Progressive salting-out of polymer chains in a liquid medium

Abstract

Provided is a method making it possible to ensure a gradual release of polymer chains within a liquid medium, the method comprising bringing the liquid medium into contact with specific solid objects formed by polymer chains soluble in the medium and carrying hydrophobic side groups ensuring physical crosslinking between the polymer chains within the solid objects. The released chains may in particular be used as inhibitors of the formation of inorganic or organic deposits (scale inhibitors) within a liquid medium, typically in the field of oil extraction.

Claims

1. A method for the gradual release of polymer chains within a liquid release medium (LRM), said method comprising a step (S) comprising contacting said medium (LRM) with solid objects, wherein the solid objects are formed by polymer chains soluble in the medium (LRM) and carrying hydrophobic side groups ensuring hydrophobic/hydrophobic physical crosslinking between said polymer chains within said solid objects, and wherein the solid objects employed in step (S) result from a step (S0) of micellar radical polymerization in which the following are brought into contact, within an aqueous medium (M): ethylenically unsaturated monomers (m1), dissolved or dispersed in said aqueous medium (M); ethylenically unsaturated monomers (m2), in the form of a micellar solution, namely containing, in the dispersed state within the medium (M), micelles comprising these hydrophobic monomers, said monomers (m2) being, in all or part, monomers carrying hydrophobic chains suitable for ensuring the desired hydrophobic/hydrophobic physical crosslinking in the solid objects employed in step (S); at least one radical polymerization initiator; and at least one radical polymerization control agent, and wherein the monomers employed in step (S0) contain crosslinking monomers (mR) comprising at least two ethylenic unsaturations separated by at least one cleavable group, and wherein the molar ratio (mR)/(m1), which corresponds to the amount of crosslinking monomers (mR) with respect to the total amount of hydrophilic monomers, is greater than 0.5% and less than or equal to 30%.

2. The method as claimed in claim 1, wherein the released polymer chains have a number average molecular weight of between 500 and 100 000 g/mol.

3. The method as claimed in claim 1, wherein the medium (LRM) is an aqueous medium and wherein the released polymer chains are water-soluble.

4. The method as claimed in claim 1, wherein the radical polymerization control agent is a compound which comprises a thiocarbonylthio —S(C═S)— group.

5. The method as claimed in claim 1, wherein the polymer chains released are polymer chains useful as scale-inhibiting, clathrate-inhibiting and/or corrosion-inhibiting agent.

6. The method as claimed in claim 5, wherein the medium (LRM) of step (S) is a liquid medium encountered during the extraction of oil within a hydrocarbon reservoir.

7. The method as claimed in claim 1, where step (S) is carried out at a temperature of greater than or equal to 50° C., and of less than or equal to 150° C.

8. The method as claimed in claim 1, wherein the at least one radical polymerization initiator is water-soluble or water-dispersible.

9. The method as claimed in claim 1, wherein the radical polymerization control agent is a xanthate.

10. The method as claimed in claim 1, wherein the molar ratio (mR)/(m1), which corresponds to the amount of crosslinking monomers (mR) with respect to the total amount of hydrophilic monomers, is greater than 1% and less than or equal to 30%.

11. The method as claimed in claim 1, wherein the molar ratio (mR)/(m1), which corresponds to the amount of crosslinking monomers (mR) with respect to the total amount of hydrophilic monomers, is greater than 2% and less than or equal to 30%.

12. The method as claimed in claim 1, wherein the molar ratio (mR)/(m1), which corresponds to the amount of crosslinking monomers (mR) with respect to the total amount of hydrophilic monomers, is less than or equal to 20%.

13. The method as claimed in claim 1, wherein the molar ratio (mR)/(m1), which corresponds to the amount of crosslinking monomers (mR) with respect to the total amount of hydrophilic monomers, is less than or equal to 10%.

14. The method as claimed in claim 1, where step (S) is carried out at a temperature between 60° C. and 120° C.

Description

EXAMPLES

Example 1

(1) The polymer P1 (polyAA/MBA/LMA/Xa) containing 0.4 mol % of Lauryl Methacrylate (LMA) and 10 mol % of N,N-methylenebisacrylamide (MBA) was prepared under the following conditions:

(2) 49.60 g of Stepanol WA Extra, 2.54 g of LMA and 19.25 g of demineralized water were introduced, at ambient temperature (20° C.), into a 200 ml HDPE flask. The mixture was left to stir using a magnetic bar for 30 min until the solution was clear. (Solution A)

(3) 7.554 g of Rhodixan A1, 131.24 g of ethanol and 33.61 g of MBA were weighed out in a 2000 ml beaker. 157.11 g of acrylic acid (AA) and 526.33 g of demineralized water are subsequently added. After stirring, the solution is homogeneous and clear. (Solution B) Solution A is added to Solution B. After stirring for 15 min, the solution remains cloudy. This new solution was charged to a Dewar flask (3000 ml) equipped with a cap which makes possible an atmospheric airtightness, an anchor stirrer, a temperature probe and a nitrogen inlet, at ambient temperature (20° C.).

(4) The mixture was degassed by bubbling with nitrogen for 60 minutes. 0.75 g of sodium formaldehyde sulfoxylate, in the form of a 10% by weight aqueous solution, and 0.75 g of sodium persulfate (10% by weight aqueous solution) were added to the medium all at once. The mixture was degassed beforehand by bubbling with nitrogen for 15 minutes.

(5) The polymerization reaction was then allowed to take place with stirring for 16 hours.

(6) At the end of the synthesis, the product is recovered in the form of a gel which will subsequently be shaped (extrusion/drying/grinding) in order to ultimately obtain a handleable granular material.

Example 2

(7) The polymer P2 (polyAA/MBA/LMA/Xa) containing 0.8 mol % of Lauryl Methacrylate (LMA) and 10 mol % of N,N-methylenebisacrylamide (MBA) was prepared under the following conditions:

(8) 97.81 g of Stepanol WA Extra, 5.00 g of LMA and 37.88 g of demineralized water were introduced, at ambient temperature (20° C.), into a 200 ml HDPE flask. The mixture was left to stir using a magnetic bar for 30 min until the solution was clear. (Solution A)

(9) 7.45 g of Rhodixan A1, 104.04 g of ethanol and 33.22 g of MBA were weighed out in a 2000 ml beaker. 154.98 g of acrylic acid (AA) and 417.54 g of demineralized water are subsequently added. After stirring, the solution is homogeneous and clear. (Solution B) Solution A is added to Solution B. After stirring for 15 min, the solution remains cloudy.

(10) This new solution was charged to a Dewar flask (3000 ml) equipped with a cap which makes possible an atmospheric airtightness, an anchor stirrer, a temperature probe and a nitrogen inlet, at ambient temperature (20° C.).

(11) The mixture was degassed by bubbling with nitrogen for 60 minutes. 0.75 g of sodium formaldehyde sulfoxylate, in the form of a 10% by weight aqueous solution, and 0.75 g of sodium persulfate (10% by weight aqueous solution) were added to the medium all at once.

(12) The mixture was degassed beforehand by bubbling with nitrogen for 15 minutes.

(13) The polymerization reaction was then allowed to take place with stirring for 16 hours.

(14) At the end of the synthesis, the product is recovered in the form of a gel which will subsequently be shaped (extrusion/drying/grinding) in order to ultimately obtain a handleable granular material.

Example 3

(15) (Counterexample)

(16) The polymer P3 (polyAA/MBA/Xa) containing 10 mol % of N,N-methylenebisacrylamide (MBA) was prepared under the following conditions:

(17) 9.09 g of Rhodixan A1, 191.10 g of ethanol, 189.13 g of acrylic acid (AA) and 40.45 g of MBA were weighed out in a 2000 ml beaker. After stirring, the MBA is not dissolved.

(18) 768.21 g of demineralized water were added; after stirring, the solution becomes clear. The pH of the solution is measured using a pH probe; the measured pH is 2.1.

(19) The solution was charged to a Dewar flask (3000 ml) equipped with a cap which makes possible an atmospheric airtightness, an anchor stirrer, a temperature probe and a nitrogen inlet, at ambient temperature (20° C.).

(20) The mixture was degassed by bubbling with nitrogen for 60 minutes. 1.80 g of sodium formaldehyde sulfoxylate, in the form of a 5% by weight aqueous solution, and 2.25 g of sodium persulfate (4% by weight aqueous solution) were added to the medium all at once.

(21) The mixture was degassed beforehand by bubbling with nitrogen for 15 minutes.

(22) The polymerization reaction was then allowed to take place with stirring for 16 hours.

(23) At the end of the synthesis, the product is recovered in the form of a gel which will subsequently be shaped (extrusion/drying/grinding) in order to ultimately obtain a handleable granular material.

Example 4

(24) (Counterexample)

(25) The polymer P4 (polyAA/MBA/Xa) containing 15 mol % of N,N-methylenebisacrylamide (MBA) was prepared under the following conditions:

(26) 8.41 g of Rhodixan A1, 191.52 g of ethanol, 170.70 g of acrylic acid (AA) and 56.11 g of MBA were weighed out in a 2000 ml beaker. After stirring, the MBA is not dissolved.

(27) 767.55 g of demineralized water were added; after stirring, the solution becomes clear. The pH of the solution is measured using a pH probe; the measured pH is 2.2.

(28) The solution was charged to a Dewar flask (3000 ml) equipped with a cap which makes possible an atmospheric airtightness, an anchor stirrer, a temperature probe and a nitrogen inlet, at ambient temperature (20° C.).

(29) The mixture was degassed by bubbling with nitrogen for 60 minutes. 0.90 g of sodium formaldehyde sulfoxylate, in the form of a 10% by weight aqueous solution, and 0.90 g of sodium persulfate (10% by weight aqueous solution) were added to the medium all at once.

(30) The mixture was degassed beforehand by bubbling with nitrogen for 15 minutes.

(31) The polymerization reaction was then allowed to take place with stirring for 16 hours.

(32) At the end of the synthesis, the product is recovered in the form of a gel which will subsequently be shaped (extrusion/drying/grinding) in order to ultimately obtain a handleable granular material.

Example 5

(33) Shaping by Extrusion and then Drying of the Gels Resulting from the Syntheses P1 and P2

(34) The gels P1 and P2 resulting from the syntheses described in examples 1 and 2 and containing approximately 75% water are then extruded and subsequently dried at 105° C. on a fluid bed.

(35) The laboratory extruder consists of a Bosch ProPower mincer fitted with grids of variable diameters: grids having perforations of 3 mm and 8 mm were used.

(36) The products after extrusion are then dried on a laboratory fluid bed (Retsch) at 105° C. for 20 minutes. A nonsticky powder is obtained directly, the particle size distribution of which was determined by means of sieves (mesh sizes from 2 mm to 0.4 mm).

(37) The particle size distributions of the powders obtained from P1 and P2 are presented in the tables below.

(38) TABLE-US-00001 % by weight % by weight 3 mm 8 mm 3 mm Fraction (mm) P1 P2 Fraction (mm) P2 x < 0.400 17.5 23.0 x < 0.500 8.0 22.8 0.400 < x < 6.7 7.2 0.500 < x < 5.8 7.2 0.500 0.710 0.500 < x < 10.1 11.2 0.710 < x < 10.6 11.1 0.630 1.000 0.630 < x < 7.5 8.1 1.000 < x < 14.0 8.0 0.710 1.400 0.710 < x < 6.1 7.0 1.400 < x < 20.9 6.9 0.800 2.000 0.800 < x < 10.1 8.4 x > 2.000 40.6 43.9 1.000 1.000 < x < 18.4 15.3 1.400 1.400 < x < 18.0 15.1 2.000 x > 2.000 5.6 4.7

Example 6

(39) Evaluation of the Release Capacity of the Materials in a Seawater Medium and at Temperature (85° C.)

(40) This example illustrates the capacity of the polymeric materials synthesized above to release scale-inhibiting polymeric units when they are subjected to an increase in temperature in a saline aqueous medium, in this instance seawater. Depending on the sensitivity to the release conditions of the crosslinking agents present in the material, the release profile and the release duration will be different for a given temperature.

(41) The polymeric materials resulting from examples 1 to 4 are dried at 105° C. for 2 hours and then lightly ground manually (size of the grains of between 0.5 mm and a few mm). For each of the products resulting from examples 1 to 4, approximately 0.5-0.6 g of dried product is introduced into a 60 ml glass flask containing 50 g of salt water (seawater), the composition of which is described below.

(42) TABLE-US-00002 Seawater Ion mg/l Salt (g/l) Na.sup.+ 31 275 NaCl 79.50 Ca.sup.2+ 2000 CaCl.sub.2•2H.sub.2O 7.34 Mg.sup.2+ 739 MgCl.sub.2•6H.sub.2O 6.18 K+ 654 KCl 1.25 Ba.sup.2+ 269 BaCl.sub.2•2H.sub.2O 0.48 Sr.sup.2+ 87.6 SrCl.sub.2•6H.sub.2O 2.35

(43) After closing the flasks, the latter are placed in ovens at 85° C.

(44) The pH of the solutions is then between 3 and 6.

(45) At regular time intervals (a few days), the water in the flasks is renewed under hot conditions (at conditioning temperature). The fraction of water replaced is retained in order to be analyzed for Total Organic Carbon content on a TOC meter (TOC-L) from Shimadzu, suitable for saline media. The Total Organic Carbon measurement makes it possible to go back to the contents of released polymers. A multiplying factor of 2 (corresponding to 50% of carbon present in a polyacrylic acid) was applied to the measured organic carbon content in order to express the results as a percentage of released polymer.

(46) The cumulative carbon contents and polymer contents measured on the 4 products resulting from examples 1 to 4, brought into contact with seawater at 85° C., are brought together in the tables below.

(47) TABLE-US-00003 P3 example 3 - 85° C. P4 example 4 - 85° C. cumulative % polymer cumulative % polymer days TOC released days TOC released 4 1230 24.6 4 824 16.5 7 1807 36.1 7 1096 21.9 11 2612 52.2 11 1705 34.1 14 2861 100 14 2533 50.6 20 3182 79 25 4905 98

(48) TABLE-US-00004 P1 example - 85° C. P2 example 2 - 85° C. cumulative % polymer cumulative % polymer days TOC released days TOC released 4 650 13 4 478 9.6 7 963 19.3 7 706 14.1 11 1687 33.7 11 1069 21.4 14 2299 46 14 1432 28.6 18 2795 56 18 1566 31.3 25 3992 80 21 2175 43.5 30 4741 95 29 2835 56.7 37 4000 80 49 4700 94

Example 7

(49) Evaluation of the Release Capacity of the Materials in a Highly Saline Medium and at Temperature (60° C. and 85° C.)

(50) This example illustrates the capacity of the polymeric materials synthesized above to release scale-inhibiting polymeric units when they are subjected to an increase in temperature in a saline aqueous medium. Depending on the sensitivity to the release conditions of the crosslinking agents present in the material, the release profile and the release duration will be different for a given temperature.

(51) The polymeric materials resulting from examples 1 to 4 are dried at 105° C. for 2 hours and then lightly ground manually (size of the grains of between 0.5 mm and a few mm). For each of the products resulting from examples 1 to 4, approximately 0.5-0.6 g of dried product is introduced into a 60 ml glass flask containing 50 g of salt water (Forties formation water), the composition of which is described below.

(52) TABLE-US-00005 Forties water Ion mg/l Salt (g/l) Na.sup.+ 31 275 NaCl 79.50 Ca.sup.2+ 2000 CaCl.sub.2•2H.sub.2O 7.34 Mg.sup.2+ 739 MgCl.sub.2•6H.sub.2O 6.18 K.sup.+ 654 KCl 1.25 Ba.sup.2+ 269 BaCl.sub.2•2H.sub.2O 0.48 Sr.sup.2+ 87.6 SrCl.sub.2•6H.sub.2O 2.35

(53) After closing the bottles, the latter are placed in ovens, one at 60° C. and the other at 85° C. The pH of the solutions is between 3 and 6.

(54) At regular time intervals, a few days in the first 2 months up to a few weeks from the third month, the water in the flasks is renewed under hot conditions (at conditioning temperature). The fraction of water replaced is retained in order to be analyzed for Total Organic Carbon content on a TOC meter (TOC-L) from Shimadzu, suitable for saline media. The Total Organic Carbon measurement makes it possible to go back to the contents of released polymers. A multiplying factor of 2 (corresponding to 50% of carbon present in a polyacrylic acid) was applied to the measured organic carbon content in order to express the results as a percentage of released polymer.

(55) The cumulative carbon contents and polymer contents measured on the 4 products resulting from examples 1 to 4, at 60° C. and at 85° C., are brought together in the tables below.

(56) TABLE-US-00006 P3 example 3 - 85° C. P4 example 4 - 85° C. cumulative % polymer cumulative % polymer days TOC released days TOC released 2 799 12.1 2.0 705 11.8 8 1420 21.5 8.0 1031 17.2 15 2934 44.5 15.0 1840 30.7 17 3714 56.3 17.0 2207 36.8 22 4603 69.7 22.0 2771 46.2 27 5445 82.5 27.0 3346 55.8 31 6222 94.3 31.0 4266 71.1 35 6419 97.3 35.0 4956 82.6 41 6514 98.7 41.0 5658 94.3 48 6520 98.8 48.0 5886 98.1 55 6520 98.8 55.0 5918 98.6 63.0 5926 98.8

(57) TABLE-US-00007 P1 example 1 - 85° C. P2 example 2 - 85° C. cumulative % polymer cumulative % polymer days TOC released days TOC released 4 667 13.3 2 387 7.7 7 859 17.2 8 709 14.2 11 1414 28.3 15 1329 26.6 14 1887 37.7 17 1418 28.4 18 2369 47.4 22 1598 32.0 21 2774 55.5 27 1754 35.1 29 3469 69.4 31 1853 37.1 36 3682 73.6 35 1980 39.7 47 3821 76.4 41 2131 42.7 78 3936 78.7 48 2219 44.5 99 3988 79.8 55 2280 45.7 131 4052 81.0 63 2323 46.6 187 4104 82.1 69 2352 47.1 76 2388 47.9 83 2415 48.4 90 2442 48.9 97 2466 49.4 108 2503 50.2 115 2528 50.7 128 2568 51.5 161 2670 53.5 183 2728 54.7 213 2792 56.0 267 2909 58.3

(58) TABLE-US-00008 P3 example 3-60° C. P4 example 4-60° C. P2 example 2-60° C. cumu- % cumu- % cumu- % lative polymer lative polymer lative polymer days TOC released days TOC released days TOC released 4 210 4.2 452 9.0 4 529 10.58 6 242 4.8 6 483 9.7 6 571 11.42 11 277 5.5 11 520 10.4 11 617 12.34 13 292 5.8 13 532 10.6 13 632 12.64 18 322 6.4 18 561 11.2 18 670 13.4 21 363 7.3 21 575.5 11.5 21 689 13.78 25 383 7.7 25 593 11.9 25 711 14.22 28 408 8.2 28 606 12.1 28 733 14.66 32 427 8.5 32 622 12.4 32 757 15.14 39 455 9.1 39 645 12.9 39 790 15.8 83 567 11.3 83 749 15.0 83 954 19.08 125 764 15.3 125 852 17.0 125 1060 21.2

Example 8

(59) Evaluation Under Static Conditions of the Limescale-Inhibiting Performance Dualities of the Polymeric Entities Released

(60) The procedure for the evaluation of the scale-inhibiting performance qualities is derived from the NACE standard TM0374-2016 (“Laboratory Screening Tests to Determine the Ability of Scale Inhibitors to Prevent the Precipitation of Calcium Sulfate and Calcium Carbonate from Solution (for Oil and Gas Production Systems)”).

(61) This procedure, called “Jar test” or “Bottle Test”, makes it possible to measure the performance qualities for inhibiting CaCO.sub.3 under static conditions. It consists in measuring the content of calcium precipitating after mixing two incompatible waters in a flask, then change in the mixture without stirring for a given time, and measurement of the calcium concentration by a volumetric method or a spectroscopic (ICP-AES) method for soluble cations. The experiments comprise a control test without inhibitor and tests in the presence of inhibitors.

(62) This evaluation is carried out at 71° C. after mixing two brines, one of which contains cations, including calcium, and the other anions, including carbonate. These brines are saturated beforehand with carbon dioxide. The inhibitor is placed in the water of the anions. The inhibitor concentration generally varies between 1 to 2 ppm and 10 ppm.

(63) In this example, as the inhibitor originates from the water fractions collected at regular intervals, a volume of the water fraction containing the released polymer (cf. withdrawals carried out in example 5) is introduced such that the final content of scale-inhibiting polymer in the test is between 4 ppm and 10 ppm as active material.

(64) The compositions of the brines are as follows:

(65) TABLE-US-00009 Water of the cations Salt (g/l) NaCl 33.00 CaCl.sub.2•2H.sub.2O 12.15 MgCl.sub.2•6H.sub.2O 3.68

(66) TABLE-US-00010 Water of the anions Salt (g/l) NaCl 33.00 NaHCO.sub.3 7.36

(67) The waters are subsequently saturated with CO.sub.2 by bubbling through the sintered tip for approximately 1 h under a flow of CO.sub.2.

(68) 50 ml of each of these waters are conditioned in polyethylene flasks.

(69) After having equilibrated the temperature of the brines at 71° C. in an oven, the contents of the “water of the anions” flask are poured into the flask containing the cations. Stirring is carried out manually and then the mixture is put back in the oven at 71° C. for 24 h.

(70) For each series of tests, two control tests are carried out: blank Min: this is a test without inhibitor; the calcium ion content will be a minimum (maximum precipitation of CaCO.sub.3). blank Max: this is a test without carbonate and without inhibitor; the water of the anions is replaced with purified water; the calcium ion content will be a maximum, because there is no precipitation.

(71) After 24 hours of testing, the flasks are taken out of the oven and left to cool. A withdrawn sample of 1 ml is then taken and then diluted in 20 ml of permuted water. A quantitative determination of calcium is carried out on these withdrawn samples and the inhibition efficiency, expressed according to the formula below, is deduced therefrom.

(72) $\%\mathrm{efficiency}=\frac{\left[C{a}^{2+}\right]-{\left[C{a}^{2+}\right]}_{\min }}{{\left[C{a}^{2+}\right]}_{\max }-{\left[C{a}^{2+}\right]}_{\min }}\star 100$
with [Ca.sup.2+].sub.max=concentration of Ca.sup.2+ in the blank Max [Ca.sup.2+].sub.min=Ca.sup.2+ concentration in the blank Min

(73) The inhibitory performance qualities of the withdrawn samples described in the preceding example 5 and containing the polymeric entities released are brought together in the tables below.

(74) TABLE-US-00011 TABLE conditioning at 85° C. Polymer % CaCO.sub.3 Release concentration inhibition Material time in the test efficiency P2 example 2 181 4 89 P2 example 2 181 8 98 P2 example 2 160 4 100 P2 example 2 160 8 100 P1 example 1 78 4 95 P1 example 1 78 8 82 P2 example 2 128 5 94 P2 example 2 128 10 98 P2 example 2 55 5 62 P2 example 2 55 10 96 P1 example 1 18 5 72 P1 example 1 18 10 90 P1 example 1 47 5 48 P1 example 1 47 10 77 P3 example 3 35 5 21 P3 example 3 35 10 45 P4 example 4 55 5 17 P4 example 4 55 10 50

(75) TABLE-US-00012 TABLE conditioning at 60° C. Release Polymer % CaCO.sub.3 time concentration inhibition Material (days) in the test efficiency P2 example 2 125 4 91 P2 example 2 125 8 96 P4 example 4 125 4 80 P4 example 4 125 8 100 P3 example 3 125 4 90 P3 example 3 125 8 99