The use of carbon dioxide to intensify oil recovery using nanoparticles

The article discusses topical issues of enhanced oil recovery using carbon dioxide (CO2) and nanoparticles. It is noted that the average oil recovery rate in the world is 10-18%, and an increase of 10-20% would significantly in-crease the reserves of raw materials and increase the competitiveness of the Russian oil industry. The limits of ap-plicability of various methods of increasing oil recovery are shown, depending on the depth of the reservoir and the viscosity of the oil. Among the gas agents, CO2 stands out for its high solubility in oil and water, favorable dynamic viscosity (2-3 times higher than that of methane or nitrogen) and compression ratio, which provides increased profitability for the extraction of residual raw materials. However, the main problem with its injection is the premature breakthrough of gas to the producing wells. An effective solution is the addition of nanoparticles (SiO2, Tio2, ZnO, Al2O3), which together with surfactants form a stable highly viscous foam structure that improves reservoir washing and reduces the mobility of CO2. Such nanosystems selectively reduce the permeability of high-speed flow channels, where CO2 moves most intensively. The key factors affecting the stability of CO2 foam with nanoparticles are analyzed: particle size (20 nm particles are the most effective, for example, hydrophilic SiO2 A300), surface wettability (optimal wetting angle 26-56°), concentration of hydrophilic nanoparticles and temperature (temperature increase reduces stability, but Al2O3 exhibits a more stabilizing effect than SiO2). The advantages of using different oxides are considered separately. It is concluded that, despite promising laboratory results, further studies of the mechanisms of interaction of nanoparticles with salt ions and polymers, as well as field tests for large-scale CO2 storage and enhanced oil recovery are needed.