Inversion agents for water-in-oil lattices and methods of use
Water-in-oil lattices of water soluble polymers and methods of using the same are presented. The lattices are made, used, and stored having about 15 wt % to 70 wt % polymer solids and further include one or more alkyl ricinoleates. We have found that C1-C6 alkyl ricinoleates added to such lattices facilitate rapid and complete dilution to less than or equal to 1 wt % polymer solids in a continuous water phase. In particular under conditions wherein the water source used to invert the latex is provided at low temperature (−10° C. to 10° C.), or includes a high level of total dissolved solids, or is both low temperature and high total dissolved solids.
1. An invertible latex comprising
a water-in-oil latex comprising 15 wt % to 70 wt % of a water soluble polymer comprising about 1 mol % to 100 mol % acrylamide residues;
0.1 wt % to 10 wt % of an inversion surfactant characterized as having a hydrophilic/lipophilic balance of 10 or greater; and
0.1 wt % to 20 wt % of an alkyl ricinoleate.
2. The latex of claim 1 comprising about 1 wt % to 20 wt % of the combination of alkyl ricinoleate and inversion surfactant.
3. The invertible latex of claim 1 wherein the alkyl ricinoleate is a C1-C6 alkyl ricinoleate.
4. The invertible latex of claim 1 comprising about 1 wt % to 10 wt % of the alkyl ricinoleate.
5. The invertible latex of claim 1 wherein the water soluble polymer further comprises one or more residues of acrylic acid and/or a conjugate base thereof.
6. The invertible latex of claim 1 , wherein the water soluble polymer further comprises one or more residues of N,N-diallyl-N,N-dimethylammonium chloride, 2-(acryloyloxy)-N,N,N-trimethylethanammonium chloride, alkyl acrylates, methacrylic acid, 2-acrylamido-2-methylpropane sulfonic acid, or two or more thereof.
7. The invertible latex of claim 1 wherein the weight-average molecular weight of the water soluble polymer is about 3×10 5 to 1×10 8 g/mol.
8. The invertible latex of claim 1 wherein the inversion surfactant comprises one or more alcohol ethoxylates.
9. The invertible latex of claim 1 wherein the latex has a bulk viscosity 30% to 95% lower than the same latex excluding the inversion agent.
10. A method of forming an invertible latex, the method comprising
(a) forming a water-in-oil latex comprising
about 15 wt % to 70 wt % of a water soluble polymer;
about 3 wt % to 50 wt % water,
about 10 wt % to 40 wt % of a compound or blend thereof that is less than 0.1 wt % soluble in water at 25° C. and is substantially a liquid over the range of 20° C. to 90° C. and comprising linear, branched, or cyclic hydrocarbon moieties; and
about 20 wt % or less of a latex surfactant; and
(b) adding an inversion surfactant and an alkyl ricinoleate to the latex to form an invertible latex.
11. The method of claim 10 comprising adding about 0.1 wt % to 20 wt % alkyl ricinoleate and about 0.1 wt % to 10 wt % of the inversion surfactant to form the invertible latex.
12. The method of claim 10 further comprising storing the invertible latex for a period of about 1 day to 5 years within a temperature range of −10° C. to 60° C.
13. A method of forming a polymer solution, the method comprising mixing a water source with an invertible latex of claim 1 , wherein the polymer solution comprises about 100 ppm to 10,000 ppm of the water soluble polymer.
14. The method of claim 13 wherein the mixing comprises adding the invertible latex to the water source in a single addition.
15. A method of recovering the hydrocarbon compounds from a subterranean reservoir, the method comprising forming a polymer solution according to claim 13 , injecting the polymer solution into the subterranean reservoir, and recovering the hydrocarbon compounds.
16. The method of claim 15 , wherein the water source is about −10° C. to 100° C.
17. The method of claim 15 wherein the water source includes about 0.1 to 30 wt % total dissolved solids.