Synthesis And Properties Of Amino Sulfonates Amphoteric Surfactants

With the importance of environmental protection and the urgent requirement to exploit oil field with low permeability reservoir and high salinity reservoir water,it is imperative to develop an environmental friendly amino sulfonate amphoteric surfactant with an excellent tolerance of salt,especially for the high valence of Ca2+,Mg2+ and so on,to successfully complete the synthesis of these compounds in the laboratory,to well investigate and know the basic properties of them,eventually to fulfill the industrial production of them and the practical application in the industry or other fields,all of which have a positive and important significance of practice and strategy.This paper focused on the investigation of the surface/interface activity of a class of amino sulfonate amphoteric surfactants designed and prepared in our laboratory,the adsorption on solid surfaces and the application in low permeability oil field.Amino sulfonate amphoteric surfactants,3-(N-alkylethylene diamine)-2-hydroxylpropane sulfonate(abbr.SADHPS),were prepared by two steps of SN2.The elementary contents of SADHPS were detected by Automatic Elementary Analyser,the molecular structures of them characterized by Infrared Spectrometer and 1H Nuclear Magnetic Resonance Spectrometer.The active concents of the products purified by organic solvents were determined by the chemical titration of quantitative analysis of potassium ferricyanide.The above analytical results show the molecular structures of goal products are expectant and their purities after purification treatment are always above 98%.The critical micelle concentrations,cmcs,of a series of surfactants SADHPS in aqueous solution were determined by the method of surface tension,and the saturated adsorption Γmax,the minimum surface area occupied by a surfactant molecule Amin s,the efficiency of reducing surface tension pC20 in the air-water interface,the surface pressure at the critical micelle concentration π cmc,standard adsorption free energy ΔGad 0 and standard micellization free energy ΔGmic 0 were calculated and compared with that of traditional surfacatants reported in the literatures.The charge square of head group of a series of surfactants SADHPS,q2(equal to 0.2082～0.3877),was calculated by the semiempirical method of quantum chemistry,being obviously more than the values of alkylbetaine Cn Be and alkyl polyoxyethylenated ether CnE8(0.0245～0.0735 and 0～0.0531,respectively).This result indicate that at isoelectric point the polar groups of SADHPS are really not neutral but weakly negative and the amphotericity of SADHPS is not enough strong responding to CnBe and CnE8.Owing to the head group with longer chain and then the larger space occupied in the air-water interface,the minimum surface areas Amin s of surfactants SADHPS are evidently larger than that of traditional ionic or nonionic surfactants reported in the literatures.In a wide range of concentration,a series of surfactants SADHPS can be stable in the double distilled water and in the formation water with high salinity,and all the curves of their dynamic interfacial tensions show L-shaped,namely,the occurrence of equilibrium interfacial tensions after short time.The time of reaching equilibrium interfacial tensions is lengthened by surfactants with longer hydrophobic chains and shortened for the higher concentrations of surfactants in the solution.The surfactant systems MS-14 or S-13 designed and screened out in the investigation can match with the formation water with different salinities,and can lower the interfacial tensions between crude oil and formation water to ultralow level in a wide range of concentration.The investigations on adsorption of the series of surfactants SADHPS on quartz and two typies of oil sands with different properties of porosity and component show that the linear relationship between saturated adsorptions on adsorbents and the chain length of hydrophobic group of these surfactants is excellent,namely,the lower saturated adsorption for the longer hydrophobic chain;the adsorption is increased if the salt in aqueous solution is added;owing to the increasing temperature exothermally,the adsorption is lowered;the adsorption is varied with the pH in aquous solution.The isotherms of a series of SADHPS on quartz and two different typies of oil sands all accord with the Langmuir model of monolayer adsorption,namely,L-type.The adsorption regular patterns of surfactant system MS-14 and S-13 on quartz are also characteristic of L-type,but both of them can be adsorbed by the molecular multilayer of 2-3 layers on two typies of oil sands from aqueous solution and their isotherms can be well explained by S-shaped curves and then their adsorptions on oil sands are obviously larger than on quartz.The adsorptions of monolayer and multilayer were decribed by the models established in the paper.From the analysis to the models,the occurrence of adsorption is performed by many mechanisms,mainly including electrostatic interaction and the formation of hydrogen bonding between absorbates and absorbent.Judging by the experimental results of displacing oil in artificial or natural cores in thelaboratory,the surfactant system MS-14 with the optimum performance is screened out.The pilot testing of MS-14 surfactant flooding in oil field with ultralow permeability was carried out.During the practice period of about 7 months,the displacing pressure of injection fluid in water well is decreased by 20%,the mean values per day both liquid level and oil level in oil well are respectively increased by 12.15%and 29.19%,the mean water ratio of liquid from oil well is decreased by 12.08%;the direct input-output ratio for the implement of surfactant flooding is 1:9.49.Consequently,these results for the application of the surfactant flooding in ultralow permeability oil field show excellent practical performance and outstanding economic benefit.