HIGH MOLECULAR WEIGHT ANIONIC POLYACRYLAMIDES

Abstract

This invention relates to a polymer composition comprising a water-soluble anionic P2 polymer obtained by radical polymerization of at least one anionic monomer, in the presence of a water-soluble homopolymer P1 with a weight-average molecular weight of between 5,000 and 100,000 daltons

said water-soluble anionic P2 polymer having a weight-average molecular weight of greater than 100,000 dalton and less than or equal to 40 million daltons,
said water-soluble P1 homopolymer having been prepared from 2-acrylamido-2-methylpropanesulphonic acid in salified form and in the presence of 200 to 20,000 ppm by weight of 2-methyl-2-propenylsulphonic acid in salified form.

Claims

1. A polymeric composition comprising a water-soluble anionic P2 polymer obtained by radical polymerization of at least one anionic monomer, in the presence of a water-soluble P1 homopolymer with an average molecular weight by weight of between 5,000 and 100,000 daltons, said water-soluble anionic P2 polymer having a weight-average molecular weight greater than 100,000 daltons and less than or equal to 40 million daltons, said water-soluble P1 homopolymer having been prepared from 2-acrylamido-2-methylpropane sulfonic acid in salified form and in the presence of 200 to 20,000 ppm by weight of 2-methyl-2-propenyl-sulfonic acid in salified form.

2. The polymeric composition according to claim 1, wherein the water-soluble P1 homopolymer is prepared in the presence of 300 to 10,000 ppm of 2-methyl-2-propenyl-sulfonic acid in salified form.

3. The polymeric composition according to claim 1, wherein the water-soluble P1 homopolymer is prepared in the presence of 300 to 10,000 ppm by weight of 2-methylidene-1,3-propylenedisulfonic acid in salified form.

4. The polymeric composition according to claim 1, wherein the salified forms of 2-acrylamido-2-methylpropane sulfonic acid and of 2-methyl-2-propenyl-sulfonic acid, as well as the salified form of 2-methylidene-1,3-propylenedisulfonic acid if present, are sodium salts.

5. The polymeric composition according to claim 1, wherein the water-soluble anionic P2 polymer has a weight average molecular weight between 1 million and 40 million daltons.

6. The polymeric composition according to claim 1, wherein the anionic monomer of the water-soluble anionic polymer P2 is selected from the group consisting of acrylic acid, methacrylic acid itaconic acid, crotonic acid, maleic acid, fumaric acid, acrylamido undecanoic acid, 3-acrylamido 3-methylbutanoic acid, maleic anhydride, 2-acrylamido-2-methylpropane sulfonic acid (ATBS) vinylsulfonic acid, vinylphosphonic acid, allylsulfonic acid, methallylsulfonic acid, 2-sulfoethylmethacrylate, sulfopropylmethacrylate, sulfopropylacrylate, allylphosphonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropane disulfonic acid, and water-soluble salts of these monomers, and mixtures thereof.

7. The polymer composition according to claim 1, wherein the water-soluble anionic P2 polymer contains between 10 and 100% in moles of anionic monomers and between 0 and 90% in moles of nonionic monomers.

8. The polymer composition according to claim 1, containing between 0.01 and 5.0% by weight of water-soluble homopolymer P1.

9. A method for recovery of hydrocarbons; well drilling; well cementing; the stimulation of hydrocarbon wells; water treatment; treatment of fermentation musts; sludge treatment; papermaking; construction; wood treatment; treatment of hydraulic composition; mining; formulation of cosmetic products; formulation of detergents; textile manufacturing; manufacture of battery components; geothermal energy; manufacture of hygienic pads; or farming, said method comprising adding the polymeric composition according to claim 1 to an aqueous solution, and using the resultant solution.

10. A method of preparing an aqueous solution comprising providing an aqueous solution and adding to it the polymeric composition according to claim 1 as a flocculant, coagulant, binding agent, fixing agent, viscosity-reducing agent, thickening agent, absorbing agent, friction-reducing agent, draining agent, drainage agent, filler retention agent, dehydrating agent, conditioning agent, stabilizing agent, fixing agent, film-forming agent, sizing agent, superplasticizer, clay inhibitor, or dispersant.

11. A method for enhanced recovery of oil and/or gas by sweeping a subterranean formation, comprising the following steps: a. preparing an injection fluid from a polymeric composition according to claim 1, with water or brine, b. injecting the injection fluid into a subterranean formation, c. sweeping the subterranean formation using the injected fluid, and d. recovering an aqueous mixture of petroleum and/or gas.

12. A method for hydraulic fracturing of a subterranean oil and/or gas reservoir, comprising the following steps: a. preparing an injection fluid from a polymeric composition according to claim 1, with water or brine, and with at least one proppant, and b. injecting said fluid into the subterranean reservoir and fracturing at least a portion thereof in order to recover oil and/or gas.

13. The polymeric composition according to claim 2, wherein the water-soluble P1 homopolymer is prepared in the presence of 300 to 10,000 ppm by weight of 2-methylidene-1,3-propylenedisulfonic acid in salified form.

14. The polymeric composition according to claim 13, wherein the salified forms of 2-acrylamido-2-methylpropane sulfonic acid and of 2-methyl-2-propenyl-sulfonic acid, as well as the salified form of 2-methylidene-1,3-propylenedisulfonic acid if present, are sodium salts.

15. The polymeric composition according to claim 14, wherein the water-soluble anionic P2 polymer has a weight average molecular weight between 1 million and 40 million daltons.

16. The polymeric composition according to claim 15, wherein the anionic monomer of the water-soluble anionic polymer P2 is selected from the group consisting of acrylic acid, methacrylic acid itaconic acid, crotonic acid, maleic acid, fumaric acid, acrylamido undecanoic acid, 3-acrylamido 3-methylbutanoic acid, maleic anhydride, 2-acrylamido-2-methylpropane sulfonic acid (ATBS) vinylsulfonic acid, vinylphosphonic acid, allylsulfonic acid, methallylsulfonic acid, 2-sulfoethylmethacrylate, sulfopropylmethacrylate, sulfopropylacrylate, allylphosphonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropane disulfonic acid, and water-soluble salts of these monomers, and mixtures thereof.

17. The polymer composition according to claim 16, wherein the water-soluble anionic P2 polymer contains between 10 and 100% in moles of anionic monomers and between 0 and 90% in moles of nonionic monomers.

18. The polymer composition according to claim 17, containing between 0.01 and 5.0% by weight of water-soluble homopolymer P1.

19. The polymeric composition according to claim 5, wherein the anionic monomer of the water-soluble anionic polymer P2 is selected from the group consisting of acrylic acid, methacrylic acid itaconic acid, crotonic acid, maleic acid, fumaric acid, acrylamido undecanoic acid, 3-acrylamido 3-methylbutanoic acid, maleic anhydride, 2-acrylamido-2-methylpropane sulfonic acid (ATBS) vinylsulfonic acid, vinylphosphonic acid, allylsulfonic acid, methallylsulfonic acid, 2-sulfoethylmethacrylate, sulfopropylmethacrylate, sulfopropylacrylate, allylphosphonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropane disulfonic acid, and water-soluble salts of these monomers, and mixtures thereof.

20. The polymer composition according to claim 19, wherein: the polymer composition contains between 0.01 and 5.0% by weight of water-soluble homopolymer P1; and the water-soluble anionic P2 polymer contains between 10 and 100% in moles of anionic monomers and between 0 and 90% in moles of nonionic monomers.

Description

EMBODIMENTS OF THE INVENTION

Example 1: Synthesis of Polymers P1a, P1b, and P1c

[0125] In a 1 liter jacketed reactor, equipped with a condenser and a stirrer, 190 g of deionized water are added to be heated to 80? C. under a nitrogen atmosphere (nitrogen flow).

[0126] A sodium persulfate solution is prepared in a dropping funnel, by dissolving 17 g of sodium persulfate in 100 g of deionized water. 690 g of a sodium salt solution of 2-acrylamido-2-methylpropane sulfonic acid (Na-AMPS) at 50% concentration by weight in water are charged into a second dropping funnel. A high pressure liquid chromatography analysis indicates a quantity of 1556 ppm (by weight/Na-AMPS) of 2-methyl-2-propenyl-sulfonic acid in the form of the sodium salt and 450 ppm (by weight/Na-AMPS) 2-methylidene-1,3-propylenedisulfonic acid in the form of a sodium salt.

[0127] The sodium persulfate solution is added to the reactor over a period of 120 minutes, and concomitantly the sodium salt solution of 2-acrylamido-2-methylpropanesulfonic acid is added over a period of 90 minutes. During the addition of these reagents and then again for 60 minutes (counted after addition of the sodium persulfate), the reaction medium is maintained at 80? C. The P1a polymer according to the invention thus obtained has a weight-average molecular weight equal to 47,000 daltons (determined from the intrinsic viscosity).

[0128] The synthesis of a P1b polymer is undertaken by carrying out the same protocol as previously (P1a polymer) with the only difference that the polymerization temperature is maintained at 100? C. The P1b polymer according to the invention thus obtained has a weight-average molecular weight equal to 24,600 daltons (determined from the intrinsic viscosity).

[0129] The synthesis of a P1c polymer is undertaken by carrying out the same protocol as previously (P1a polymer) with the only difference that 2-methylpropane sulfonic acid in salified form (Na-AMPS) contains an amount of 102 ppm of acid 2-methyl-2-propenyl-sulfonic acid as the sodium salt and 80 ppm of 2-methylidene-1,3-propylenedisulfonic acid as the sodium salt. The P1c polymer according to the invention thus obtained has a weight-average molecular weight equal to 245,000 daltons (determined from the intrinsic viscosity).

[0130] All the P1 polymers previously described are in the form of an aqueous solution with a concentration of 40% by weight of a 2-methylpropanesulfonic acid homopolymer in the form of the sodium salt in water.

Examples 2: Synthesis of Polymeric Compositions Comprising the P2a and P2b Polymers According to the Invention and the Comparative P2c Polymer (P2 Polymers: Acrylamide/Acrylate Sodium Polymers)

[0131] In a 1000 mL beaker, 389 g of deionized water, 102 g of acrylic acid (90% concentration by weight in water), 396 g of acrylamide (50% concentration by weight in water) and 16 g of polymer P1a (40% concentration by weight in water).

[0132] The solution thus obtained is cooled to between 5 and 10? C., and is neutralized with 113 g of sodium hydroxide solution (NaOH) at 50% concentration by weight in water while maintaining a temperature below 10? C. The solution is then transferred to an adiabatic polymerization reactor. Nitrogen bubbling is then carried out for 30 minutes in order to eliminate all traces of dissolved oxygen.

[0133] The following are then added to the reactor: [0134] 0.45 g of 2,2-azobisisobutyronitrile, [0135] 1.5 mL of an aqueous solution at 2.5 g/L of 2,2-Azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, [0136] 1.5 mL of an aqueous solution of 1 g/L of sodium hypophosphite, [0137] 1.5 mL of an aqueous solution of 1 g/L of tert-butyl hydroperoxide, [0138] 1.5 mL of an aqueous solution of 1 g/L of ammonium sulfate and iron (II) hexahydrate (Mohr's salt).

[0139] After a few minutes, the nitrogen bubbling is stopped. The exothermic polymerization reaction takes place for 4 hours to reach a temperature peak. At the end of this period, the polymer gel obtained is chopped then dried and then ground again to obtain a P2a polymer according to the invention in the form of a powder with an average molecular weight by weight equal to 24,230,600 daltons (determined from the intrinsic viscosity).

[0140] A P2b polymer is obtained by applying the same protocol but in the absence of polymer P1. The P2b polymer according to the invention thus obtained has a weight-average molecular weight equal to 24,320,500 daltons (determined from the intrinsic viscosity).

[0141] A P2c polymer is obtained by applying the same protocol with, instead of the P1a polymer: the P1c polymer. The P2c polymer according to the invention thus obtained has a weight-average molecular weight equal to 24,400,500 daltons (determined from the intrinsic viscosity).

Examples 3: Synthesis of Polymeric Compositions Comprising the P2d and P2e Polymers According to the Invention and the Comparative Polymers P2f and P22 (P2 Polymers: sodium 2-acrylamido-2-methylpropane sulfonate homopolymers)

[0142] In a 1000 mL beaker, 584 g of deionized water and 300 g of sodium 2-acrylamido-2-methylpropane sulfonate (50% concentration by weight in water) and 14 g of polymer P1a (40% concentration by weight in water) are added.

[0143] The solution thus obtained is cooled to between 5 and 10? C., and is neutralized with 116 g of sodium hydroxide solution (NaOH) at 50% concentration by weight in water while maintaining a temperature below 10? C. The solution is then transferred to an adiabatic polymerization reactor. Nitrogen bubbling is then carried out for 30 minutes in order to eliminate all traces of dissolved oxygen.

[0144] The following are then added to the reactor: [0145] 0.45 g of 2,2-azobisisobutyronitrile, [0146] 1.5 mL of an aqueous solution at 2.5 g/L of 2,2-Azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, [0147] 1.5 mL of an aqueous solution of 1 g/L of sodium hypophosphite, [0148] 1.5 mL of an aqueous solution of 1 g/L of tert-butyl hydroperoxide, [0149] 1.5 mL of an aqueous solution of 1 g/L of ammonium sulfate and iron (II) hexahydrate (Mohr's salt).

[0150] After a few minutes, the nitrogen bubbling is stopped. The exothermic polymerization reaction takes place for 4 hours to reach a temperature peak. At the end of this period, the polymer gel obtained is chopped then dried and then ground again to obtain a P2d polymer according to the invention in the form of a powder with a weight average molecular weight equal to 8,630,200 daltons (determined from the intrinsic viscosity).

[0151] A P2e polymer is obtained by applying the same protocol with, instead of the P1a polymer: the P1b polymer. The P2e polymer thus obtained in powder form has a weight average molecular weight of 8,400,000 daltons (determined from the intrinsic viscosity).

[0152] A P3f polymer is obtained by applying the same protocol with, instead of the P1a polymer: the P1c polymer. The P2f thus obtained in powder form has a weight average molecular weight equal to 8,500,000 daltons (determined from the intrinsic viscosity).

[0153] A P2g polymer is obtained by applying the same protocol but in the absence of polymer P1. The comparative P2g polymer according to the invention thus obtained in powder form has a weight average molecular weight equal to 8,230,100 daltons (determined from the intrinsic viscosity).

[0154] A P2g polymer is obtained by applying the same protocol but with the addition of 60 g of polymer P1b. The P2g polymer according to the invention thus obtained in powder form has a weight average molecular weight equal to 4,890,250 daltons (determined from the intrinsic viscosity).

Examples 4: Synthesis of Polymeric Compositions Comprising the Polymers P2h According to the Invention and the Comparative Polymers P2i and P2j (Polymers P2: ter-polymers acrylamide/acrylate of sodium/2-acrylamido-2-methylpropane sodium sulfonate)

[0155] In a 1000 mL beaker, are added 461 g of deionized water, and 105 g of sodium 2-acrylamido-2-methylpropane sulfonate acid (50% concentration by weight in water), 30 g of acrylic acid (90% concentration by weight in water) and 10 g of polymer P1b (40% concentration by weight in water).

[0156] The solution thus obtained is cooled to between 5 and 10? C., and is neutralized with 74 g of sodium hydroxide solution (NaOH) at 50% concentration by weight in water while maintaining a temperature below 10? C. The solution is then transferred to an adiabatic polymerization reactor. Nitrogen bubbling is then carried out for 30 minutes in order to eliminate all traces of dissolved oxygen.

[0157] The following are then added to the reactor: [0158] 0.45 g of 2,2-azobisisobutyronitrile, [0159] 1.5 mL of an aqueous solution at 2.5 g/L of 2,2-Azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, [0160] 1.5 mL of an aqueous solution of 1 g/L of sodium hypophosphite, [0161] 1.5 mL of an aqueous solution of 1 g/L of tert-butyl hydroperoxide, [0162] 1.5 mL of an aqueous solution of 1 g/L of ammonium sulfate and iron (II) hexahydrate (Mohr's salt).

[0163] After a few minutes, the nitrogen bubbling is stopped. The exothermic polymerization reaction takes place for 4 hours to reach a temperature peak. At the end of this period, the polymer gel obtained is chopped then dried and then ground again to obtain a P2h polymer according to the invention in the form of a powder with a weight average molecular weight equal to 14,630,600 daltons (determined from the intrinsic viscosity).

[0164] A P2i polymer is obtained by applying the same protocol but in the absence of polymer P1. The P2i polymer according to the invention thus obtained in powder form has a weight average molecular weight equal to 14,780,500 daltons (determined from the intrinsic viscosity).

[0165] A P2j polymer is obtained by applying the same protocol with, instead of the P1a polymer: the P1c polymer. The P2j polymer thus obtained in powder form has a weight average molecular weight of 14,000,800 daltons (determined from the intrinsic viscosity).

Examples 5: Comparison of the Dissolution Rates of the P2 Polymers

[0166] P2 polymer solutions are prepared at an active concentration of 1000 ppm in deionized water or in a brine containing water, 30,000 ppm NaCl, and 3000 ppm CaCl.sub.2, 2H.sub.2O. The aqueous solutions are stirred and the powder is introduced slowly into the vortex formed by the magnetic bar. The complete dissolution time of the polymer in aqueous solution corresponds to the time from which the maximum viscosity of the polymer solution is reached.

TABLE-US-00001 TABLE 1 Dissolution time Dissolution time in deionized water in brine Polymer (minutes) (minutes) P2a (invention) 100 150 P2b (comparative) 125 195 P2c (comparative) 122 190 P2d (invention) 53 80 P2e (invention) 51 74 P2f (comparative) 67 100 P2g (comparative) 69 105 P2h (invention) 81 118 P2i (comparative) 92 141 P2j (comparative) 91 139

Examples 6: Measurement of the Resistance to the Chemical Degradation of P2 Polymer Solutions

[0167] Chemical degradation resistance tests are carried out under aerobic conditions in the presence of different concentrations of iron (II) (2, 10, and 20 ppm) in a brine composed of water, 37,000 ppm NaCl, 5,000 ppm Na.sub.2SO.sub.4 and 200 ppm of NaHCO.sub.3 (the ppm are expressed by weight relative to the weight of the brine). The results obtained after 24 hours of bringing the P2 polymer solution into contact with the contaminant (iron 11) are presented in Table 2.

TABLE-US-00002 TABLE 2 Loss of Loss of Loss of viscosity viscosity viscosity with 2 ppm of with 10 ppm of with 20 ppm of Polymer iron II, in % iron II, in % iron II, in % P2a (invention) 4 11 28 P2b (comparative) 7 18 35 P2c (comparative) 6 18 34 P2d (invention) 5 12 29 P2e (invention) 5 11 27 P2f (comparative) 8 19 36 P2g (comparative) 9 18 36 P2h (invention) 4 13 29 P2i (comparative) 8 19 35 P2j (comparative) 7 19 34

Examples 7: Measurement of the Filtration Quotient of P2 Polymer Solutions

[0168] The P2 polymer solutions were prepared at an active concentration of 1,000 ppm in a brine containing water, 30,000 ppm of NaCl and 3,000 ppm of CaCl.sub.2, 2H.sub.2O (the ppm are expressed by weight relative to the weight of the brine). The filtration quotient (FR) was measured on filters having a pore size of 3 ?m representative of low permeability deposits. The results are shown in Table 3.

TABLE-US-00003 TABLE 3 Molecular weight Filtration Quotient Polymer (in daltons) (FR) P2a (invention) 24,230 600 1.1 P2b (comparative) 24,320 500 1.17 P2c (comparative) 24,400 500 1.22 P2d (invention) 8,630 200 1.09 P2e (invention) 8,400 000 1.05 P2f (comparative) 8,500,000 1.19 P2g (comparative) 8,230,100 1.21 P2h (invention) 14,630,600 1.09 P2i (comparative) 14,780 500 1.23 P2j (comparative) 14,000,800 1.22

Example 8: Flow Loop Friction Reduction Test

[0169] The P2 polymers are dissolved with stirring at a concentration of 10,000 ppm in a brine composed of water, 85 g of sodium chloride (NaCl), and 33.1 g of calcium chloride CaCl.sub.2), 2H.sub.2O per liter of brine. The polymer saline solutions thus obtained are then injected at a concentration of 0.05 pptg into the brine recirculated for the Flow Loop tests. The Flow Loop consists of a recirculation loop with an internal diameter of 1.27 cm, a pump and multiple pressure sensors installed along the recirculation loop. The Flow Loop is thus previously filled with 20 liters of brine, and is recirculated at a rate of 24 gallons per minute. The percentage of friction reduction is thus determined thanks to the measurement of pressure variations measured inside the Flow Loop. The performance of polymers is measured according to the maximum friction reduction obtained, and the time required to obtain this maximum.

[0170] A product is all the more efficient when the maximum friction reduction is high, and the time required to obtain it is short.

TABLE-US-00004 TABLE 4 Time to reach Maximum friction maximum friction Polymer reduction (%) reduction (seconds) P2a (invention) 51 13 P2b (comparative) 43 12 P2c (comparative) 40 16 P2d (invention) 46 13 P2e (invention) 38 12 P2f (comparative) 39 16 P2g (comparative) 38 17 P2h (invention) 31 14 P2i (comparative) 24 22 P2j (comparative) 25 20