Methods for selecting surfactant solutions for use in enhanced oil recovery processes

A method for selecting a surfactant solution for use in an enhanced oil recovery process comprising:

• contacting crude oil with each of a brine solution and a surfactant solution comprising brine and surfactant to produce a crude/brine, mixture and a crude/surfactant mixture, respectively, wherein an interface forms between the brine solution and the crude oil and an interface forms between the surfactant solution and the crude oil, and wherein the surfactant solution comprises at least 0.1 wt. % surfactant;
• compressing the interlace between the crude oil and the brine solution in the crude/brine mixture in a Langmuir trough to measure a first interface pressure versus surface area isotherm:
• compressing the interface between the crude oil and the surfactant solution in the crude/surfactant mixture in a Langmuir trough to measure a second interface pressure versus surface area isotherm;
• calculating a first interface compression energy by integrating the first interface pressure versus surface area isotherm;
• calculating a second interface compression energy by integrating the second interface pressure versus surface area isotherm;
• and
• selecting the surfactant solution for use in an enhanced oil recovery process, wherein the surfactant solution is selected if the order of magnitude of the second interface compression energy is at least two less than the order of magnitude of the first interface compression energy, and the interface between the crude oil and the surfactant solution exhibits Winsor type I phase behavior, wherein the surfactant stays in an aqueous phase of an oil-in-water microemulsion.