Wettability modification of muscovite surfaces using silica nanoparticles synthesized from rice husk

Nanoparticles, such as silica nanoparticles (SNPs), can alter the wettability of reservoir rock surfaces, thereby enhancing oil recovery. This study investigated microscopic mechanisms of wettability alteration by SNPs derived from rice husk (RH-SNPs) as a sustainable agent for enhanced oil recovery. We have conducted contact angle measurements, and observations using scanning electron microscope (SEM) and atomic force microscopy (AFM). The adsorption behavior of RH-SNPs (0.12 wt%) in saline solutions (0.1 to 0.8 M) was investigated. Experiments were conducted on muscovite surfaces pretreated with potassium chloride and calcium chloride solutions to investigate how the ionic conditions of the surface influenced RH-SNPs adsorption and wettability. The RH-SNPs caused contact angles to decrease from 26°–38° to 18°–20° in different saline environments. This wettability alteration was caused by the irreversible adsorption of RH-SNPs. Both the RH-SNPs and muscovite surface were negatively charged. Irreversible adsorption occurred only when the muscovite surface was pretreated with an aqueous solution of calcium chloride. This is because the calcium ions formed localized positive sites that interacted with the deprotonated silanol groups on the RH-SNPs, promoting stable wettability alteration. AFM and SEM confirmed the structural stability of RH-SNPs adsorption, reinforcing its role in sustained wettability modification. These findings highlight the potential of RH-SNPs to enhance oil recovery efficiency, suggesting that similar wettability alteration can be achieved to that of SNPs from other sources but in an eco-friendly way.