An emulsion in the sense of enhanced oil recovery is essentially a stable mixture of water, oil, and an emulsifier. Once you've done your primary oil recovery, oil is left in tiny fissures in the rock. You would like to be able to wash it out of those fissures and recover it, and you can do that by adding essentially soap and water to make a stable emulsion which can be pumped out.
That should at least give you a starting point.
One of my first research projects outside of college involved screening surfactants for their ability to make stable emulsions of water and various samples of crude oil