Approved for public release; distribution in unlimited. / This thesis develops and implements a Control Moment Gyroscope (CMG) steering law, controller and active balancing system for a three-axis satellite simulator (TASS). The CMGs are configured in a typical pyramid configuration (the fourth CMG position being null). The development was done primarily with simulation and experiments utilizing Real Time Workshop and XPC Target of MATLAB and SIMULINK. The TASS is a double circular platform mounted on a spherical air bearing with the center of rotation (CR) about the approximate physical geometric center of the simulator. The TASS utilizes three moveable masses in the three body axes for balancing which actively eliminate any center of gravity (CG) offset and return the CG to the CR. The TASS supports an optics payload designed to acquire, track and point a received laser beam onto an off-satellite target. The target may be stationary or moving. Actively balancing the TASS reduces the torque output requirement for the CMGs while maintaining either a stabilized level platform or a particular commanded attitude. Reduction or elimination of torque output from the CMGs results in a more stabilized platform, less structural induced vibration, less jitter in payload optics and less power required in spacecraft applications. / Lieutenant Commander, United States Navy

The continuous rising of anthropogenic emission into the atmosphere as a consequence of industrial growth is becoming uncontrollable, which causes heating up the atmosphere and changes in global climate. Therefore, CO2 emission becomes a big problem and key issue in environmental concerns. There are several options discussed for reducing the amount of CO2 emitted into the atmosphere. CO2 sequestration is one of these options, which involves the capture of CO2 from hydrocarbon emission sources, e.g. power plants, the injection and storage of CO2 into deep geological formations, e.g. depleted oil reservoirs. The complexity in the structure of geological formations and the processes involved in this method necessitates the use of numerical simulations in revealing the potential problems, determining feasibility, storage capacity, and life span credibility. Field K having 32o API gravity oil in a carbonate formation from southeast Turkey was studied. Field K was put on production in 1982 and produced until 2006, which was very close to its economic lifetime. Thus, it was considered as a candidate for enhanced oil recovery and CO2 sequestration. Reservoir rock and fluid data was first interpreted with available well logging, core and drill stem test data. Monte Carlo simulation was used to evaluate the probable reserve that was 7 million STB, original oil in place (OOIP). The data were then merged into CMG/STARS simulator. History matching study was done with production data to verify the results of the simulator with field data. After obtaining a good match, the different scenarios were realized by using the simulator. From the results of simulation runs, it was realized that CO2 injection can be applied to increase oil recovery, but sequestering of high amount of CO2 was found out to be inappropriate for field K. Therefore, it was decided to focus on oil recovery while CO2 was sequestered within the reservoir. Oil recovery was about 23% of OOIP in 2006 for field K, it reached to 43 % of OOIP by injecting CO2 after defining production and injection scenarios, properly.

To meet the goal of atmospheric stabilization of carbon dioxide (CO2 ) levels a technological transformation should occur in the energy sector. One strategy to achieve this is carbon sequestration. Carbon dioxide can be captured from industrial sources and sequestered underground into depleted oil and gas reservoirs. CO2 injected into geological formations, such as mature oil reservoirs can be effectively trapped by hydrodynamical (structural), solution, residual (capillary) and mineral trapping methods. In this work, a case study was conducted using CMG-STARS software for CO2 sequestration in a mature oil field. History matching was done with the available production, bottom hole pressures and water cut data to compare the results obtained from the simulator with the field data. Next, previously developed optimization methods were modified and used for the case of study. The main object of the optimization was to determine the optimal location, number of injection wells, injection rate, injection depth and pressure of wells to maximize the total trapped amount of CO2 while enhancing the amount of oil recovered. A second round of simulations was carried out to study the factors that affect the total oil recovery and CO2 &not / storage amount. These include relative permeability end points effect, hysteresis effect, fracture spacing and additives of simultaneous injection of carbon dioxide with CO and H2S. Optimization runs were carried out on a mildly heterogeneous 3D model for variety of cases. When compared with the base case, the optimized case led to an increase of 20% in the amount of oil that is recovered / and more than 95% of the injected CO2 was trapped as solution gas on and as an immobile gas. Finally, an investigation of the economical feasibility was accomplished. NPV values for various cases were obtained, selected and studied yielding in a number of cases that are found to be applicable for the field of concern.

In this thesis axial flux and radial flux brushless dc motors will be studied as a drive motor for the control of moment gyroscope wheel. Design equations for axial flux and radial flux brushless dc motor topologies will be reviewed. Based on these equations radial and axial flux motors with different number of poles will be designed that meet control moment gyroscope wheel application requirements. The results will be evaluated in terms of efficiency, torque/mass and torque/volume, and suitability for the control moment gyroscope application.

The subject of this thesis covers the process of online parameter estimation of agile satellites. Accurate knowledge of parameters such as moment of inertia and centre of mass play a crucial role in satellite attitude control and pointing performance. Typically, identification of parameters such as these is performed on-ground using post-processing algorithms. This thesis investigates the potential of performing the identification procedures in real-time on-board operating satellites, using only measurements available from typical satellite attitude sensors.    The thesis covers the areas of system identification and modelling of spacecraft attitude dynamics. An algorithm based on the Unscented Kalman Filter is developed for online parameter estimation of spacecraft moment of inertia parameters. The proposed method is successfully validated, both through simulation environments, and in practice using Airbus’ satellite hardware demonstrator INTREPID, a three-axis air-bearing table equipped with CMG actuators and typical attitude sensors.

Carbon dioxide is one of the greenhouse gases which have strong impacts on the environment and its amount in the atmosphere is far beyond to be ignored. Carbon dioxide levels are projected to be reduced by sequestering it directly to the underground. High amounts of carbon dioxide can be safely stored in underground media for very long time periods. Storage in depleted gas reservoirs provides an option for sequestering carbon dioxide. In 2002, production of Kuzey Marmara gas reservoir has been stopped due to gas storage plans. Carbon dioxide sequestration in Kuzey Marmara field has been considered in this study as an alternative to the gas storage projects. Reservoir porosity and permeability maps were prepared with the help of Surfer software demo version. These maps were merged with the available Kuzey Marmara production information to create an input file for CMG-GEM simulator and a three dimensional model of the reservoir was created. History match of the field model was made according to the 1998-2002 production data to verify the similarity between the model and actual reservoir. Kuzey Marmara field is regarded as a candidate for future gas storage projects. The reservoir still contains producible natural gas. Four different scenarios were prepared by considering this fact with variations in the regional field properties and implemented into previously built simulation model. These scenarios primarily focus on sequestering carbon dioxide while producing as much as natural gas possible. After analyzing the results from the scenarios it is realized that / CO2 injection can be applied to increase natural gas recovery of Kuzey Marmara field but sequestering high rate CO2 emissions is found out to be inappropriate.