Drilling is one of the important aspects in the oil and gas industry due to the high demand for energy worldwide. Drilling time is considered as the major part of the operations time where the penetration rate (ROP) remains as the main factor for reducing the time. Maximizing ROP to lower the drilling cost is the main aim of operators. However, high ROP if not controlled may impact on the well geometry in terms of wellbore instability, cavities, and hole diameter restrictions. Accordingly, more time is needed for the other operations that follow such as: pool out of hole (POOH), casing running, and cementing. Bit wear is considered as the essential issue that influences in direct way on the bit performance and reduce ROP. Predicting the abrasive bit wear is required to estimate the right time when to POOH to prevent any costly job to fish any junk out to the surface. The two-common types of bits are considered in the research, rock bits (roller cone bits) and Polycrystalline Diamond Compact bits (PDC). This study focuses more on PDC bits because about 60% of the total footage drilled in wells worldwide were drilled by PDC bits and this is expected to reach 80% in 2020. The contribution of this research is to help reducing the drilling cost by developing new tools not to estimating the time when to POOH to surface but also to measure the wear and enhance the accuracy of prediction the bit efficiency. The work is broken down into four main stages or models to achieve the objective: The first stage; estimating of the rock abrasiveness and calculate the dynamic dulling rate of the rock bit while drilling. The second stage; estimating the PDC abrasive cutters wear by driving a new model to determine the mechanical specific energy (MSE), torque, and depth of cut (DOC) as a function of effective blades (EB). The accuracy of the predicted wear achieves 88% compared to the actual dull grading as an average for bits used in five wells. The third stage; modifying the previous MSE tool to develop a more accurate approach; effective mechanical specific energy (EMSE), to predict the PDC bit efficiency in both the inner and outer cone to match the standard bit dulling. The fourth stage; predicting ROP while PDC drilling in hole by accounting three parts of the process: rock drillability, hole cleaning, and cutters wear. The results achieve an enhancement of about 40% as compared to the available previous models. Consequently, the developed models in this study provide a novelty on understanding in more details the bit rock interface process and gain an idea of the relationship between the drilling parameters to enhance the bit performance and avoid damaging the bit. This is basically about optimisation the controllable factors such as: weight on bit (WOB), rotary speed (RPM), and flow rate. The result is the reduction in time losses and the operations cost. To ensure reliability and consistency of the proposed models, they were validated with several vertical oil wells drilled in Libya. The results from the validation of the models are consistent with the real field data. The research concludes that the developed models are reliable and applicable tool for both: to assist decision-makers to know when to pull the bit out to surface, and also to estimate the bit performance and wear.

The aim of this thesis is the structural design small drilling rigs for drilling wells. Drilling rig will be used for drilling wells up to 200 mm diameter rotary drilling technology with irrigation water. The first part is a literature search of small drilling rigs. In the second part, then custom design a small drilling rig.

Goal of the diploma thesis is to explain what does the term of controlled horizontal drilling mean and where it can be performed. Furthermore, it wants to show what to pay attention to during designing as well as during the actual pilot drill. Additionally, to show that pilot drill cannot be performed based on the project in all scenarios. Theoretical part of the thesis explains how the technology works and which auxiliaries are necessary to successfully perform controlled pressure. This technology is explained step by step in the practical part of the thesis to show how to proceed during the realization of controlled pressure.

Das Abteufen von Tiefbohrungen in hochfesten und abrasiven Gesteinen ist mit marktüblichen Drehbohrwerkzeugen verhältnismäßig langsam und kostenintensiv. Als vielversprechend gelten drehschlagende Bohrverfahren. Existierende Imlochbohrhämmer sind jedoch nicht mit konventionellen feststoffhaltigen Bohrspülungen kompatibel. Eine mögliche Lösung stellt ein indirekter Antrieb des Schlagwerks mithilfe eines abgeschlossenen Ölkreislaufs dar. Im Rahmen der Arbeit wurde der Laborprototyp eines ölhydraulisch angetriebenen Bohrhammers hergestellt und in Form von übertägigen Schlag- und Bohrversuchen auf einem Versuchsstand erprobt. Die Schlagversuche deuten auf Mängel in der verwendeten Ventiltechnik hin. Bei den Bohrversuchen mit 12 ¼ Zoll (311 mm) Bohrmeißeldurchmesser konnte dennoch eine gesteinszerstörende Wirkung festgestellt werden. Außerdem wurde eine Parameterstudie mithilfe numerischer Simulation durchgeführt. Diese zeigt das Potenzial des Schlagwerks unter idealisierten Bedingungen und gibt Hinweise für die Weiterentwicklung.

Capítulo 1. Objetivos: Medir e comparar o perfil de tensão residual da cerâmica de recobrimento aplicada sobre infraestruturas em zircônia tetragonal policristalina estabilizada por ítria (Y-TZP), em um compósito de alumina/zircônia (ZTA) e em uma alumina policristalina (AL). Material e Métodos: Os perfis de tensão residual de cada um dos materiais foi medido por meio do método \"hole-drilling\" em discos de 19 mm de diâmetro e 2,2 mm de espessura (0,7 mm de infraestrutura + 1,5 mm de porcelana de cobertura) .Resultados: Os espécimes de AL exibiram tensões de compressão que aumentaram numericamente com a profundidade, enquanto que as tensões compressivas mudaram para tensões de tração no interior das amostras de Y-TZP. As amostras de ZTA exibiram tensões de compressão na superfície, decrescendo com a profundidade até 0,6 mm, tornando-se compressivas novamente próximo à infraestrutura. Conclusão: O ZTA não apresentou tensões de tração em nenhum ponto ao longo da espessura da cerâmica de recobrimento. A AL apresentou um perfil de tensão residual mais favorável, gerado pelas tensões compressivas. A Y-TZP apresentou o perfil mais desfavorável, por apresentar tensões de tração próximo à infraestrutura. Capítulo 2. Objetivos: 1) Comparar os coeficientes de susceptibilidade ao crescimento subcrítico (n), de uma zircônia tetragonal policristalina estabilizada por ítria, obtidos por meio de dois ensaios de fadiga: cíclica e dinâmica. 2) Verificar o efeito da frequência usada no ensaio de fadiga cíclica no tempo de vida característico. Material e Métodos: Espécimes em forma de barras (25 mm x 4 mm x 3 mm) foram confeccionadas de acordo com as recomendações do fabricante. Os ensaios de fadiga dinâmica (n=70) e de fadiga cíclica (n=75) foram realizados por meio de resistência à flexão em quatro pontos para a obtenção dos parâmetros de crescimento de trincas subcrítico (SCG). O ensaio de fadiga cíclica também foi realizado em duas frequências (2 e 10 Hz), utilizando valores de tensão máxima entre 350 e 600 MPa. Todos os espécimes fraturados foram inspecionados em microscópio eletrônico de varredura para que fosse identificada a origem da fratura. Os dados de fadiga dinâmica foram analisados por meio das fórmulas apresentadas na ASTM C 1368-00. Os dados de fadiga cíclica foram analisados por meio da estatística de Weibull e por meio de análise tipo \"General Log Linear Model\". Resultados: A Y-TZP apresentou valores dos parâmetros de SCG obtidos no ensaio de fadiga dinâmica de ?fo = 667 MPa e n = 54. Os parâmetros de Weibull obtidos a partir dos resultados do mesmo ensaio foram de m = 7,9, ?0 = 968,9 MPa e ?5% = 767 MPa. Os parâmetros de Weibull obtidos no ensaio de fadiga cíclica foram estatisticamente semelhantes para as duas frequências utilizadas, o m* foi de 0,17 para 2Hz e de 0,21 10Hz; os tempos de vida característicos (?, em número de ciclos) foram de 1,93 x 106 e 40.768, respectivamente para 2 e 10 Hz. O valor de n obtido na fadiga cíclica foi de 48 e 40, nas frequências de 2 e 10 Hz, respectivamente. Não foi observado o efeito da frequência da aplicação da tensão, do nível de tensão, nem da interação dos dois no tempo de vida da Y-TZP, quando analisados pelo General Log Linear Model. Conclusão: Os coeficientes de susceptibilidade ao crescimento subcrítico (n) obtidos por meio de fadiga cíclica e dinâmica foram semelhantes para a Y-TZP testada. Os extensos intervalos de confiança obtidos nos ensaios de fadiga cíclica indicaram não haver efeito da frequência usado nesse método de fadiga nos tempos de vida característicos da Y-TZP testada. / Chapter 1. Objective: was: to measure and compare the residual stress profile in the veneering ceramic layered on three different polycrystalline ceramic frame-work materials: Y-TZP, alumina polycrystalline (AL) and zirconia toughened alumina (ZTA).Materials and Methods. The stress profile was measured with the hole-drilling method in bilayered disk samples of 19 mm diameter with a 0.7 mm thick Y-TZP, AL or ZTA framework and a 1.5 mm thick layer of the corresponding veneering ceramic. Results: The AL samples exhibited increasing compressive stresses with depth, while compressive stresses switching into interior tensile stresses were measured in Y-TZP samples. ZTA samples exhibited compressive stress at the ceramic surface, decreasing with depth up to 0.6 mm from the surface, and then becoming compressive again near the framework. Conclusions: Y-TZP samples exhibited a less favorable stress profile than those of AL and ZTA samples. Chapter 2. Objectives: 1) To compare the stress corrosion coefficient (n) of a Y-TZP, obtained by two fatigue tests: cyclic and dynamic and 2) Evaluate the effect of frequency used in the cyclic fatigue test in the characteristic lifetime. Methods: Bar shaped specimens (4 mm x 25 mm x 3 mm) were prepared according to the manufacturer\'s recommendations. The dynamic fatigue test (n = 70) and cyclic fatigue (n = 75) were performed by four-point bending to obtain the slow crack growth parameters (n) .The cyclic fatigue test was also conducted in two frequencies (2 and 10Hz), using stress levels between 350 and 600 MPa. All fractured specimens were inspected by SEM so that the origin of the fracture were identified. The dynamic fatigue data were analyzed using the formulas given in ASTM C 1368-00. Cyclic fatigue data were analyzed using Weibull statistics and by the Log General Linear Model. Results: The material showed values of parameters obtained in the SCG assay dynamic fatigue ?fo = 667 and n = 54. The Weibull parameters obtained from the same test results were m = 7.9, ?0 = 968, 9 and ?5% = 767. The Weibull parameters obtained by cyclic fatigue were statistically similar for the two frequencies used, the m* was 0.17 (2 Hz) and 0.21 (10 Hz); characteristic lifetimes (?) were 1.93 x 106 and 40768, respectively. The n value obtained by cyclic fatigue was 48 and 40 at frequencies of 2 and 10 Hz, respectively. There was no effect of the frequency, the stress level or the interaction of the two in the Y-TZP lifetime, when analyzed by General Log Linear Model. Conclusion: The n values obtained by cyclic and dynamic fatigue tests were similar to Y-TZP tested. The extensive confidence intervals obtained in cyclic fatigue tests showed no effect of frequency used this method in fatigue characteristic lifetimes of the Y-TZP tested.

O desmonte de rocha com uso de explosivos, aplicado à extração subterrânea de recursos minerais é uma tarefa impar que exige perícia e planejamento detalhado. Nesse contexto, essa dissertação tem sua relevância devido à apresentação de metodologias que visam aprimorar os processos envolvidos com o desmonte de rocha com uso de perfurações radiais, aplicado ao método de mineração subterrânea câmaras transversais, variante do método sublevel stoping. Para cumprir esse objetivo foram estabelecidas metodologias embasadas na utilização de registros sismográficos dos desmontes, mapeamento por laser das câmaras de lavra, registros operacionais da mina estudada. As metodologias aplicadas nas operações de mina incluíram: a segregação entre as atividades de perfuração e desmonte de rocha para assim aprimorar o ciclo operacional, a implantação de desmontes massivos como forma de aumentar a taxa de produção. A mudança na geometria das câmaras, a fim preservar o teto das mesmas. Um experimento com diferentes arranjos de retardo nos desmontes, como forma de determinar a configuração temporal menos nociva em termos de vibração, e por fim, a aplicação de uma nova malha de perfuração baseada no método dos triângulos reorientados de Hagan (1988), que visava diminuir a necessidade de perfuração e melhorar a distribuição energética dos desmontes em leque. As modificações propostas geraram resultados positivos, respectivamente quanto: aumento da eficiência dos ciclos de perfuração em 49% e aumento de 54% na produtividade das câmaras no período estudado, devido a implementação de desmontes massivos somados a segregação das atividades de perfuração e desmonte. Observou se a diminuição significativa da sobre-quebra (back break) do teto, da mesma forma os danos aos cabos de ancoragem (cable-bolts) foram reduzidos, resultados estes oriundos das modificações na geometria das câmaras. Os testes com diferentes arranjos de retardos demonstraram que o arranjo: 50ms entre furos e 200ms entre linhas, gerou a menor intensidade de vibração. O teste com o padrão de perfuração baseado na técnica de Hagan apresentou melhor índice de perfuração específica, porém, resultou em uma recuperação menor do que a média usual das câmaras, (76% contra 85%). Pode-se concluir que as metodologias propostas foram validas como medidas de aprimoramento das operações de perfuração e desmonte de rocha, a exceção da técnica dos triângulos reorientados de Hagan. Também foi possível concluir que a razão entre os valores de retardos intra linhas (L-L) e intra furos (F-F) influi diretamente na intensidade de vibração. / The blasting of rocks, applied to the underground extraction of mineral resources is a difficult task that requires expertise and detailed planning. In this context, this dissertation has its relevance due to the presentation of methodologies that aim to improve the processes involved with the blasting of rocks utilizing ring drilling, applied to the underground mining method transversal stopes, a variant of the method sublevel stoping. To fulfill this objective, methodologies based on the use of seismographic records of the blasting events, laser scanners of the stopes and operational records of the mine were used, as well as the use of Micromine software. The methodologies applied in mine operations included: segregation between rock drilling and blasting activities to improve the operational cycle, the implantation of the concept of mass blasting as a way to increase the production rate, the change in the drilling pattern in order to preserve the roof of the stopes, an experiment with different arrangements of delays for the blasting, as a way to determine the less harmful configuration in terms of vibration and finally the application of a new drilling pattern based on the reoriented triangles method of Hagan (1988), which aimed to reduce the need for drilling and to improve the energy distribution of the rings of drilling. The proposed modifications generated positive results, respectively: increase in the efficiency of the drilling cycles by 49% and a 54% increase in the productivity of the studied period, due to the implementation of mass blasting concept added to the segregation of drilling and blasting activities. It was observed that the significant decrease of the back break of the roof, in the same way the damages to the cables of reinforcement (cable-bolts) were reduced, as a result from the modifications in the drillings. The tests with different delay arrangements showed that the arrangement: 50ms between holes and 200ms between rows, generated the lowest vibration intensity. The Hagan technique-based drilling test showed a better specific drilling index, but resulted in a lower ore recovery than the usual to the stopes mean (76% vs. 85%). It can be concluded that the proposed methodologies were valid as measures of improvement of the operations of drilling and blasting of rock, except for the technique of the reoriented triangles of Hagan. It was also possible to conclude that the ratio between inter ring and inter-hole delays directly influences the vibration intensity.

In the most of the drilling operations it is obvious that a considerable amount of money is spent for drilling related problems / including stuck pipe, lost circulation, and excessive mud cost. In order to decrease the percentage of non-productive time (NPT) caused by these kind of problems, the aim is to control annular frictional pressure losses especially in the fields where pore pressure and fracture pressure gradient is too close which is called narrow drilling window. If we can solve these problems, the budget spent for drilling the wells will fall, therefore enabling the industry to be able to drill wells that were previously uneconomical. Managed Pressure Drilling (MPD) is a new technology that allows us to overcome these kinds of drilling problems by controlling the annular frictional pressure losses. As the industry remains relatively unaware of the full spectrum of benefits, this thesis involves the techniques used in Managed Pressure Drilling with an emphasis upon revealing several of its lesser known and therefore less appreciated applications.

With the goal to continue interplanetary exploration and search for past or existent life on Mars, software and hardware for unmanned subsurface drills are being developed. Unlike drilling on Earth, interplanetary exploration drills operate with very low available power and require on-board integrated health monitoring systems, with quick-response recovery procedures, under complete autonomous operations. As many drilling faults are not known a priori, Earth-based direction and control of an unmanned interplanetary drilling operation is not practical. Such missions also require advanced robotic systems that are more susceptible to structural and mechanical failures, which motivates a need for structural health monitoring techniques relevant to interplanetary exploration systems. Structural health monitoring (SHM) is a process of detecting damage or other types of defects in structural and mechanical systems that have the potential to adversely affect the current or future performance of these systems. Strict requirements for interplanetary drilling missions create unique research problems and challenges compared with SHM procedures and techniques developed to date. These challenges include implementing sensors and devices that do not interfere with the drilling operation, producing "real-time" diagnostics of the drilling condition, and developing an automation procedure for complete autonomous operations. Thus, the completed thesis work presents basic research leading to the dynamic analysis of rotating structures with specific application to interplanetary subsurface drill systems, and the formulation of an autonomous, real-time, dynamics-based SHM technique for drilling applications. This includes modeling and validating the structural dynamic system, with and without damage or faults, for a prototype interplanetary subsurface drill, exploring the use of Laser Doppler Velocimeter sensors for use in real-time SHM, developing signal filters to remove inherent harmonic components from the dynamic signal of rotating structures, developing an automation procedure with the associated software, and validating the SHM system through laboratory experiments and field tests. The automated dynamics-based structural health monitoring technique developed in this thesis presents advanced research accomplishments leading to real-time, autonomous SHM, and it has been validated on an operating dynamic system in laboratory and field tests. The formulated SHM and drilling operation also met or exceeded all specified requirements. Other major contributions of this thesis work include the formulation and demonstration of real-time, autonomous SHM in rotating structures using Laser Doppler Velocimeter sensors.

Torpedo-shaped anchors serve as foundations for risers and floating structures in the deep-water marine environment. Such cone-tipped, cylindrical steel pipes, ballasted with concrete and scrap metal, penetrate the seabed by the kinetic energy they acquire during free fall. Estimation of the embedment depth is a crucial part of the design process in that the pull-out capacity is strongly dependent on the strength of the surrounding soil. This dissertation presents the development of a procedure based on a computational fluid dynamics (CFD) model for the prediction of the embedment depth of torpedo anchors. By means of a representation of the soil as a viscous fluid, the CFD model leads not only to the resisting forces on the anchor but the distributions of pressure and shear in the soil as well. These distributions are then imported in another computational tool for finite-element (FE) analysis of coupled deformation and fluid flow in porous media for further simulations of reconsolidation of the soil next to the anchor and, ultimately, short-term and long-term capacity estimation. This dissertation presents CFD results for torpedo-anchor installation in soil, comparisons with experimental data and, finally, results from FE analysis of soil reconsolidation and anchor pull-out. / text

Gashydratlagerstätten sind in Permafrostgebieten und unter dem Meeresboden zu finden. Das energetische Potential der weltweiten Gashydratvorkommen, vor allem im submarinen Bereich, ist enorm. Derzeit existiert aber noch keine Technologie mit der sie kommerziell erschlossen werden können. Die größten Herausforderungen bei der bohrtechnischen Erschließung submariner Gashydratlagerstätten werden in der Richtbohrtechnik in geringverfestigten Sedimenten, der Bohrlochstabilität, der Einhaltung eines sehr engen Druckfensters sowie in der Vermeidung ungewollter Dissoziationsvorgänge während des Bohrprozesses gesehen. In der Arbeit werden mögliche Ansätze für die bohrtechnische Erschließung von submarinen Gashydratlagerstätten, speziell für das gerichtete Bohren in unkonsolidierten Formationen, zusammengetragen. Es werden verschiedene Erschließungskonzepte diskutiert und schließlich wird die Machbarkeit von zwei Bohrkonzepten untersucht. Das erste Konzept zielt in erster Linie auf die Herstellung vertikaler Bohrungen zu Produktionstestzwecken in Gashydratlagerstätten ab. Auf Grundlage eines vorhandenen Meeresbodenbohrgerätes wird eine neuartige Technologie entwickelt, mit der eine Tiefsee-Gashydratbohrung abgeteuft, verrohrt und komplettiert werden kann, ohne dass eine Bohrplattform oder ein Bohrschiff eingesetzt werden muss. Das zweite Konzept beinhaltet die Herstellung von horizontalen Produktionsbohrungen für eine kommerzielle Gashydratnutzung. Es wird untersucht, ob und unter welchen Bedingungen solche Bohrungen mit konventionellem Equipment machbar sind. Es wird aufgezeigt, dass die Herausforderungen gemeistert werden können und die bohrtechnische Erschließung submariner Gashydratlagestätten mit beiden Konzepten grundsätzlich machbar erscheint.