A Study On Emulsification Effect Of Surfactant Micellar Solutions Flooding In Low Permeability Reservoir

With the constant exploring and discovery of low permeability reservoir in recent years,the proportion of low permeability reserves has gone beyond 60%.The current development of low permeability reservoirs is still in the stage of secondary oil recovery,because of the serious scaling of alkali in low permeable oil fields and injection difficulties of polymer molecules,the traditional tertiary oil recovery technique in low permeable oil fields does not adapt and a large number of remaining oil residue underground,it is urgent to find methods of adapting tertiary oil recovery in low permeable oil reserves.Micellar solution flooding technology is one of the effective ways to improve recovery efficiency,compared with the surfactant flooding,micellar solution and hydrocarbons under the condition of shear displacement in reservoirs spontaneously form microemulsion and improve oil displacement efficiency.Micellar solution flooding can alter the displacing agent fluidity and have a certain degree of fluidity controlling effect,possessing great research value.Therefore,this article obtains from the formula of micellar solution displacement system,measured the concentration of critical micelle concentration,oil/water interfacial tension and emulsifying rate and other parameters of various surfactants,comprehensively selected anionic(sodium dodecyl sulfate,sodium dodecyl sulfate),nonionic(alkyl phenol polyoxyethylene ether,Tween80)and amphoteric ionic(carboxyl betaine,sulfo betaine)surfactant,added various cosurfactant and measured the interfacial tension and emulsification rate between micellar solution system and crude oil,Screened of different carbon chain length of alcohol to cosurfactant and got best micellar solution flooding system formula: 4wt% sulfo betaine isobutanol+2wt%.Then apply the formula for low permeability core displacement experiment,using the method of control of a single variable,respectively from the petrophysical properties,core fluid and displacement conditions analysis the influence factors emulsifying effect of micellar solution flooding.Finally,proceeding microscopic and macroscopic oil displacement experiments,from the micro level,the micellar solution system can effectively displace membrane,gutta,columnar and residual oil blind end and its displacement effect significantly better than surfactant solution with the same interfacial tension;From the macro level,when the permeability variation coefficient is 0.67,micellar solution flooding improve oil recovery by about 2% on the basis of surfactant flooding to improve oil recovery by about 5% and the research results have important significance for the development of low permeability reservoirs tertiary oil recovery technology.