Experimental Study On Displacement Characteristics Of Nanoparticle Stabilized Foam In Porous Media

China is currently facing a severe energy situation,and how to increase the production of low permeability oil reservoirs has become a key research topic.In this paper,three low-permeability cores with different permeability（1 m D,10 m D,50 m D）were used to inject gas,activator foam and nano particle stabilized foam respectively,and their displacement pressure difference and oil recovery characteristics in porous media were studied experimentally.The applicability of nano particle stabilized foam technology in low permeability reservoirs is analyzed by comparing the experimental results.The experimental results indicate that:（1）Through the analysis of the experimental results under different permeability cores and different back pressure conditions,it can be concluded that the displacement pressure of the CO₂ activator foam is significantly higher than that of the N₂ foam,and at the same time,the enhanced recovery effect of the CO₂ foam is far better than that of the N₂ foam under the supercritical condition.The maximum oil phase recovery of CO₂foam is 25.48%,while that of N₂ foam is 18.06%.This is because CO₂ foam has low surface tension and viscosity,as well as high interphase diffusion capacity,thus improving oil recovery.However,N₂ foam has poor solubility and is difficult to dissolve in oil and water.（2）By adding nano particles into the activator solution,the results were compared with those of activator foam in supercritical state.The results show that the CO₂ foam produced by adding nano particles is more stable in core displacement,the differential pressure in low permeability cores is higher than that of activator foam,and the effect of enhanced production is obviously superior to that of activator foam.The oil recovery of CO₂ foam stabilized by nanoparticles can reach 34.69%,while that of activator foam is 25.48%.The results of this study have a certain significance in understanding the mechanism of stabilizing foam crude oil by nanoparticles and guiding the practice of increasing crude oil production in low permeability reservoirs.