Reducing Heavy Oil Flow Resistance in Porous Media Using the Chemical Energy of Supersaturated CO₂

The formidable high pressure gradients encountered in porous media saturated with heavy oil pose displacement challenges to displacement processes, thereby constraining production and recovery efficiencies. Traditional thermal approaches, such as steam flooding, not only are economically burdensome but also contribute significantly to CO2 emissions. To mitigate these limitations, we introduce a novel approach that harnesses the latent chemical energy stored in dissolved CO2 to alleviate the flow resistance of heavy oil. Experiments demonstrate a significant improvement in heavy oil mobility when CO2 microbubbles are formed within saturated pores, highlighting a promising method for enhancing oil recovery. Furthermore, the diffusion of CO2 from the oil to the rock interfaces can create a protective CO2 layer, which significantly reduces the pore-level flow resistance. Additionally, the dissolved CO2 diminishes the adhesive interactions between oil droplets and rock surfaces, making it easier for the oil to detach and mobilize. This research uncovers pore-size-specific mechanisms of CO2-assisted oil recovery, showing that CO2 has a pronounced effect in smaller pores by markedly decreasing flow resistance, while its impact in larger pores is less significant.