Preparation and Mechanism of EP-HMTA-SiO2 Nanocomposite Polymer Gel for Enhancing Oil Recovery

During oilfield production, organic substances such as asphaltenes and resins present in crude oil are prone to adsorb onto the surfaces of reservoir rocks. This adsorption process can lead to the conversion of hydrophilic rock surfaces into more oleophilic interfaces, which in turn reduces the permeability and porosity of the reservoir, ultimately affecting the overall recovery efficiency. Consequently, targeted modification of reservoir wettability presents a promising strategy for enhancing recovery rates. In this study, a polymer layer comprising large molecular side chains and hydroxyl groups was synthesized on the surface of nano-SiO2 to enhance the thermal stability of the polymer. Additionally, the hydroxyl groups were employed to improve the wettability of the core material and reduce interfacial tension. The polymers were characterized using techniques such as FTIR and TG, and the results revealed that the modified SiO2 exhibited superior performance in reducing both interfacial tension and contact angle when compared to the SiO2. Injection of a 0.4 wt% EP-HMTA-SiO2 solution resulted in an increase in recovery rates by 16.4% and 13.2% in medium- and low-permeability cores, respectively.