Browsing by Subject "Natural gas liquids"
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Item Life cycle greenhouse gas emissions of systems using light alkane resources(2021-12-03) Chen, Qining; Allen, David T.; Dunn, Jennifer B; Brennecke, Joan F; Stadtherr, Mark AExpanded production of natural gas and natural gas liquids have motivated proposals for modular and distributed processes to utilize the light alkane resources. The design of modular systems requires mappings of the temporal and spatial availabilities of the light alkane feedstocks. In addition, as the worldwide ambitions in reducing carbon footprints grow, the uses of the light alkane resources may be strictly limited by the greenhouse gas footprints of the light alkane feedstocks and supply chains. Therefore, the understanding of both production and emission characteristics of light alkane resources, as well as the emissions along the light alkane supply chains from production through downstream manufacturing, are of great significance. This thesis uses the Eagle Ford Shale as a prototypical upstream oil and gas region and examines the feedstock compositions, production magnitudes, and temporal evolutions of feedstock availability for the modular chemical manufacturing that utilizes light alkane resources as feedstocks, at various operation scales. Emissions associated with light alkanes production are also estimated at various spatial scales in the Eagle Ford Shale and the spatial variabilities in emissions have been examined. These spatial variabilities in upstream emissions, mainly due to the varying production characteristics, can lead to great differences in the emission estimates of downstream chemical manufacturing operations that utilize the light alkane resources. Different upstream emission accounting and reporting methods can also lead to significant differences in the emission estimates of downstream chemicals and fuels. This indicates that tracking the origins of feedstock sources, as well as applying consistent and transparent metrics for measuring and reporting emissions from upstream oil and gas production are very important in the utilization of the light alkane resources. The estimates of emissions from light alkane production and supply chains favor detailed emission inventories with fine temporal and spatial resolutions, however, such emission inventories are rarely available in public accessible databases. The Methane Emission Estimation Tool examined in this thesis, together with the methane emission monitoring network conceptually designed and theoretically evaluated in this thesis, will enable detailed emission estimates for light alkanes production and supply chains.Item Nanoparticle-stabilized natural gas liquid emulsions for heavy oil recovery(2017-05) Griffith, Nicholas Daniel; Daigle, HughThe transport of nanoparticle-stabilized emulsions through porous media and its effects on enhanced oil recovery are only marginally understood. This thesis explores the characteristics of nanoparticle-stabilized emulsion flow in porous media, especially in respect to its residual oil recovery capabilities. Widely available, low-cost natural gas liquids were emulsified in brines using polyethylene glycol-coated silica nanoparticles. Emulsions with various aqueous nanoparticle phases and oil phases were generated via beadpack co-injection or sonication at varying salinities for observations of emulsion characteristics. In general it was found that high-salinity emulsions generated via sonication were more robust: statically and dynamically more stable than their lower salinity counterparts. Emulsions generated via beadpack co-injection displayed non-Newtonian shear-thinning rheology and larger droplet sizes. Emulsions generated via sonication displayed Newtonian rheology and much smaller droplet sizes. Coreflood experiments were conducted to assess the effects of different emulsion properties on residual oil recovery of heavy oils, effective permeability reduction capabilities (i.e. conformance control), and in-situ emulsion stability. During low salinity emulsion floods, no emulsion was produced in the effluent. However, by increasing the salinity, emulsion was produced in the effluent and up to 89% residual mineral oil was recovered at low injection rates (~16 ft/day). Increases in residual oil recovery during high salinity floods can be explained by DLVO and Filtration theory. By increasing the ionic concentration, the magnitude of repulsive electrostatic double layer forces are decreased, leading to increased droplet interception on grain surfaces. This results in more efficient droplet-pore throat blockage, therefore, redirecting displacing fluids into less permeable zones. Increasing the magnitude of the zeta-potential of injected emulsions resulted in marginal increases in oil recovery, significant reductions in effective permeability, and in-situ emulsion stability. It was concluded that at high zeta-potentials, emulsion droplets are likely repulsed via electrostatic repulsive forces rather than through mechanical bridging of aggregates between droplets, as observed in high salinity emulsions. The increase in permeability reduction in the high zeta-potential case occurs due to the droplets’ increased resistance to flow through a pore throat, a product of increased repulsive forces between droplets and grains encountered at tight constrictions