Low Permeability Reservoirs Microemulsion Oil Displacement System Optimized Formulation And Performance Evaluation

Domestic oilfields at later stage of high water cut,oil field production is weak.Application of chemical flooding technology to improve recovery efficiency are the main measures at present each big oilfield,and have achieved good development effect.Low permeability reservoirs because of pore throat is narrow,the reservoir heterogeneity is serious,high injection pressure,etc,polymer molecules are difficult to enter into the low permeability reservoir.At present,the low permeable oil fields are mainly composed of water flooding development,recovery efficiency is low.As the country has increased the demand for oil energy,to the production requirement of the low permeable oil fields also gradually increased.For that in the low permeability reservoirs of microemulsion flooding technology research,in order to reasonable and efficient development of low permeable oil fields.This article first to determine the three types of anionic surfactant,three kinds of nonionic surfactants,amphoteric ionic surfactant critical micelle concentration,parameters such as the minimum interfacial tension and solubilization capacity.With sodium dodecyl sulfate,twain-20,lauryl betaine as preparation of microemulsion anionic,nonionic microemulsion,the main agent of amphoteric ionic microemulsion.After respectively n-butyl alcohol,isoamyl alcohol,hexyl alcohol mixed with the selection of surfactant,again to measure their interfacial tension and solubilization parameters,etc.Optimizing the preparation of microemulsion n-butyl alcohol as surfactant.Before the preparation of microemulsion was studied the influence factors of microemulsion phase behavior,because the inorganic salt is a common material in the strata,this paper studies the effect of inorganic salt on the microemulsion.By salinity scanning and alcohol degree scanning experiments,the results showed that salt or alcohol can through reduce the repulsion between the surfactant molecules,adjust surfactant HLB value,increase the flexibility of interfacial film role,such as microemulsion phase behavior change.And inorganic salt with charge,the greater the effect was more obvious.Studies have shown that phase microemulsion flooding potential maximum,so the use of orthogonal experimental method with sodium dodecyl sulfate,twain-20,lauryl betaine as the main agent of phase microemulsion,and to evaluate the performance.Experimental results show that three kinds of microemulsion can achieve ultra-low interfacial tension,interfacial tension of betaine type microemulsion,lowest 0.0026 mN/m.Three kinds of particle size of microemulsion peak between 0.08 mu m ~ 0.1 microns,can easily through low permeability core porosity.Micro emulsion viscosity were 7.2,8.5,7.4 mPa s,have a good ability to reduce the water flow rate.Solubilization ability,SDS microemulsion solubilization ability,the strongest reached 11.7 mL/g,twain-20 and BS-12 microemulsion solubilization parameters were 9.5 m L/g,10.6mL/g.Stability,anionic emulsion and the stability of the amphoteric ionic microemulsion is higher.Nonionic microemulsion are greatly influenced by temperature,when the temperature is higher than that of nonionic surfactant cloud point,the phenomenon such as microemulsion appear statified turbidity.Oil displacement experiment shows: betaine type microemulsion for with ultra-low interfacial tension and good solubilization parameter,improve the recovery rate is the largest,is 16.45%.Twain-20 microemulsion middle and improve oil recovery amplitude of 14.96%.SDS type microemulsion can improve the recovery rate of 13.88%.To estimate cost of oil displacement when the same volume of crude oil extraction,twain-20 microemulsion cost is highest,the lowest cost of SDS type microemulsion.Expect oil prices above $75 a barrel could consider using SDS microemulsion for development.