The thesis investigates the behaviour of aqueous montmorillonite suspensions and also the interactions between montmorillonite as a free standing film and in highly dispersed aqueous suspension with water soluble polymers used as additives in water based drilling fluids. FTIR microscopy and FTIR ATR spectroscopy have been employed to study in-situ dehydration of fully dispersed aqueous montmorillonite suspensions. The IR spectrum of the dispersed bentonite shows significant differences from that of a dry bentonite powder, which have been attributed to the hydration of the exchangeable cation. Drying, or concentrated salt solution causes the differences to disappear and this is attributed to the exchangeable cation settling back to its ditrigonal cavity in the silicate sheet of the mineral under these conditions. The adsorption of various molecular weights of neutral polyacrylamide (PAM) onto montmorillonite has been studied using FTIR transmission, ATR spectroscopy and XRD. Shifts seen in the NH[2] stretching and bending bands have been interpreted as being due to H-bonding with the outer co-ordination sphere of exchangeable cations. KCl has shown to have some influence on this system. Another neutral polymer used extensively in water based drilling fluids is polyalkylglycol (PAG). The adsorption of two molecular weights of this polymer from aqueous solutions of various concentrations have been monitored both in the presence and absence of KCl. The physical form of the montmorillonite (either as a free standing film or as a dispersed suspension), the concentration of the polymer solution, the polymer molecular weight and the presence of KCl all have significant effects on the adsorption of polymer. The stabilisation of montmorillonite films by PAG and PAG/KCl solutions has been monitored by ATR spectroscopy, and the dehydration of these films by polymer has been monitored using FTIR spectroscopy and XRD. The interaction of PAG is thought to be via hydrogen bonding with the innermost co-ordination sphere of the exchangeable cations which thus presents a hydrophobic surface to solvent molecules, preventing the film from collapse. Since all water based drilling fluids are multi-component systems, techniques previously used have been employed to study the competitive adsorption of the polyalkylglycol and polyacrylamide components. Preferential adsorption of the PAG is seen in these systems either due to the mass transport effects (PAG is considerably smaller than PAM) or due to PAG removing all but the inner cation hydration sphere, and presenting a hydrophobic surface for the PAM, and therefore preventing its adsorption.

Orientador: Paulo Roberto Ribeiro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-24T14:14:36Z (GMT). No. of bitstreams: 1 LimaNeto_EpaminondasGonzaga_M.pdf: 3589611 bytes, checksum: e5bb12837c541392cc224ea75b48dc4b (MD5) Previous issue date: 2014 / Resumo: O cenário das perfurações de poços de petróleo vem mudando ao longo do tempo. Tanto pela necessidade do suprimento da demanda crescente por petróleo e gás quanto pela queda na produção de campos maduros, a perfuração de poços tem se deparado com ambientes mais agressivos a cada dia: maiores temperaturas, maiores pressões, maior afastamento em relação à costa e ambientes quimicamente mais hostis. A presença considerável de dióxido de carbono - CO2 - nos reservatórios aponta para uma maior preocupação na perfuração de poços em tais formações uma vez que, se esse componente adentra ao poço numa situação de kick, sua interação com a lama de perfuração pode alterar características importantes desse fluido, tais como: densidade, viscosidade e acidez. Este trabalho tem por objetivo investigar o comportamento PVT de sistemas contendo CO2 e líquidos com composição similar aos fluidos de perfuração à base de óleo: n-parafina pura e emulsão inversa. Foram realizados um estudo experimental de tais sistemas, uma simulação computacional, uma análise estatística dos dados obtidos para esse sistema com o intuito de avaliar as melhores correlações matemáticas para representação dos dados experimentais e aplicações de tais correlações em exemplos de controle de poço. Os resultados experimentais mostram que a simulação consegue reproduzir bem os dados experimentais (desvios de até 16%), apenas subestimando-os em frações molares de CO2 mais elevadas. Comparando os dados para o CO2, obtidos neste trabalho, com dados para o metano, obtidos da literatura, observa-se que o sistema contendo CO2 apresenta, dentre outras características, maior fator de formação de volume e solubilidade até 15 vezes maior que o sistema contendo metano. Por fim, ao examinar os exemplos de controle de poço, percebe-se que quanto maior é o teor de CO2 no sistema, maior é o valor do pit gain, tornando a presença de CO2 no sistema favorável à detecção do kick / Abstract: The scenario of oil and gas well drilling has been changing over the years. Not only because the need of supplying the increasing demand for petroleum and gas but also due to the decrease on the production of mature fields, well drilling has been constantly facing aggressive environments: higher temperatures, higher pressures, higher offshore distances and hazardous chemical environments. The presence of carbon dioxide - CO2 - on reservoirs leads to a concern on well drilling in these formations because the entrance of this gas into the well, in a kick situation, and its interaction with the drilling fluid can change important characteristics of this fluid such as: density, viscosity and acidity. This work aims to evaluate the PVT behavior of the systems containing CO2 and liquids similar to the ones used as base for oil-based drilling fluids: n-paraffin and inverse emulsion. An experimental study of these systems, a computational simulation, a statistical analysis of the data acquired aiming to evaluate the best mathematical correlations to represent these data and applications of these correlations were carried out. The experimental results show that the simulation can reproduce satisfactorily the experimental data (deviations up to 16%), only underestimating them at higher CO2 molar fractions. When comparing the data for CO2, obtained in this work, and the ones for methane, obtained from literature, it is possible to notice that the system containing CO2 has, among other characteristics, higher oil volume formation factor and solubility 15 times greater than the system containing methane. Finally, by examining well control examples, one can notice that the pit gain assumes higher values as the CO2 content increases making the presence of CO2 in the system favorable to kick detection / Mestrado / Explotação / Mestre em Ciências e Engenharia de Petróleo

Orientador: Paulo Roberto Ribeiro / Dissertação (mestrado) - Universidade Estadual de Campinas. Faculdade de Engenharia Mecanica e Instituto de Geociencias / Made available in DSpace on 2018-08-12T18:02:11Z (GMT). No. of bitstreams: 1 PaulaJunior_RubensRibeirode_M.pdf: 2205711 bytes, checksum: 8d99ae4553a735e11f7c7662c3878d30 (MD5) Previous issue date: 2008 / Resumo: O trabalho apresenta uma revisão da literatura sobre poços HPHT, abordando o desafio na construção dos mesmos, com ênfase no aspecto de segurança de poço. Do ponto de vista de desenvolvimento, o trabalho envolveu a implementação de um modelo de controle de poços com fluidos de perfuração não aquosos em software existente (Unikick), que incorpora correlações empíricas derivadas de resultados experimentais com n-parafina e diesel. A importância dessa implementação deve-se ao fato de que a previsão do comportamento das pressões, vazões e volumes desenvolvidos em um poço durante a detecção e circulação de um kick de gás, é muito útil para o engenheiro de perfuração que poderá tomar decisões sobre a maneira mais segura de lidar com estas situações. Alguns estudos de casos foram realizados através de comparação dos resultados obtidos pelo Unikick e outros simuladores disponíveis e análise de sensibilidade de parâmetros. Nessa análise, foram simuladas circulações de kicks em terra e marítimos em várias lâminas d'água, com trajetórias verticais e horizontais e observados os comportamentos de parâmetros importantes durante o controle do poço, como a pressão no choke, pit gain e vazão de gás na superfície. / Abstract: The first part of the work provides a review of the literature on HPHT wells, addressing the challenge in the construction of these wells, emphasizing the safety aspects. From the point of view of development, the work involved an implementation of a well control model for nonaqueous drilling fluids using existing software (Unikick), that incorporates empirical correlations derived from experimental results with n-paraffin and diesel. The importance of this implementation is due to the fact that the estimation of the behavior of pressures, flow rates and volumes developed inside a well during gas kick detection and circulation out of the well is very useful for the drilling engineer to take decisions about the safest way to handle these situations. Some case studies were performed through the comparison of simulated results from Unikick and other simulators available and a sensitivity analysis. In this analysis, some kick circulations were simulated in onshore and offshore wells with various water depths, vertical and horizontal trajectories, when important parameters of well control were observed, such as choke pressure pit gain and gas flow rate at surface. / Mestrado / Explotação / Mestre em Engenharia Mecânica