Superparamagnetic iron oxide nanoparticles (IO NPs) can be utilized as contrasting agents for electromagnetic imaging of subsurface formations for the purpose of enhanced imaging of the distribution of oil in the reservoir. However, bare IO NPs are unstable under working conditions for subsurface applications, namely high temperature and high salinity. Furthermore, minerals present in subsurface reservoirs will interact with these nanoparticles and cause particle adsorption during transport. This research is focused on addressing these issues by engineering functional nanoparticles that (1) remain dispersed under high temperature and high salinity conditions, and (2) minimally interact with the subsurface porous environment.<br/>A novel coating method to efficiently synthesize polymer-grafted IO NPs was developed. By using amine in concert with silica coating on IO NPs, one can modify the surface of synthesized IO NP cores with polyelectrolytes to provide electrostatic stabilization of the colloids and, at the same time, attain low adsorption on the anionic media in modeled subsurface environments. This platform coating strategy is demonstrated with highly magnetic IO NP cores synthesized by thermal decomposition in triethylene glycol. The effects of various parameters on IO core synthesis and particle stabilization was studied by an array of characterization techniques and static batch adsorption tests in concentrated brine. Specifically, the parameters for complete silica coating of IO NPs were studied and their effects on the amine functionalization of IO NPs were investigated. A complete coating on nanoparticles with controlled cluster size and surface amine density enabled the successful grafting of polymers. The compatibility of the grafting scheme across different systems was demonstrated. This result allows one to attach polyelectrolytes to any particles of interest with high magnetic susceptibility, colloidal stability and low adsorption in the subsurface environment.

Stability and transport properties of magnetic nanoparticles under high temperature, high salinity aqueous conditions for oil reservoir imaging<br />

249th National Meeting (2015)

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