Micro and nanobubbles technologies as a new horizon for CO2-EOR and CO2 geological storage techniques: A review

CO2 capture, utilization, and storage technology are one of the most effective methods to reduce CO2. Although this technology has been relatively mature, the main problems limiting the large-scale application are the se-curity of geological storage. The advantage of micro and nanobubbles is widely acknowledged due to their size and stability. Micro and nanobubbles are tiny gas-liquid dispersion systems with unique physical characteristics. The important features of micro and nanobubbles include their excellent stability, high internal pressure, extremely large surface-to-volume ratio, and high gas dissolution rate, which lead to promising applications in various fields. This review discussed the studies conducted in the areas of micro and nanobubbles with a special emphasis on CO2-EOR and CO2 geological storage. The micro and nanobubbles classifications and their composition were briefly introduced. The preparation methods of micro and nanobubbles and the main factors affecting their properties were investigated in detail. The characterization parameters with state-of - the art measuring and analysis techniques of microbubble and nanobubble technologies were summarized. Furthermore, the major applications in CO2-EOR and CO2 geological storage were discussed. Base on this review, various potential areas,and gaps for MNB research in CO2- EOR and CO2 geological storage fields are identified for further investigations.