Thesis (Ph. D.)--University of Notre Dame, 2007. / Thesis directed by George S. Howard for the Department of Psychology. "December 2007." Includes bibliographical references (leaves 45-56).

The further exploration and development of Pabst Gas Field with faulted sand reservoirs require an understanding of the properties and roles of faults, particularly Low Throw near Vertical Faults (LTNVFs), in gas migration and accumulation at a reservoir scale. This study presents numerical modeling of gas migration and accumulation processes in Pabst Field. Based on studies of the reservoirs, structure, faults, and fluid properties of the field, reservoir scale modeling was performed to determine the gas supply style and the fault properties by means of hundreds of iterations in which the fault properties and gas supply pattern were modified to match the gas distribution obtained from modeling with the gas distribution inferred from seismic data constrained by well data and production data. This study finds that in the main three sand reservoirs of Pabst Field the overlying younger sands cut down into the underlying older sands, so that partial connections between the three sands allow gas communication among the sands. Meanwhile, three fault families break up the three sands into numerous compartments. A primary fault and large synthetic and antithetic faults act as gas migration pathways: the synthetic and antithetic faults are inlets for gas flow and the primary fault is an outlet, and LTNVFs act as barriers to gas flow. Modeling requires fault properties in the field to change while the field is formed. The porosity and permeability of the faults in Pabst Field are 10% and 0.1 md, respectively, during gas charging of the sand reservoirs. But when there is no gas charging and large gas columns are maintained, the porosity and permeability of the faults decrease to 6% and 0.001 md, respectively. Pabst Field probably has an impulse gas charge history. Fault opening and closing, gas charge and recharge, and replacement of gas by formation water may occur. A combination of stratigraphy, structure, overpressure and gas charge rate control gas migration style, gas charge history, and gas distribution in the field. The significance of the study is that this improved numerical approach for modeling gas migration into and through specifically faulted sand reservoirs fills the gap between basin modeling and production modeling.

Taking cognisance of the fact that SSFs the major producers of maize in Zambia were most affected by the 1991 agricultural policy reforms, from 2005 onward, the state became very active in the maize market and production systems in order to mitigate their problems. The main objective of this study is to investigate to what extent the maize policy changes have contributed to the SSFs’ vulnerability to exploitation. This information will be of use in the policy formulation process to ensure that the formulation of policies take a holistic approach to mitigation of the SSFs’ vulnerabilities. The study draws from political economy, peasant rationality and risk aversion theories to explain the phenomenon under study. Qualitative research methodology was used to collect and analyse both the secondary and the primary data. The study indicates that the prevailing dual system where the state marketing system exists side by side with the private sector has resulted in forms of exploitation which can broadly be classified as petty and structural forms of exploitation. Several factors could be said to exacerbate SSFs’ vulnerability to exploitation such as FRA’s delay in opening its marketing season; delays in paying the SSFs’ for their maize by government/FRA; lack of monitoring of the FRA buying agents’ activities; SSFs’ passivity, and incomplete information.

The further exploration and development of Pabst Gas Field with faulted sand reservoirs require an understanding of the properties and roles of faults, particularly Low Throw near Vertical Faults (LTNVFs), in gas migration and accumulation at a reservoir scale. This study presents numerical modeling of gas migration and accumulation processes in Pabst Field. Based on studies of the reservoirs, structure, faults, and fluid properties of the field, reservoir scale modeling was performed to determine the gas supply style and the fault properties by means of hundreds of iterations in which the fault properties and gas supply pattern were modified to match the gas distribution obtained from modeling with the gas distribution inferred from seismic data constrained by well data and production data. This study finds that in the main three sand reservoirs of Pabst Field the overlying younger sands cut down into the underlying older sands, so that partial connections between the three sands allow gas communication among the sands. Meanwhile, three fault families break up the three sands into numerous compartments. A primary fault and large synthetic and antithetic faults act as gas migration pathways: the synthetic and antithetic faults are inlets for gas flow and the primary fault is an outlet, and LTNVFs act as barriers to gas flow. Modeling requires fault properties in the field to change while the field is formed. The porosity and permeability of the faults in Pabst Field are 10% and 0.1 md, respectively, during gas charging of the sand reservoirs. But when there is no gas charging and large gas columns are maintained, the porosity and permeability of the faults decrease to 6% and 0.001 md, respectively. Pabst Field probably has an impulse gas charge history. Fault opening and closing, gas charge and recharge, and replacement of gas by formation water may occur. A combination of stratigraphy, structure, overpressure and gas charge rate control gas migration style, gas charge history, and gas distribution in the field. The significance of the study is that this improved numerical approach for modeling gas migration into and through specifically faulted sand reservoirs fills the gap between basin modeling and production modeling.

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In this study, we establish a car model which better resembles a real car and compare with the simplified car model as a reference. When taking the circular polarization antenna into consideration, we need the refined car model in the simulation. Besides, TPMS antenna measurements are conducted and the results are compared with the simulation to verify the accuracy of our simulation. The result of the simulation shows that the signal cannot be received when TPMS antenna is mounted on the rear tires. Proper solution is suggested to alleviate this problem. Due to the limitation of the measurement environment, we consider using scale-sized car model for the measurement of the antenna radiation pattern. Also, we compare the radiation pattern in the scale-sized car model with that in the full-sized car model. For the measurement of the vehicular antenna, we find that using the scale-sized car model for the preliminary estimation of the antenna radiation pattern is feasible and practicable.

Formation of scale in oilfield pipework has long been a problem. It is also likely that scale might form in the near well-bore region of the reservoir. This thesis examines the simulation of the formation damage possible due to scale, supported by experiments involving mixing brines in sandstone cores. Simulation was performed using a network model to represent the sandstone. The model was "damaged" using precipitation theory and observations on the damage caused to experimental cores. Experiments were performed, using quarried sandstone, to provide data for tuning and matching the model. The experiments used a pressure-tapped core holder to provide more detailed information on the scaling process and a new, two fluid, injection system for better control over mixing of the brines. The experiments demonstrated that permeability loss would be most rapid in the initial stages of scaling. The rate of permeability loss decreased with decreasing supersaturation of the brine mix and Increasing distance from the point of mixing. Characterisation of the permeability decline demonstrated a linear correlation between the damage rate and the initial permeability. Some effects on permeability damage due to morphology of the scale crystals were noted. The crystal morphology was shown to be mainly dependant on the solution composition rather than its supersaturation. Results from the model indicated a great sensitivity to the "poro-perm" characteristics of the network model representing the sandstone. No matching of results to experiments was achieved, but the trends with relation to the permeability change were modelled successfully.

My doctoral research focused on birds in the urban environment of Tucson, Arizona. Urban environments present unique challenges and opportunities for ecological research and conservation, and my work illustrates these aspects. From 2003-2008, I coordinated the Tucson Bird Count (TBC), a citywide bird survey program conducted by volunteer birders. My work with the TBC suggests that citizen-scientists may represent a valuable resource for ecologists because they can collect data over large scales and/or time periods. However, the environmental changes induced by humans in urban areas can also have significant negative impacts on native wildlife. My research indicates that for many native bird species, these impacts can be reduced through the actions of individual homeowners, neighborhood groups, and city and regional planners and managers. In working to maintain these species, it is important to consider both the specific habitat features important for each species, as well as the scale at which the species respond to these features.

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