The variation in the cleat permeability of coalbed methane (CBM) reservoirs is attributed primarily to two cardinal processes, with opposing effects. Increase in effective stresses with reduction in pore pressure tends to decrease the cleat permeability, whereas the sorption-induced coal matrix shrinkage actuates reduction in the effective stresses which increases the reservoir permeability. The net effect of the two processes determines the pressure-dependent-permeability and, hence, the overall trend of CBM production with depletion. Several analytical models have been developed and used to predict the dynamic behavior of CBM reservoir permeability during production through pressure depletion, all based on combining the two effects. The purpose of this study was to introduce modifications to two most commonly used permeability models, namely the Palmer and Mansoori, and Shi and Durucan, for permeability variation and evaluate their performance when projecting gas production. The basis for the modification is the linear relationship between the volume of sorbed gas and the associated matrix shrinkage. Hence, the impact of matrix shrinkage is incorporated as a function of the amount of gas produced, or that remaining in coal, at any time during production. Since the exact production from a reservoir is known throughout its life, this significantly simplifies the process of permeability modeling. Furthermore, the modification is also expected to streamline the process of modeling by classifying the shrinkage parameters for coals of different regions, but with similar characteristics. A good analogy is the San Juan basin, where sorption characteristics of coal are so well understood and defined that operators no longer carry out laboratory sorption work. The goal is to achieve the same for incorporation of the matrix shrinkage behavior. Another modification is to incorporate the matrix, or grain, compressibility effect of coal as a correction factor in the Shi and Durucan model so as to assess the permeability variation based on the true shrinkage of coal matrix with reservoir drawdown. Finally, application of the modified models may be carried out for scenarios where the gas content of coal varies with time, either due to injection of a second gas to enhance the recovery of methane, or gas enhancing techniques, such as, bio-stimulation of coal. The original models are currently unable to handle this, particularly when the gas content of the reservoir increases. The research is aimed at simplifying and, in fact, improving the performance of the theoretical models in predicting the variation of coal reservoir permeability.

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Doctor of Philosophy / Department of Biology / Brett K. Sandercock / Samantha Wisely / Anthropogenic activities and climate change have dramatically altered landscapes worldwide. The ability of species to cope and adapt to ongoing changes is likely a function of their behavior, movements, and sensitivity to fragmentation. Greater Prairie-Chickens (GPC) are a lek mating grouse native to the Great Plains Landscape Conservation Cooperative (GPLCC), for which inbreeding depression and anthropogenic avoidance are a concern. The goals of my dissertation were to: 1) identify genetic correlates of male performance which may influence population viability under current land use practices, 2) identify GPC habitat characteristics and delineate areas of critical GPC habitat necessary for GPC conservation, and 3) identify the relative importance of distance and habitat quality for maintaining genetic connectivity among spatially structured populations. First, I found male reproductive success and survival to be positively associated with genetic diversity. Using multistate modeling in Program Mark, male survival across the observed range of variation in number of alleles (15-22) increased more than fourfold from 0.17 to 0.77. Second, I found 35-40% of Kansas, and 1.5 % (11,000 Km squared) of the GPLCC, were considered high-quality lek habitats. Top performing logistic models predicting lek presence (wi=0.95) included strong effects of grassland cover and avoidance of anthropogenic disturbance. When this model was applied to putative future landscapes based on climate change and current land use trends over a 70-year period, I found a 27-40% reduction in habitat area and a 137 Km southeast shift in habitat distribution. Under equilibrium conditions we expect isolation by distance (IBD) to explain the distribution of genetic diversity. However, if the landscape restricts dispersal, then we might observe isolation by resistance (IBR). I used model selection procedures to choose among competing IBR or IBD models to explain the distribution of genetic diversity among GPC populations across Kansas and the GPLCC. IBD was never supported (R-square<0.02, P>0.09). The best models for Kansas (R2=0.69, P<0.02) and for the GPLCC (R-square=0.46, P<0.02) indicated that human-mediated landscape changes have influenced landscape permeability for dispersal. The integration of behavioral, landscape, and genetic data provided new insights on prairie-chicken ecology, and is a powerful approach for developing conservation strategies for sensitive species.

L'utilisation de filtres plissés dans le domaine du traitement de l'air est extrêmement fréquente en raison de leur simplicité d'utilisation et de maintenance. Néanmoins, au cours du colmatage, la perte de charge augmente considérablement avec le dépôt de particules. Par conséquent le débit de filtration n'est plus maintenu et une détérioration des médias peut se produire. Il est essentiel de caractériser cette évolution en fonction des conditions opératoires pour mieux concevoir ces équipements. Les travaux ont consisté en une étude expérimentale de l'influence des conditions opératoires sur la géométrie du dépôt par des observations en Tomographie d'Émission MonoPhotonique. Une approche numérique a consisté, dans un premier temps, en une étude de la perméabilité de médias bien caractérisés afin de valider le code GeoDict. Dans un deuxième temps, une étude de la vitesse de l'air a été entreprise sur les médias plissés. La confrontation des résultats numériques avec les données expérimentales nous a permis une validation du code dans les gammes de propriétés des médias et de vitesses typiques. Concernant les médias bimodaux, l'acquisition rapide de données a permis de tester différentes corrélations analytiques afin de classifier les modèles existants d'une manière qui facilite leur utilisation. Si les résultats expérimentaux obtenus sur la localisation du dépôt préférentiel initial dans les filtres plissés sont encourageants, notamment vis-à-vis des simulations d'écoulement réalisées avec GeoDict, ceux issus des acquisitions sur les filtres précolmatés sont à prendre avec prudence et suggèrent d'apporter un certain nombre d'amélioration à notre technique / Pleated filters are widely used in air treatments because of the advantageous effective surface to overall dimension ratio they offer. Their major drawback though resides in their reduced lifetime which still needs to be controlled. Indeed, when clogging, the pressure drop considerably increases, the filtration flow is then no longer maintained which might lead to the deterioration of the media. It is then crucial to characterize the evolution of the pressure drop under operating conditions in order to best design these equipments. Part of our work consisted in studying how the operating conditions influence the geometry of the deposit. To do so, we used Single-Photon Emission Computed Tomography (SPECT), a non-destructive imaging technique that keeps intact the particle structuring. The visualization of aerosol deposit at the beginning of the filtration process allows observing preferential particle deposition on the whole height of the pleat. A numerical approach was used to study the permeability of bimodal fibrous media and we experimentally studied the local velocity as well as the biphasic flow inside pleated filter media. Comparison between experiments and simulations allowed us to validate the Geodict code for a wide range of media properties and velocities. Regarding bimodal fibrous media, the fast data acquisition has allowed testing several existing models which resulted in classifying them in a unique way. If the experimental results on the initial deposition in pleated filters are encouraging, those related to beforehand clogging point to several improvements regarding the technique we used