US Patent 9822297 Invertible water-in-oil latices and methods of use

Invertible latices suitable for use in enhanced oil recovery are formed by adding a first inversion surfactant and a second inversion surfactant to a water-in-oil latex comprising about 15 wt % to 50 wt % of a water soluble polymer having a net ionic charge. The first inversion surfactant has a hydrophilic/lipophilic balance of about 15 to 35 and an ionic charge that is the opposite of the net ionic charge of the polymer. The second inversion surfactant has a hydrophilic/lipophilic balance of between about 8 and 20. The invertible latices are diluted in a single step to provide dilute latices having 10,000 ppm or less polymer solids.