Abstract: The influence of salt,isoamyl alcohol and surfactant concentration on the compound system of oil/water interfacial tension is researched in this paper.The minimum carbon number of n-alkane of three kinds of alkylbenzene sulfonate isomers is studied.Results show that when the mass of salt,alcohol,alkylbenzene sulfonate,is 0.3%，1.5% and 0.1% respectively,the interfacial tension values can be achieved 0.001 mN/m.When the mass of alcohol,alkylbenzene sulfonate unchanged,with the carbon number of oil phase growing,the salt content at which the interfacial tention reaches 0.001mN/m increases by 0.28%~0.32%,0.32%~0.38% and 0.37%~0.48% respectively.The nmin of three isomers increases with the aromatic moving from the edge to the centre in the long alkyl chain,followed by 10,11,16.Under the condition of the mass of alcohol,salt unchanged,the interfacial tention between alkylbenzene sulfonate solution and corresponding alkane can reach 0.001mN/m while the mass of three kinds of alkylbenzene sulfonate isomers is 0.08%~ 0.16%.

Key words: sulfonate, salt, isoamyl alcohol, interfacial tension, minimum carbon number of n-alkane, EOR