Double layer chemical encapsulation of SiO2 nanoparticles for interfacial tension reduction under low salinity condition

Recently, rapid growth of nanotechnology has accelerated immensely, and has provided adequate scientific evidence supporting nanoparticles (NPs) as revolutionary agents for oil reservoirs, particularly, for interfacial tension reduction (IFT). For this reason, this paper present synthesis, characterization, and IFT evaluation of new double layer encapsulated SiO2 NPs. The synthesis has been initiated via precursor polyacrylic acid (PAA) to form a first layer intermediate product (SiO2-g-PAA). Subsequently, the SiO2-g-PAA was then individually condensed with Xanthan polymer and 3-aminopropyltriethoxysilane (KH550), to establish double layer products; SiO2-g-PAA-Xanthan and SiO2-g-PAA-KH550, respectively. The products were characterized using Fourier Transform Infrared (FTIR), Field Emission Scanning Electron Microscope (FESEM) and X-ray Diffraction (XRD). Spinning Drop equipment was used to assess the nanofluid's IFT reduction effects at 0.01, 0.03 & 0.05 in low salinity (0.3 NaCl) by comparing with the baseline brine IFT. The FTIR results have confirmed the syntheses of the products, while the FESEM micrographs have described the surface morphologies and average particle size within the nanoscale (36 nm for SiO2-g-PAA-Xanthan & 61 nm for SiO2-g-PAA-KH550). Interestingly, the XRD patterns of all the grafted NPs exhibit amorphous behaviours at 20 θ similar to pure SiO2. The IFT investigations revealed that the brine/oil baseline IFT was recorded to be 9.9 ± 0.07 mN/m, however, upon introducing pure SiO2 NPs into the system at 0.01, 0.03 and 0.05 , the IFT reduced to a range of 6�8 mN/m (20�33 efficiency). However, in the presence of SiO2-g-PAA-KH550, extraordinary reduction of the IFT was achieved to a range of 0.5�0.7 mN/m with significant reduction efficiency up to 94 with respect to a baseline IFT. This is due to the terminal PAA-KH550 on the surface of the SiO2. However, in the case of terminal PAA-xanthan in the SiO2-g-PAA-Xanthan, the polymer did not influence the IFT remarkably, with the IFT reduction efficiency even far lower than the untreated SiO2. Thus, a grafted double layer NPs containing a terminal PAA-KH550 could be an ideal candidate for potential application in chemical EOR due to a remarkable demonstration of IFT reduction which is one of the preconditions governing the successful EOR operation in oil fields. © 2022 Elsevier B.V.