A practical bit condition monitoring system is a necessary component of autonomous drilling. Tricone bits are widely used in blasthole drilling in mining. Bits experience a variety of wear mechanisms during the operation and rolling element failure is the dominant catastrophic failure mode of tricone bits. Bit lifetime and performance significantly vary based on the working condition and the critical components of the bit i.e. rolling elements, are invisible to the direct condition monitoring systems. At McGill University, extensive research work is conducted to develop an indirect bit condition monitoring and failure prediction approach relying on the vibration signals and the technology is currently patent pending. This article presents real-world experimental evidence to show the unreliability of conservative bit changing strategy based on the bit operation life or drop in the rate of penetration (ROP) and ineffectiveness of direct wear monitoring techniques to cover the dominant failure mode.

Volcanic rocks from the Davis Strait were studied to elucidate the tectonomagmatic processes during rifting and the start of seafloor spreading, and the formation of the Ungava transform zone between Canada and Greenland. The rocks are from the wells Hekja O-71, Gjoa G-37, Nukik-2 and Hellefisk-1, and from dredges on the northern Davis Strait High. Ages range from Danian to Thanetian (dinocyst palynozones P2 to P5, 62.5–57.2 Ma). The rocks are predominantly basaltic, but include picrites on the Davis Strait High. Calculated mantle potential temperatures for the Davis Strait High are c. 1500°C, suggesting the volume of magma generated was large; this is consistent with geophysical evidence for magmatic underplating in the region. The rare earth element patterns indicate residual mantle lithologies of spinel peridotite and, together with Sr–Nd isotopes, indicate melting beneath regionally extensive, depleted asthenosphere beneath a lithosphere of thickness similar to, or thinner than, beneath Baffin Island and distinctly thinner than beneath West Greenland. Some sites include basalts with more enriched compositions. Depleted and enriched basalts in the Hellefisk well show contemporaneous melting of depleted and enriched mantle components in the asthenosphere. The Hekja and Davis Strait High basalts and picrites have unique, ultradepleted compositions with (La/Sm)N < 0.5, (Tb/Lu)N < 1 and Nb/Zr = 0.013–0.027. We interpret these compositions as a product of the melting regime within the Ungava transform zone, where the melting column would be steep-sided in cross-section and not triangular as expected at normal spreading ridges. Magmatism along the transform stopped when the tectonic regime changed from transtension to transpression during earliest Eocene time.

Owing to soaring energy needs and improved drilling technology, offshore hydrocarbon activities have been on the rise in recent years. A delimited maritime boundary is an essential precondition for the establishment of a safe and stable environment which will facilitate investment and development. Nevertheless, the conclusion of delimitation agreements can be a difficult task due to competing interests and long-standing enmities among neighbouring countries. Significant maritime areas remain undelimited. In order to avoid the problems of both unilateral activities and a complete ‘moratorium’ in undelimited areas, Articles 74(3) and 83(3) of the 1982 United Nations Convention on the Law of the Sea impose two obligations of conduct: pending delimitation agreement, States are under duty to ‘make every effort to enter into provisional arrangements of a practical nature’, while, at the same time, the interested parties should refrain from acts that might ‘jeopardize or hamper the reaching of the final agreement’. Bearing this in mind, it is argued that unilateral drilling and, under certain circumstances, unilateral seismic surveys in undelimited maritime areas should not be allowed and such conduct might trigger State responsibility. However, given that complete inactivity in such areas was not the intention of the drafters of the Convention, it is argued that several activities may be permitted as long as they are performed in good faith and do not put any final agreement at risk.

Development of shale gas by hydraulic fracturing (‘fracking’) is opposed by campaigners who propose (inter alia) that freshwater aquifers could be polluted by upward migration of fractures and any fluids they contain. Prima facie hydrogeological analysis of this proposition has been undertaken. For it to occur, two conditions must be satisfied:

1. (i) sufficient hydraulic interconnection (i.e., a continuous permeable pathway); and

2. (ii) a sustained driving head, oriented upwards.

With regard to (i), shale gas developers have a major vested interest in avoiding creating such hydraulic connection, as it would result in uneconomically excessive amounts of water needing to be pumped from their wells to achieve gas production. In relation to (ii), nominal upward hydraulic gradients will typically only be developed during fracking for periods of a few hours, which is far too brief to achieve solute transport over vertical intervals of one or more kilometres; thereafter, depressurisation of wells to allow gas to flow will result in downward hydraulic gradients being maintained for many years. The proposition is therefore found to be unsupportable. Albeit for contrasting motivations, developers and environmental guardians turn out to have a strong common interest in avoiding inter-connection to aquifers.

A powerful illustration of the potential long-term effects of fracking is provided by the hydrogeological history of underground coal mining in the UK. Where large-scale mining proceeded from the surface downwards, major hydraulic inter-connection of shallow and deep zones resulted in widespread water pollution. However, where new mines were developed at depth without connections to shallow old workings (as in the Selby Coalfield, Yorkshire), complete hydraulic isolation from the near-surface hydrogeological environment was successfully maintained. This was despite far greater stratal disruption and induced seismicity than shale gas fracking could ever produce. The lesson is clear: without hydrogeological connectivity to shallow aquifers, shale gas fracking per se cannot contaminate shallow ground water.

Residual stress states in engineering structures are usually determined by measuring components of stress tensors with depth below the material surface. There are destructive and nondestructive methods to measure strain tensor components and convert them into stress tensor components by a variety of techniques derived from constitutive (material) equations. In this study, four methods for determining the strain tensor components are presented: X-ray diffraction method (XRDM), magnetic Barkhausen noise method (MBNM), hole drilling method (HDM), and cut-and-section method (CSM); the first two are nondestructive, and the third and fourth are semidestructive and destructive, respectively. A complementarity of the experimental and two numerical methods such as boundary element method and finite element method is explained. An application of the experimental and numerical methods to measure residual stress states in an industrial component, an L-shaped part of a supporting column in a high voltage structure, is presented.

In industrial area, drilling is one of the most commonly used machining operations. Today, conventional drilling methods have found their limits in deep hole drilling. To be able to push these limits, we have developed a new technology: vibratory drilling. The aim of this study is to determine the influence of the twist drill geometry on performance of the self vibratory drilling head. For that reason, it is necessary to identify the geometrical properties which have the strongest influence on axial vibrations of twist drill and on chip fragmentation. Moreover, we have also validated the experimental results by a simulator which can predict the behaviour of the self vibratory drilling head by taking into account geometrical defects of the tool.

Silicon carbide particulate reinforced aluminum (Al/SiCp) Metal Matrix Composites (MMC) is finding increased applications in Industries due to its unique advantages. Holes are to be drilled in many applications for joining and assembly purposes. Friction drilling is a newer non-traditional hole-making chip less process used to make holes in a single step. The manuscript first discusses the mechanical properties such as tensile strength and micro hardness of Al/SiCp-MMC composites, then it discusses the roundness (hole diameter accuracy) errors on dry friction drilled holes. The parameters considered for the experiments are: the composition of work piece, work piece thickness, spindle speed, and feed rate. The results indicated that the increase in the composition of wt% of SiCp particles increases the tensile strength, hardness. The drilling test results indicated that moderate wt% of SiCp gives better results. Higher spindle speeds and higher feed rates increase the roundness error. The highly influential parameter which affects the roundness error is feed rate. Increase in plate thickness also increases the roundness error in drilling of MMC composites.

L'augmentation de la productivité des opérations de perçage est un problème industriel qui existe depuis longtemps. Un des facteurs limitants dans les opérations de perçage est l'évacuation du copeau dès que le trou devient trop profond. La mauvaise évacuation du copeau entraîne souvent une mauvaise qualité de la surface usinée et le bris de l'outil. Pour résoudre ce problème, une technique de perçage vibratoire à basse fréquence auto-entretenu a été développée et dont le but est une meilleure fragmentation du copeau afin d'améliorer son évacuation. Pour cela, un porte-outil de perçage spécifique a été mis en place. La génération naturelle des vibrations de l'outil est fortement conditionnée par le choix des conditions de coupe et de la géométrie du foret. De plus, les phénomènes de talonnage perturbent le bon fonctionnement de la tête en amortissant les vibrations. Pour prédire le comportement du porte-outil de perçage vibratoire, une modélisation des différents efforts issus des différents phénomènes de coupe le long de l'arête du foret ainsi que la génération de la surface usinée a été effectuée. Ces modèles sont maintenant intégrés dans un simulateur numérique permettant d'étudier, en particulier, l'influence du talonnage sur le comportement du porte-outil de perçage vibratoire. Différentes campagnes d'essais sont réalisées pour permettre la validation des différents modèles intégrés dans le simulateur.

L'utilisation du perçage laser s'avère une alternative incontournable lorsque le diamètre de perçage est aux environs de 10 à 50 $\mu $m, domaine où les moyens conventionnels deviennent difficiles à mettre en œuvre et coûteux. De plus il se présente comme une technique de choix pour un certain nombre de matériaux : les composites, les mous et les ultradurs, qui ne sont pas travaillés facilement au niveau microscopique avec les outils de coupe mécaniques. Nous avons apporté la preuve que des conditions d'expérience bien choisies sont capables de produire des micro-trous avec des rapports de forme records (jusqu'à 600) dans des polymères purs comme les PET, PI, PC, PS, PMMA, PEEK,... Par exemple des trous de diamètre typiquement dans les 30 $\mu $m peuvent être aussi longs que 18 mm, profondeur à laquelle la vitesse tombe presque à zéro, et le profil devient stationnaire. D'autres matériaux (métaux, céramiques), qui peuvent être de la même façon micropercés par laser, n'offrent pas les mêmes rapports de forme aussi élevés. Les mécanismes du processus de perçage ont été étudiés en détail et un modèle analytique original a été construit récemment. Les divers résultats expérimentaux, obtenus avec le laser KrF, sont revus en insistant sur les paramètres conduisant à la formation de "bons" trous avec les rapports de forme élevés. Pour les applications il est aussi important de noter que de tels rapports de forme élevés sont obtenus avec la configuration ordinaire du laser KrF ayant une divergence de 3 mrad en standard. Cependant, comme le modèle le montre, il y a encore de l'espace pour une amélioration du rapport de forme en utilisant un faisceau avec une divergence plus faible (la limite théorique est 0,2 mrad). De nouveaux travaux de recherche se poursuivent actuellement.