An empirical correlation between low interfacial tension and micellar size and solubilization for petroleum sulfonates in enhanced oil recovery

Abstract

This paper describes some scientific methods for formulating ultralow interfacial tension systems for enhanced oil recovery. The recovery activity was judged by the solubilization of crude oil and the emulsion droplet size formed by the crude oil and the surfactant solutions. Dynamic light scattering was used in measuring the partical size. UV absorption measurement was applied to evaluate the solubilization capacity. Spinning drop apparatus was employed in determining the ultralow interfacial tension. Detailed procedures will be shown on: (1) to find a proper composition for preparing a petroleum sulfonate mixture; and (2) to find the optimum electrolyte concentration to achieve ultralow interfacial tension. The final ultralow interfacial tension systems will be proved by the spinning drop experiment. It was found that a surfactant system which can achieve ultralow interfacial tension has the following characteristics: (1) the surfactant solution contains micelles of around 100 nm in size; (2) the surfactant solution has high solubilization power; and (3) the emulsions formed by the surfactant solution and crude oil has droplet size below 200 nm. Under our experimental conditions, the process of lowering the interfacial tension seems to follow the diffusion controlled solubilization mechanism.