Aromatic rich hydrocarbon phase is separated from lube base stock by using solvent extraction method. Acetonitrile is used as solvent. Sodium petroleum sulphonates are prepared by sulphonation with concentrated (98%) sulphuric acid followed by neutralization with alkali solution. The formation of high molecular weight oil soluble petroleum sulphonates, i.e., benzene soluble and chloroform soluble sulphonates constitute only 45% of the total sulphonates produced. Low concentration surfactant slugs are prepared using isoamyl alcohol as cosurfactant and sodium chloride as brine, while oil soluble sulphonates are surfactants. Both chloroform and benzene soluble sulphonates could produce low interfacial tension (IFT) in the order of 10(-2) mN/m against Naharkatiya (NHK) crude oil. Chloroform soluble sulphonate produce ultra low IFT against heptane, while higher molecular weight benzene soluble sulphonate gives lowest IFT against nonane. The interfacial activity of chloroform soluble sulphonates indicate that heptane is the equivalent alkane carbon number (EACN) of NKK crude oil.