Stabilization of Magnetite Nanofluid and its Transport in Porous Media
Date
2022-06-03
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Abstract
The objective of the research is to test the transportability of magnetic (magnetite, Fe3O4) nanoparticles in porous media and evaluate its application as a subsurface monitoring tool. The unique properties of magnetic nanoparticles make them a strong contrast agent against reservoir rocks and fluids as they exhibit a high magnetic response. Nanoparticles can be potentially applied to carbon capture and storage projects for monitoring the containment of CO2 underground. A stable nanofluid dispersion must be attained to facilitate long distance transport of nanoparticles in porous media. Achieving a stabilized nanofluid is a major challenge since nanoparticles have a tendency to aggregate due to their high surface energy. The principles of surface/colloidal chemistry and electric double layer are applied for the selection of surfactants to achieve stabilized nanofluid dispersions. For nanoparticle applications in subsurface, the salinity of reservoir water needs to be considered. The dispersion of nanoparticles is first achieved in DI water before establishing a nanofluid in the presence of high salinity. In DI water, the two surfactants that successfully dispersed the nanoparticles are CTAB (positively charged) and SDBS (negatively charged). In a saline environment, it is found that nanoparticles are destabilized and agglomerated immediately due to compressing electric double layer. Stabilized nanofluid is obtained in 6wt% KCl by combining DDBSA and non-ionic NP-9 as the dispersants. Nanofluid injection experiments are conducted to test the transport of nanoparticles in porous media. The injection test is coupled with the Bartington MS2C core logging sensor to track in-situ real-time transport by measuring the volumetric magnetic susceptibility of the nanoparticles. Experiments are conducted in 3 Phases: Phase 1 in high permeability sandpacks, Phase 2 in limestone cores with moderate/low permeability, and Phase 3 in sandstone cores which is the most representative of a CO2 sequestration reservoir. This research provides methodologies in achieving stable nanofluid dispersion in both DI water and brine as well as establishing in-situ real-time transport monitoring of nanoparticles in different types of porous media.
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Keywords
Magnetic nanoparticles, Subsurface monitoring
Citation
Liu, A. (2022). Stabilization of Magnetite Nanofluid and its Transport in Porous Media (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.