Method of evaluating surfactants for enhanced oil recovery

A method of evaluating a surfactant comprising:

• preparing a first emulsion comprising an aqueous phase, an oleaginous phase, and a first surfactant;
• determining an average droplet size of oleaginous phase droplets in the first emulsion;
• preparing a second emulsion comprising the same aqueous phase as the first emulsion, the same oleaginous phase as the first emulsion, and a second surfactant, wherein the first surfactant is different from the second surfactant,
• wherein a concentration of the first surfactant and a concentration of the second surfactant are the same;
• determining an average droplet size of oleaginous phase droplets in the second emulsion;
• comparing the average droplet size of the of the oleaginous phase droplets in the first emulsion to the average droplet size of the oleaginous phase droplets in the second emulsion;
• and
• based on the comparing of the average droplet sizes, determining a relative interfacial tension of the first surfactant as compared to the second surfactant.