https://repositorio.ufu.br/handle/123456789/20867 Thu, 03 Sep 2026 23:14:42 GMT 2026-09-03T23:14:42Z https://repositorio.ufu.br/handle/123456789/50007 Title: Análise multivariada aplicada à caracterização química de rochas carbonáticas do marco Lula, pré-sal da Bacia de Santos Abstract: Since the discovery of the pre-salt reserves in the Santos Basin, significant progress has been made in understanding non-marine carbonate reservoirs, although debates persist regarding depositional processes and spatial distribution. In this context, the Lula’s Fingers stands out, located at the top of the Barra Velha Formation, near the evaporitic succession of the Ariri Formation. This interval is characterized by total and spectral gamma-ray anomalies, particularly uranium, and gathers consistent evidence of microbial activity and subaerial exposure, contrasting with the classical abiotic precipitation model. Given the relevance of the Lula’s Fingers, this study aims to identify and describe the textures, sedimentary structures, and diagnostic chemical signatures of the interval, as well as to compare results from wells drilled in the Tupi and Iracema Fields. To achieve this, a multi-technical and multi-scale analysis was proposed, involving drill cores, petrographic thin sections, and chemical analyses via portable X-ray fluorescence (p-XRF) and SEM-EDS from three wells (A, B, and C). Quantitative p­XRF chemical data were processed using an unsupervised machine learning algorithm to define chemical facies, while SEM-EDS point data were used to refine these facies and improve the understanding of compound distribution. Results show that the Lula’s Fingers is essentially composed of in situ rocks, calcilutites (CLU), spherulestones (SPH), and shrubstones (SHB), and reworked rocks, such as calcarenites (CRE) and calcirrudites (CRU), with a notable recurrence of CLU featuring irregular or crenulated laminations. The proportion and stacking patterns of these lithologies vary significantly between wells, with distinct features in Well C (Iracema Field) suggesting a different tectonic pattern compared to the Tupi High. Multivariate cluster analysis identified four common chemical facies (FQ1, FQ2, FQ3, and FQ4) across all three wells, with a localized occurrence of FQ5 in Well C. These facies record distinct diagenetic and depositional processes, including dolomitization, silicification, increased detrital input, high evaporation rates, and hydrothermal influence. Probability analysis indicates the establishment of microbial plains associated with the shallow lacustrine pre-salt system, with evidence of marine incursions. This integrated approach not only advances data processing methodologies but also provides a better understanding of the paleoenvironmental evolution of the Lula’s Fingers, reinforcing the importance of integrating petrographic and chemical data in characterizing complex depositional systems such as the pre-salt of the Santos Basin. Thu, 19 Mar 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/50007 2026-03-19T00:00:00Z https://repositorio.ufu.br/handle/123456789/49979 Title: Aplicação de Rock typing na caracterização de reservatórios do pré-sal na Bacia de Santos: um estudo de caso com fácies químicas Abstract: Driven by the discovery of large oil reserves in the pre-salt interval of the Brazilian eastern margin basins, the last few decades have been marked by significant advances in the understanding of non-marine carbonate rocks. Despite this progress, understanding the heterogeneities of these rocks remains a significant challenge. Therefore, using an integrated approach, this study incorporates: (i) lithological and mineralogical data acquired at macro- and microscopic scales; (ii) geochemical data, expressed through chemical facies defined by multivariate analysis; and (iii) porosity (%) and permeability (mD) data, all obtained from core samples from two wells (A and B) drilled in the Tupi Field, pre-salt of the Santos Basin. The study aims to integrate the rock typing classification method with petrographic and geochemical data to deepen the understanding of depositional and diagenetic controls on the permeability–porosity properties of pre-salt carbonate rocks. The results indicate that, although similar, the analyzed successions present particularities regarding the relative abundance of lithologies and primary chemical composition, especially with respect to siliciclastic contribution. Although they exhibit the same dolomite textures (blocky, mosaic, lamellar, fringing, saddle, and rhombohedral) and silica textures (microcrystalline, macrocrystalline, and chalcedony), there is a clear differentiation between the wells in terms of the intensity of depositional processes. This diversity becomes evident when establishing relationships among lithologies, chemical facies, dolomite and silica textures, and Global Hydraulic Elements (GHE), which categorize the study intervals according to flow capacity. As a general trend, Well A presents a highly heterogeneous multi-petrotype system (GHE 1 to 9), with a predominance of GHE 4 and 5. In this case, the diagenetic influence did not follow a simple inversely proportional relationship; partial dolomitization and fracturing of silicified intervals contributed to the best petrophysical performance (GHE 8 and 9), identified in the intermediate portion of the Barra Velha Formation. In contrast, Well B revealed a more homogeneous reservoir with moderate performance (GHE 1 to 8, predominantly GHE 4 and 5). Its best interval (GHE 8) is also located in the intermediate portion of the well, within the Barra Velha Formation, influenced not only by diagenesis but also by greater detrital contribution. Thus, the quality of pre-salt reservoirs results from the interaction between depositional inheritance and diagenetic processes, configuring a variable and heterogeneous permeability–porosity system and making multi-technique integration indispensable for its characterization. Wed, 18 Mar 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/49979 2026-03-18T00:00:00Z https://repositorio.ufu.br/handle/123456789/49883 Title: Distribuição espacial e a diferenciação de Latossolos localizados no interflúvio dos Rios Bagagem-Perdizes e entornos (MG) Abstract: Oxisols cover approximately one third of the Brazilian territory, occurring mainly in tabular to gently convex reliefs. In Monte Carmelo (MG), this pattern is evident in the interfluve between the Bagagem and Perdizes rivers, located at the contact between the Paraná Sedimentary Basin and the Brasília Fold Belt. This study aims to understand the spatial distribution of Oxisol covers in the interfluve and differentiate representative soil profiles using morphological, mineralogical, magnetic, and morphoscopic criteria. The methodology includes morphometric mapping, morphological description, and mineralogical, magnetic, and morphoscopic analyses. Hypsometric, slope, terrain ruggedness index, and topographic position index maps allowed the recogmition of more pronounced dissection in the Bagagem River valleys than in the Perdizes River valley. Photopedology identified twelve Oxisol covers, distributed in continuous corridors across the interfluve, with a progressive reduction in thickness and extent toward the Paranaíba River. Red Oxisols predominate, along with Red-Yellow Oxisols and Ultisols. In the clay fraction of diagnostic horizons, gibbsite, kaolinite, hematite/maghemite, and goethite predominate. Magnetic analysis identified four magnetic susceptibility classes and three apparent conductivity classes. Morphoscopy allowed evaluation of sand-fraction composition, focused on dufferences in quartznpercentages. Data integration defined three geomorphological domains: Summit Tabular Surface, comprising LV-CI and LV-R; Transitional, with LVA-AE and LV-ASF; and Convex Interfluves in Dissected Forms, with LV-MTC, LV-SF, LV-C, LV-P, and CM. These results highlight the influence of relief and parent material on pedogenetic evolution and their spatial organization. Fri, 31 Jul 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/49883 2026-07-31T00:00:00Z https://repositorio.ufu.br/handle/123456789/49738 Title: Caracterização estrutural da zona de cisalhamento Douradinho na região entre Coromandel/MG e Abadia dos Dourados/MG Abstract: This Bachelor's Thesis aimed to characterize the Douradinho Shear Zone, a regional deformation zone with a preferential NW–SE trend, located between the municipalities of Coromandel and Abadia dos Dourados, Minas Gerais, Brazil. The structure affects rocks of the Monte Carmelo Complex, Abadia dos Dourados Complex, and Araxá Group, constituting a structurally significant feature within the southern portion of the Brasília Belt. A multiscale approach was employed based on the integration of morphostructural, airborne geophysical, field geological, microstructural, and three-dimensional geological modeling data. The analysis of Digital Elevation Models (DEM), combined with the interpretation of gamma-ray spectrometric and magnetic data, revealed a strong NW–SE structural control over the relief and drainage network, evidenced by rectilinear channel segments and fluvial deflection anomalies. Geophysical products revealed radiometric and magnetic contrasts associated with the different geological units, indicating that the granitic bodies acted as relatively more competent domains during regional deformation, promoting strain partitioning along their margins. Three-dimensional geological modeling demonstrated the spatial continuity of these structures at depth and enabled the correlation between geophysical domains and surface observations. Petrographic and microstructural analyses identified intracrystalline deformation features and dynamic recrystallization in quartz, associated with the predominantly brittle behavior of feldspars, indicating deformation under low-grade greenschist facies metamorphic conditions. Furthermore, the observed mineral assemblage suggests that the structure acted as a conduit for the circulation of fluids. Although no diagnostic kinematic indicators were identified to unequivocally determine the sense of movement of the structure, the integration of the different datasets allowed the characterization of the spatial distribution of deformation and the role played by the Douradinho Shear Zone in the lithostructural arrangement of the local geological units. The results contribute to the understanding of the structural evolution of the southern portion of the Brasília Belt and provide a basis for future tectonic and geophysical investigations in the region. Tue, 28 Jul 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/49738 2026-07-28T00:00:00Z