Study On Nanosheets Oil Displacement System Properties And Characteristics Of Relative Permeability Curve In Low Permeability Reservoir

Low permeability reservoirs have high development difficulty due to the characteristics such as small pores and large pore throat ratio,and the application effect of conventional production techniques is poor,which leads it is urgent to find new methods to enhance oil recovery.Nano-materials have become a research hotspot in the field of EOR because of their good injectability due to scale effect.In this paper,nanosheets are taken as research object,static properties evaluation,seepage flow pattern analysis and oil displacement mechanism research have been carried out.Firstly,the static properties such as reducing interfacial tension,wetting reversal and emulsification are evaluated;Secondly,through the measurement of relative permeability curve and the observation of output liquid,the seepage flow pattern between nanosheets and oil is studied;Finally,the visual model is used to simulate the seepage flow process of nanosheets to reveal the micro mechanism of nanosheets seepage flow,screen the injection parameters and clarify the situation of extracting remaining oil and oil displacement mechanism of nanosheets.The static experiment results show that the nanosheets can reduce the oil-water interfacial tension to the order of 10^-1m N/m,transfer surface from lipophilic property to hydrophilic property,and the oil in water emulsion has good stability.The relative permeability curve determination experiment results show that compared with water flooding,nanosheets flooding can improve the seepage state of oil-water two-phase,widen the two-phase region,reduce the residual oil saturation and enhance oil recovery;the emulsification of output liquid is affected by factors such as nanosheets concentration,core permeability,water cut and standing time.The visual model experiment results show that the injection mode of single round large slug and the injection volume of 0.4 PV have good oil displacement effect.The nanosheets change the existing status of oil in the pores and improve the flowability of oil by the mechanism of wetting reversal and mobility control,which drive out a large amount of remaining oil.Therefore,based on the interfacial properties analysis,master seepage flow pattern and oil displacement mechanism,is of great significance to promote the high effective development of low permeability reservoirs and the reasonable application of nanosheets material.