In this study, it was aimed to develop conservation methodologies for the historic sandstones using the case of Nemrut Mount Monument to help their survival in open air conditions. The main conservation approach of this study was holistic as well as aiming at minimum intervention targeted to the problem areas. The most important weathering forms of Nemrut Sandstones were material loss due to loss of scales and granular disintegration as well as detachments by scales, back weathering due to loss of scales, cracking, granular disintegration, rounding/notching and discoloration/biological deposition. Deterioration mechanisms of sandstones were studied on deteriorated and relatively sound sandstones by nondestructive methods of UPV and QIRT, and by microstructural analyses using thin section, XRD and SEM-EDX analyses. In addition, the changes in physical and physcomechanical properties such as, color, bulk density, effective porosity, hydric, hygric and thermal dilatation and CEC of clays were determined. Sandstone deterioration was caused by swelling of clay minerals distributed in their matrix and clay accumulations between the detaching scales. Considerable thermal dilatation characteristics was also an important decay factor. Iron oxides caused discoloration at the surfaces, their phase changes was thought to be important in decay. The use of surfactant DAA, to control clay swelling was found to decrease the hydric dilatation by 40%. The consolidation treatments with nanosilica and silicate dispersions namely Funcosil KSE500STE, SytonX3, KSE300 and KSE100 have improved physicomechanical properties as followed by UPV measurements and decreased hydric dilatation. Their long term behaviour needed to be further investigated.

Made available in DSpace on 2014-12-17T15:42:30Z (GMT). No. of bitstreams: 1 KeilaRS_TESE.pdf: 2025404 bytes, checksum: f62ed0f0a6e3ff3ceed81829e8165b40 (MD5) Previous issue date: 2014-05-16 / Petr?leo Brasileiro SA - PETROBRAS / The role of carboxymethylcellulose (CMC) in association to calcium carbonate particles (CaCO3) in most water-based drilling fluids is to reduce the fluid loss to the surrounding formation. Another essential function is to provide rheological properties capable of maintaining in suspension the cuttings during drilling operation. Therefore, it is absolutely essential to correlate the polymer chemical structure (degree of substitution, molecular weight and distribution of substituent) with the physical-chemical properties of CaCO3, in order to obtain the better result at lower cost. Another important aspect refers to the clay hydration inhibitive properties of carboxymethylcellulose (CMC) in drilling fluids systems. The clay swelling promotes an undesirable damage that reduces the formation permeability and causes serious problems during the drilling operation. In this context, this thesis consists of two main parts. The first part refers to understanding of interactions CMC-CaCO3, as well as the corresponding effects on the fluid properties. The second part is related to understanding of mechanisms by which CMC adsorption occurs onto the clay surface, where, certainly, polymer chemical structure, ionic strength, molecular weight and its solvency in the medium are responsible to affect intrinsically the clay layers stabilization. Three samples of carboximetilcellulose with different molecular weight and degree of substitution (CMC A (9 x 104 gmol DS 0.7), CMC B (2.5 x 105 gmol DS 0.7) e CMC C (2.5 x 105 gmol DS 1.2)) and three samples of calcite with different average particle diameter and particle size distribution were used. The increase of CMC degree of substitution contributed to increase of polymer charge density and therefore, reduced its stability in brine, promoting the aggregation with the increase of filtrate volume. On the other hand, the increase of molecular weight promoted an increase of rheological properties with reduction of filtrate volume. Both effects are directly associated to hydrodynamic volume of polymer molecule in the medium. The granulometry of CaCO3 particles influenced not only the rheological properties, due to adsorption of polymers, but also the filtration properties. It was observed that the lower filtrate volume was obtained by using a CaCO3 sample of a low average size particle with wide dispersion in size. With regards to inhibition of clay swelling, the CMC performance was compared to other products often used (sodium chloride (NaCl), potassium chloride (KCl) and quaternary amine-based commercial inhibitor). The low molecular weight CMC (9 x 104 g/mol) showed slightly lower swelling degree compared to the high molecular weight (2.5 x 105 g/mol) along to 180 minutes. In parallel, it can be visualized by Scanning Electron Microscopy (SEM) that the high molecular weight CMC (2.5 x 105 g/mol e DS 0.7) promoted a reduction in pores formation and size of clay compared to low molecular weight CMC (9.0 x 104 g/mol e DS 0.7), after 1000 minutes in aqueous medium. This behavior was attributed to dynamic of interactions between clay and the hydrodynamic volume of CMC along the time, which is result of strong contribution of electrostatic interactions and hydrogen bounds between carboxylate groups and hydroxyls located along the polymer backbone and ionic and polar groups of clay surface. CMC adsorbs on clay surface promoting the skin formation , which is responsible to minimize the migration of water to porous medium. With the increase of degree of substitution, it was observed an increase of pores onto clay, suggesting that the higher charge density on polymer is responsible to decrease its flexibility and adsorption onto clay surface. The joint evaluation of these results indicate that high molecular weight is responsible to better results on control of rheological, filtration and clay swelling properties, however, the contrary effect is observed with the increase of degree of substitution. On its turn, the calcite presents better results of rheological and filtration properties with the decrease of average viii particle diameter and increase of particle size distribution. According to all properties evaluated, it has been obvious the interaction of CMC with the minerals (CaCO3 and clay) in the aqueous medium / O papel da carboximetilcelulose (CMC) em associa??o com o carbonato de c?lcio (CaCO3) na maioria dos fluidos de perfura??o base ?gua ? reduzir a perda de fluido para a forma??o. Outra fun??o essencial ? promover propriedades reol?gicas capazes de manter em suspens?o os cascalhos durante a opera??o de perfura??o. Dessa forma, ? absolutamente essencial correlacionar a estrutura qu?mica do pol?mero (grau de substitui??o, massa molar e distribui??o do substituinte) com as propriedades f?sicoqu?micas do CaCO3, de forma a obter o melhor resultado a mais baixo custo. Outro importante aspecto refere-se ?s propriedades de inibi??o da CMC em rela??o ? hidrata??o de argilas presentes na forma??o rochosa. O inchamento de argilas promove um dano indesej?vel que reduz a permeabilidade da forma??o e causa s?rios problemas durante a perfura??o. Nesse contexto, essa Tese consiste de duas partes principais. A primeira parte refere-se ao entendimento das intera??es CaCO3-CMC, assim como os efeitos correspondentes ?s propriedades do fluido. A segunda parte est? relacionada ao entendimento dos mecanismos pelos quais a adsor??o da CMC ocorre na aresta da argila, onde, certamente, a estrutura qu?mica do pol?mero, for?a i?nica, massa molar e sua solubilidade no meio s?o respons?veis por afetar intrinsecamente a estabiliza??o das camadas da argila. Foram utilizadas no estudo tr?s amostras de carboximetilcelulose com diferentes massas molares e graus de substitui??o: CMC A (9 x 104 gmol DS 0.7), CMC B (2.5 x 105 gmol DS 0.7) e CMC C (2.5 x 105 gmol DS 1.2)) e tr?s amostras de calcita (CaCO3), com diferentes di?metros m?dios de part?culas e curvas de distribui??o em tamanho. O aumento do grau de substitui??o da CMC contribuiu para o aumento da densidade de carga do pol?mero e dessa forma, reduziu sua estabilidade em salmoura, promovendo agrega??o e o aumento do volume de filtrado. Por sua vez, o aumento da massa molar promoveu um aumento das propriedades reol?gicas com a redu??o do volume de filtrado. Ambos os efeitos est?o diretamente ligados ao volume hidrodin?mico da mol?cula do pol?mero no meio. A granulometria das part?culas do CaCO3 influenciou n?o somente as propriedades reol?gicas, devido ? adsor??o de pol?meros em sua superf?cie, mas tamb?m as propriedades de filtra??o. Foi observado que o menor volume de filtrado foi obtido pelo uso da amostra de CaCO3 de menor tamanho de part?cula com a faixa mais ampla de dispers?o em tamanho. Com rela??o ? inibi??o de inchamento de argilas, a efici?ncia da CMC foi comparada a outros produtos comumente empregados (cloreto de s?dio (NaCl), cloreto de pot?ssio (KCl) e um inibidor comercial ? base de amina quatern?ria). A CMC de baixa massa molar (9 x 104 g/mol) propiciou grau de inchamento da bentonita ligeiramente mais baixo que a CMC de alta massa molar (2.5 x 105 g/mol), no decorrer de 180 minutos. Por outro lado, p?de ser visualizado por microscopia eletr?nica de varredura que a CMC de maior massa molar (2.5 x 105 g/mol e DS 0.7) promoveu uma redu??o na forma??o e no tamanho dos poros da argila comparada ? CMC de menor massa molar (9.0 x 104 g/mol e DS 0.7), ap?s 1000 minutos em meio aquoso. Esse comportamento foi atribu?do ? din?mica das intera??es entre a argila e a cadeia polim?rica da CMC ao longo do tempo, que ? resultado da forte contribui??o das intera??es eletrost?ticas e liga??es de hidrog?nio entre os grupos carboxilato e hidroxila localizados ao longo da cadeia polim?rica e os s?tios i?nicos e polares da superf?cie da argila. A CMC adsorve na superf?cie da matriz de argila promovendo a forma??o de uma pel?cula , a qual ? respons?vel por minimizar a migra??o da ?gua para o meio poroso. Com o aumento do grau de substitui??o, foi observado aumento de poros na matriz de argila, sugerindo que a maior densidade de cargas no pol?mero diminui a sua flexibilidade e a adsor??o sobre a matriz argilosa. A an?lise conjunta dos resultados vi indica que altas massas molares da CMC propiciam melhores resultados no controle das propriedades reol?gicas, de filtra??o e de inchamento de argilas, entretanto, efeito contr?rio ? observado com o aumento do grau de substitui??o. Por sua vez, o CaCO3 apresenta melhores resultados de propriedades reol?gicas e de filtra??o com a diminui??o do di?metro m?dio das part?culas e aumento da distribui??o em tamanho. Em todas as propriedades analisadas, foram evidentes os sinais de intera??o da CMC com os minerais (carbonato de c?lcio e argila) presentes no meio aquoso

An aqueous nanoparticle dispersion is a complex fluid whose mobility in porous media is controlled by four key factors: the conditions necessary for the stability of nanoparticle dispersions, the kinetics of nanoparticle aggregation in an unstable suspension, the rheology of stable or unstable suspensions, and the interactions between the nanoparticles and oil/water interface and mineral surfaces. The challenges in controlling nanoparticle transport come from the variations of pH and ionic strength of brine, the presence of stationary and mobile phases (minerals, oil, water and gas), the geochemical complexity of reservoir rocks, and pore-network. The overall objective of this work is to achieve a better understanding of nanoparticle transport in porous media based on a systematic experimental and theoretical study of above factors. For this purpose, the critical conditions for the aqueous stability of nanoparticles are identified and fit by a theoretical model, which describes the interaction energy between silica nanoparticles. Above critical conditions nanoparticle aggregation becomes significant. A model for the aggregation kinetics is developed and validated by experiments. A mechanistic model for predicting the viscosity of stable and unstable silica nanoparticle dispersions over a wide range of solid volume fraction is developed. This model is based on the concept of effective maximum packing fraction. Adsorption experiments with silica nanoparticles onto quartz, calcite and clay surfaces and interfacial tension measurements provide insightful information on the interaction of the nanoparticles with minerals and decane/water interface. The extent of nanoparticle adsorption on mineral/water and decane/water interfaces is evaluated based on DLVO theory and Gibbs’ equation. Visual observations and analytical methods are used to understand the interaction of nanoparticles with clay. The characterization of nanoparticle behavior in bulk phases is built into an understanding of nanoparticle transport in porous media. In particular, the rheology of nanoparticle dispersions flowing through permeable media is compared with those determined using a rheometer. In the presence of residual oil, the retention of silica nanoparticles at water/oil interface during steady flow is investigated. The results from batch experiments of nanoparticle adsorption are used to explain the flow behavior of these nanoparticles in a glass bead pack at residual oil saturation. / text