Study On The Mechanism Of Three-Phase Foam Profile Control And Flooding In High Water-Cut Reservoir

In order to ensure national energy security,it is necessary to strengthen the research on new reservoir development technologies and improve domestic oil recovery.At present,most reservoirs are in high water-cut stage after long-term waterflooding in the old oil fields in eastern China,but there is still a large amount of remaining oil in the formation,which has great development potential.In order to meet the demands of high water-cut reservoir profile control and flooding and promote the development of carbon sequestration technology under the background of"carbon neutrality",the main content of this paper is CO₂-microsphere-water-based three-phase foam profile control and flooding system.In this paper,polymer microspheres were synthesized by reverse-phase suspension polymerization method,and Warning-Blender method was used to screen and mix the three-phase foam system.The seepage and displacement laws of three-phase foam in porous media were studied by microscopic etching model,and the mechanism and effect of three-phase foam displacement were further studied by plugging and oil displacement experiments in sand filled tube core model.The size of the synthesized microspheres ranged from 5μm to 20μm.The three-phase foam formula was selected as 0.3%foaming agent S-11+2000 mg/L polymer microspheres by laboratory experiments.In the evaluation of the stability of three-phase foam,the resistance of three-phase foam to Na⁺and Ca²⁺and the stability of temperature change are obviously better than that of two-phase foam.The mechanism of three-phase foam flooding was studied by micro-etching model,which included expanding sweep volume,plugging large but not small,plugging water but not blocking oil,and microspheres synergistic plugging.Improving oil washing efficiency,emulsification,stripping,carrying crude oil.In the core block oil displacement experiments,table with two-phase foam,microspheres activator solution compared to the three-phase foam has better performance,carrying,sealing,migration for 1～3μm² for permeability core can be effectively suppressed,32.5%of the total increase recovery efficiency in and alignment flooding experiments,it was significantly higher than 16.7%of microsphere surfactant solution and 23.9%of two-phase foam.Three-phase foam is more capable of spreading to low permeability core and using residual oil.