Mechanisms of microbubble vibration in water-gas dispersion system enhancing microscopic oil displacement efficiency

Two etching models, the spherical-rod standard pore channel and the pore structure, were used to conduct displacement experiments in the water-gas dispersion system to observe the morphological changes and movement characteristics of microbubbles. Additionally, numerical simulation methods were employed for quantitative analysis of experimental phenomena and oil displacement mechanisms. In the experiment, it was observed that microbubble clusters can disrupt the pressure equilibrium state of fluids within the transverse pores, and enhancing the overall fluid flow; bubbles exhibit a unique expansion-contraction vibration phenomenon during the flow process, which is unobservable in water flooding and gas flooding processes. Bubble vibration can accelerate the adsorption and expansion of oil droplets, and promote the emulsification of crude oil, thereby improving microscopic oil displacement efficiency. Combining experimental data with numerical simulation analysis of bubble vibration effects, it was found that microbubble vibrations exhibit characteristics of a sine function, and the energy release process follows an exponential decay pattern; compared to the gas drive front interface, microbubbles exhibit a significant “rigidity” characteristic; the energy released by microbubble vibrations alters the stability of the seepage flow field, resulting in significant changes to the flow lines; during the oil displacement process, the vast number of microbubbles can fully exert their vibrational effects, facilitating the migration of residual oil and validating the mechanism of the water-gas dispersion system enhancing microscopic oil displacement efficiency.