Estudo e aplicação da transformada de Fourier na regularização de dados sísmicos na exploração de petróleo

In the oil prospection research seismic data are usually irregular and sparsely sampled along the spatial coordinates due to obstacles in placement of geophones. Fourier methods provide a way to make the regularization of seismic data which are efficient if the input data is sampled on a regular grid. However, when these methods are applied to a set of irregularly sampled data, the orthogonality among the Fourier components is broken and the energy of a Fourier component may "leak" to other components, a phenomenon called "spectral leakage". The objective of this research is to study the spectral representation of irregularly sampled data method. In particular, it will be presented the basic structure of representation of the NDFT (nonuniform discrete Fourier transform), study their properties and demonstrate its potential in the processing of the seismic signal. In this way we study the FFT (fast Fourier transform) and the NFFT (nonuniform fast Fourier transform) which rapidly calculate the DFT (discrete Fourier transform) and NDFT. We compare the recovery of the signal using the FFT, DFT and NFFT. We approach the interpolation of seismic trace using the ALFT (antileakage Fourier transform) to overcome the problem of spectral leakage caused by uneven sampling. Applications to synthetic and real data showed that ALFT method works well on complex geology seismic data and suffers little with irregular spatial sampling of the data and edge effects, in addition it is robust and stable with noisy data. However, it is not as efficient as the FFT and its reconstruction is not as good in the case of irregular filling with large holes in the acquisition.

Análise comparativa de diferentes configurações de poços no processo de combustão in-situ

With an increasing number of mature fields, heavy oil recovery has performed one of the great challenges of the oil industry. The Brazilian Northeast, for example, has numerous heavy oil reservoirs are explored with the use of thermal methods. Among the types of methods used for heavy oil, there is the method of in-situ combustion, a technique in which heat is produced within the container, unlike the injection of heated fluid when the heat is generated at the surface and transported to the reservoir. In this type of process, it is common to use vertical wells as injectors and producers. However, methods which use horizontal wells like oil producers are increasingly studied because of greater contact area between the formation and combustion front. Thus, the main objective of this work was to study the different configurations of wells (CIS THAITM and CAGD) in the process of in-situ combustion in oil recovery using a semi-synthetic tank with Brazilian Northeast features. The method "toe-to-heel air injection" (THAITM) is a process of enhanced oil recovery, which is the integration of in-situ combustion with technological advances in drilling horizontal wells. This method uses horizontal wells such as oil producers, keeping vertical injection wells for injecting air. The oil drain process by differential gravitational assisted with combustion (CAGD) is an integrated, in this configuration the horizontal injector well is drilled at the top formation with a horizontal production well in the lower section. The simulations were performed in a commercial program of thermal processes, called "STARS" (Steam, Thermal, and Advanced Processes Reservoir Simulator), the company CMG (Computer Modelling Group). An analysis of the air flow injection was performed and it was found that each method had a maximum injection to the base model, a show that through this air injection limit was reduced cumulative production of oil. Analyses of operating parameters were used: injection flow, configuration and completion of wells. In the sensitivity analysis we found that the air injection flow showed greater influence on THAI method, since the CIS method the completion of the wells was the most influential parameter and CAGD configuration wells showed the greatest influence in the recovered fraction. The economic results have shown that the best case obtained in CAGD method because, despite having higher initial cost showed the best financial return compared to the best cases the CIS and THAI.

Análise comparativa de diferentes configurações de poços no processo de combustão in-situ

With an increasing number of mature fields, heavy oil recovery has performed one of the great challenges of the oil industry. The Brazilian Northeast, for example, has numerous heavy oil reservoirs are explored with the use of thermal methods. Among the types of methods used for heavy oil, there is the method of in-situ combustion, a technique in which heat is produced within the container, unlike the injection of heated fluid when the heat is generated at the surface and transported to the reservoir. In this type of process, it is common to use vertical wells as injectors and producers. However, methods which use horizontal wells like oil producers are increasingly studied because of greater contact area between the formation and combustion front. Thus, the main objective of this work was to study the different configurations of wells (CIS THAITM and CAGD) in the process of in-situ combustion in oil recovery using a semi-synthetic tank with Brazilian Northeast features. The method "toe-to-heel air injection" (THAITM) is a process of enhanced oil recovery, which is the integration of in-situ combustion with technological advances in drilling horizontal wells. This method uses horizontal wells such as oil producers, keeping vertical injection wells for injecting air. The oil drain process by differential gravitational assisted with combustion (CAGD) is an integrated, in this configuration the horizontal injector well is drilled at the top formation with a horizontal production well in the lower section. The simulations were performed in a commercial program of thermal processes, called "STARS" (Steam, Thermal, and Advanced Processes Reservoir Simulator), the company CMG (Computer Modelling Group). An analysis of the air flow injection was performed and it was found that each method had a maximum injection to the base model, a show that through this air injection limit was reduced cumulative production of oil. Analyses of operating parameters were used: injection flow, configuration and completion of wells. In the sensitivity analysis we found that the air injection flow showed greater influence on THAI method, since the CIS method the completion of the wells was the most influential parameter and CAGD configuration wells showed the greatest influence in the recovered fraction. The economic results have shown that the best case obtained in CAGD method because, despite having higher initial cost showed the best financial return compared to the best cases the CIS and THAI.

Estudo da influência da adição de níquel em alumina pela rota da metalurgia do pó

Ceramic materials alumina basis have been widely used in structural components, mainly because owning properties such as high hardness, chemical inertness and good wear resistance, however, the low toughness is a factor that compromises its use in many other applications, featuring the addition of nickel as a possible solution to this problem, in this context, this work aims to study the addition of nickel alumina using the route of powder metallurgy processing of the material. The percentage of nickel were added 2, 4 and 6 wt%; and each composition to high energy milling in a planetary mill was performed for 2, 4, 9 and 16h. Subsequently, the samples were compacted at 300 MPa and sintered in a vacuum oven at 1400⁰C for 2h. The samples were characterized as the physical and mechanical properties, observing, in general, an improvement in sinterability of the material with increasing grinding time and nickel content, and mixing with a decrease of porosity and increase of hardness, density values above 80% of theoretical were obtained. The milling time of 4 hours and addition of 2% nickel, particularly if achieved higher hardness (HV 1068.7 +/- 32.6) and density of about 99% theoretical density.

Estudo da influência da adição de níquel em alumina pela rota da metalurgia do pó

Ceramic materials alumina basis have been widely used in structural components, mainly because owning properties such as high hardness, chemical inertness and good wear resistance, however, the low toughness is a factor that compromises its use in many other applications, featuring the addition of nickel as a possible solution to this problem, in this context, this work aims to study the addition of nickel alumina using the route of powder metallurgy processing of the material. The percentage of nickel were added 2, 4 and 6 wt%; and each composition to high energy milling in a planetary mill was performed for 2, 4, 9 and 16h. Subsequently, the samples were compacted at 300 MPa and sintered in a vacuum oven at 1400⁰C for 2h. The samples were characterized as the physical and mechanical properties, observing, in general, an improvement in sinterability of the material with increasing grinding time and nickel content, and mixing with a decrease of porosity and increase of hardness, density values above 80% of theoretical were obtained. The milling time of 4 hours and addition of 2% nickel, particularly if achieved higher hardness (HV 1068.7 +/- 32.6) and density of about 99% theoretical density.

Efeito da adição de WC e Co na sinterização e propriedades mecânicas da alumina

Composites based on alumina (Al2O3), tungsten carbide (WC) and cobalt (Co) exhibit specific properties such as low density, high oxidation resistance, high melting point and high chemical inertia. That composite shows to be a promising material for application in various fields of engineering. In this work, the mechanical properties of the composite (Al2O3 – WC – Co), particularly density and hardness, were evaluated according to the effects of the variables of powder processing parameters, green compact and sintered. Powder composites with the composition of 80 wt% Al2O3, 18 wt% WC and 2 wt% Co were processed by high energy ball milling in a planetary mill for 50 hours as well as mixed by manual mixing in a glass vessel with the same proportion. Samples were collected (2, 10, 20, 30, 40 and 50 hours) during the milling process. Then, the powders were compacted in a cylindrical die with 5 mm in diameter in a uniaxial press with pressures of 200 and 400 MPa. The sintering was in two stages: first, the solid phase sintering was performed at 1126 and 1300 °C for 1 hour with a heating rate of 10 °C/min in a resistive furnace under argon atmosphere for green samples compacted in 200 and 400 MPa; the second sintering was performed on dilatometer in solid phase at 1300 °C for green sample compacted in 200 MPa, another sintering also was performed on dilatometer, this time in liquid phase at 1550 °C for green samples compacted in 200 and 400 MPa, with the same parameters used in resistive furnace. The raw materials were characterized by X – ray diffraction (XRD), X – ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and laser particlemeter. The sintered samples were subjected to microhardness testing. The results showed that high energy milling achieved to the objectives regarding the particle size and the dispersion of composite phases. However, the hardness did not achieve to significant results, this is an indication that the composite has low fracture toughness.

Efeito da adição de WC e Co na sinterização e propriedades mecânicas da alumina

Composites based on alumina (Al2O3), tungsten carbide (WC) and cobalt (Co) exhibit specific properties such as low density, high oxidation resistance, high melting point and high chemical inertia. That composite shows to be a promising material for application in various fields of engineering. In this work, the mechanical properties of the composite (Al2O3 – WC – Co), particularly density and hardness, were evaluated according to the effects of the variables of powder processing parameters, green compact and sintered. Powder composites with the composition of 80 wt% Al2O3, 18 wt% WC and 2 wt% Co were processed by high energy ball milling in a planetary mill for 50 hours as well as mixed by manual mixing in a glass vessel with the same proportion. Samples were collected (2, 10, 20, 30, 40 and 50 hours) during the milling process. Then, the powders were compacted in a cylindrical die with 5 mm in diameter in a uniaxial press with pressures of 200 and 400 MPa. The sintering was in two stages: first, the solid phase sintering was performed at 1126 and 1300 °C for 1 hour with a heating rate of 10 °C/min in a resistive furnace under argon atmosphere for green samples compacted in 200 and 400 MPa; the second sintering was performed on dilatometer in solid phase at 1300 °C for green sample compacted in 200 MPa, another sintering also was performed on dilatometer, this time in liquid phase at 1550 °C for green samples compacted in 200 and 400 MPa, with the same parameters used in resistive furnace. The raw materials were characterized by X – ray diffraction (XRD), X – ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and laser particlemeter. The sintered samples were subjected to microhardness testing. The results showed that high energy milling achieved to the objectives regarding the particle size and the dispersion of composite phases. However, the hardness did not achieve to significant results, this is an indication that the composite has low fracture toughness.

Estudo da eficiência dos adsorventes de Al2O3 e Fe/Al2O3 para remoção de BTX presente em água contaminada com gasolina

Contamination of groundwater by BTX has been featured in recent decades. This type of contamination is due to small and continuous leaks at gas stations, causing serious problems to public health and the environment. Based on these antecedents, the search for new alternatives for treating contaminated water is shown to be essential. Therefore, this study aimed to evaluate the efficiency of removal of BTX by adsorption processes employing commercial alumina (Al2O3) and alumina supported with iron (Fe/Al2O3) as adsorbents. It was prepared by a in a synthetic gasoline solution and distilled water to simulate an actual sample. Initially, the adsorbents were characterized by techniques XRD, TG / DTG, XRF, FTIR and SEM/EDS, several trials, where he was placed synthetic solution to react in the presence of Al2O3 and Fe/Al2O3 in a closed, mechanical stirring system were performed varying the catalyst concentration 2, 4 and 6 g.L-1 every 0, 10, 30 60, 90 and 120 min, aliquots were taken and brought to analysis by gas chromatography flame ionization with headspace extraction. The results indicated that the absorbent which has higher BTX removal capacity was the Fe/Al2O3 at a concentration of 6 g.L-1, pH = 4 and time of 90 minutes reaction, resulting in an efficiency, resulting in a 86,5% efficiency for benzene removal, for the 95,4% toluene, 90,8% for ɱ,ρ- xylene and 93.7% for the θ-xylenes. Subsequently, we performed a kinetic study of the reactions, the values of experimental adsorption capacity (qe) showed agreement with the values of the theoretical adsorption capacity (qc) to the pseudo-second-order model in the adsorption tests using 2 and 6 gL-1 of Al2O3 and assays using 2, 4 and 6 g.L-1 of Fe/Al2O3. A fact corroborated by the R2 values, thus indicating that the chemical interactions are present in the adsorption mechanisms of BTX.

Estudo da sinterização e oxidação anódica na produção de um capacitor eletrolítico de nióbio

It seeks to find an alternative to the current tantalum electrolytic capacitors in the market due to its high cost. Niobium is a potential replacement for be lighter and cheaper than tantalum. They belong to the same table group periodically and thus exhibit several physical and chemical properties similar. Niobium is used in many technologically important applications, and Brazil has the largest reserves, around 96%. These electrolytic capacitors have high specific capacitance, so they can store high energy in small volumes compared to other types of capacitors. This is the main attraction of this type of capacitor because is growing demand in the production of capacitors with capacitance specifies increasingly high, this because of the miniaturization of various devices such as GPS devices, televisions, computers, phones and many others. The production route of the capacitor was made by powder metallurgy. The initial niobium poder was first characterized by XRD, SEM and laser particle size to then be sieved into particle size 400mesh. The powder was then compacted at pressure of 150MPa and sintered at 1400, 1450 and 1500°C using two sintering time 30 and 60min. Sintering is an important part of the process as it affects properties as porosity and surface cleaning of the samples, which greatly affected the quality of the capacitor. After sintering the samples were underwent a process of anodic oxidation (anodizing), which created a thin film of niobium pentoxide over the whole surface of the sample, this film is the dielectric capacitor. The anodizing process variables influenced a lot in film formation and consequently the capacitor. The samples were characterized by electrical measurements of capacitance, loss factor and ESR (equivalent series resistance). The sintering has affected the porosity and in turn the specific area of the samples. The capacitor area is directly related to the capacitance, that is, the higher the specific area is the capacitance. Higher sintering temperatures decrease the surface area but eliminate as many impurities. The best results were obtained at a temperature of 1400°C with 60 minutes. The most interesting results were compared with the specific capacitance and ESR for all samples.

Estudo da sinterização e oxidação anódica na produção de um capacitor eletrolítico de nióbio

It seeks to find an alternative to the current tantalum electrolytic capacitors in the market due to its high cost. Niobium is a potential replacement for be lighter and cheaper than tantalum. They belong to the same table group periodically and thus exhibit several physical and chemical properties similar. Niobium is used in many technologically important applications, and Brazil has the largest reserves, around 96%. These electrolytic capacitors have high specific capacitance, so they can store high energy in small volumes compared to other types of capacitors. This is the main attraction of this type of capacitor because is growing demand in the production of capacitors with capacitance specifies increasingly high, this because of the miniaturization of various devices such as GPS devices, televisions, computers, phones and many others. The production route of the capacitor was made by powder metallurgy. The initial niobium poder was first characterized by XRD, SEM and laser particle size to then be sieved into particle size 400mesh. The powder was then compacted at pressure of 150MPa and sintered at 1400, 1450 and 1500°C using two sintering time 30 and 60min. Sintering is an important part of the process as it affects properties as porosity and surface cleaning of the samples, which greatly affected the quality of the capacitor. After sintering the samples were underwent a process of anodic oxidation (anodizing), which created a thin film of niobium pentoxide over the whole surface of the sample, this film is the dielectric capacitor. The anodizing process variables influenced a lot in film formation and consequently the capacitor. The samples were characterized by electrical measurements of capacitance, loss factor and ESR (equivalent series resistance). The sintering has affected the porosity and in turn the specific area of the samples. The capacitor area is directly related to the capacitance, that is, the higher the specific area is the capacitance. Higher sintering temperatures decrease the surface area but eliminate as many impurities. The best results were obtained at a temperature of 1400°C with 60 minutes. The most interesting results were compared with the specific capacitance and ESR for all samples.

Estudo da injeção de água e gás em um reservatório com características do pré-sal brasileiro

The pre-salt province is composed by large amounts of light oil and with good quality, a reality that puts Brazil in a strategic position facing the great demand for energy worldwide. In this province are the largest discoveries in the world in the last ten years; areas as Libra, Franco and Lula field, everyone containing volumes greater than 8 billion recoverable oil barrels. To develop and optimize the production of these fields, a study was done for choosing the improved oil recovery methods. The main motivations were the presence of carbon dioxide (CO2) as a contaminant and the strategic decision of do not discard it, combined with high GOR (gas-oil ratio) of the reservoir fluid. The method should take advantage of the unique abundant resources: seawater and produced gas. This way, the process of matching these resources in the water alterning gas injection (WAG) became a good option. In this master’s dissertation, it was developed a reservoir model with average characteristics of the Brazilian pre-salt, where was applied the improved oil recovery method of water alternating gas. The production of this reservoir was analyzed by parameters as: the first fluid injected in the injection process, position of the injection wells completion, injection water and gas rate and cycle time. The results showed a good performance of the method, with up to 26% of gains in the recovery factor regarding the primary recovery, since the application of water injection and gas, individually, was not able to overcome 10 % of gain. The most influential parameter found in the results was the cycle time, with higher recovery factor values obtained with the use of shorter times.

Estudo de tensoativos na organofilização de argila bentonítica para uso em fluido de perfuração à base de óleo

Due to the great challenges encountered in drilling wells, there is a need to develop fluids with appropriated properties and able to meet all the requirements of drilling operations. The physicochemical and rheological properties must be carefully controlled so that a fluid can exercise all its functions. In perforations sensitive to contact with water and "offshore", it becomes necessary the use of oil based drilling fluids, but the bentonite clay cannot be used without a previous surface modification so that their surfaces become hydrophobic. Lately, the oil companies in Brazil use imported organoclays in the preparation of oil-based drilling fluids. The study aimed to modify a calcium clay to increase the affinity of the same organic phase of oil-based drilling fluids, applying three surfactants (OCS, CTAB and UTM 150) at different concentrations. The results indicated that the surfactants UTM 150 and CTAB showed better results compared to OCS. Considering the type of surfactant and concentration as variables used in the statistical analysis, the results indicated that only the surface tension and concentration of calcium oxide in response to organophilization process showed statistically significant effects. The organophilizated clay has potential for application in oil-based drilling fluids.

Estudo de usuários em bibliotecas públicas e universitárias: em foco as dissertações defendidas no CMCI/UFPB

CARVALHO, Andréa Vasconcelos ; DINIZ, I. C. S. ; MEDEIROS, J. B. . Estudo de usuários em bibliotecas públicas e universitárias: em foco as dissertações defendidas no CMCI/UFPB. Informação & Sociedade. Estudos, João Pessoa, v. 12, n. 2, 2002

Biblioteca Digital de Teses e Dissertações: grau de utilização pelos mestrandos do curso de Ciência da Informação das Universidades Públicas Brasileiras

A pesquisa aborda o uso das Tecnologias de Informação e Comunicação, que vem revolucionando as atividades e ocasionando muitas mudanças relacionadas ao acesso e uso de informações. O objetivo foi analisar o grau de utilização do conhecimento científico produzido pelos Programas de Pós-Graduação das Universidades Públicas Brasileiras, através da BDTD, pelos mestrandos dos referidos programas. Nos procedimentos metodológicos realizados, procurou-se inicialmente analisar o amplo espectro da população do corpus da pesquisa. Em razão da impossibilidade de trabalhar com os Programas de Pós-Graduação como um todo, optou-se por fazer um recorte, elegendo os cursos de Pós-Graduação em Ciência da Informação, vez que estes representam o principal segmento social de interesse da pesquisa. Foi utilizado o método de estudo de usuários, onde se optou por adotar o grupo, “estudos orientados aos usuários”, que identifica as necessidades e comportamento de acesso e uso da informação. Para coletar os dados, elaborou-se um questionário semi-estruturado com 25 questões, que versavam sobre o uso, dificuldades de acesso e recuperação da informação, bem como a satisfação na utilização dessa fonte informacional. Dentre os vários resultados obtidos, podemos destacar o fato de que a maioria dos mestrandos (71,8%) só teve contato com a BDTD somente no momento em que se encontrava cursando o mestrado e, somente 24,3%, tiveram contato durante a graduação. Estes resultados representam um problema, que pode afetar o bom desempenho do projeto BDTD, o qual consiste em disseminar e divulgar a produção científica dos Programas de Pós-Graduação das Universidades Públicas Brasileiras para a sua comunidade. Foi observado também, que os mestrandos oriundos do curso de Biblioteconomia tende a ter contato com a BDTD bem mais cedo do que mestrandos de outros cursos de graduação. A fim de minimizar o problema detectado, propõe-se uma divulgação mais eficaz na graduação através de dois procedimentos: Primeiro, o docente deve fazer uma divulgação mais eficaz da BDTD junto aos discentes de todos os cursos de graduação; segundo: deverá ser feita a divulgação na mídia eletrônica, através da inserção de ícones da BDTD, nos portais dos Departamentos dos Cursos de Graduação das Universidades Públicas Brasileiras. Acredita-se que com estes procedimentos seja possível aperfeiçoar o uso dessa fonte de informação científica.

Coevolução e as práticas isomórficas de gestão: um estudo sobre os processos de mudanças institucionais no Instituto Federal de Educação, Ciência e Tecnologia do RN

The Federal Institution for Education, Science and Technology, in its historical path, has been living different changes. The transformations occurred along the way have been determined by coercive forces from the institutional environment, which has became more and more broad and complex throughout the time, obtaining diverse characteristics and new elements such as non institutional factors1 which started to contribute with the other changes. In this context, this work aims to study the isomorphic practices of the managers in the institutional changes process of the IFRN in 1998 and 2008, as of a theoretical coevolutionary perspective (CHILD; RODRIGUES; LEWIN; CARROL; VOLBERDA, 2003). This theory brings a new point of view for the organization analysis to the organizational studies, since it offers a non deterministic and non linear lection of the evolution process, which means, a coevolution. Thus, the organizations and their institutional and non institutional environment auto evolve, auto organize and auto reproduce. Therefore, the institutional and non institutional factors of the macro environment keep a continuous interdependence relationship with the organizations. For the means of this study, it is important to understand that is impossible to comprehend the object, the isomorphic practices, without considering that the previous institutional changes and its evolutions, its continuations and discontinuations, important in the coevolution process. As such, to call upon the institutional historical track is a fundamental aspect to materialize this study, for the recursive movement is indeed present in the coevolution. Another important point to make this research effective is that it is not possible to abdicate from the hologramatic view2 of this study, which considers the object, the isomorphic practices, part of the whole and this whole is also in the parts, therefore it is impossible to comprehend the object of study outside the context where it belongs. With this, as of the objective previously proposed, it is necessary to describe the characteristics of coevolution of the institutional changes related in 1998 and 2008; analyze the dynamic of the isomorphic mechanisms in its respective institutional change process; and describe the lessons learned which the isomorphic practices left to the IFRN, regarding its benefits and difficulties. All these transformations happened through coercive forces3 of the institutional environment. As of the Nineties, these forces became stronger, the environment became broader and more complex, with the emergency of new environmental factors. This study proposed to study the managing process and its practices, related to the micro environment, although it is required to articulate these actions, the demands and requirements from the macro environment. To make this research effective, semi structured interviews have been conducted with the managers who participated in both institutional change processes. In the results analysis, it has been possible to verify the particularity of each change, the one from 1998 with a strong normative action of the managers against coercive forces from the government for the search of recognition and the institutional legitimation and the one in 2008, which has been characterized by the normative action by managers in agreement with the coercive forces from the government, in favor of the government policy for the technological professional education. However, the results analysis it is possible to notice the evidence of a belonging feeling from the interviewed managers