In this study, a mathematical model is developed for investigating the discrete sound propagation in viscoelastic medium to identify its viscoelastic properties. The outcome of the model suggests that pulse repetition frequency is a very important parameter for the determination of relaxation time. Adjusting the order of magnitude of the pulse repetition frequency, the corresponding relaxation time which has similar magnitude with pulse repetition frequency is filtered while the others in the spectrum are discarded. Discrete relaxation spectrum can be obtained by changing the magnitude of the pulse repetition frequency. Therefore, the model enables to characterize the relaxation times by ultrasonic measurements.

Made available in DSpace on 2014-12-17T15:42:26Z (GMT). No. of bitstreams: 1 FranciscaSHTP_TESE.pdf: 2918129 bytes, checksum: e712b711537d456c1dd4eaa0f003f3af (MD5) Previous issue date: 2013-04-01 / The construction of wells is one of the most important activities of the oil industry. The drilling process is the set of activities and operations to design, program and perform the opening thereof. During this process, the cuttings are removed by the drilling fluid, or mud, and carted to the surface. This fluid is injected into the drill string and returns to the surface through the annular space between the well walls and the drill string. After the descent of the column casing, the annular space between the casing string and the walls of the borehole is filled with cement so as to secure the spine and prevent any migration of fluids between the various permeable zones traversed by the well behind of the coating. To ensure the good quality of the cementation scrubbers are used mattresses which are pumped ahead of the cement slurry so as to avoid contamination of the drilling fluid paste, or vice versa, and assist in the removal of plaster, formed by drilling fluid of the borehole walls, thus enabling a better cement bond to the well. Within this context, this work aims to evaluate the efficiency of mattresses scrubbers, the basis of ionic and nonionic surfactants, on the removal of nonaqueous drilling fluid, based on n-paraffin in oil wells, and the compatibility between the Mattress relations washer / drilling fluid bed scrubber / cement paste mattress washer / cement slurry / drilling fluid and the drilling fluid / cement slurry using laboratory tests rheology, thickening time and compressive strength. Also technique was performed X-ray diffraction (XRD) for a more detailed analysis of these mixtures with hydrated cement paste. In compatibility tests the conditions of temperature and pressure used in the same laboratory procedure simulating the conditions of oil wells, the well is considered the depth of 800 m. The results showed that the compositions of the mattress washer nonionic, KMS obtained a 100% efficient in removing the non-aqueous drilling fluid, and the best formulation showed good results with respect to compliance testing / A constru??o de po?os ? uma das atividades mais importantes da ind?stria do petr?leo. O processo de perfura??o de po?os ? o conjunto de atividades e opera??es destinadas a projetar, programar e realizar a abertura dos mesmos. Durante este processo, os cascalhos s?o removidos pelo fluido de perfura??o, ou lama, e carreados at? a superf?cie. Este fluido ? injetado no interior da coluna de perfura??o e retorna ? superf?cie atrav?s do espa?o anular entre as paredes do po?o e a coluna de perfura??o. Ap?s a descida da coluna de revestimento, o espa?o anular entre a coluna de revestimento e as paredes do po?o ? preenchido com cimento, de modo a fixar a coluna e evitar que haja migra??o de fluidos entre as diversas zonas perme?veis atravessadas pelo po?o, por tr?s do revestimento. Para garantir a boa qualidade da cimenta??o, s?o utilizados os colch?es lavadores, que s?o bombeados ? frente da pasta de cimento, de modo a evitar a contamina??o da pasta pelo fluido de perfura??o, ou vice-versa, al?m de auxiliar na remo??o do reboco, formado pelo fluido de perfura??o, das paredes do po?o, possibilitando assim uma melhor ader?ncia do cimento ao po?o. Dentro deste contexto, este trabalho tem como objetivo avaliar a efici?ncia de colch?es lavadores, a base de tensoativos i?nico e n?o i?nico, na remo??o do fluido de perfura??o n?o aquoso, ? base de n-parafina, em po?os de petr?leo, e a compatibilidade entre as rela??es colch?o lavador/fluido de perfura??o, colch?o lavador /pasta de cimento, colch?o lavador /pasta de cimento/fluido de perfura??o e fluido de perfura??o/pasta de cimento utilizando os ensaios laboratoriais de reologia, tempo de espessamento e resist?ncia ? compress?o. Tamb?m foi realizada a t?cnica difra??o de raios X (DRX) para uma an?lise mais detalhada dessas misturas com a pasta hidratada de cimento. Nos ensaios de compatibilidade as condi??es de temperatura e press?o utilizadas nos procedimentos laboratoriais simularam as mesmas condi??es dos po?os de petr?leo, sendo a profundidade do po?o considerada de 800 m. Os resultados mostraram que as composi??es do colch?o lavador n?o i?nico, o KMS, obtiveram uma efici?ncia de 100% na remo??o do fluido de perfura??o n?o aquoso e a sua melhor formula??o apresentou resultados satisfat?rios em rela??o aos testes de compatibilidade

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In this thesis was designed, manufactured and tested the fourth evolution of a slit-flow rheometer with another necessary parts, eg. rheometer`s holder, drive frame and important jig tools. The rheometer is able to measure rheological properties of magnetic and non-magnetic fluids at very high shear rates, which commercial rheometers can not reach. It is designed for 200 bar pressure and maximum load 15 kN. The construction of the slit-flow rheometer with it`s holder and drive frame improves user friendliness, accelerates change of the fluid sample and expands research opportunities thanks to a big space for additional adjustments. It is possible to use different length of the slit and thanks to a changeable inserts it is possible to change parameters of the slit (roughness of the walls, wall material, thickness of the slit). A part of this thesis was focused on illation of necessary equations for planning calibration measurements. Aim of these measurements is to obtain minor pressure losses dependence on Reynolds number for specific slit.

Gashydrate sind natürlich vorkommende feste Verbindungen aus Wasser und Gas, deren Erschließung als zukünftige Energiequelle von Interesse ist. Für die bohrtechnische Erschließung mariner Gashydratlagerstätten ist eine leistungsfähige Bohrspülung notwendig. Das vom Bohrmeißel gelockerte Sediment und darin enthaltenes Gashydrat werden durch die Bohrspülung nach übertage transportiert. Die Gashydratpartikel verlassen beim Aufsteigen im Ringraum in ca. 300 m Wassertiefe ihren Stabilitätsbereich und dissoziieren in Wasser und Gas. Um eine Verdünnung und eine Dichteerniedrigung der Bohrspülung zu verhindern, soll das Gashydratbohrklein stabilisiert werden. Gleichzeitig darf sich in der Bohrspülung bei Anwesenheit von freiem Gas in der Lagerstätte kein neues Gashydrat bilden. Die Arbeit beschäftigt sich mit der Suche nach Additiven, welche die Gashydratneubildung und -dissoziation gleichzeitig hemmen. Es wurde ein Schüttelautoklav genutzt, um die Dissoziationstemperatur von Methanhydrat bei ca. 85 bar zu ermitteln und die Verzögerung des Hydratzerfalls bei Anwesenheit verschiedener Additive zu vergleichen. Es konnte ein Additiv gefunden werden, das diese Anforderungen erfüllt. Des Weiteren wurden neue rheologische Untersuchungsprogramme für verschiedene Spülungstypen erarbeitet, die eine detaillierte Charakterisierung der Fließfähigkeit, Thixotropie und Geleigenschaften von Bohrspülungen erlauben.