Simulation Of Dynamic Interface Change Of Foam Fluid Seepage And Oil Displacement In Microscale

Foam can solve the problems of serious water invasion in the late stage of conventional reservoir flooding,gas channeling in unconventional reservoirs,and low producing rate of low permeability reservoirs caused by heterogeneity.At present,the research mainly focuses on macro displacement,ignoring the changes in the microstructure and interface of foam,which cannot truly reflect its dynamic mechanism.In view of this,starting from the microstructure of foam,establishes a simplified micropore structure model,uses the level set method to build a foam seepage model,tracks the gas-liquid interface,simulates the dynamic process of foam seepage,and analyzes the seepage characteristics and the influencing factors such as gas-liquid ratio,flow rate,pore structure,wettability,surface tension,etc;Using phase field method and separated multiphase flow theory,simplified micropore structure and complex micropore structure are established,foam oil displacement model is constructed,foam oil displacement process is simulated,and foam oil displacement mechanism and flow rate,pore structure,wettability,interfacial tension,initial oil saturation and other influencing factors are analyzed.The results show that the gas liquid ratio of foam can produce good plugging effect within a certain range,and if it exceeds the range,the plugging effect will decline.There is an optimal gas liquid ratio,which is about 2:1 in this paper;The flow rate has a minimum value for the generation of continuous foam.If the maximum value is exceeded,continuous foam can be generated;The greater the surface tension is,the greater the pressure peak value is,and there is also a maximum extreme value of the surface tension to produce continuous foam;The wetting angle also has a range for the generation of continuous foam;The size of pore throat in pore structure is inversely proportional to the extreme value of pressure.When foam passes through homogeneous formation,the pressure change curve is relatively slow,while when it passes through heterogeneous formation,the pressure change curve fluctuates greatly;Foam flooding mainly reflects the mechanism of "variable diameter piston" and "negative pressure drainage",and can better displace out the oil in the blind end;Within a certain range,the larger the flow rate,the higher the oil displacement efficiency;The larger the pore throat is,the better the oil displacement effect is,but If the pore throat is too large,the oil displacement effect will be weakened;Wettability has little effect on foam flooding;Both high and low interfacial tensions can play a better oil displacement effect.The greater the oil-water interfacial tension is,the stronger the negative pressure drainage effect of foam is,the weaker the breaking and regeneration ability of foam is,and the greater the displacement pressure is.The lower the initial oil saturation,the stronger the effect of foam flooding,but the displacement pressure will rise.Complex micropore foam displacement shows that foam still has good oil displacement effect under complex geological conditions.