A systematic investigation on the properties of silica nanoparticles “multipoint”-grafted with poly(2-acrylamido-2-methylpropanesulfonate-co-acrylic acid) in extreme salinity brines and brine-oil interfaces

Nanoparticles (NPs) may have great potential for various subsurface applications including oil and gas recovery, reservoir imaging, and environmental remediation. One of the important challenges for these down-hole applications is to achieve colloidal stability in subsurface media at high salinity and high temperature. It has been previously shown that several functional NPs “multipoint”-grafted with anionic poly(2-acrylamido-2-methyl-1-propanesulfonate-co-acrylic acid, AMPS-co-AA) exhibited remarkable colloidal stabilities in specific environments mimicking the harsh subsurface aquatic media, such as American Petroleum Institute (API) brine. However, many important properties of such particles other than the colloidal stabilities must be studied in a more systematic fashion for a wide range of salt concentrations (Cs). Herein, we investigate various properties of the silica (SiO2) NPs “multipoint”-grafted with poly(AMPS-co-AA), SiO2-g-poly(AMPS-co-AA), in NaCl and CaCl2 solutions across a range of salini...