Experimental Study On Rheological Properties Of Nanoparticle Stabilized Foam

In recent years,people have paid more and more attention to CO₂ emission reduction and reuse.Among them,the use of CO₂ can effectively improve the oil recovery?EOR?,and has broad application prospects in CO₂ storage and oil reservoir stimulation.CO₂foam flooding is widely used in major oilfields at home and abroad because of its fluidity ratio controllability,profile control flooding,and wide application range.In this study,the static and rheological properties of CO₂ nano-foams are experimentally studied.AOS is used as the blowing agent and SiO₂ nanoparticles are used as the foam stabilizer.The experiment is designed according to the orthogonal principle,and the static characteristics of the foam are analyzed through the foam observation system.Then,according to the law of rheological characteristics of non-Newtonian fluids,the dynamic characteristics of the foam in the glass pipe are studied.This experiment has important guiding significance for the future research on the rheological properties of CO₂ nano-foam in porous media under high temperature and high pressure conditions.Experimental results show that:?1?Using the orthogonal experiment method,within the range of the experiment,the smaller nanoparticle size and the higher surfactant concentration can obtain better foam generation capacity and foam stability;moderate nanoparticle concentration can CO₂nanofoam has the longest stabilizing effect;higher temperature and solution salinity have a significant negative effect on the static behavior of the foam;range analysis indicates that the surfactant concentration is the most important factor affecting the height and half-life performance of the CO₂ nanofoam;Using the parameter combination of 0.15wt%surfactant concentration,0.1wt%nanoparticle concentration and 7nm particle size recommended by the orthogonal experiment,good foam static characteristics are obtained,and the robustness of the orthogonal experiment design method is verified.?2?After adding SiO₂ nanoparticles,the non-Newtonian fluid characteristics of the foam change with the foam quality,that is,when the critical foam mass is reached,the power law index of the foam fluid changes;N₂ nanofoam compared to CO₂ nanofoam The apparent viscosity of the foam is large;with the increase of shear rate and foam quality,the salt-containing nanofoam exhibits a non-Newtonian behavior from shear thickening to shear thinning,and its apparent viscosity is much lower than that of the salt-free state.The presence of oil has no significant effect on the rheology of CO₂nano-stabilized foam.