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dc.contributor.advisorRuben Juanes.en_US
dc.contributor.authorFu, Xiaojing, Ph. D. Massachusetts Institute of Technologyen_US
dc.contributor.otherMassachusetts Institute of Technology. Department of Civil and Environmental Engineering.en_US
dc.date.accessioned2017-09-15T15:34:31Z
dc.date.available2017-09-15T15:34:31Z
dc.date.copyright2017en_US
dc.date.issued2017en_US
dc.identifier.urihttp://hdl.handle.net/1721.1/111445
dc.descriptionThesis: Ph. D., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2017.en_US
dc.descriptionCataloged from PDF version of thesis.en_US
dc.descriptionIncludes bibliographical references (pages 159-175).en_US
dc.description.abstractOngoing efforts to mitigate climate change include the understanding of natural and engineered processes that can impact the global carbon budget and the fate of greenhouse gases (GHG). Among engineered systems, one promising tool to reduce atmospheric emissions of anthropogenic carbon dioxide (CO₂) is geologic sequestration of CO₂ , which entails the injection of CO₂ into deep geologic formations, like saline aquifers, for long-term storage. Among natural contributors, methane hydrates, an ice-like substance commonly found in seafloor sediments and permafrost, hold large amounts of the world's mobile carbon and are subject to an increased risk of dissociation due to rising temperatures. The dissociation of methane hydrates releases methane gas-a more potent GHG than CO₂-and potentially contributes to a positive feedback in terms of climatic change. In this Thesis, we explore fundamental mechanisms controlling the physics of geologic CO₂ sequestration and natural gas hydrate systems, with an emphasis on the interplay between multiphase flow-the simultaneous motion of several fluid phases and phase transitions-the creation or destruction of fluid or solid phases due to thermodynamically driven reactions. We first study the fate of CO₂ in saline aquifers in the presence of CO₂ -brine-carbonate geochemical reactions. We use high-resolution simulations to examine the interplay between the density-driven convective mixing and the rock dissolution reactions. We find that dissolution of carbonate rock initiates in regions of locally high mixing, but that the geochemical reaction shuts down significantly earlier than shutdown of convective mixing. This early shutdown reflects the important role that chemical speciation plays in this hydrodynamics-reaction coupled process. We then study hydrodynamic and thermodynamic processes pertaining to a gas hydrate system under changing temperature and pressure conditions. The framework for our analysis is that of phase-field modeling of binary mixtures far from equilibrium, and show that: (1) the interplay between phase separation and hydrodynamic instability can arrest the Ostwald ripening process characteristic of nonflowing mixtures; (2) partial miscibility exerts a powerful control on the degree of viscous fingering in a gas-liquid system, whereby fluid dissolution hinders fingering while fluid exsolution enhances fingering. We employ this theoretical phase-field modeling approach to explain observations of bubble expansion coupled with gas dissolution and hydrate formation in controlled laboratory experiments. Unraveling this coupling informs our understanding of the fate of hydrate-crusted methane bubbles in the ocean water column and the migration of gas pockets in hydrate-bearing sediments.en_US
dc.description.statementofresponsibilityby Xiaojing Fu.en_US
dc.format.extent175 pagesen_US
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsMIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582en_US
dc.subjectCivil and Environmental Engineering.en_US
dc.titleMultiphase flow in porous media with phase transitions : from CO₂ sequestration to gas hydrate systemsen_US
dc.typeThesisen_US
dc.description.degreePh. D.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Civil and Environmental Engineering
dc.identifier.oclc1003292875en_US


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