To improve CO 2 adsorption performance of nanoparticle absorbents, a novel tertiary amine functionalized nano-SiO 2 (NS-NR 2 ) was synthesized based on the 3-aminopropyltrimethoxysilane (KH540) modified nano-SiO 2 (NS-NH 2 ) via methylation. The chemical structure and performances of the NS-NR 2 were characterized through a series of experiments, which revealed that NS-NR 2 can react with CO 2 in water and nanofluid with low viscosity revealed better CO 2 capture. The CO 2 capture mechanism of NS-NR 2 was studied by kinetic models. From the correlation coefficient, the pseudo second order model was found to fit well with the experiment data. The influencing factors were investigated, including temperature, dispersants, and cycling numbers. Results has shown the additional surfactant to greatly promote the CO 2 adsorption performance of NS-NR 2 because of the better dispersity of nanoparticles. This work proved that NS-NR 2 yields low viscosity, high capacity for CO 2 capture, and good regenerability in water. NS-NR 2 with high CO 2 capture will play a role in storing CO 2 to enhanced oil recovery in CO 2 flooding.

During CO 2 flooding, serious gas channeling occurs in ultra-low permeability reservoirs due to the high mobility of CO 2. The chief end of this work was to research the application of responsive nanoparticles for mobility control to enhance oil recovery. Responsive nanoparticles were developed based on the modification of nano-silica (SiO 2) by 3-aminopropyltrimethoxysilane (KH540) via the Eschweiler-Clark reaction. The proof of concept for responsive nanoparticles was investigated by FT-IR, 1 H-NMR, TEM, DLS, CO 2 /N 2 response, wettability, plugging performance, and core flooding experiments. The results indicated that responsive nanoparticles exhibited a good response to control nanoparticle dispersity due to electrostatic interaction. Subsequently, responsive nanoparticles showed a better plugging capacity of 93.3% to control CO 2 mobility, and more than 26% of the original oil was recovered. Moreover, the proposed responsive nanoparticles could revert oil-wet surfaces to water-wet, depending on surface adsorption to remove the oil from the surface of the rocks. The results of this work indicated that responsive nanoparticles might have potential applications for improved oil recovery in ultra-low permeability reservoirs.