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Os m?todos de monitoramento s?o essenciais para a obten??o de informa??es relevantes para as empresas tomarem decis?es. Nesse contexto, prop?s-se estudar solu??es para monitorar a integridade das pastas de cimentos de po?os expostos a ambientes ricos em CO2. No estudo de desenvolvimento de m?todo quantitativo, foram calibrados e validados modelos de regress?o parcial de m?nimos quadrados (PLS), quantificando, com base nos dados de espectroscopia de infravermelho com transformada de Fourier (FTIR), o conte?do de CaCO3 em pastas de cimento que passaram pelo processo de carbonata??o. No estudo de geoqu?mica isot?pica, identificou-se que o pH do meio reacional e a solubilidade e pH das fases minerais dos materiais ciment?cios s?o os principais par?metros que influenciam nos fatores cin?ticos e termodin?micos e no equil?brio/distribui??o dos is?topos de carbono (13C e 12C) ao longo do sistema reacional e observou-se o potencial dos m?todos de is?topos est?veis para discriminar a origem do CO2. Assim, na presente tese de doutorado: (i) foram desenvolvidas solu??es r?pidas e confi?veis para monitorar o conte?do de CaCO3 em pastas de cimento carbonatado por FTIR e (ii) foi confirmado o potencial dos dados de is?topos est?veis de carbono (? 13C) para diferenciar a origem do CO2 que induziu o processo de degrada??o das pastas de cimento de po?os. A partir dos resultados, pode-se concluir que foram obtidos dados consistentes que levaram ? proposi??o de novas alternativas para estudar e monitorar a integridade das pastas de cimento de po?os expostos a ambientes ricos em CO2. Dessa forma, o presente trabalho p?de contribuir para o desenvolvimento da ?rea de engenharia e tecnologia de materiais ciment?cios para aplica??o em po?os de ?leo e g?s (O&G) e no contexto de Captura e Armazenamento de Carbono (CCS). Monitoring methods are essential for obtaining relevant information for companies to make decisions. In this context, it was proposed to study solutions to monitor the integrity of cement pastes from wells exposed to CO2-rich environments. In the quantitative method development study, partial least squares (PLS) regression models were calibrated and validated, quantifying, based on Fourier-transform infrared spectroscopy (FTIR) data, the CaCO3 content in cement pastes that underwent the carbonation process. In the isotopic geochemistry study, it was identified that the pH of the reaction medium and the solubility and pH of the mineral phases of cementitious materials are the main parameters that influence the kinetic and thermodynamic factors and the balance/distribution of carbon isotopes (13C and 12C) throughout the reaction system, and it was observed the potential of the stable isotope methods to discriminate the origin of CO2. Thus, in the present doctoral thesis: (i) rapid and reliable solutions were developed to monitor the CaCO3 content in carbonated cement pastes by FTIR and (ii) it was confirmed the potential of stable carbon isotopes (? 13C) data to differentiate the origin of CO2 that induced the degradation process of the well cement pastes. From the results, it can be concluded that consistent data were obtained that led to the proposition of new alternatives to study and monitor the integrity of cement pastes from wells exposed to CO2-rich environments. In this way, the present work could contribute to the development of the area of engineering and technology of cementitious materials for application in oil and gas (O&G) wells and in the Carbon Capture and Storage (CCS) context.

Proveniência por métodos isotópicos em duas unidades litodêmicas – o Complexo Metamórfico Porongos (CMP) no domínio central-oriental do Cinturão Dom Feliciano (CDF) e a Suíte Metamórfica Várzea do Capivarita (SMVC), localizada no domínio leste do CDF - apresentou áreas-fonte similares nos dois casos: Os metassedimentos do CMP, na região das Antiformes de Santana da Boa Vista e Serra dos Pedrosas, foram depositados entre 785 e 595 Ma (U-Pb em zircão detrítico por LA-ICP-MS). Apresentam registros de áreas-fonte com predominância de idades de ca. 2.2 – 2.0 Ga, mesmas idades do embasamento da região, o Complexo Encantadas. As assinaturas isotópicas de 207Pb/204Pb X 206Pb/204Pb mostraram pouca relação dos metassedimentos do CMP com áreas-fonte do cráton Rio de La Plata, e εNd variando entre -13 a -6.5, com valores menos negativos para amostras onde foram obtidos zircões com mesma idade do vulcanismo félsico do CMP. Outros registros incluem idades de 1.5-1.4 Ga, cujas assinaturas εHf indicam fontes juvenis, possivelmente relacionadas a um sistema de rifteamento registrado nos Anortositos Capivarita. Na Antiforme Capané, zircões datados em SHRIMP e LA-ICP-MS de rochas metavulcânicas intermediárias a félsicas indicaram idades de 663 ± 2.7 Ma, representando um vulcanismo mais jovem do que aquele encontrado anteriormente no CMP, vinculado à fusão parcial crustal. Novos dados U-Pb em zircão confirmam registro do metavulcanismo de 783.4 ± 3.9 Ma nos metassedimentos, comparáveis a idades obtidas nos Gnaisses Cerro Bori, interpretados como um arco continental de ca. 800 Ma. Zircões detríticos de rochas metassedimentares da SMVC apresentaram registros de ca. 2.2 – 2.0 Ga, além de idades de ca. 1.4 Ga e idade máxima de deposição de 714.3 ± 3.9 Ma, com pico metamórfico registrado em borda metamórfica de zircões com 618 ± 7.3 Ma εHf predominantemente negativas. Mármores apresentaram razões 87Sr/86Sr de 0.70609, o que permite deduzir uma idade de deposição mais antiga que 715 Ma, próximo dos valores encontrados em mármores na região de Arroio Grande. A comparação dos isótopos de Hf com rochas do Cinturão Damara nos crátons Kalahari e Congo, cuja amalgamento junto ao Rio de La Plata deu origem ao Gondwana Ocidental, mostram que existe pouca ou nenhuma relação com áreas-fonte dos metassedimentos do CMP e SMVC no Neoproterozóico. Estes dados levam a dedução de que acresção de terrenos ou microcontinentes com características de embasamento, nesse caso denominado aqui como Embasamento Encantadas, cuja evolução se dá com acresção de um arco continental de idades entre 780 e 660 Ma, é a origem de parte das áreas-fonte do CMP, e possivelmente foi um dos eventos tectônicos que controlaram evolução do terreno ao longo do CMP e SMVC. Isotopic provenance realized in two lithodemic units – Porongos Metamorphic Complex (PMC), in the central-eastern domain of the Dom Feliciano Belt (DFB) and the Várzea do Capivarita Metamoprhic Suite (VCMS), in the eastern domain of the same belt – presented similar source-areas in both cases: The PMC metasediments, in Santana da Boa Vista and Serra dos Pedrosas Antiforms were deposited between 785 and 595 Ma (LA-ICP-MS detrital zircon U-Pb). Both PMC and VCMS displayed source-areas with ages varying from ca. 2.2 – 2.0 Ga, which is the same age presented in the regional basement, the Encantadas Complex. 207Pb/204Pb X 206Pb/204Pb isotopic signatures displayed little resemblance between CMP metasediments and possible source-areas in the Rio de La Plata Craton, and εNd varied between -13 to -6.5, with less negative values in samples were where obtained zircons with the same age of felsic volcanism in the PMC. Others records included ages from 1.5 to 1.4 Ga, with εHf signatures indicating juvenile sources, possibly related to a rifting system recorde in the Capivarita Anorthosite. In the Capané Antiform, SHRIMP and LA-ICP-MS U-Pb zircon ages from felsic to intermediary metavolcanic rocks displayed 663 ± 2.7 Ma, which is a younger record than the previously obtained in the PMC, and can be related to partial crustal fusion. Also new U-Pb detrital zircon ages confirm the record of the metavolcanics of 783.4 ± 3.9 Ma in the metasediments, comparable to the ages obtained in the Cerro Bori orthogneisses, interpreted as a continental arc of ca. 800 Ma. Metasedimentary rocks of VCMS displayed zircons with ca. 2.2-2.0 Ga, besides ages of ca. 1.4 Ga and maximum depositional age of 714.3 ± 3.9 Ma, with metamorpich peak recorded in metamorphic rims of 618 ± 7.3 Ma and negative εHf signatures. Marbles presented 87Sr/86Sr ratios of 0.70609, which can be deducted as an older than 715 Ma depositional age, near values obtained to Arroio Grande marbles. Comparison of Hf signatures with rocks from Damara Belt of Kalahari and Congo Cratons, whose assembly with Rio de La Plata to form West Gondwana in Neoproterozoic, displayed little to no relationship with the source-areas of PMC and VCMS metasediments I in the Neoproterozoic. This indicates that terrain or a microcontinent accretion with basement features, in this case the Encantadas Basement, whose evolution underwent accretion in a continental arc between 780 to 660 Ma, it’s the source to part of the PMC , and possible was one of the tectonic events that controlled terrain evolution in the PMC and VCMS.

The most recent submarine eruption observed offshore the Azores archipelago occurred between 1998 and 2001 along the submarine Serreta ridge (SSR), ~ 4–5 nautical miles WNW of Terceira Island. This submarine eruption delivered abundant basaltic lava balloons floating at the sea surface and significantly changed the bathymetry around the eruption area. Our work combines bathymetry, volcanic facies cartography, petrography, rock magnetism and geochemistry in order to (1) track the possible vent source at seabed, (2) better constrain the Azores magma source(s) sampled through the Serreta submarine volcanic event, and (3) interpret the data within the small-scale mantle source heterogeneity framework that has been demonstrated for the Azores archipelago. Lava balloons sampled at sea surface display a radiogenic signature, which is also correlated with relatively primitive (low) 4He/3He isotopic ratios. Conversely, SSR lavas are characterized by significantly lower radiogenic 87Sr/86Sr, 206Pb/204Pb and 208Pb/204Pb ratios than the lava balloons and the onshore lavas from the Terceira Island. SSR lavas are primitive, but incompatible trace-enriched. Apparent decoupling between the enriched incompatible trace element abundances and depleted radiogenic isotope ratios is best explained by binary mixing of a depleted MORB source and a HIMU­type component into magma batches that evolved by similar shallower processes in their travel to the surface. The collected data suggest that the freshest samples collected in the SSR may correspond to volcanic products of an unnoticed and more recent eruption than the 1998–2001 episode.