Comportamento reológico de materiais cimentícios para poços de petróleo contendo naftaleno condensado ou policarboxilato

Pastas a base de cimento Portland são utilizadas na cimentação de poços de petróleo. Elas consistem de uma mistura de partículas sólidas de cimento dispersas em água e aditivos. Atualmente, diversos materiais alternativos são utilizados como aditivos, objetivando a modificação e a melhoria das propriedades das pastas de cimento, especialmente no aumento da fluidez. Novos aditivos plastificantes são capazes de suportar as diversas condições de poços, promovendo propriedades no estado fluido compatíveis às condições exigidas para cimentação.Dispersantes são os componentes da pasta que garantem fluidez, além de proporcionar controle na água perdida por filtração na formação porosa, garantindo o sucesso da operação de bombeio. Em deter minados campos, além do efeito da profundidade, as condições geológicas das formações promovemvariações do gradiente de pressão e temperatura ao longo da profundidade vertical do poço. Recentemente, diversos aditivos químicos da indústria da construção civil tem sido estudados em condições de cimentação de poços de petróleo. Vários produtos testados tem apresentado desempenho superior aos produtos normalmente empregados pela indústria de petróleo com boa relação custo/benefício em função do volume de mercado da construção civil. Resultados promissores na seleção de aditivos com função dispersante da construção civil para operações de cimentação de poços de petróleo onshore foram obtidos para temperaturas até 80°C. O potencial de uso desses aditivos permite estabelecer novas soluções para problemas encontrados na cimentação de poços de petróleo HPHT, poços sujeitos à injeção de vapor, poços depletados e poços produtores de gás. Na construção civil, os superplastificantes permitem reduzir o fator água/cimento das argamassas proporcionando melhoria de propriedades como resistência mecânica e fluidez. Assim, o objetivo deste trabalho foi o estudo e a caracterização reológica de pastas constituídas de cimento Portland, água e aditivos do tipo plastificante, com função dispersante a base de naftaleno condensado e policarboxilato, na faixa de temperaturas de 58°C e 70ºC. As condições utilizadas para a avaliação dos aditivos alternativos foram baseadas em uma cimentação primária para um poço hipotético de 2200 m de profundidade e gradientes geotérmicos de 1,7°F/100 pés e 2,1°F/100 pés. Os resultados demonstraram a grande eficiência e o poder dispersivo do policarboxilato para as temperaturas estudadas. O aditivo promoveu alta fluidez, sem efeitos de sedimentação da pasta. O dispersante à base de naftaleno reduziutant o a viscosidade plástica como o limite de escoamento acimada concentração a partir de 0,13%. O modelo de Bingham descreveu bem o comportamento reológico das pastas com policarboxilato para todas as concentrações

Compósitos Portland-biopolímeros para cimentação de poços de petróleo

The oil production in mature areas can be improved by advanced recovery techniques. In special, steam injection reduces the viscosity of heavy oils, thus improving its flow to surrounding wells. On the other hand, the usually high temperatures and pressures involved in the process may lead to cement cracking, negatively affecting both the mechanical stability and zonal isolation provided by the cement sheath of the well. The addition of plastic materials to the cement is an alternative to prevent this scenario. Composite slurries consisting of Portland cement and a natural biopolymer were studied. Samples containing different contents of biopolymer dispersed in a Portland cement matrix were prepared and evaluated by mechanical and rheological tests in order to assess their behavior according to API (American Petroleum Institute) guidelines. FEM was also applied to map the stress distribution encountered by the cement at bottom bole. The slurries were prepared according to a factorial experiment plan by varying three parameters, i.e., cement age, contents of biopolymer and water-to-cement ratio. The results revealed that the addition of the biopolymer reduced the volume of free water and the setting time of the slurry. In addition, tensile strength, compressive strength and toughness improved by 30% comparing hardened composites to plain Portland slurries. FEM results suggested that the stresses developed at bottomhole may be 10 to 100 times higher than the strength of the cement as evaluated in the lab by unconfined mechanical testing. An alternative approach is proposed to adapt the testing methodology used to evaluate the mechanical behavior of oilwell cement slurries by simulating the confined conditions encountered at bottornhole

Efeito da adição de fibras da palma do licuri (syagrus coronata) no comportamento físico e mecânico de compósitos de matriz cimentícia

This research was motivated by the requirement of asbestos s replacement in building systems and the need to generate jobs and income in the country side of the state of Bahia, Brazil. The project aimed at using fibers from licuri leaves (syagrus coronata), an abundant palm in the region, to produce composites appropriate for the sustainable production of cement fibre reinforced products in small plants. The composites were produced in laboratory using Portland cement CP-II-F32, sand, water, licuri palm fiber contents of 1.0, 1.5 and 2.0% by weight of binder (two different fiber length) and metakaolin. The latter was chosen as an additional binder for its efficiency to reduce the alkalinity of cementitious matrixes therefore preventing the degradation of vegetable fibers. The characterization of the composite components was carried out by sieving and laser particle size analyses, thermal analysis, fluorescence and X-ray diffraction. The composites performance was evaluated by 3- point-bending tests, compressive strength, ultrasound module of elasticity, free and restrained shrinkage, water capillarity absorption and apparent specific gravity. It has been found that the addition of fibers increased the time to onset of cracking over 200.00% and a 25% reduction in cracks opening in the restrained shrinkage test. The capillary absorption reduced about 25% when compared to fiber-free composites. It was also observed with regard to flexural strength, compressive strength and specific gravity, that the addiction of fibers did not affect the composite performance presenting similar results for compounds with and without fibers. In general it can be stated that the reinforced composite fibers of palm licuri presents physical and mechanical characteristics which enable them to be used in the intended proposals of this research

Pastas compósitas cimento/sílica/polímero para cimentação de poços de baixa profundidade sujeitas à injeção de vapor

The production of heavy oil fields, typical in the Northeastern region, is commonly stimulated by steam injection. High bottom hole temperatures are responsible not only for the development of deleterious stresses of the cement sheath but also for cement strength retrogression. To overcome this unfavorable scenario, polymeric admixtures can be added to cement slurries to improve its fracture energy and silica flour to prevent strength retrogression. Therefore, the objective of the present study was to investigate the effect of the addition of different concentrations of polyurethane (5-25%) to cement slurries containing 40% BWOC silica flour. The resulting slurries were characterized using standard API (American Petroleum Institute) laboratory tests. In addition to them, the mechanical properties of the slurries, including elastic modulus and microhardness were also evaluated. The results revealed that density, free water and stability of the composite cement/silica/polyurethane slurries were within acceptable limits. The rheological behavior of the slurries, including plastic viscosity, yield strength and gel strength increased with the addition of 10% BWOC polyurethane. The presence of polyurethane reduced the fluid loss of the slurries as well as their elastic modulus. Composite slurries also depicted longer setting times due to the presence of the polymer. As expected, both the mechanical strength and microhardness of the slurries decreased with the addition of polyurethane. However, at high bottom hole temperatures, the strength of the slurries containing silica and polyurethane was far superior than that of plain cement slurries. In summary, the use of polyurethane combined with silica is an interesting solution to better adequate the mechanical behavior of cement slurries to heavy oil fields subjected to steam injection

Estudo da formulação de pré-misturas secas para a cimentação de poços em terra

An economical solution for cementing oil wells is the use of pre-prepared dry mixtures containing cement and additives. The mixtures may be formulated, prepared and transported to the well where is added water to be pumped.Using this method, becomes dispensable to prepare the cement mixes containing additives in the cementing operation, reducing the possibility of error. In this way, the aim of this work is to study formulations of cement slurries containing solid additives for primary cementing of oil wells onshore for typical depths of 400, 800 and 1,200 meters. The formulations are comprised of Special Class Portland cement, mineral additions and solids chemical additives.The formulated mixtures have density of 1.67 g / cm ³ (14.0 lb / gal). Their optimization were made through the analysis of the rheological parameters, fluid loss results, free water, thickening time, stability test and mechanical properties.The results showed that mixtures are in conformity the specifications for cementing oil wells onshore studied depths

Efeito da adição de microfibras de lã de vidro na tenacidade à ruptura de pastas de cimento para poços de petróleo

Although there are a wide variety of additives that act in fresh state, to adjust the properties of cement, there is also a search by additions that improve the tenacity of the cement in the hardened state. This, in turn, can often be increased by inserting fibers, which act on the deflection of microcracks. This study aimed to use a microfiber glass wool (silica-based) as an additive reinforcing the cement matrix, improving the rupture tenacity, in order to prevent the propagation of microcracks in the cement sheath commonly found in oil wells submitted to high temperatures. The fibers were added at different concentrations, 2 to 5% (BWOC) and varied average sizes, grinding for 90 s, 180 s, 300 s, 600 s. The cement slurries were made with a density of 1,90 g/ cm3 (15,6 lb/gal), using Portland cement CPP- Special Class as the hydraulic binder and 40% silica flour. The characterization of the fiber was made by scanning electron microscopy (SEM), particle size by sieving, X-ray fluorescence (XRF), X-ray diffraction (XRD) and thermogravimetry (TG / DTG). Were performed technological tests set by the API (American Petroleum Institute) by rheology, stability, free water, compressive strength, as well as testing rupture energy, elastic modulus and permeability. The characterization results showed good thermal stability of the microfiber glass wool for application in oil wells submitted to steam injection and, also, that from the particle size data, it was possible to suggest that microfibers milled up to 300 s, are ideal to act as reinforcement to the cement slurries. The rheological parameters, there was committal of plastic viscosity when larger lengths were inserted of microfiber (F90). The values obtained by free water and stability were presented according to API. The mechanical properties, the incorporation of microfiber to the cement slurries gave better rupture tenacity, as compared to reference cement slurries. The values of compressive strength, elastic modulus and permeability have been maintained with respect to the reference cement slurries. Thus, cement slurries reinforced with microfiber glass wool can ensure good application for cementing oil wells submitted to steam injection, which requires control of microcracks, due to the thermal gradients

Efeito da adição de cargas minerais leves na resistência mecânica de grautes para cimentação de poços offshore

The preparation of cement slurries for offshore well cementing involves mixing all solid components to be added to the mixing water on the platform. The aim of this work was to study the formulation of pre-prepared dry mixtures, or grouts, for offshore oilwell cementing. The addition of mineral fillers in the strength of lightweight grouts applied for depths down to 400 m under water depths of 500 m was investigated. Lightweight materials and fine aggregates were selected. For the choice of starting materials, a study of the pozzolanic activity of low-cost fillers such as porcelain tile residue, microsilica and diatomaceous earth was carried out by X-ray diffraction and mechanical strength tests. Hardened grouts containing porcelain tile residue and microsilica depicted high strength at early ages. Based on such preliminary investigation, a study of the mechanical strength of grouts with density 1.74 g/cm3 (14.5 lb/gal) cured initially at 27 °C was performed using cement, microsilica, porcelain tile residue and an anti-foaming agent. The results showed that the mixture containing 7% of porcelain tile residue and 7% of microsilica was the one with the highest compressive strength after curing for 24 hours. This composition was chosen to be studied and adapted for offshore conditions based on testes performed at 4 °C. The grout containing cement, 7% of porcelain tile residue, 7% of active silica and admixtures (CaCl2), anti-foaming and dispersant resulted satisfactory rheology and mechanical strength after curing for 24 hours of curing

Description of a new species of skate of the genus Malacoraja Stehmann, 1970: the first species from the southwestern Atlantic Ocean, with notes on generic monophyly and composition (Chondrichthyes: Rajidae)

O primeiro registro para o Atlântico Sul ocidental de uma espécie do gênero Malacoraja Stehmann, 1970 é feita com base na descrição de Malacoraja obscura, espécie nova, proveniente do talude continental do Sudeste brasileiro dos estados do Espírito Santo e Rio de Janeiro em profundidades de 808-1105 m. A espécie nova é conhecida através de cinco exemplares e é distinta de seus congêneres pela sua coloração dorsal composta por numerosas manchas esbranquiçadas e pequenas na região do disco e nadadeiras pélvicas, por apresentar uma fileira irregular de espinhos ao longo da superfície dorsal mediana da cauda a qual persiste em espécimes maiores (desde a base da cauda até dois-terços do seu comprimento numa fêmea de 680 mm de comprimento total, CT) e uma região pequena desprovida de dentículos na base ventral da cauda (estendendo somente até a margem distal da nadadeira pélvica). Outros caracteres diagnósticos em combinação incluem a ausência de espinhos escapulares em indivíduos maiores, número elevado de fileiras dentárias (64/62 fileiras num macho subadulto de 505 mm de CT e 76/74 numa fêmea de 680 mm de CT) e de vértebras (27-28 Vtr, 68-75 Vprd), coloração ventral do disco uniformemente castanha escura, duas fenestras pós-ventrais na cintura escapular, fenestra pós-ventral posterior grande, forame magno circular e dois forames para a carótida interna na placa basal ventral do neurocrânio. Machos adultos não são conhecidos, porém uma descrição anatômica de M. obscura, sp. nov., é fornecida. Comparações são realizadas com todo o material conhecido de M. kreffti, com a literatura sobre M. senta e com material abundante de M. spinacidermis da África do Sul; M. obscura, sp. nov., assemelha-se mais a M. spinacidermis do Atlântico Sul oriental em esqueleto dérmico, coloração e tamanho. Malacoraja é monofilético devido à sua espinulação e apêndices rostrais conspícuos e é aparentemente composta por dois grupos de espécies, um para M. obscura e M. spinacidermis e outro para M. kreffti e M. senta, porém a elucidação das relações filogenéticas entre as espécies necessita de mais informações anatômicas, principalmente das duas últimas espécies.

Construção e validação de instrumento simplificado para diagnóstico de disfunção temporomandibular em pacientes adultos

As disfunções temporomandibulares (DTM) representam a maior causa de dor não dentária da região orofacial. Dada sua alta prevalência na população em geral e a existência de inúmeros instrumentos diagnósticos não padronizados, buscou-se elaborar e validar um questionário simples, de acessibilidade ampla e aplicação prática, com vistas a contribuir para o diagnóstico e o estudo epidemiológico das mesmas. A estratégia utilizada na montagem do instrumento foi estabelecida com base na avaliação criteriosa de questionários já existentes na literatura, validação de expertos na área de DTM, validação fatorial, de face (na primeira fase do estudo) e, frente ao padrão ouro (RDC/TMD), na segunda fase do estudo. Na primeira fase, participaram 160 indivíduos. A consistência interna resultou num Coeficiente Alfa de Cronbach de 0,752 para o questionário com sete itens; enquanto que para o questionário com cinco itens, este resultado foi de 0,694, não sendo o mesmo, considerado baixo por avaliar apenas cinco questões e ainda, em razão do tema central da pesquisa ser bastante subjetivo. A análise fatorial confirmatória apontou para uma variância total dos fatores extraídos do questionário com sete itens, de 58,2 % e do questionário com cinco itens de 70,04%. Portanto, o questionário com cinco questões, apresentou resultados estatísticos superiores ao de sete questões. Na validação frente ao padrão ouro (RDC/TMD), foram avaliados 99 indivíduos tendo sido testados os dois questionários, com sete e com cinco questões. Na estrutura com sete questões, ao se categorizar as mesmas por totais de pontos obtidos, em quatro condições, obteve-se o melhor resultado quando se considerou com DTM a faixa entre 10 e 21 pontos, sendo 85,1% positivos também no RDC/TMD, com acurácia de 90,1% e Kappa 0,817. Nesta condição, a sensibilidade encontrada foi de 95% (IC 95%, 91 a 99), especificidade de 87% (IC 95%, 81 a 93), VPP 85%, VPN 96%, LR+ 7,3 e LR- 17,4. Quando os dados foram avaliados para o questionário com cinco questões (QST/DTM), pode-se observar que o melhor ponto de corte foi quando se considerou como portadores de DTM, os indivíduos na faixa entre 7 e 15 pontos, com acurácia de 85,8% e Kappa 0,817. Nesta condição, a sensibilidade foi 88% (IC 95%, 81,6 a 94,4), especificidade 84% (IC 95%, 76,8 a 91,2), VPP 80%, VPN 90,5%, LR+ 5,5 e LR- 7,0. A simplicidade do presente questionário (QST/DTM) com apenas cinco questões, possibilita seu uso como elemento de triagem inicial na área da dor orofacial em disfunção temporomandibular, com boa compreensibilidade, confiabilidade, reprodutibilidade e possibilidade de aplicação em pesquisas epidemiológicas. Concluiu-se que o questionário aqui validado, permite sua aplicação de forma simples tanto por profissionais e pesquisadores da Odontologia como de outras áreas da saúde

Um olhar sociológico sobre a criança e o brincar: espaço e tempo de construção, reinvenção e aprendizagem

This research I discuss the play, also talking with the other subjects that make up the universe in which the play is inserted, such as family, school and culture. The fundamental proposition of this dissertation assumes that the absence of play in children's lives affect their physical structure, psychological, biological, cultural, social, historical and theirs development. The initial questions were: What are the spacetimes reserved in the school for play? What is the importance of play in the development of children? Does the school recognize the importance of play in its social space? How the children perceive and use the spacetimes to play at school? Are there spacetimes at school to play? This is a theoretical and empirical research of exploratory study. The research‟s field was the Municipal School Professor Ulysses Góes, located in district of Nova Descoberta, in Natal, Rio Grande do Norte and, as research techniques, I used: participant observation, photography, structured interviews with students and questionnaires with teachers. The results indicate that for most of children, the school allows the play, few disagree with this preposition.Teachers recognize the importance of play in school, but for various reasons do not provide your practice. The dissertation points the possibility of new studies and developments for the theme.

A dimensão simbólica e midiática da política e a história da dona de casa que virou guerreira : a construção da imagem pública de Wilma de Faria em 2002 e 2006

This paper examines two aspects. First, the symbolic dimension of politics and some of the elements that make up this universe, as the scenario, the representation, the myth, the spectacle, the media and the political and electoral marketing. We assume that the policy brings together a set of traits related to both reason and the human subjectivity, and can not be summed up in just a few calculations based on rationality. In the case of elections, in a process (ritual, according Irlys Barrier) of choice, there is a meeting of two systems of representations: to that transmitted by a political actor, in a scene from a particular context, based on a life trajectory unique, and the other from the public, crossed by social relations, situations own wishes, desires, expectations and unique perspectives. Between them there are the means of mass media (especially television), and with them the advent of language media and advertising applied to politics, changing the layout of public visibility and inaugurating what Rejane Accioly Carvalho will call the "aesthetics of mostrabilidade". This does not necessarily mean a preponderance of media on politics as a whole but only its adaptation to that with regard to contact with the public, the ad extra portion of the policy, according to Wilson Gomes. In a second aspect, try to apply these elements to a specific study to verify them in building an effective public image, in this case, the current governor of Rio Grande do Norte, Wilma de Faria. The concept of public image is from the book of Wilson Gomes The transformation was visible in the mass media, and relates to a conceptual image to fix "personality traits" through political history, personal conduct, action of image makers and the public reception. For this we will review some videos aired on Free Time for political propaganda in the years 2002 and 2006.

Plano de Desenvolvimento da Escola (PDE): o processo de implantação de uma nova proposta de descentralização em duas escolas da rede municipal de ensino de Natal de 1999 a 2002

The 1988 Constitution was the legal marc to define changes in Brazilian State with major importance to the layout of public politician. In that moment of redefinitions e openness to new ways the redemocratization, participation and decentralization of public school had as their starter the elementary school. This work focus on the manage of FUNDESCOLA, particularly one of its politics called PDE (Educational Development Plan) wich purpose is guarantee a better quality in teaching and spread out democracy throughout its methodology. It was chosen two public schools: Professor Ulisses de Góis and Antonio Campos. The theoretical and methodological orientation is based on the theory of participative democracy developed by authors such as Putnam and Pateman. They says that a cultural background precedes individual participation in society. The collected data (educational legislation, surveys with all sectors of schools and technicians of Natal educational secretary, and relevant documents of de institutions) showed that PDE. Implementation had opposite runnings in the schools studied. In one, as a consequence of bad preparations of its teachers to absorve its methodology, PDE failed. In another way, PDE achieved its goals, especially helping the structure of action plans of the school and the administrative organization making possible several pedagogic activities planned. The work concludes that the main factor the failure or success of PDE relies on the organizational (both political and pedagogical) structure of each school. This discovery implies three important guidelines when comes to formulation of public politicians: a) Constitution of school; b) the local actors who manages the actions; c) the colletive interest in taking part of decisions

Teodora e Porcina: faces simbólicas da natureza em narrativas de mulheres sábias

This research looks at the collective imagination in which it keeps alive the issue of heroin wise. Two wise women appear in the narratives of popular history and the History of Donzela Theodora and History Imperatriz Porcina, collated by Luís da Câmara Cascudo in his Five Books of the People. The universality, mobility and circularity of these narratives are discussed by authors such as Bakhtin and Guinzburg. The research is developed from three key categories: Knowledge Magic as the knowledge of tradition (Almeida), sensitive knowledge (Levi-Strauss), thought mythical / magical / symbolic (Morin); Wise Women as carriers of this knowledge, which merge and overlap with the imagery of witches and healers; and Mythical Elements which corresponds to the archetypal images (Jung and Silveira), symbols and other images that relate to the magic universe, the magical beliefs and practices considered, ie belonging to the imaginary magic (Bethencourt). Porcina and Theodora are understood as bearers of knowledge of Métis (Detienne and Vernant), or the cunning intelligence, the manipulation of phármakon (Derrida), the healing potion, which may be the word or ointment of the herb. The route takes us to meet the great archetype of the Wise Woman as psychic power of the feminine, the anima. Narratives are medicinal balms (Estes) and is the clash between the anima and its embodiments by wise women, and animus, his opponents, which gives the transmutation of the psyche, a work comparable to that of alchemyThe Knowledge Magic, operating through the female, myth and nature can recover from its essential value to the emerging paradigm that suggests a more complete human science and a more plural

O santo do purgatório:a transformação mítica do cangaceiro Jararaca em herói

This research intends to narrate the journey of a simple man who was turned into a saint by a group of believers in Mossoró, west of Rio Grande do Norte. We recognized in the story of José Leite Santana, the "cangaceiro" Jararacá, an appropriated land to build an investigative approach of how characters as different as bandit and saint can be interconnected. From the believers speech, a narrative was created about these detachments of concepts based on the hero myth that is shown here as a part of men´s dealing with death

Entre a Anta e a Cruz: história e memória da cidade de Nova Cruz - RN

Dans ce travail, nous étudions la construction narrative du passé de la ville de Nova Cruz, dans l´agreste potiguar. Les récits soulignent l´existence d´un corpus narratif homogène qui fait référence à l´occupation du lieu et à l´évangelisation de ses habitants. Ainsi, les images des saints et des missionaires civilisateurs de l´espace qui domestiquent les manifestations d´un esprit autochtone sauvage, habitants du milieu naturel, sont recurrentes dans la description des personnages du passé. Observant la continuité sémantique des différentes versions de l´histoire de la ville, nous nous proposons d´analyser d´une manière conjointe les textes de l´historiographie locale et les témoignages oraux collectés. Comme il a été possible de le constater, les chemins de l´écrit et de l´oral se croisent en plusieurs occasions, obéissant à des logiques locales de représentations du passé. Ainsi, notre étude porte sur des champs communs à l´Anthropologie, à l´Histoire e à la Littérature. Les reconstructions narratives du passé local sont aussi activées par des faits plus récents, des "marques de la mémoire" comme le marché, le train, la croix et le réservoir, symboles d´une époque d´abondance qui suit l´action civilisatrice des personnages ancestraux