Stability Mechanism And Seepage Characteristics Of CO₂ Dry Foam Reinforced Nanoparticle

CO₂ flooding is a relatively mature displacement technology,which can reduce the emission of greenhouse gas CO₂ by burying it underground.However,during the process of oil displacement,CO₂ tends to produce gravity differentiation and gas channeling,which affect the oil displacement efficiency.The foam system can control the CO₂ mobility and improve the problem of CO₂ displacement channeling.In connection with the special reservoir geological conditions in China,many reservoir resources to be exploited are located in arid and water-deficient areas,so reducing the water content of CO₂ foam and exploring the CO₂ foam system with low water content has become a hot topic in our research.In this paper,the appropriate ratio of Si O₂ nanoparticles and surfactant was optimized through the laboratory foam evaluation experiment,and the synergistic mechanism of Si O₂ nanoparticles and surfactant in the CO₂ dry foam system was explored,and the influence of particle concentration,temperature,surfactant concentration and other factors on the CO₂ dry foam system was identified.The results show that the increase in temperature will reduce the stability of the CO₂ dry foam system,but has little effect on the interfacial viscoelasticity.The concentration of1.0wt%Si O₂ particles and 0.2wt%surfactant concentration can produce a good synergistic effect,Adsorbed on the surface of the bubble,prevent gas diffusion and liquid precipitation rate,strengthen the performance of CO₂ dry foam system.Using light dry etching microscopic model for CO₂ foam system in porous media seepage experiments,and explore the CO₂ displacement performance of dry foam system before and after strengthening the change,experiments show that the strength of the interface film of the CO₂ dry foam system after Si O₂ nanoparticles strengthening is increased,the bubble by the narrow channel extrusion has recover deformation counterforce to the wall,to wall on the adhesion of crude oil squeeze away,the resistance to deformation of the interface properties to improve the oil recovery has an important significance.Finally,the plugging ability and oil displacement efficiency of the CO₂ dry foam system strengthened by nanoparticles on the formation were studied through core displacement and shred experiments.The experiment proves that the CO₂ dry foam system reinforced by 1.0wt%nanoparticles has good sealing performance for the formation,and the system can enter the formation with lower permeability,which improves the swept area and oil washing efficiency.