Effect of Sodium Hydroxide on the Interfacial Tension of Hydrocarbon—Water System

An ultra-low IFT (interfacial tension) is required between the liquid–liquid systems to dislodge the crude oil completely from the pores of the formation. As a huge amount of alkali is used for this purpose, scale formation and formation damage near wellbore region is a common issue. To perform an economically and environmentally viable process, it is obligatory to design the process with low and optimum concentration of alkali. Moreover, if the concentration of alkali is properly designed according to the oil chemistry, the alkali flooding alone could result in a favorable recovery for high acid number crude oil. So, the present study utilized low concentration of NaOH, to understand the behavior of alkali at the IFT of hydrocarbon–water system. Hydrocarbons like heptane and benzene were selected to understand the influence of hydrocarbon type on the IFT reduction. It was found that the IFT between the hydrocarbon–water system continuously decreases with an increase in NaOH concentration; moreover, a minimum concentration of 100 ppm is required to initiate reduction reaction. It is evident to state that IFT is dependent upon type of the hydrocarbon, because the enhanced reduction is observed in aromatics–water system using NaOH due to stronger cation-π interaction.