Made available in DSpace on 2014-12-17T14:08:56Z (GMT). No. of bitstreams: 1 LuannaCMP_DISSERT.pdf: 3195149 bytes, checksum: 9c2b834c5beeb3439f6a0d1955159637 (MD5) Previous issue date: 2013-09-02 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / 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 / Embora exista uma grande variedade de aditivos que atuam no estado fresco, para ajuste das propriedades do cimento, existe tamb?m uma busca por adi??es que melhorem a tenacidade do cimento no estado endurecido. Esta, por sua vez, pode comumente ser aumentada pela inser??o de fibras, as quais agem na deflex?o de microtrincas. Este trabalho tem como objetivo utilizar microfibras de l? de vidro (? base de s?lica) como aditivo de refor?o ? matriz ciment?cia, melhorando a tenacidade ? ruptura, a fim de evitar a propaga??o de microfissuras na bainha cimentante comumente encontradas em po?os de petr?leo submetidos a altas temperaturas. As fibras foram adicionadas em diferentes teores, de 2 a 5% (BWOC), e variados tamanhos m?dios, obtidos variando o tempo de moagem de 90 s, 180 s, 300 s e 600 s. As pastas foram formuladas com densidade de 1,90 g/ cm3 (15,6 lb/gal), utilizando o cimento Portland CPP-Classe Especial como aglomerante hidr?ulico e 40% de s?lica flour. A caracteriza??o da fibra foi feita por microscopia eletr?nica de varredura (MEV), granulometria por peneiramento, fluoresc?ncia de raios X (FRX), difra??o de raios X (DRX) e termogravimetria (TG/DTG). Foram realizados ensaios tecnol?gicos padronizados pela API (American Petroleum Institute) de reologia, estabilidade, ?gua livre, resist?ncia ? compress?o, bem como testes de energia de ruptura, m?dulo de elasticidade e permeabilidade. Os resultados da caracteriza??o mostraram boa estabilidade t?rmica da microfibra de l? de vidro para aplica??o em po?os submetidos ? inje??o de vapor. A partir dos dados de granulometria, foi poss?vel verificar que microfibras mo?das at? 300 s s?o ideais para agirem como refor?o ? pasta de cimento. Dos par?metros reol?gicos, houve o comprometimento da viscosidade pl?stica quando foram inseridos comprimentos maiores de microfibra (F90). Os valores obtidos de ?gua livre e estabilidade se apresentaram conformes ? norma API. Das propriedades mec?nicas, a incorpora??o de microfibra ? pasta de cimento conferiu melhor tenacidade ? ruptura, comparada a pasta de refer?ncia. Os valores obtidos de resist?ncia ? compress?o, m?dulo de elasticidade e permeabilidade foram mantidos com rela??o ? pasta padr?o. Desse modo, pastas ciment?cias refor?adas com microfibra de l? de vidro podem garantir boas aplica??es em cimenta??o de po?os de petr?leo sujeitas ? inje??o de vapor, que exija o controle de microfissuras em virtude do gradiente de temperatura

Made available in DSpace on 2014-12-17T14:08:56Z (GMT). No. of bitstreams: 1 LornnaLAG_DISSERT.pdf: 2131175 bytes, checksum: 63e4a76183bcbcfcae20c296d8b0364d (MD5) Previous issue date: 2014-01-31 / Cementing operation is one of the most important stages in the oil well drilling processes and has main function to form hydraulic seal between the various permeable zones traversed by the well. However, several problems may occur with the cement sheath, either during primary cementing or during the well production period. Cements low resistance can cause fissures in the cement sheath and compromise the mechanical integrity of the annular, resulting in contamination of groundwater and producing zones. Several researches show that biomass ash, in particular, those generated by the sugarcane industry have pozzolanic activity and can be added in the composition of the cementing slurries in diverse applications, providing improvements in mechanical properties, revenue and cement durability. Due to the importance of a low cost additive that increases the mechanical properties in a well cementing operations, this study aimed to potentiate the use of sugarcane bagasse ash as pozzolanic material, evaluate the mechanisms of action of this one on cement pastes properties and apply this material in systems slurries aimed to cementing a well with 800 m depth and geothermal gradient of 1.7 ?F/100 ft, as much primary cementing operations as squeeze. To do this, the ash beneficiation methods were realized through the processes of grinding, sifting and reburning (calcination) and then characterization by X-ray fluorescence, XRD, TG / DTG, specific surface area, particle size distribution by laser diffraction and mass specific. Moreover, the ash pozzolanic activity added to the cement at concentrations of 0%, 20% and 40% BWOC was evaluated by pozzolanic activity index with lime and with Portland cement. The evaluation of the pozzolanic activity by XRD, TG / DTG and compressive strength confirmed the ash reactivity and indicated that the addition of 20% in the composition of cement slurries produces improvement 34% in the mechanical properties of the slurry cured. Cement slurries properties evaluated by rheological measurements, fluid loss, free fluid, slurry sedimentation, thickening time and sonic strength (UCA) were satisfactory and showed the viability of using the sugarcane ash in cement slurries composition for well cementing / A opera??o de cimenta??o ? uma das etapas mais importantes no processo de perfura??o de po?os de petr?leo e tem a fun??o primordial de promover a veda??o hidr?ulica entre as diversas zonas perme?veis atravessadas pelo po?o. No entanto, v?rios problemas podem ocorrer com a bainha de cimento, seja durante a cimenta??o prim?ria ou no decorrer do per?odo produtivo do po?o. Cimentos de baixa resist?ncia podem causar trincas na bainha de cimento e comprometer a integridade mec?nica do anular, resultando em contamina??o de len??is fre?ticos e zonas produtoras. V?rias pesquisas comprovam que cinzas de biomassa, em particular, as geradas pela ind?stria sucroalcooleira apresentam atividade pozol?nica e podem ser adicionadas na composi??o das pastas cimentantes em diversas aplica??es, proporcionando benef?cios nas propriedades mec?nicas, no rendimento e na durabilidade do cimento. Dada a import?ncia de um aditivo de baixo custo e que aumenta as propriedades mec?nicas em uma opera??o de cimenta??o de po?os, este trabalho objetivou potencializar o uso da cinza de biomassa da cana-de-a??car (CBCC) como material pozol?nico, avaliar os mecanismos de atua??o desta nas propriedades de pastas de cimento e aplicar este material em sistemas de pastas destinadas ? cimenta??o de um po?o com 800 m de profundidade e gradiente geot?rmico de 1,7 ?F/100 p?s, tanto para as opera??es de cimenta??o prim?ria quanto corretiva (squeeze). Para isso, foram realizados m?todos de beneficiamento da cinza atrav?s dos processos de moagem, peneiramento e requeima (calcina??o) e, em seguida, a caracteriza??o por fluoresc?ncia de raios-X, DRX, TG/DTG, superf?cie espec?fica, granulometria a laser e massa espec?fica. Al?m disso, a atividade pozol?nica da cinza, adicionada ao cimento nas concentra??es de 0% (pasta padr?o), 20% e 40% BWOC, foi avaliada pelo ?ndice da atividade pozol?nica com a cal e com o cimento Portland. A avalia??o da atividade pozol?nica atrav?s das an?lises de DRX, TG/DTG e resist?ncia ? compress?o comprovaram a reatividade do material e indicaram que a adi??o de 20% de cinza na composi??o das pastas produz melhorias em at? 34% das propriedades mec?nicas da pasta endurecida. As propriedades das pastas avaliadas atrav?s dos ensaios de propriedades reol?gicas, perda de filtrado, ?gua livre, estabilidade, tempo de espessamento e resist?ncia ? compress?o (UCA) mostraram-se satisfat?rias e indicaram a viabilidade da utiliza??o da cinza na composi??o das pastas de cimento para po?os de petr?leo

A exploração dos recursos naturais e a degradação do meio ambiente têm sido fonte de preocupação no âmbito mundial. A busca por soluções alternativas que não causem ou que diminuam os impactos ambientais tornou-se comum na sociedade. Nesse contexto, a pavimentação vem contribuindo significativamente com soluções alternativas para destinação final de diversos tipos de resíduos, principalmente os oriundos da indústria da construção civil que sempre foi uma das maiores geradoras. Os resíduos da construção e demolição (RCD) podem ser transformados em agregados reciclados de ótima qualidade e podem ser aplicados em diversos serviços de engenharia. Os agregados reciclados, segundo a NBR 15116 (ABNT, 2004), são separados em misto e de concreto (ARC). No Brasil existem poucas pesquisas com o ARC, no entanto, as que existem e as pesquisas internacionais relatam que uma característica marcante do ARC é a cimentação própria. Portanto, o objetivo desta pesquisa é estudar o comportamento mecânico, ao longo do tempo de cura, do agregado reciclado de concreto proveniente da Usina de Reciclagem de São Carlos e de sua mistura com um solo laterítico, a fim de utilizá-los na construção de pavimentos. O estudo envolveu a análise dos resultados de resistência à compressão simples, módulo tangente, módulo de resiliência, deformação permanente e índice de suporte Califórnia (CBR) de corpos-de-prova de ARC e da sua mistura com solo laterítico, moldados em diferentes energias de compactação e ensaiados com tempos de cura variados. Ao final, concluiu-se que o agregado reciclado de concreto (ARC) é uma alternativa para construção de bases de pavimentos, podendo também substituir o agregado natural da mistura solo arenoso laterítico - brita descontínua, muito utilizada nas rodovias do interior de São Paulo. / Natural resources exploitation and the environmental degradation are a worldly problem nowadays. Searching for alternative solutions is something usual in most countries. Pavement systems are now contributing significantly with these alternative solutions by using the waste of construction demolition. This specific kind of waste can turn into mixed recycled aggregate or recycled concrete aggregate. There are just few researches in Brazil about the use of recycled concrete aggregate (RCA), however international researches have shown that this aggregate has a very characteristic and positive mark: self cementation. This research has got the objective of studying the mechanic behavior of the recycled concrete aggregate and its mix with lateritic soil on the construction of base pavements with different analytic basis. The study involved the analysis of the laboratorial tests results of the unconfined compressive strength, tangent modulus, resilient modulus, permanent deformation and California Bearing Ration (CBR) of RCA specimens and its mix with lateritic soil, molded in different compaction energy and tested in different curing times. In conclusion, this kind of recycled aggregate has proved to be a sustainable alternative for the natural aggregate in the construction of many roads in small cities of the State of São Paulo - Brazil.

[pt] Esta dissertação investiga escoamentos multifásicos de deslocamento de fluidos em geometrias anulares envolvidas em operações de cimentação de poços com fluidos espumados. A cimentação desempenha um papel relevante na integridade de poços e algumas aplicações requerem pastas leves com alta resistência à compressão, e o cimento espumado atende a este propósito. Para modelar adequadamente a complexidade do escoamento - que compreende comportamento não-newtoniano e elevada compressibilidade - um modelo tridimensional de dinâmica computacional de fluidos (CFD) foi desenvolvido a partir do código aberto OpenFOAM. As equações de conservação da massa, momento e fases são solucionadas em uma geometria anular, considerando o efeito da pressão na densidade e na reologia dos fluidos, e o método Volume of Fluid (VoF) foi usado para capturar a interface entre fluidos. Os modelos foram validados com soluções exatas para escoamento monofásico axissimétrico com fluidos incompressíveis e compressíveis, e com modelos constitutivos newtonianos e não-newtonianos. Além disso, simulações multifásicas estimaram a eficiência de deslocamento do fluido de perfuração pela pasta de cimento em diferentes condições – constraste de densidade e de viscosidade, ecentricidade e vazões de bombeio – e com diferentes correlações para a reologia dos fluidos espumados. Finalmente, simulações de deslocamento com fluidos com densidade e reologia constante (não-espumados) foram utilizadas para comparação. Os resultados indicam que a eficiência no deslocamento com a técnica de cimentação espumada é superior em condições similares e ilustra que as pastas espumadas são menos suceptíveis a gerarem falhas quanto condições desafiadoras estão presentes. / [en] This master dissertation investigates multiphase displacement flow in annular geometries involved in well cementing operations with foamed cement slurries and spacers. Well cementing plays a relevant role in well integrity and some applications require combining a low-density cement slurry with high compressive strength, and foamed cement suits this purpose. To properly model the displacement complexity involving foamed fluids flow - pressure and temperature dependent densities and non-Newtonian rheology - a 3-dimensional computational fluid dynamics (CFD) model was developed from the open-source OpenFOAM toolbox. The mass, momentum and phase conservation equations are solved in an annular geometry, taking the effect of pressure in the fluid density and rheology, and the volume-of-fluid (VoF) method was used to capture the interface between the fluids. The models were validated using exact solutions for axisymmetric single-phase flow with incompressible and compressible fluids, and Newtonian and non-Newtonian constitutive models. Further, multiphase simulations were performed to estimate the removal efficiency of the drilling fluid by the foamed cement slurry/spacer in different conditions – density and viscosity contrast, eccentricities, and flow rate - and with different correlations for the foamed cement rheological behavior. Finally, the displacement simulations with constant density and rheology displacing fluids (unfoamed) were performed and used to compare the results with the foamed displacing fluids. The results indicate that the displacement efficiency with a foamed cement technique outperforms constant density lightweight cement slurries with similar conditions and are much less sensitive to impairment when challenging conditions are present.

The construction industry is the largest consumer of materials in our society. Approximately 40% of all materials used are related to this section of the industry. Equivalent is the impact of the sector’s activities to the environment in terms of non-renewable energy sources (grey energy), gas emissions (mainly CO2), solid waste, etc. With concrete being the most widely used construction material (second only to water in total volumes consumed annually by society) and cement being the essential “glue” in concrete, emphasis should be placed on investigating and enforcing appropriate ways, methodologies and policies, to make cement manufacturing and the construction industry in general a more environmental friendly sector. At the same time, by considering, at one hand the significant amount of research and breakthroughs achieved on structural materials and design, as well as the level of sophistication of the modern European Standards and structural codes, and on the other hand, the increasing cases of premature deterioration of concrete structures, particular emphasis should also be placed on safeguarding the service life of reinforced concrete structures (in addition to tackling their environmental burden). That is why it is very important to introduce the sustainable way of thinking and the concept of industrial ecology on the preliminary design stages of a structure, on the material selection process and on the service life estimation stage, in achieving a robust durable reinforced concrete (RC) structure (for a given service life) with the minimum environmental burden. Thus, the main objective of the present Thesis is to focus on identifying and quantifying a structured framework of the appropriate methodologies in formulating an Integrated Design Process (IDP) for the design of durable and sustainable structures at the minimum environmental and economical cost (without compromising issues of structural safety) and also in identifying and demonstrating ways of industrial ecology for the sustainable development of the cement and construction industry. The present Thesis contributes to the evaluation of the environmental cost of each component of concrete and to provide the best possible mix design configuration (by means of a holistic analytical software tool) in terms of low environmental cost, as well as, to assess this proposed configuration in terms of strength and durability requirements. Overall, it has to be emphasized that through the present Thesis a new indicator is proposed for design purposes: the environmental cost, which can be added to the existing strength, durability and economic cost indicators towards an integrated design optimization of concrete structures. Finally, it is concluded that the incorporation of new Supplementary Cementing Materials (SCM), as biomass ashes and especially Rice Husk Ash (RHA), offers new perspectives for decreasing the environmental cost of constructions. / Η κατασκευαστική βιομηχανία αποτελεί τον μεγαλύτερο καταναλωτή υλικών στην κοινωνία μας. Περίπου το 40% όλων των υλικών που χρησιμοποιούνται σχετίζονται με αυτόν τον τομέα της βιομηχανίας. Αντίστοιχο αντίκτυπο έχουν και οι δραστηριότητες του τομέα στο περιβάλλον σε ότι αφορά τις μη ανανεώσιμες πηγές ενέργειας («γκρίζα» ενέργεια), αέριες εκπομπές (κυρίωςCO2 ), στερεά απόβλητα, κλπ. Δεδομένου ότι το σκυρόδεμα αποτελεί το πιο ευρέως χρησιμοποιούμενο δομικό υλικό (δεύτερο μετά το νερό σε συνολικούς όγκους που καταναλώνονται ετησίως από την κοινωνία) και ότι το τσιμέντο είναι η απαραίτητη «κόλλα» στο σκυρόδεμα, έμφαση πρέπει να δοθεί στη διερεύνηση και επιβολή κατάλληλων τρόπων, μεθοδολογιών και πολιτικών για τη μετατροπή της τσιμεντοβιομηχανίας και της κατασκευαστικής βιομηχανίας σε έναν γενικά περισσότερο περιβαλλοντικά φιλικό τομέα. Ταυτόχρονα, λαμβάνοντας υπόψη από τη μια μεριά τη σημαντική ποσότητα έρευνας και τα επιτεύγματα σχετικά με τα δομικά υλικά και τον σχεδιασμό, και επιπλέον το επίπεδο της επιτήδευσης των σύγχρονων Ευρωπαϊκών Προτύπων και κατασκευαστικών κανονισμών, και από την άλλη μεριά τις αυξανόμενες περιπτώσεις της πρώιμης φθοράς των κατασκευών από σκυρόδεμα, ιδιαίτερη έμφαση θα πρέπει να δοθεί στη διασφάλιση της διάρκειας ζωής των κατασκευών οπλισμένου σκυροδέματος (σε συνδυασμό με την αντιμετώπιση της περιβαλλοντικής τους επιβάρυνσης). Για το λόγο αυτό είναι ιδιαίτερα σημαντική η εισαγωγή του βιώσιμου τρόπου σκέψης και της έννοιας της βιομηχανικής οικολογίας στα προκαταρκτικά στάδια σχεδιασμού μιας κατασκευής, κατά τη διαδικασία επιλογής υλικών και κατά το στάδιο εκτίμησης της διάρκειας ζωής, ώστε να επιτευχθεί μια εύρωστη, ανθεκτική κατασκευή οπλισμένου σκυροδέματος (για δεδομένη διάρκεια ζωής) με την ελάχιστη περιβαλλοντική επιβάρυνση. Συνεπώς, ο κύριος στόχος της παρούσας Διατριβής είναι να επικεντρωθεί στον εντοπισμό και ποσοτικοποίηση ενός δομημένου προτύπου κατάλληλων μεθοδολογιών για τον σχηματισμό μιας Ενοποιημένης Διαδικασίας Σχεδιασμού για τον σχεδιασμό ανθεκτικών και βιώσιμων κατασκευών με το ελάχιστο περιβαλλοντικό και οικονομικό κόστος (χωρίς συμβιβασμούς σε θέματα που άπτονται της κατασκευαστικής ασφάλειας) και επίσης για την αναγνώριση και επίδειξη τρόπων βιομηχανικής οικολογίας για την βιώσιμη ανάπτυξη της βιομηχανίας τσιμέντου και σκυροδέματος. Η παρούσα Διατριβή συνεισφέρει στην αξιολόγηση του περιβαλλοντικού κόστους κάθε συστατικού του σκυροδέματος αλλά και στην παροχή ενός καλύτερου δυνατού σχεδιασμού σύνθεσης σκυροδέματος (μέσω ενός ολιστικού αναλυτικού λογισμικού) υπό όρους χαμηλού περιβαλλοντικού κόστους, καθώς και στο να αξιολογήσει την προτεινόμενη σύνθεση υπό όρους αντοχής και απαιτήσεων ανθεκτικότητας. Συνολικά, πρέπει να τονισθεί ότι στη παρούσα Διατριβή προτείνεται για πρώτη φορά ένας νέος δείκτης για σκοπούς σχεδιασμού: το περιβαλλοντικό κόστος, το οποίο μπορεί να προστεθεί στους υπάρχοντες δείκτες αντοχής, ανθεκτικότητας και οικονομικού κόστους προς μια ολοκληρωμένη αριστοποίηση σχεδιασμού κατασκευών από σκυρόδεμα. Τέλος, προκύπτει το συμπέρασμα ότι η ενσωμάτωση νέων συμπληρωματικών υδραυλικών υλικών (SCM: Supplementary Cementing Materials), όπως οι τέφρες βιομάζας και ειδικά η τέφρα φλοιού ρυζιού (RHA: Rice Husk Ash), προσφέρει νέες προοπτικές για τη μείωση του περιβαλλοντικού κόστους σκυροδέματος.

The need for energy and the associated economic benefits from the oil and gas deposits found mainly in the Niger Delta region of Nigeria necessitated the exploration and exploitation activities being carried out by the oil and gas Companies. However, these exploration and exploitation activities due to their unpredictable nature have a huge potential for environmental pollution as been experienced in the form of oil spills, gas flaring, irresponsible disposal of waste and several other activities that have resulted in the environmental degradation of the Niger Delta region. In the light of these, the Federal Government of Nigeria having experienced the consequences of pollution of the environment during the Koko Toxic Waste Dump incident in the then Bendel State in 1987 established a regulatory body tasked with the responsibility of harmonizing the economic interest from the oil and gas exploration and exploitation activities with the sustainability of the natural environment by developing well structured and articulated policies aimed at guiding the operations of the oil and gas operators, track their compliance and administer appropriate punitive measures for non compliance. However, this research work which is aimed at evaluating the impact of the environmental protection policies in upstream oil and gas activities in the Niger Delta region, involved the use of questionnaires and interviews. These questionnaires were completed by the management and staff of three major oil and gas companies operating within the area, the Department of Petroleum Resources and members of the Host communities. The interview was carried out to provide relevant feedback on their assessment of the impact made by the environmental protection policies on the upstream oil and gas activities in their operational areas/host communities. The study however concluded that “Although there is a regulatory body tasked with the responsibility to develop, implement and track compliance of the environmental protection policies in the upstream oil industry, the body is ineffective and as such the impact of the environmental protection policies is inadequate. Appropriate informed recommendations on the improvement strategies to the identified gaps that resulted in the unfavorable conditions were also provided. / Thesis (M.Ing. (Development and Management Engineering))--North-West University, Potchefstroom Campus, 2011

The need for energy and the associated economic benefits from the oil and gas deposits found mainly in the Niger Delta region of Nigeria necessitated the exploration and exploitation activities being carried out by the oil and gas Companies. However, these exploration and exploitation activities due to their unpredictable nature have a huge potential for environmental pollution as been experienced in the form of oil spills, gas flaring, irresponsible disposal of waste and several other activities that have resulted in the environmental degradation of the Niger Delta region. In the light of these, the Federal Government of Nigeria having experienced the consequences of pollution of the environment during the Koko Toxic Waste Dump incident in the then Bendel State in 1987 established a regulatory body tasked with the responsibility of harmonizing the economic interest from the oil and gas exploration and exploitation activities with the sustainability of the natural environment by developing well structured and articulated policies aimed at guiding the operations of the oil and gas operators, track their compliance and administer appropriate punitive measures for non compliance. However, this research work which is aimed at evaluating the impact of the environmental protection policies in upstream oil and gas activities in the Niger Delta region, involved the use of questionnaires and interviews. These questionnaires were completed by the management and staff of three major oil and gas companies operating within the area, the Department of Petroleum Resources and members of the Host communities. The interview was carried out to provide relevant feedback on their assessment of the impact made by the environmental protection policies on the upstream oil and gas activities in their operational areas/host communities. The study however concluded that “Although there is a regulatory body tasked with the responsibility to develop, implement and track compliance of the environmental protection policies in the upstream oil industry, the body is ineffective and as such the impact of the environmental protection policies is inadequate. Appropriate informed recommendations on the improvement strategies to the identified gaps that resulted in the unfavorable conditions were also provided. / Thesis (M.Ing. (Development and Management Engineering))--North-West University, Potchefstroom Campus, 2011

Made available in DSpace on 2014-12-17T14:07:00Z (GMT). No. of bitstreams: 1 MariaDMP_pre_textuais_ate_cap_3.pdf: 1552357 bytes, checksum: 286c69a88a6d2c4ec8689ee9514da8ec (MD5) Previous issue date: 2008-10-28 / Oil wells subjected to cyclic steam injection present important challenges for the development of well cementing systems, mainly due to tensile stresses caused by thermal gradients during its useful life. Cement sheath failures in wells using conventional high compressive strength systems lead to the use of cement systems that are more flexible and/or ductile, with emphasis on Portland cement systems with latex addition. Recent research efforts have presented geopolymeric systems as alternatives. These cementing systems are based on alkaline activation of amorphous aluminosilicates such as metakaolin or fly ash and display advantageous properties such as high compressive strength, fast setting and thermal stability. Basic geopolymeric formulations can be found in the literature, which meet basic oil industry specifications such as rheology, compressive strength and thickening time. In this work, new geopolymeric formulations were developed, based on metakaolin, potassium silicate, potassium hydroxide, silica fume and mineral fiber, using the state of the art in chemical composition, mixture modeling and additivation to optimize the most relevant properties for oil well cementing. Starting from molar ratios considered ideal in the literature (SiO2/Al2O3 = 3.8 e K2O/Al2O3 = 1.0), a study of dry mixtures was performed,based on the compressive packing model, resulting in an optimal volume of 6% for the added solid material. This material (silica fume and mineral fiber) works both as an additional silica source (in the case of silica fume) and as mechanical reinforcement, especially in the case of mineral fiber, which incremented the tensile strength. The first triaxial mechanical study of this class of materials was performed. For comparison, a mechanical study of conventional latex-based cementing systems was also carried out. Regardless of differences in the failure mode (brittle for geopolymers, ductile for latex-based systems), the superior uniaxial compressive strength (37 MPa for the geopolymeric slurry P5 versus 18 MPa for the conventional slurry P2), similar triaxial behavior (friction angle 21? for P5 and P2) and lower stifness (in the elastic region 5.1 GPa for P5 versus 6.8 GPa for P2) of the geopolymeric systems allowed them to withstand a similar amount of mechanical energy (155 kJ/m3 for P5 versus 208 kJ/m3 for P2), noting that geopolymers work in the elastic regime, without the microcracking present in the case of latex-based systems. Therefore, the geopolymers studied on this work must be designed for application in the elastic region to avoid brittle failure. Finally, the tensile strength of geopolymers is originally poor (1.3 MPa for the geopolymeric slurry P3) due to its brittle structure. However, after additivation with mineral fiber, the tensile strength became equivalent to that of latex-based systems (2.3 MPa for P5 and 2.1 MPa for P2). The technical viability of conventional and proposed formulations was evaluated for the whole well life, including stresses due to cyclic steam injection. This analysis was performed using finite element-based simulation software. It was verified that conventional slurries are viable up to 204?F (400?C) and geopolymeric slurries are viable above 500?F (260?C) / Po?os sujeitos ? inje??o c?clica de vapor apresentam importantes desafios para desenvolvimento de pastas de cimenta??o, devido principalmente aos esfor?os de tra??o causados pelos gradientes t?rmicos durante a sua vida ?til. Falhas em cimenta??es que empregaram pastas convencionais de elevada resist?ncia ? compress?o levaram ao emprego de pastas mais flex?veis e/ou d?cteis, com destaque para as pastas de cimento Portland com adi??o de l?tex. Recentes pesquisas t?m apresentado pastas geopolim?ricas como alternativa. Estas pastas cimentantes s?o baseadas na ativa??o alcalina de aluminosilicatos amorfos como o metacaulim ou a cinza volante e possuem propriedades vantajosas como alta resist?ncia ? compress?o, r?pido endurecimento e estabilidade t?rmica. Encontram-se na literatura formula??es geopolim?ricas b?sicas que atendem ?s especifica??es da ind?stria de petr?leo, incluindo reologia, resist?ncia ? compress?o e tempo de espessamento. Neste trabalho, desenvolveu-se novas formula??es geopolim?ricas ? base de metacaulim, silicato de pot?ssio, hidr?xido de pot?ssio, micross?lica e fibra mineral, utilizando o estado da arte em composi??o qu?mica, modelagem de misturas e aditiva??o para otimizar as propriedades relevantes para a cimenta??o de po?os. Partindo de raz?es molares consideradas ideais na literatura (SiO2/Al2O3 = 3,8 e K2O/Al2O3 = 1,0), realizou-se um estudo de misturas secas baseado no modelo do empacotamento compress?vel, obtendo-se um volume ?timo de 6% para o material s?lido adicional. Este material (micross?lica e fibra mineral) serve tanto como fonte de s?lica adicional (no caso da micross?lica) quanto refor?o mec?nico, principalmente no caso da fibra mineral, a qual incrementou a resist?ncia ? tra??o. Realizou-se o primeiro estudo mec?nico triaxial desta classe de pastas. Para efeito de compara??o, tamb?m foi realizado um estudo mec?nico de pastas convencionais ? base de l?tex. Apesar de diferen?as no modo de ruptura (fr?gil no caso dos geopol?meros, d?ctil no caso das pastas com l?tex), a superior resist?ncia compressiva uniaxial (37 MPa para a pasta geopolim?rica P5 versus 18 MPa para a pasta convencional P2), comportamento triaxial similar (?ngulo de atrito 21? para P5 e P2) e menor rigidez (na regi?o el?stica 5,1 GPa para P5 versus 6,8 GPa para P2) das pastas geopolim?ricas permitiu uma capacidade de absor??o de energia (155 kJ/m3 para P5 versus 208 kJ/m3 para P2) compar?vel entre as duas, sendo que os geopol?meros atuam no regime el?stico, sem a microfissura??o presente nas pastas com l?tex. Assim, os geopol?meros estudados neste trabalho devem ser dimensionados para aplica??es no regime el?stico para evitar fraturas fr?geis. Finalmente, a resist?ncia ? tra??o do geopol?mero ? originalmente pobre (1,3 MPa para a pasta geopolim?rica P3) devido ? sua estrutura fr?gil. Entretanto, ap?s a aditiva??o desse sistema com fibra mineral, a resist?ncia ? tra??o do mesmo tornou-se equivalente (2,3 MPa para P5 e 2,1 MPa para P2) ? das pastas com l?tex. A viabilidade t?cnica das formula??es convencionais e geopolim?ricas foi avaliada durante toda a vida ?til do po?o, incluindo os esfor?os devidos ? inje??o c?clica de vapor. Esta an?lise foi feita utilizando um software de simula??o ? base de elementos finitos. Verificou-se que as pastas convencionais s?o vi?veis at? a temperatura de 204?C (400?F) e as geopolim?ricas acima de 260?C (500?F)

[pt] Umas das etapas mais complexas e críticas durante a construção de poços de petróleo é o processo de cimentação primária, definido como: O processo de instalação de cimento no anular entre o revestimento e a formação exposta ao poço [1]. Ela fornece isolamento zonal permanente para evitar contaminação ou migração de fluidos indesejáveis no anular, protege o revestimento da ocorrência de corrosão e fornece estabilidade hidráulica e mecânica para o revestimento ao longo da vida produtiva do poço de petróleo. Neste processo, ainda na etapa de perfuração, irregularidades na seção transversal (washouts) podem ser geradas como resultado de diversos colapsos parciais da seção do poço aberto em decorrência da presença de rochas pouco consolidadas da formação. Uma operação de cimentação primária bem sucedida dependerá se o sistema de fluidos espaçadores e a pasta de cimento deslocam de forma adequada e completa o fluido de perfuração do anular e washouts. Motivados por esse problema industrial, a presente dissertação usa um simulador numérico DNS (Direct Numerical Simulation) com o objetivo de analisar sistematicamente o comportamento hidrodinâmico e calcular a eficiência do deslocamento entre dois fluidos newtonianos miscíveis através de um anular contendo uma expansão seguida de uma contração abrupta. Investigamos como diferentes viscosidades e densidades dos fluidos, um injetado e outro deslocado, a miscibilidade entre eles, a taxa de injeção e a dimensão do washout retangular afetam o escoamento bifásico. Consideramos uma geometria axissimétrica durante processos de deslocamentos verticais, e as equações governantes são resolvidas em coordenadas cilíndricas, permitindo investigar diferentes aberturas anulares. Devido à miscibilidade entre os fluidos, nossos resultados preveem eficiências de deslocamento altíssimas, próximas a 100 Fluidos não-newtonianos são usualmente utilizados durante o processo industrial de cimentação primária de poços de petróleo. Contudo, as altas eficiências de deslocamentos encontradas em nossos resultados motivam estudos futuros sobre a influência da miscibilidade em deslocamentos de fluidos complexos. Estes resultados também motivam o uso de fluidos espaçadores para tentar controlar as propriedades de interface. Desta forma, é possível que a utilização de sistemas que se aproximem das condições reológicas e hidrodinâmicas de deslocamento entre fluidos newtonianos miscíveis poderá contribuir para um aumento da eficiência de deslocamento e, consequentemente, otimizar o processo de deslocamento de sistemas de fluidos, tendo em vista melhorias na integridade da cimentação de poços de petróleo. / [en] One of the most complex and critical stages during the construction ofoil wells is the primary cementing process, defined as the process of installingcement in the annulus between the casing and the exposed formation to thewell [1]. Primary cementing provides permanent zonal isolation to preventcontamination or migration of unwanted fluids in the annulus, protects thecasing from corrosion, and provides hydraulic and mechanical stability forthe casing throughout the productive life of the oil well. In this process,during the drilling stage, irregularities in the cross-section (washouts) can begenerated because of various partial collapses of the open wellbore section dueto the presence of poorly consolidated rocks in the formation. A successfulprimary cementing operation will depend on whether the spacer fluid systemand cement slurry adequately and completely displace the drilling fluid fromthe annulus and washouts.Motivated by this industrial problem, the present dissertation uses aDirect Numerical Simulation (DNS) numerical simulator to systematically analyze the hydrodynamic behavior and calculate the displacement efficiency between two miscible newtonian fluids through an annulus containing an expansion followed by an abrupt contraction. We investigate how different viscositiesand densities of the injected and displaced fluids, their miscibility, injectionrate, and the dimension of the rectangular washout affect the two-phase flow.We consider an axisymmetric geometry during vertical displacement processes,and the governing equations are solved in cylindrical coordinates, allowing theinvestigation of different annular clearances. Due to the miscibility betweenthe fluids, our results predict very high displacement efficiencies, close to 100Non-newtonian fluids are commonly used during the industrial processof primary cementing of oil wells. However, the high displacement efficienciesfound in our results motivate further studies on the influence of miscibilityin displacements of complex fluids. These results also encourage the use ofspacer fluids attempting to control the interfacial properties. Therefore, the useof systems that approximate the rheological and hydrodynamic conditions ofdisplacement between miscible newtonian fluids may contribute to an increasein displacement efficiency and, consequently, optimize the displacement processof fluid systems, aiming at improvements in the integrity of well cementing.