The effect of mixed surfactants on enhancing oil recovery

Micelles composed of mixed surfactants with different structures (mixed micelles) are of great theoretical and industrial interest. This work pertains tomaximizing interfacial tension (IFT) reduction via surfactant pairs. In this respect, four types of fatty acid amides based on lauric, myristic, palmitic, and stearic acids were blended with dodecyl benzene sulfonic acid at a molar ratio of 4∶1 and designated as A₁, A₂, A₃, and A₄, respectively. The IFT was measured for each blend at different concentrations using Badri crude oil. The most potent formula (A₄) was evaluated for using in enhanced oil recovery (EOR). The IFT was tested in the presence of different electrolyte concentrations with different crude oils at different temperatures. Finally several runs were devoted to study the displacement of Badri crude oil by A₄ surfactant solution using different slug sizes of 10, 20, and 40% of pore volume (PV). The study reveled that Badri crude oil gave ultra-low IFT at lowest surfactant concentration and 0.5% of NaCl. The recovery factor at a slug size of 20% PV was 83% of original oil in place compared with 59% in case of conventional water flood.