AN ABSTRACT OF THE DISSERTATION OFSUMAN SAURABH, for the Doctor of Philosophy degree in Engineering Science, presented on August 30, 2019, at Southern Illinois University Carbondale.TITLE: GEOMECHANICAL STATE OF ROCKS WITH DEPLETION IN UNCONVENTIONAL COALBED METHANE RESERVOIRSMAJOR PROFESSOR: Dr. Satya HarpalaniOne of the major reservoir types in the class of unconventional reservoirs is coalbed methane. Researchers have treated these reservoirs as isotropic when modeling stress and permeability, that is, mechanical properties in all directions are same. Furthermore, coal is a highly sorptive and stress- sensitive rock. The focus of this dissertation is to characterize the geomechanical aspects of these reservoirs, strain, stresses, effective stress and, using the information, establish the dynamic flow/permeability behavior with continued depletion. Several aspects of the study presented in this dissertation can be easily extended to shale gas reservoirs. The study started with mechanical characterization and measurement of anisotropy using experimental and modeling work, and evaluation of how the sorptive nature of coal can affect the anisotropy. An attempt was also made to characterize the variation in anisotropy with depletion. The results revealed that the coals tested were orthotropic in nature, but could be approximated as transversely isotropic, that is, the mechanical properties were isotropic in the horizontal plane, but significantly different in vertical direction. Mechanical characterization of coal was followed by flow modeling. Stress data was used to characterize the changes in permeability with depletion. This was achieved by plotting stress path followed by coal during depletion. The model developed was used to successfully predict the permeability variation in coal with depletion for elastic deformations. As expected, the developed model failed to predict the permeability variation resulting from inelastic deformation given that it was based on elastic constitutive equations. Hence, the next logical step was to develop a generalized permeability model, which would be valid for both elastic and inelastic deformations. Investigation of the causes of coal failure due to anisotropic stress redistribution during depletion was also carried out as a part of this study. It was found that highly sorptive rocks experience severe loss in horizontal stresses with depletion and, if their mechanical strength is not adequate to support the anisotropic stress redistribution, rock failure can result. In order to develop a generalized permeability model based on stress data, stress paths for three different coal types were established and the corresponding changes in permeability were studied. Stress path plotted in an octahedral mean stress versus octahedral shear stress plane provided a signal for changes in the permeability for both elastic as well as inelastic deformations. This signal was used to develop a mechanistic model for permeability modeling, based on stress redistribution in rocks during depletion. The model was able to successfully predict the permeability variation for all three coal types. Finally, since coal is highly stress- sensitive, changes in effective stresses were found to be the dictating factor for deformations, changes in permeability and possible failure with depletion. Hence, the next step was to develop an effective stress law for sorptive and transversely isotropic rocks. For development of an effective stress law for stress sensitive, transversely isotropic rocks, previously established constitutive equations were used to formulate a new analytical model. The model was then used to study changes in the variation of Biot’s coefficient of these rocks. It was found that Biot’s coefficient, typically less than one, can take values larger than one for these rocks, and their values also change with depletion. The study provides a methodology which can be used to estimate the Biot’s coefficient of any rock. As a final step, preliminary work was carried out on the problem of under-performing coal reservoirs in the San Juan basin, where coal is extremely tight with very low permeability. An extension of the work presented in this dissertation is to use the geomechanical characterization techniques to unlock these reservoirs and improve their performance. The experimental data collected during this preliminary study is included in the last chapter of the dissertation.

Diploma thesis deals with the application of unconventional technologies of wire electro discharge machining in the production in the manufacture of punch with a focus on effective use of EDM machines for the manufacture of components with the similar character.

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Thesis advisor: Kevin Bedell / Over 20 years ago, Blagoev et. al. predicted an s-wave pairing instability in a ferromagnetic Fermi liquid (FFL) as a consequence of spin fluctuations [5]. Shortly after, it was discovered that, when magnetic interactions in the ferromagnetic superconductor UGe2 dominate, quasiparticles with parallel spin form pairs in odd-parity orbitals; i.e., a form of spin-triplet p-wave superconductivity emerges, in contrast to Blagoev et. al.'s prediction [6]. In this work, we return to this issue by introducing the effects of a gapped amplitude (or "Higgs") mode on the vertex corrections and subsequent form of Cooper pairing. As the Higgs mode only propagates in the presence of a finite spin current, such an amplitude mode results in strong momentum-dependence in the many-body vertex. This results in the emergence of an unconventional form of superconductivity mediated by unconventional low-energy modes in a weak itinerant ferromagnet. / Thesis (BS) — Boston College, 2021. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Scholar of the College. / Discipline: Physics. / Discipline: Mathematics.

This thesis investigates the many extraordinary physical properties of the candidate p-wave ferromagnetic superconductors UCoGe and URhGe, and proposes theoretical predictions for p-wave superconductors yet to be discovered. In particular, we carry out angular dependent quantum field theoretical calculations of the thermodynamic H - T phase diagram known as the upper critical field, or more appropriately for ferromagnetic superconductors the upper critical induction, for various p-wave superconducting order parameter symmetries including: The axial Anderson-Brinkman-Morel(ABM) state, the chiral Scharnberg-Klemm (SK) state, and the completely broken symmetry polar state (CBS), as well as for some other states with partially broken symmetry (PBS) superconducting order parameter symmetries. The most notable contribution of the work presented in this thesis is the application of the Klemm-Clem transformations to analytically calculate the full angular and temperature dependencies of the upper critical field for orthorhombic materials, which may prove to be useful to experimentalists in identifying these exotic states of matter experimentally. Second, this work formulates a double spin-split ellipsoidal Fermi surface (FS) model for ferromagnetic superconductors in the normal state, which introduces a field dependence to the effective mass in one crystallographic direction on the dominant Fermi surface and to the chemical potential, and is subsequently applied to the normal state of URhGe to explain theoretically the anomalous specific heat data of Aoki and Flouquet. Extension of this work to understanding the still elusive reentrant high-field superconducting phase of URhGe and the S-shaped upper critical field curve for external magnetic field parallel to the b-axis direction inUCoGe is discussed. Third, this work also presents theoretical fits to the upper critical field data of Kittika et al. for Sr2RuO4 using the helical p-wave states and including Pauli limiting effects of the three components of the triplet pair-spin fixed to the highly conducting layers by strong spin-orbit coupling.

Geologic sequestration of CO2 into unmineable coal seams is proposed as a way to mitigate the greenhouse gas effect and potentially contribute to economic prosperity through enhanced methane recovery. In 2009, the Virginia Center for Coal and Energy Research (VCCER) injected 907 tonnes of CO2 into one vertical coalbed methane well for one month in Russell County, Virginia (VA). The main objective of the test was to assess storage potential of coal seams and to investigate the potential of enhanced gas recovery. In 2014, a larger scale test is planned where 20,000 tonnes of CO2 will be injected into three vertical coalbed methane wells over a period of a year in Buchanan County, VA. During primary coalbed methane production and enhanced production through CO2 injection, a series of complex physical and mechanical phenomena occur. The ability to represent the behavior of a coalbed reservoir as accurately as possible via computer simulations yields insight into the processes taking place and is an indispensable tool for the decision process of future operations. More specifically, the economic viability of projects can be assessed by predicting production: well performance can be maximized, drilling patterns can be optimized and, most importantly, associated risks with operations can be accounted for and possibly avoided. However, developing representative computer models and successfully simulating reservoir production and injection regimes is challenging. A large number of input parameters are required, many of which are uncertain even if they are determined experimentally or via in-situ measurements. Such parameters include, but are not limited to, seam geometry, formation properties, production constraints, etc. Modeling of production and injection in multi-seam formations for hydraulically fractured wells is a recent development in coalbed methane/enhanced coalbed methane (CBM/ECBM) reservoir modeling, where models become even more complex and demanding. In such cases model simulation times become important. The development of accurate simulation models that correctly account for the behavior of coalbeds in primary and enhanced production is a process that requires attention to detail, data validation, and model verification. A number of simplifying assumptions are necessary to run these models, where the user should be able to balance accuracy with computational time. In this thesis, pre- and post-injection simulations for the site in Russell County, VA, and preliminary reservoir simulations for the Buchanan County, VA, site are performed. The concepts of multi-well, multi-seam, explicitly modeled hydraulic fractures and skin factors are incorporated with field results to provide accurate modeling predictions. / Ph. D.

Hydraulic fracturing has been increasingly used in the USA to economically extract natural gas and oil from newly discovered shale plays. Despite new, more severe, and long term impacts of hydraulic fracturing compared to conventional drilling, regulatory practices are mostly implemented by states that regulate with older regulations that were were written before the widespread use of hydraulic fracturing. This dissertation presents three essays on the economics of hydraulic fracturing. A standard renewable lease in hydraulic fracturing runs for a five-year primary term. The first essay examines the effect of initial contract length on extraction behavior and social costs. It finds that the rate of extraction decreases over time for both, the social planner and the private extractor. In addition, the social planner has a more stable extraction path compared to the private extractor. Holding other things equal, if the social planner seeks to induce a private extractor to leave a higher in situ stock un-extracted, then the optimal contract duration is longer. Simulations illustrate the magnitude of social costs inherent in hydraulic fracturing and non-optimal fixed contract lengths. The second essay investigates the impact of the significantly increased bonding requirements for horizontal wells introduced in West Virginia in December, 2011, on the probability of violation committed by those wells. Results suggest that the increased bonding requirement has reduced the probability of violation by 2.6 to 3.2 percentage points. Moreover, it slightly reduces the number of violations done by horizontal wells. Finally, the third essay explores several aspects of Act-13, introduced on February 14, 2012, by Pennsylvania. This act imposes new fees that are assessed annually for fifteen years, on all unconventional gas wells in Pennsylvania. This chapter explores the impacts of Act-13 on the likelihood of an unconventional well's shut-down, rate of extraction, and probability of violation. Results suggest that wells incurring this increased fee schedule have a significantly higher likelihood (more than three times) of shut-down. Also, Act-13 have reduced the extraction rate, and the probability of violation committed by unconventional wells in Pennsylvania. / Ph. D.

This study examined Scottish Highlanders who defended the southern border of British territory in the North American theater of the War of the Austrian Succession (1739-1748). A framework was established to show how Highlanders were deployed by the English between 1745 and 1815 as a way of eradicating radical Jacobite elements from the Scottish Highlands and utilizing their supposed natural superiority in combat. The case study of these Highlanders who fought in Georgia and Florida demonstrated that the English were already employing Highlanders in a similar fashion in North America during the 1730s and 1740s. British government sources and correspondence of colonial officials and military officers were used to find the common Highlander's reactions to fighting on this particular frontier of the Empire. It was discovered that by reading against what these officials wrote and said was the voice of the Highlander found, in addition to confirming a period of misrepresentation of Highland manpower in the colony of Georgia during the War of Jenkins' Ear that adhered to the analytical framework established.

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Two research projects are proposed that rely on Tools for open Reconfigurable Computing (TORC) and the openness of the Xilinx tool chain. The first project, the Embedded FPGA Transmitter, relies on the ability to add arbitrary routes to a physical FPGA which serve no obvious purpose. These routes can then mimic an antenna and transmit directly from the FPGA. This mechanism is not supported utilizing standard hardware description languages; however, the Embedded FPGA Transmitter requires measurements on a real FPGA to determine success. The second project is a back-end tools accelerator designed to reduce the compilation time for FPGA times. As the complexity of FPGAs have exceeded over a million logic cells, the compilation problem size has greatly expanded. The open-source project, TORC, provides an excellent framework for new FPGA research that provides physical, real-world results to ensure the applicability of the research. / Master of Science