Synthesis and dispersion stability of seawater-based nano-smart water for application in high-temperature and high-salinity conditions

Abstract

This study presents nano-smart water synthesized with grafted SiO2 nanoparticles dispersed potential determining ion (PDI) controlled seawater to enhance oil recovery in carbonate reservoirs with high temperatures and high salinity. Phase behavior observation, dynamic light scattering (DLS), and transmission electron microscopy (TEM) were performed to evaluate the dispersion stability of the synthesized nano-smart water with different particle concentrations at 25 ℃ and 80 ℃. In addition, a fluid miscibility test (FMT) was conducted using seawater with controlled salinity and PDI type and concentration. The results of dispersion stability showed that stable fluids without aggregation and precipitation, with an average particle size of less than 100 nm, could be synthesized at room and high temperature in seawater at the nanoparticle concentration 0.5 wt% or more. The dispersion stability of the synthesized nano-smart water was successfully achieved without aggregation and precipitation, with an average particle size of less than 100 nm, at room and high temperatures when the nanoparticle concentration is higher than 0.5 wt%. After performing the FMT with a high-salinity level of up to 200,000 ppm, and implementing PDI control using K+, Mg2+, Cl-, and SO42-, the nanoparticles in nano-smart water still had an average particle size ranging from 32.2 to 54.1 nm. This indicates that the colloidal dispersion was stable despite the high-salinity levels and PDI control. Therefore, the SW-based nano-smart water is expected to be used as a stable injection fluid in high-temperatures and high-salinity carbonate reservoirs.