Traditional gas separation technologies are thermally-driven and can have adverse environmental and economic impacts. Gas separation membrane processes are not thermally-driven and have low capital and operational costs which make them attractive alternatives to traditional technologies. Polymers are easily processed into large, defect-free membrane modules which have made polymeric membranes the industrial standard; however, polymers show separation efficiency-productivity trade-offs and are often not thermally or chemically robust. Molecular sieves, such as zeolites, have gas separation properties that exceed polymeric materials and are more thermally and chemically robust. Unfortunately, formation of large, defect-free molecular sieve membranes is not economically feasible. Mixed matrix membranes (MMMs) combine the ease of processing polymeric materials with the superior transport properties of molecular sieves by dispersing molecular sieve particles in polymer matrices to enhance the performance of the polymers. MMMs with high molecular sieve loadings were made using polyvinyl acetate (PVAc) and various molecular sieves. Successful formation of these MMMs required substantial modifications to low loading MMM formation techniques. The gas separation properties of these MMMs show significant improvements over PVAc properties, especially for high pressure mixed carbon dioxide-methane feeds that are of great industrial relevance.

Gas hydrate consists of guest gas molecules encaged in water molecules. Methane is the most common guest molecule in natural hydrates. Methane hydrate forms under high fluid pressure and low temperature and is found in marine sediments or in permafrost region. Methane hydrate can be an energy resource (world reserves are estimated in 20,000 trillion m3 of CH4), contribute to global warming, or cause seafloor instability. Research documented in this thesis starts with an investigation of hydrate formation and growth in the pores, and the assessment of formation rate, tensile/adhesive strength and their impact on sediment-scale properties, including volume change during hydrate formation and dissociation. Then, emphasis is placed on identifying the advantages and limitations of different gas production strategies with emphasis on a detailed study of CH4-CO2 exchange as a unique alternative to recover CH4 gas while sequestering CO2. The research methodology combines experimental studies, particle-scale numerical simulations, and macro-scale analyses of coupled processes.

The New Albany Shale is an Upper Devonian organic-rich gas shale located in the Illinois Basin. A factor influencing gas production from the shale is the natural fracture system. I test the hypothesis that a combination of outcrop and core observations, rock property tests, and geomechanical modeling can yield an accurate representation of essential natural fracture attributes that cannot be obtained from any of the methods alone. Field study shows that New Albany Shale outcrops contain barren (free of cement) joints, commonly oriented in orthogonal sets. The dominant set strikes NE-SW, with a secondary set oriented NNW-SSE. I conclude that the joints were likely created by near-surface processes, and thus are unreliable for use as analogs for fractures in the reservoir. However, the height, spacing, and abundance of the joints may still be useful as guides to the fracture stratigraphy of the New Albany Shale at depth. The Clegg Creek and Blocher members contain the highest fracture abundance. Fractures observed in four New Albany Shale cores are narrow, steeply-dipping, commonly completely sealed with calcite and are oriented ENE-WSW. The Clegg Creek and Blocher members contain the highest fracture abundance, which is consistent with outcrop observations. Fractures commonly split apart along the wall rock-cement interface, indicating they may be weak planes in the rock mass, making them susceptible to reactivation during hydraulic fracturing. Geomechanical testing of six core samples was performed to provide values of Young’s modulus, subcritical index, and fracture toughness as input parameters for a fracture growth simulator. Of these inputs, subcritical index is shown to be the most influential on the spatial organization of fractures. The models predict the Camp Run and Blocher members to have the most clustered fractures, the Selmier to have more evenly-spaced fractures, and the Morgan Trail and Clegg Creek to have a mixture of even spacing and clustering. The multi-faceted approach of field study, core work, and geomechanical modeling I used to address the problem of fracture characterization in the New Albany Shale was effective. Field study in the New Albany presents an opportunity to gather a large amount of data on the characteristics and spatial organization of fractures quickly and at relatively low cost, but with questionable reliability. Core study allows accurate observation of fracture attributes, but has limited coverage. Geomechanical modeling is a good tool for analysis of fracture patterns over a larger area than core, but results are difficult to corroborate and require input from outcrop and core studies. / text

Dissociation of gas hydrates has been the primary concern of the oil and gas industry for flow assurance, mainly in an offshore environment. There is also a growing interest in the rapid formation of gas hydrates for gas storage, transport of natural gas and carbon sequestration. In this thesis, we experimentally measure the kinetics of formation and dissociation of methane hydrates and the effect of various anionic and cationic surfactants such as sodium dodecyl sulfate (SDS), cetyl trimethylammonium bromide (CTAB) and alpha olefin sulfonate (AOS) on the association/dissociation rate constants. The importance and necessity of micelle formation in these surfactants has been studied. The effect of foam generation on the rate of formation of these hydrates has also been measured. SDS was found to significantly decrease the induction time for hydrate formation. There was an added decrease in the induction time when a foamed mixture of water and SDS was used. On the other hand CTAB and AOS had an inhibiting effect. The contribution of micelles towards promoting hydrate formation was demonstrated with a series of experiments using SDS. The micelles formed by these surfactants appear to serve as nucleation sites for the association of hydrates. New experimental data is presented to show that some surfactants and the use of foam can significantly increase the rate of hydrate formation. Other surfactants are shown to act as inhibitors. A new experimental setup is presented that allows us to distinguish between surfactants that act as promoters and inhibitors for hydrate formation. / text

No description available.

Mixtures of bacterial and thermogenic methane are found both at vents at the seafloor and in reservoirs in the deep subsurface of the Gulf of Mexico continental slope. The C1-C5 gas that most recently charged reservoirs of Jolliet (GC 184), Genesis (GC 160/161) and Petronius (VK 786) fields is estimated to include 17%-28%, 31%-51%, 31%-49% bacterial methane, respectively. Geochemical assessment of the reservoir gas in the fields show that the gas may be the product of thermal cracking of Upper Jurassic crude oil before final migration to the reservoirs. The gas from three different fields is of similar thermal maturity levels. In contrast to oil in reservoirs in the fields, which shows biodegradation effects, the C1-C5 reservoir gas is unaltered by biodegradation. Late gas migration may have occurred at or near present burial depth and flushed the reservoir system of previously biodegraded hydrocarbon gas to include any previous bacterial methane. Molecular and isotopic properties of reservoir gas and oil suggest that bacterial methane mixed with thermogenic hydrocarbon gas before entering the reservoirs. Thus the source of the bacterial methane is logically deeper than the present depth (>~4 km) and temperatures of the reservoirs. High sedimentation rate and low geothermal gradient may offer conditions favorable for generation and preservation of bacterial methane in deep subsurface petroleum system of the Gulf slope. Bacterial methane dispersed across the large drainage areas of the deep subsurface petroleum system may have been swept by migrating fluids at >4 km, and then charged both vents (GC 185, GC 233 and GC 286) at the seafloor and reservoirs in the deep subsurface. The volume of bacterial methane from geologically significant depth in rapidly subsiding basins may be underestimated.

The presence of structure H (sH) methane hydrate in natural environments, in addition to the well-known structure-I (sI) and II (sII) hydrates, has recently been documented. Methane in the presence of condensates (C5-C7) forms sH hydrate at lower pressure than the sI hydrate. Thus, the occurrence of sH methane hydrate is likely to have both beneficial and negative practical implications. On the negative side, in the presence of condensate, sH hydrate may form and plug gas transmission pipelines at lower pressures than sI hydrate. On the other hand, sH hydrate can be synthesized at lower pressures and exploited to store methane. The existence of natural hydrates containing sH hydrate may also be expected in shallow offshore areas. There are at least 26 large guest molecules known as sH hydrate formers and each of them produces a sH hydrates with different properties. The hydrate stability, the cage occupancies and the rates of hydrate formation depend on the type of large molecule selected. Consequently, it is essential to understand how the host and the guest molecules interact. Studies at the molecular-level are therefore indispensable in providing information that is not obtainable from experiments or too costly to acquire. Free energy calculations are performed to determine the relative stability among different sH hydrate systems and the preferable cage occupancy. The latter would give indications of how much methane gas can be stored in the hydrate. The interaction of guest molecule inside the hydrate cage is also investigated. The results are related to the physical and chemical properties of gas hydrates observed from the experiments or reported in the literature.

Hydrate phase equilibria for the CO2, CH4 and natural gas in silica gel pores of nominal pore diameters 6, 30 and 100 nm were measured, and compared with the calculated results based on van der Waals and Platteeuw model. At a specific temperature, three-phase hydrate–water-rich liquid–vapor (HLV) equilibrium curves for pore hydrates were shifted to the higher pressure condition depending on pore sizes when compared with those of bulk hydrates. The activities of water in porous silica gels were modified to account for capillary effect, and the calculated results were in good agreement with the experimental data. To investigate the formation kinetics of each system, the isobaric method was applied. It was found that there were no difference in structure between hydrate in silica gel pore and that in bulk free state. Results showed that hydrate formation in the silica gel pores indicated significantly faster rates, intensively reduced induction times, increased gas consumption and conversion of water to hydrate as compared to hydrate formation in bulk free water or fine ice powder. Utilizing these superior characteristics, formation of hydrate in porous material is expected to present the process on gas separation or storage.

Energy storage technology is needed for the storage of surplus baseload generation and the storage of intermittent wind power, because it can increase the flexibility of power grid operations. Underground storage of hydrogen with natural gas (UHNG) is proposed as a new energy storage technology, to be considered for utility-scale energy storage applications. UHNG is a composite technology: using electrolyzers to convert electrical energy to chemical energy in the form of hydrogen. The latter is then injected along with natural gas into existing gas distribution and storage facilities. The energy stored as hydrogen is recovered as needed; as hydrogen for industrial and transportation applications, as electricity to serve power demand, or as hydrogen-enriched natural gas to serve gas demand. The storage of electrical energy in gaseous form is also termed “Power to Gas”. Such large scale electrical energy storage is desirable to baseload generators operators, renewable energy-based generator operators, independent system operators, and natural gas distribution utilities. Due to the low density of hydrogen, the hydrogen-natural gas mixture thus formed has lower volumetric energy content than conventional natural gas. But, compared to the combustion of conventional natural gas, to provide the same amount of energy, the hydrogen-enriched mixture emits less carbon dioxide. This thesis investigates the dynamic behaviour, financial and environmental performance of UHNG through scenario-based simulation. A proposed energy hub embodying the UHNG principle, located in Southwestern Ontario, is modeled in the MATLAB/Simulink environment. Then, the performance of UHNG for four different scenarios are assessed: injection of hydrogen for long term energy storage, surplus baseload generation load shifting, wind power integration and supplying large hydrogen demand. For each scenario, the configuration of the energy hub, its scale of operation and operating strategy are selected to match the application involved. All four scenarios are compared to the base case scenario, which simulates the operations of a conventional underground gas storage facility. For all scenarios in which hydrogen production and storage is not prioritized, the concentration of hydrogen in the storage reservoir is shown to remain lower than 7% for the first three years of operation. The simulation results also suggest that, of the five scenarios, hydrogen injection followed by recovery of hydrogen-enriched natural gas is the most likely energy recovery pathway in the near future. For this particular scenario, it was also found that it is not profitable to sell the hydrogen-enriched natural gas at the same price as regular natural gas. For the range of scenarios evaluated, a list of benchmark parameters has been established for the UHNG technology. With a roundtrip efficiency of 39%, rated capacity ranging from 25,000 MWh to 582,000 MWh and rated power from 1 to 100 MW, UHNG is an energy storage technology suitable for large storage capacity, low to medium power rating storage applications.

Russia has supplied natural gas to Europe reliably for nearly four decades. But recent changes in Russian behaviour and policy, combined with EU-driven regulatory changes, have created a state of flux, and considerable concern in Europe. I address the question of possible Russian hegemony in European gas relations, and ask whether Moscow’s ambitions represent a security threat to Europe. Positioning these questions within the context of a European natural gas regime (NGR), I take a historical-comparitive approach, dividing the evolution of the NGR into three phases. Phase one moves from the origin of the cross-border trade in Europe in the 1960s to the 1991 Soviet dissolution; phase two explores the turbulent post-Soviet decade to 1999; and phase three addresses the era of Vladimir Putin from 2000 to 2010. For each phase, I assess hegemony by drawing on regime concepts offered by Alt et al, which I modify for application to the idiosyncratic realm of natural gas. The evidence suggests that Germany, not Russia, is more appropriately considered hegemonic, having acquired gas influence in the 1970s that it has not relinquished. However, there are also indications that a German-Russian ‘co-hegemony’ could be developing, characterized by disproportionate Russian influence in Central Europe, giving rise to possible tension between EU values, governance and responsibilities on one hand, and Russian influence associated with co-hegemony on the other. Despite this, I suggest that Russian aspirations constitute no imminent security threat to Europe – European gas actors are well entrenched, and Moscow faces strong disincentives to threaten its European buyers. ‘Co-hegemony’ could challenge the regime’s integrity, but evidence to date suggests that the EU and Gazprom prefer patience and compromise to brinkmanship, and that actor interest in maintaining the flow of gas suggests greater optimism than dread. ‘Security’ is therefore not as sound as it would be if Russia were an EU member or if it had ratified the Energy Charter Treaty, but emerging dynamics do not suggest imminent peril either. I conclude by discussing possible directions for future research. / A regime-based exploration of Euro-Russian gas dynamics, with attention to the new profile of Russia in the relationship and the limits of its coercive ability.