The shift of hydrocarbon exploration and production to deepwater has resulted in new opportunities for the petroleum industry(in this project, the deepwater depth greater than 1,000 ft) but also, it has introduced new challenges. In 2001,more than 999 Bcf of associated gas were produced from the Gulf of Mexico, with deepwater associated gas production accounting for 20% of this produced gas. Two important issues are the potential environmental impacts and the economic value of deepwater associated gas. This project was designed to test the viability of storing associated gas in a saline sandstone aquifer above the producing horizon. Saline aquifer storage would have the dual benefits of gas emissions reduction and gas storage for future use. To assess the viability of saline aquifer storage, a simulation study was conducted with a hypothetical sandstone aquifer in an anticlinal trap. Five years of injection were simulated followed by five years of production (stored gas recovery). Particular attention was given to the role of relative permeability hysteresis in determining trapped gas saturation, as it tends to control the efficiency of the storage process. Various cases were run to observe the effect of location of the injection/production well and formation dip angle. This study was made to: (1) conduct a simulation study to investigate the effects of reservoir and well parameters on gas storage performance; (2) assess the drainage and imbibition processes in aquifer gas storage; (3) evaluate methods used to determine relative permeability and gas residual saturation ; and (4) gain experience with, and confidence in, the hysteresis option in IMEX Simulator for determining the trapped gas saturation. The simulation results show that well location and dip angle have important effects on gas storage performance. In the test cases, the case with a higher dip angle favors gas trapping, and the best recovery is the top of the anticlinal structure. More than half of the stored gas is lost due to trapped gas saturations and high water saturation with corresponding low gas relative permeability. During the production (recovery) phase, it can be expected that water-gas production ratios will be high. The economic limit of the stored gas recovery will be greatly affected by producing water-gas ratio, especially for deep aquifers. The result indicates that it is technically feasible to recover gas injected into a saline aquifer, provided the aquifer exhibits the appropriate dip angle, size and permeability, and residual or trapped gas saturation is also important. The technical approach used in this study may be used to assess saline aquifer storage in other deepwater regions, and it may provide a preliminary framework for studies of the economic viability of deepwater saline aquifer gas storage.

The research on Determination of Residual Gas Saturation and Gas-Water Relative Permeability in Water-Driven Gas Reservoirs is divided into four stages: literature research, core-flooding experiments, development and application of a new technique for reservoir simulation. Overall, all stages have been completed successfully with several breakthroughs in the areas of Special Core Analysis (SCAL), reservoir engineering and reservoir simulation technology.Initially, a literature research was conducted to survey all available core analysis techniques and their individual characteristics. The survey revealed that there are several core analysis techniques for measuring residual gas saturation (Sgr) and hence, the lack of a commonly agreed method for measuring Sgr. The often-used core analysis techniques are steady-state displacement, co-current imbibition, centrifuge and counter-current imbibition. In this research, all centrifuge tests were performed with a decane-brine system to investigate the possibility of replacing gas with a 'model fluid' to minimise errors due to gas compressibility. Furthermore, Sgr is a function of testing temperature and pressure, types of fluid, wettability, viscosity, flow rate and overburden pressure. Consequently, large uncertainties are associated with measured Sgr and the recoverable gas reserves for water-driven gas reservoirs.Due to the lack of a common method for measuring Sgr, the first important step is to clarify which is the most representative core analysis technique for measuring Sgr. In Stage 2 of the research, core analysis experiments were performed with uniform fluids and ambient temperature. In the core flooding experiments, four different sets of core plugs from various gas reservoirs were selected to cover a wide range of permeability and porosity. Finally, all measured Sgr from the various common core analysis techniques ++ / were compared.The evidence suggested that steady-state displacement and co-current imbibition tests are the most representative techniques for reservoir application. Steady-state displacement also yields the complete relative permeability (RP) data but it requires long stabilisation times and is costly.In the third stage, a new technique was successfully developed for determining both Sgr and gas-water RP data. The new method consists of an initial co-current imbibition experiment followed by the newly developed correlation (Mulyadi, Amin and Kennaird correlation). Co-current imbibition is used to measure the end-point data, for example, initial water saturation (Swi) and Sgr. The MAK correlation was developed to extend the co-current imbibition test by generating gas-water relative permeability data. Unlike previous correlations, MAK correlation is unique because it incorporates and exhibits the formation properties, reservoir conditions and fluid properties (for example, permeability, porosity, interfacial tension and gas density) to generate the RP curves. The accuracy and applicability of MAK correlations were investigated with several sets of gas-water RP data measured by steady-state displacement tests for various gas reservoirs in Australia, New Zealand, South-East Asia and U.S.A. The MAK correlation proved superior to previously developed correlations to demonstrate its robustness.The purpose of the final stage was to aggressively pursue the possibility of advancing the application of the new technique beyond special core analysis (SCAL). As MAK correlation is successful in describing gas water RP in a core plug scale, it is possible to extend its application to describe the overall reservoir flow behaviour. This investigation was achieved by implementing MAK correlation into a 3-D reservoir simulator (MoReS) and performing simulations on a producing ++ / field.The simulation studies were divided into two categories: pre and post upscaled application.The case studies were performed on two X gas-condensate fields: X1 (post upscaled) and X2 (pre upscaled) fields. Since MAK correlation was developed for gas-water systems, several modifications were required to account for the effect of the additional phase (oil) on gas and water RP in gas-condensate systems. In this case, oil RP data was generated by Corey's equations. Five different case studies were performed to investigate the individual and combination effect of implementing MAK correlation, alternative Swi and Sgr correlations and refining porosity and permeability clustering. Moreover, MAK correlation has proven to be effective as an approximation technique for cell by cell simulation to advance reservoir simulation technology.

<p>The residual gas fraction is an important parameter to get good performance with high efficiency and low emissions in the HCCI-engine. </p><p>The goal in this thesis is to formulate an algorithm for estimation of the residual gas fraction based on the cylinder pressure. The estimation is improved if also the exhaust gas temperature is used together with the cylinder pressure. </p><p>The formulated algorithm has then been tested on data from a single cylinder engine running in HCCI-mode during steady state conditions. An error of 4% was noted compared with the residual gas fraction obtained from simulations. </p><p>The thesis also investigates the effects of some possible error sources.</p>

The residual gas fraction is an important parameter to get good performance with high efficiency and low emissions in the HCCI-engine. The goal in this thesis is to formulate an algorithm for estimation of the residual gas fraction based on the cylinder pressure. The estimation is improved if also the exhaust gas temperature is used together with the cylinder pressure. The formulated algorithm has then been tested on data from a single cylinder engine running in HCCI-mode during steady state conditions. An error of 4% was noted compared with the residual gas fraction obtained from simulations. The thesis also investigates the effects of some possible error sources.

The IFMIF accelerator will accelerate two 125mA continuous wave (cw) deuteron beams up to 40MeV and blasts them onto a liquid lithium target to release neutrons. The very high beam power of 10MW pose unprecedented challenges for the accelerator development. Therefore, it was decided to build a prototype accelerator, the Linear IFMIF Prototype Accelerator (LIPAc), which has the very same beam characteristic, but is limited to 9 MeV only. In the frame of this thesis, diagnostics devices for IFMIF and LIPAc have been developed. The diagnostics devices consist of beam loss monitors and interceptive as well as non-interceptive profile monitors. For the beam loss monitoring system, ionization chambers and diamond detectors have been tested and calibrated for neutron and γ radiation in the energy range expected at LIPAc. During these tests, for the first time, diamond detectors were successfully operated at cryogenic temperatures. For the interceptive profilers, thermal simulations were performed to ensure safe operation. For the non-interceptive profiler, Ionization Profile Monitors (IPMs) were developed. A prototype has been built and tested, and based on the findings, the final IPMs were designed and built. To overcome the space charge of accelerator beam, a software algorithm was written to reconstruct the actual beam profile.

Modern engines are faced with increasingly stringent requirements for reduced fuel consumptionand lower emissions. A technique which can partly be used to reduce emissionsof nitrogen oxides is recirculation of combusted gases (Exhaust Gas Recirculation, EGR). Ingasoline engines, it also has the advantage that it can save fuel by reducing pumping losses.To large mixture of EGR in the air to the cylinders will however affect the combustion stabilitynegatively. To investigate EGR rate and dynamics with respect to different actuatorinputs, the thesis develops an engine model that includes EGR. The model focus on the airflow in the engine and extends an existing mean value engine model. Two types of EGRsystemare investigated. They are short-route EGR which is implemented between intakemanifold and exhaust manifold and long-route EGR which is implemented between compressorand turbine. The work provides a simulation study that compares both stationaryand transient properties of the two EGR-systems, such as fuel consumption, maximum EGR,and rise time with respect to different actuators.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20926号 / 理博第4378号 / 新制||理||1629(附属図書館) / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)教授 生形 貴男, 教授 酒井 治孝, 教授 田上 高広 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

To meet the constantly restricting emission regulations and develop better strategiesfor engine control systems, thorough knowledge of engine behavior is crucial.One of the characteristics to evaluate engine performance and its capabilityfor power generation is in-cylinder pressure. Indeed, most of the diagnosis andcontrol signals can be obtained by recording the cylinder pressure trace and predictingthe thermodynamic variables [3].This study investigates the correlation between the in-cylinder pressure andtotal trapped gas mass [10] with the main focus on estimating the in-cylinder gasmass as a part of a lab measuring procedure using the in-cylinder pressure sensors,or as a real-time method for implementation in an engine control unit thatare not equipped with the cylinder pressure sensors. The motivation is that precisedetermination of air mass is essential for the fuel control system to convey themost-efficient combustion with lower emissions delivered to the after-treatmentsystem [10].For this purpose, a six-cylinder Diesel engine is used for recording the enginespeed, engine torque, measuring the cylinder pressure profile resolved bythe crank angle, intake and exhaust valve phasing as well as intake and exhaustmanifold pressures and temperatures. Next, the most common ways of estimatingthe in-cylinder trapped gas mass are studied and the most reliable ones areinvestigated in-depth and a model with the acceptable accuracy in different operatingconditions is proposed, explained and implemented. The model in has athermodynamics basis and the relative errors is lower than 3% in all the investigatedtests. Afterwards, the most important findings are highlighted, the sourcesof errors are addressed and a sensitivity analysis is performed to evaluate themodel robustness. Subsequently, method adjustment for other operating conditionsis briefly explained, the potential future work is pointed and a complete setof results is presented in Appendix B.

L’émission électronique par effet de champ est un domaine qui concerne de nombreuses applications techniques. Dans ce travail, nous avons réalisé une étude essentiellement expérimentale des différents paramètres susceptibles d’avoir une influence sur l’émission électronique. En première partie, nous exposons les résultats obtenus pour un champ électrique homogène correspondant aux faibles intensités de courant. Le rôle de la distance inter-électrodes à champ constant et l’influence de la rugosité de surface sur l’émission électronique ont été étudiés. Nous discutons la méthode classique de Fowler-Nordheim utilisée pour le dépouillement des mesures en y portant un regard critique. Un modèle simple visant à prendre en compte l’échauffement des sites émetteurs est proposé. La seconde partie concerne l’effet de l’injection de gaz sur l’émission électronique, effet qui se traduit par une diminution du courant émis quand on augmente la pression de 10⁻⁶ Pa à 10⁻² Pa à champ macroscopique constant. Nous exposons des résultats montrant un effet de seuil concernant l’apparition de l’effet du gaz sur l’émission électronique. Nous présentons également des résultats pour différents matériaux de cathode et pour différents gaz (He, H₂, N₂, Ar). Une réversibilité de cet effet est montrée après le pompage pour redescendre à 10⁻⁵ Pa. La décroissance de courant par effet de gaz est interprétée par la diminution de la valeur du facteur d’accroissement local du champ électrique (β) au niveau des émetteurs à cause du bombardement de ces sites par les ions créés à leur proximité. Un calcul du flux d’ions bombardant un site émissif a permis d’estimer le temps nécessaire pour modifier un émetteur de façon cohérente avec les observations expérimentales. La théorie de la migration des atomes en surface de l’électrode en présence d’un champ électrique est proposée pour expliquer la réversibilité de l’effet de gaz observée qui est, selon cette théorie, liée à l’augmentation de la valeur de β au niveau des émetteurs. / Field electronic emission is a domain which concerns numerous different technical applications. In this work, we have taken an essentially experimental approach to study various parameters having influence on field emission. In the first part of the thesis, we have described the results obtained with a homogeneous electric field with relatively weak field emission. The role of the inter-electrode distance at constants field as well as that of the cathode surface roughness on field emission are studied. The classical method of Fowler-Norheim was then used for the analysis of the measurements. A simple model aiming to take into account the effect of the heating of the emission sites is then proposed. The second part of the theses concerns the effect of the injection of gas on the field emission; this effect being to significantly reduce emission intensity when the gas pressure is raised from 10⁻⁶ to 10⁻² Pa at constant field. A threshold value of emission intensity is shown to be necessary for the observation of this gas effect. The effect of different gas types (He, H₂, N₂, Ar) and cathode materials are also described. The gas effect is shown to be reversible upon lowering of the gas pressure to 10⁻⁵ Pa. The reduction in current is interpreted by a lowering of the field enhancement factor (β) of emission sites by ionic bombardment by ions created locally (within distances on the order of microns) near the cathode surface. A calculation of the flux of bombarding ions is used to estimate the time necessary to modify an emission site in a way corresponding to the observations. The phenomenon of surface migration in the presence of intense electric field is then proposed to explain the reversibility of the gas effect, increasing the local field enhancement factor.

IFMIF sera constitué de deux accélérateurs de deutons délivrant des faisceaux continus de 125mA et d’énergie 40MeV qui bombarderont une cible de lithium liquide. Face à cette très haute puissance faisceau de 10 MW, de nouveaux défis doivent être relevés pour le développement de tels accélérateurs. C’est pour cette raison qu’a été prise la décision de construire un accélérateur prototype, LIPAc (Linear IFMIF Prototype Accelerator) ayant les mêmes caractéristiques faisceau qu’IFMIF, mais avec une énergie limitée à 9MeV. Dans le cadre de cette thèse, des instruments de diagnostics faisceau ont été développés pour IFMIF et LIPAc. Ces diagnostics concernent des moniteurs de pertes faisceau ainsi que des profileurs transverse de faisceau travaillant en mode intercepteur ou non.Pour la surveillance des pertes faisceau, des chambres à ionisation et des détecteurs au diamant ont été testés et calibrés en neutrons et en γ dans la gamme en énergie de LIPAc. Lors de ces expériences, pour la première fois des diamants ont été testés avec succès à des températures cryogéniques. Pour les profileurs interceptant le faisceau, des simulations thermiques ont été réalisées afin d’assurer leur bon fonctionnement. Pour les profileurs n’interceptant pas le faisceau, des moniteurs basés sur l’ionisation du gaz résiduel (IPM) contenu dans le tube faisceau ont été développés. Un prototype a été construit et testé, puis s’inspirant de ce retour d’expérience les IPMs finals ont été conçus et construits. Pour contrecarrer la charge d’espace générée par le faisceau, un algorithme a été élaboré afin de reconstruire le profil réel du faisceau. / The IFMIF accelerator will accelerate two 125mA continuous wave (cw) deuteron beams up to 40MeV and blasts them onto a liquid lithium target to release neutrons. The very high beam power of 10MW pose unprecedented challenges for the accelerator development. Therefore, it was decided to build a prototype accelerator, the Linear IFMIF Prototype Accelerator (LIPAc), which has the very same beam characteristic, but is limited to 9 MeV only. In the frame of this thesis, diagnostics devices for IFMIF and LIPAc have been developed. The diagnostics devices consist of beam loss monitors and interceptive as well as non-interceptive profile monitors. For the beam loss monitoring system, ionization chambers and diamond detectors have been tested and calibrated for neutron and γ radiation in the energy range expected at LIPAc. During these tests, for the first time, diamond detectors were successfully operated at cryogenic temperatures. For the interceptive profilers, thermal simulations were performed to ensure safe operation. For the non-interceptive profiler, Ionization Profile Monitors (IPMs) were developed. A prototype has been built and tested, and based on the findings, the final IPMs were designed and built. To overcome the space charge of accelerator beam, a software algorithm was written to reconstruct the actual beam profile.