Conformance Control and Oil Displacement Dynamics: The Role of Size-Controlled Microbubbles in Enhanced Oil Recovery

Abstract During the development of low permeability reservoirs, strong heterogeneity often results in low displacement efficiency. Microbubble flooding technology has received significant attention and has been introduced into tertiary oil recovery due to its smaller diameter and high stability. To further explore the reservoir adaptability of microbubbles in low permeability reservoirs and analyze the interaction mechanisms between microbubbles and crude oil, this study focused on the generation of microbubble by microfluidic method and the conformance performance characteristics of microbubbles. The results indicate that the generated microbubble sizes are from 50 to 220 μm. Small gas-liquid ratio, small necking sizes, and low surface tensions are the main factors to influence the size of microbubbles. According to the results of microfluidic experiments, size-controlled microbubble produced by adjusting gas-liquid ratio can enter to low permeability area and increase the seepage resistance in the high permeability area, which can improve the sweep efficiency significantly. Three major oil displacement mechanisms also were identified: wrapped liquid film, direct displacement, and co-directional liquid film flow. The study proves the flexibility of microbubble technology in low permeability reservoirs and provides a theoretical basis for its wider range of applications.