asymmetric accretion along low-angle normal faults, i.e., the Oceanic Core Complexes, laterally associated with other morpho-tectonic features. The dataset consists of multi-beam bathymetry (100 m/pixel) and ship gravity (1,750 m/pixel) covering an area of 40,000 km2. Seismicity and satellite free-air anomaly data are included. Three oceanic transform faults and nine non-transform offsets were identified and mapped along the ridge axis. Oceanic Core Complexes are characterized by corrugated and non-corrugated massifs, back-tilted ridges indicating detachment breakaways, and various detachment morphologies. These features typically exhibit bathymetric patterns that are roughly parallel to the accretion direction, positive Bouguer anomalies, and low seismic activity. Twelve Oceanic Core Complexes consistently occur at non-transforming discontinuities and asymmetric accretion segments. These mantle outcroppings indicate a low melt supply during the recent tectono-magmatic evolution of this region of the Mid-Atlantic Ridge.
Accurate seismic first arrival picking is fundamental for geophysical interpretation and subsurface imaging. This study evaluates the performance of wavelet-based denoising techniques combined with the Translation-Invariant Shrinkage (TIS) algorithm to enhance first arrival detection. The Higher Density Discrete Wavelet Transform (HDDWT) and Double Density Wavelet Transform (DDWT) are applied to synthetic and real seismic datasets with varying noise levels. Results indicate that HDDWT outperforms DDWT in preserving critical low-frequency components and maintaining signal fidelity, particularly under high noise conditions. The P-phase Picker algorithm, when integrated with HDDWT, achieves superior accuracy and reliability in first arrival detection. These findings underscore the potential of HDDWT and TIS as robust tools for improving seismic data quality and enhancing interpretation workflows.
Among the methods for mitigating the first-order effects of the ionosphere, the Klobuchar model and final Global Ionosphere Maps (GIM) produced by the International GNSS Service (IGS) are widely used. Previous studies have looked at their effectiveness in discrete periods and locations of Brazil, but this may have led to incomplete conclusions. Aiming to contribute to this discussion, this paper presents a more comprehensive evaluation of the Klobuchar model and IGS GIM performances in single-point positioning using data from the whole year of the solar cycle 24 peak from six stations of Brazilian Network for Continuous Monitoring of the GNSS Systems (RBMC). When compared to the solution without using correction for the ionosphere, improvements of approximately 39% and 52% were obtained with the Klobuchar model and the GIM, respectively. The results suggest that the lower intensity of solar cycle 24, the location of the GNSS station relative to the geomagnetic equator, and the occurrence of post-sunset ionospheric irregularities contribute to the worse performance of the assessed models when compared to research done with GNSS data from solar cycle 23.
The present study integrates the magnetometric with petrographic data from the Morro de São João (MSJ) Alkaline Complex to investigate the magmatic evolution of the complex. The findings emphasize the critical role of magma mixing processes in shaping the textural and compositional diversity of MSJ rocks. The complex is a circular and conical body of approximately 10 km² located southeast of Rio de Janeiro composed of alkaline rocks strongly-silica undersaturation. The study used conventional petrographic analysis and aeromagnetic data processing, such as the Total Gradient Amplitude (TGA) and Reduction to the pole (RTP) maps to reveal the presence of multiple anomalous domains, supporting the hypothesis of non-cogenetic magmatic bodies that interacted during magma mixing events. To accomplish these objectives, this study employs a cross-correlation method to estimate the magnetization direction of the magnetic source. From a geodynamic perspective, the evolution of the MSJ’s evolution is supposed to be closely linked to geomagnetic polarity reversals, mantle plume activity, and extensional tectonic processes associated with the break-up of the Gondwana paleocontinent. These factors contributed to the generation of alkaline magmatism through the decompression of the subcontinental lithospheric mantle and the thermal influence of deep mantle plumes.
Ocean bottom nodes (OBNs) are a recent technological solution used for seismic data acquisition. Despite of various advantages compared to conventional methods of measurement, the amount of data acquired in OBNs campaigns poses challenges to energy management and data transmission, ultimately limiting the time the device can acquire data on the seabed. To deal with these disadvantages, compression techniques and prediction models have been proposed in the literature and in both approaches the type of trace is an important information. In this work, strategies for developing seismic trace classifier models are assessed aiming to classify seismic traces from ocean bottom nodes into active, passive and microseism. The models were developed based on the machine learning algorithms decision tree and neural networks. Moreover, different features were used in the training process in order to analyze physical quantity dependent and agnostic classifier models. Five different datasets and thousands of traces were used for training and testing the models developed. Models outputs are explored in terms of confusion matrix, accuracy, precision and recall. Results have shown that the use of acceleration and velocity data for classification of microseism and passive traces led to a lower accuracy when compared to the use of sound pressure data. In addition, no relevant difference was found between the decision tree and neural networks for the classification task.
