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.
1. A method of recovering hydrocarbon compounds from a subterranean reservoir, the method comprising:
a) forming a water-in-oil latex comprising about 15 wt % to 50 wt % of a water soluble polymer having at least about 50 mole % acrylamide content;
b) adding about 0.1 wt % to 2.0 wt % of a first inversion surfactant having an ionic charge and a hydrophilic/lipophilic balance of about 15 to 35 to the water-in-oil latex to form an intermediate latex;
c) adding about 0.2 wt % to 4.0 wt % of a second inversion surfactant having a hydrophilic/lipophilic balance of between about 8 and 20 to the intermediate latex to form an invertible latex;
d) adding a water source to the invertible latex in a single addition to form a dilute latex comprising about 100 ppm to 10,000 ppm of the water soluble polymer;
e) injecting the dilute latex into the subterranean reservoir; and
f) recovering the hydrocarbon compounds, wherein the water source is a high temperature water source, high total dissolved solids water source, or both.
2. A method of recovering hydrocarbon compounds from a subterranean reservoir, the method comprising:
a) forming a water-in-oil latex comprising about 15 wt % to 50 wt % of a water soluble polymer having at least about 50 mole % acrylamide content and comprising a nonionic surfactant having an hydrophilic/lipophilic balance of about 2 to 8;
b) adding to a water source a first inversion surfactant having an ionic charge and a hydrophilic/lipophilic balance of about 15 to 35 to form a surfactant-containing water;
c) adding about 0.2 wt % to 4.0 wt % of a second inversion surfactant having a hydrophilic/lipophilic balance of between about 8 and 20 to the water-in-oil latex to form an invertible latex;
d) adding the surfactant-containing water to the invertible latex in a single addition to form a dilute latex comprising about 100 ppm to 10,000 ppm of the water soluble polymer;
e) injecting the dilute latex into the subterranean reservoir; and
f) recovering the hydrocarbon compounds, wherein the water source is a high temperature water source, high total dissolved solids water source, or both.