A novel method of predicting pore pressure has been invented. The method utilizes currently recorded drilling measurements to predict the pore pressure of the formation through which the bit is drilling. The method applies Mohr’s Theory to describe the stresses at the bottom of the borehole. From the stress state and knowledge of Mohr’s Envelope, the pore pressure is predicted. To verify the method, a test procedure was developed. The test procedure enabled systematic collection and processing of the drilling data to calculate the pore pressure prediction. The test procedure was then applied to industry data that was recorded at the surface. The industry data were composed of wells from different geographical regions. Two conclusions were deduced from the research. First, Mohr’s Theory indicates that the model is valid. Second, because of too much variation in the torque measurements the model cannot be proved and requires further investigation.

L’introduction massive des alliages de titane pour les pièces de structures aéronautiques a soulevé de nouvelles problématiques d’usinage. Du fait que les matériaux réfractaires présentent de faibles propriétés thermiques leur mise en forme par usinage à sec est difficile. L’objectif industriel est d’améliorer la productivité de l’usinage des alliages de titane afin d’en réduire les coûts. Des travaux concernant la coupe du Ti6Al4V α+β, du Ti54M et du Ti6Al4V traité β ont été réalisés pour mettre en évidence les différences d’usinabilité entre ces trois matériaux. Ces travaux mettent en avant une forte influence du comportement orthotrope et de l’hétérogénéité de la microstructure lamellaire, ainsi que de la taille des grains du Ti6Al4V traité β sur la mise en forme par coupe. L’étude sur l’usure des outils par diffusion montre que le principal élément de diffusion est le titane et que par conséquent aucune différence n’est observée entre les trois matériaux. Pour confirmer que la diffusion est le mode d’usure principal, des essais de perçage instrumentés avec un système de mesure de température sans fil ont été effectués. Les températures à l’arrière de l’arête de coupe atteignent des températures supérieures à 500°C pour de faibles vitesses de coupe. A cette température le phénomène de diffusion est thermiquement activé et confirme les hypothèses évoquées précédemment. Enfin, pour avoir une compréhension des différences d’usinabilité mises en évidence lors des travaux expérimentaux, une recherche sur le comportement des matériaux (Johnson-Cook) et la mise en place d’une simulation numérique ont été réalisées. Les simulations réalisées à l’aide des lois de comportement identifiées précédemment modélisent précisément l’usinage du Ti6Al4V α+β et du Ti54M. L’hétérogénéité du Ti6Al4V traité β ne permet pas une bonne modélisation de la formation du copeau. Une modélisation polycristalline serait plus adaptée. / The massive introduction of titanium alloys onto the aeronautical structures parts has raised new problems in the machining process. Because of their low thermal properties (refractory materials), they are considered as difficult to cut material. The industrial aim is therefore to improve the productivity of the titanium alloy’s machining and to reduce their costs. Some research on Ti6Al4V α + β, Ti54M and β-treated Ti6Al4V cutting was carried out to point out machinability’s differences between these three materials. This work highlights a strong influence of the orthotropic behavior and the heterogeneity of the lamellar microstructure as well as the grain size of the β-treated Ti6Al4V on cutting. The study on the tool wear diffusion shows that the main diffusion element is titanium and therefore no difference is observed between those three materials. To check that diffusion is the main wear mode, instrumented drilling tests with a wireless temperature measurement device were performed. Temperatures behind the cutting edge reach temperatures above 500 °C for low cutting speeds. At this temperature the phenomenon of diffusion is thermally activated. Finally, in order to have an understanding of the machinability consistencies, a research on the materials’ behavior (Johnson-Cook) and the implementation of a numerical simulation were realized. The simulations carried out, using the previously identified behavior’s laws, model precisely the machining of the Ti6Al4V α+β and Ti54M. The heterogeneity of the β-treated Ti6Al4V does not allow a good modeling of the chip formation. Polycrystalline modeling would be more appropriate.

The supply and demand situation is crucial for the oil and gas industry during the first half of the 21st century. For the future, we will see two trends going in opposite directions: a decline in discoveries of conventional oil and gas reservoirs and an increase in world energy demand. Therefore, the need to develop and produce unconventional oil and gas resources, which encompass coal-bed methane, gas-shale, tight sands and heavy oil, will be of utmost importance in the coming decades. In the past, large-scale production from tight gas reservoirs occurred only in the U.S. and was boosted by both price incentives and well stimulation technology. A conservative study from Rogner (1997) has shown that tight gas sandstone reservoirs would represent at least over 7,000 trillion cubic feet (Tcf) of natural gas in place worldwide. However, most of the studies such as the ones by the U.S. Geological Survey (U.S.G.S.) and Kuuskraa have focused on assessing the technically recoverable gas resources in the U.S. with numbers ranging between 177 Tcf and 379 Tcf. During the past few decades, gas production from tight sands field developments have taken place all around the world from South America (Argentina), Australia, Asia (China, Indonesia), the Russian Federation, Northern Europe (Germany, Norway) and the Middle East (Oman). However, the U.S. remains the region where the most extensive exploration and production for unconventional gas resources occur. In fact, unconventional gas formations accounted for 43% of natural gas production and tight gas sandstones represented 66% of the total of unconventional resources produced in the U.S. in 2006. As compared to a conventional gas well, a tight gas well will have a very low productivity index and a small drainage area. Therefore, to extract the same amount of natural gas out of the reservoir, many more wells will have to be drilled and stimulated to efficiently develop and produce these reservoirs. Thus, the risk involved is much higher than the development of conventional gas resources and the economics of developing most tight gas reservoirs borders on the margin of profitability. To develop tight gas reservoirs, engineers face complex problems because there is no typical tight gas field. In reality, a wide range of geological and reservoir differences exist for these formations. For instance, a tight gas sandstone reservoir can be shallow or deep, low or high pressure, low or high temperature, bearing continuous (blanket) or lenticular shaped bodies, being naturally fractured, single or multi-layered, and holding contaminants such as CO2 and H2S which all combined increase considerably the complexity of how to drill a well. Since the first tight gas wells were drilled in the 1940's in the U.S., a considerable amount of information has been collected and documented within the industry literature. The main objective of this research project is to develop a computer program dedicated to applying the drilling technologies and methods selection for drilling tight gas sandstone formations that have been documented as best practices in the petroleum literature.