A study on enhancing oil recovery efficiency through bubble displacement based on microfluidic technology

Tight sandstone contains a large number of oil and gas resources, but because of its ultra-low porosity, permeability, and strong hydrophilicity, the oil recovery is low. Microfluidic technology, as an emerging research technique, offers advantages in visualizing fluid flow, reducing experimental reagent consumption, and accurately simulating the pore structure of sandstone using microfluidic chips. This study presents an effective research methodology for improving tertiary oil recovery efficiency in sandstone. By analyzing pore slice images of sandstone cores and employing image processing techniques, the study extracted characteristic dimensions of the sandstone and designed a microfluidic chip. A displacement system was constructed using high-speed cameras, constant-pressure pumps, and microscopes to monitor the oil displacement process. A bubble generation device based on ultrafiltration membranes was proposed to introduce generated bubbles into the microfluidic chip with a sandstone structure for oil displacement studies. Real-time monitoring of the displacement process was conducted. Water and foam were used as displacing agents to investigate the displacement process in the microfluidic chip mimicking the sandstone core structure. Additionally, analysis and comparison were performed on foam formulation, surfactant concentration, and foam proportion, quantitatively evaluating the oil displacement efficiency under various experimental conditions. The proposed research is helpful for the understanding of the foam flooding process on a micro-scale and of significant application potential for the enhanced oil recovery of sandstone reservoirs.