| Micro-foam is a micron-sized foam with a particle size in the range of 0-100?m.The bubbles are wrapped by a multi-layer liquid film,which can effectively prevent the adjacent bubbles from merging.Micro-foam flooding has the characteristics of ordinary foam flooding,but it has better mechanical strength and better stability.Micro-foam is small in size therefore it has characteristics of good injection with lower injection pressure.In this paper,we compared and screened the varieties and concentrations of frother and foam stabilizer of micro-foam system optimized the method and conditions of micro-foam preparation.A complete micro-foam system formula was obtained with0.3%SDS+0.3%Material SD-200Y,stirring speed was 7000r/min,stirring time was3min.Through the test of different temperature,salinity,oil content on the system,that the micro-foam system can adapt to the salinity range of 0-6000mg/L,the temperature should be less than 50?,and oil content should not exceed 30%.In this paper,the susceptibility range of microfuel system permeability was analyzed by measuring the resistance factor of micro-foam flooding under different permeability conditions.The suitability of micro-foam system under different permeability was analyzed by calculating the matching relationship between micro-foam size and pore throat size under steady injection pressure.It is found that the micro-foam system has good adaptability to the core with the permeability range of more than 1300×10-3?m2.The adaptability of systems whose permeability within1001300×10-3?m2 is good.And system has poor adaptability to the core with the permeability range of less than 100×10-3?m2.Compare the mean pore throat radius with the average bubble radius under steady pressure,when the core permeability over than 150×10-3?m2,the difference between the mean radius of foam and the average pore throat radius is greatly reduced,that is,the permeability of the microfuel system should be greater than 150×10-3?m2.In the micro-foam flooding experiments,In the micro-foam flooding experiment,within the permeability range 10×10-3?m23000×10-3?m2,with the increase of permeability,the enhanced oil recovery increased from 14.78%to 19.27%,indicating that the adaptability of micro-foam system under high permeability conditions was better than the lower.This is because in the low permeability conditions that crude oil driving is difficult,with the low resistance factor,the improving recovery rate is low;In medium and high permeability conditions,foam size and throat size matching good,the resistance factor is higher,Jamin effect plays a major role,so the improving recovery rate is higher.The micro-foam system in this paper has good injection and stability,and provides theoretical basis and technical guidance for the future application and development of micro-foam flooding. |
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