Combination for filtrate control and gas migration

Abstract

The present invention relates to the use of a combination of block polymers and particular compositions in a fluid injected under pressure into an oil-bearing rock, where: the fluid comprises solid particles and/or is brought into contact with solid particles within the oil-bearing rock following the injection thereof, the combination comprises (i) a polymer comprising: —a first block that is adsorbed on at least a portion of the particles; and —a second block, having a composition different from that of the first, and having a weight-average molecular weight of greater than 10 000 g/mol, for example greater than 100 000 g/mol, and that is soluble in the fluid; (ii) particles suitable for providing a gas barrier effect, preferably a latex and/or silica particles.

Claims

1. A method, comprising injecting a fluid (F) under pressure into a subterranean formation, wherein said fluid (F) comprises solid particles (p) or is brought into contact with solid particles (p) within the subterranean formation subsequent to its injection, and a combination comprising: (i) a block polymer (P) comprising: a first block (A) which is adsorbed on at least a portion of the solid particles (p); and a second block (B) with a composition distinct from that of said first block (A), with a weight-average molecular weight of greater than 10,000 g/mol and less than 1,000,000 g/mol and which is soluble in fluid (F), and (ii) particles capable of providing a gas barrier effect; wherein the amount of the particles capable of providing the gas barrier effect is between 1.5 to 6% by weight and the amount of the block polymer (P) is from 0.1% to 0.5% by weight, with respect to the solid particles (p) in the fluid.

2. The method according to claim 1, wherein the particles capable of providing a gas barrier effect (ii) are a latex.

3. The method according to claim 2, wherein the latex is in the form of a suspension containing from 40% to 50% by weight of dry latex.

4. The method according to claim 3, wherein the concentration of the block polymer (P) with respect to that of the dry latex is between 4% and 8% by weight.

5. The method according to claim 1, wherein the latex is made of styrene/butadiene.

6. The method according to claim 5, wherein the styrene/butadiene ratio by weight is between 30:70 and 70:30.

7. The method according to claim 6, wherein the styrene/butadiene ratio by weight is between 40:60 and 60:40.

8. The method according to claim 1, wherein the particles capable of providing a gas barrier effect (ii) are silica particles.

9. The method according to claim 8, wherein the silica particles are in the amorphous form.

10. The method according to claim 8, wherein the silica particles are dispersed or in the form of aggregates consisting of individual particles of 5 nm to 5 μm.

11. The method according to claim 1, wherein the fluid (F) is an aqueous fluid and wherein the block (B) is a block at least predominantly composed of monomer units selected from the group consisting of the monomer units U1 to U5 defined below, and the mixtures of these monomer units: monomer units U1: monomer units comprising an acrylamide functional group, monomer units U2: monomer units comprising a sulfonic acid or sulfonate functional group, monomer units U3: neutral monomer units, esters of α,β-ethylenically unsaturated mono- or dicarboxylic acids with C.sub.2-C.sub.30 alkanediols or polyethylene glycols, and tetrahydrofurfuryl acrylate, vinylacetamide, vinylpyrrolidone, N-vinylpiperidone, N-vinylcaprolactam, N-vinyl-5-methyl-2-pyrrolidone, N-vinyl-5-ethyl-2-pyrrolidone, N-vinyl-6-methyl-2-piperidone, N-vinyl-6-ethyl-2-piperidone, N-vinyl-7-methyl-2-caprolactam or N-vinyl-7-ethyl-2-caprolactam, monomer units U4: monomer units carrying ammonium groups, including amides of α,β-ethylenically unsaturated mono- or dicarboxylic acids with diamines having at least one primary or secondary amine group; N,N-diallylamines or N,N-diallyl-N-alkylamines, monomer units U5: acrylate monomer units carrying a COOH or COO— group, wherein the block (B) optionally comprises hydrophobic monomers in a proportion of 0.05% to 10% by weight, with respect to the total weight of monomer units in the block (B).

12. The method according to claim 11, wherein the block (B) optionally comprises hydrophobic monomers in a proportion of 0.05% to 10% by weight, with respect to the total weight of monomer units in the block (B).

13. The method according to claim 1, wherein the fluid (F) is an oil cement grout which comprises the block polymer (P) as an additive.

14. The method according to claim 13, wherein: the block (B) comprises monomer units U1 comprising an acrylamide functional group, and optionally units U2 comprising a sulfonic acid or sulfonate functional group; and the block (B) has a weight-average molecular weight of between 150 000 and 750 000 g/mol.

15. The method according to claim 14, wherein the block (B) comprises dimethylacrylamide (DMA) units, and optionally units U2 comprising acrylamidomethylpropanesulfonic acid (AMPS), and/or has a weight-average molecular weight of between 200 000 and 700 000 g/mol.

16. The method according to claim 1, wherein the second block (B) has a weight-average molecular weight of between 10 000 and 750 000 g/mol.

17. The method according to claim 1, wherein the particles capable of providing a gas barrier effect are a latex and/or silica particles.

Description

EXAMPLE 1

Synthesis of poly(acrylic acid)-b-poly(N,N-di methylacrylamide-co-AMPS) Diblock Copolymers

(1) 1.1: Synthesis of Living Poly(Acrylic Acid) Blocks Having a Xanthate Ending (Short Blocks A1 to A4)

(2) 30 g of acrylic acid in an aqueous solvent (namely 70 g of distilled water for the blocks A1-A3—a mixture of 35 g of distilled water and 28 g of ethanol for the block A4) and O-ethyl S-(1-(methoxycarbonyl)ethyl) xanthate of formula (CH.sub.3CH(CO.sub.2CH.sub.3))S(C═S)OEt (in the amounts shown in table 1 below, where the value of the theoretical number-average molecular weight expected (M.sub.n, th), calculated by the ratio of the amount of monomer to the amount of xanthate, is also shown) and 312 mg of 2,2′-azobis(2-methylpropionamidine) dihydrochloride were introduced into a 250 ml round-bottomed flask at ambient temperature. The mixture was degassed by bubbling with nitrogen for 20 minutes.

(3) The round-bottomed flask was subsequently placed in an oil bath thermostatically controlled at 60° C. and the reaction medium was left stirring at 60° C. for 4 hours.

(4) On conclusion of these four hours, the conversion was determined by .sup.1H NMR.

(5) An analysis by size exclusion chromatography in a mixture of water and acetonitrile (80/20) additivated with NaNO.sub.3 (0.1N) with an 18-angle MALS detector provides the weight-average molar mass (M.sub.w) and polydispersity index (M.sub.w/M.sub.n) values given in table 1 below.

(6) TABLE-US-00001 TABLE 1 blocks A1-A4 Block M.sub.n, th Xanthate Conversion M.sub.w synthesized (g/mol) (g) (.sup.1H NMR) (g/mol) M.sub.w/M.sub.n A1 10 000  0.624 99.5% 22 000  1.8 A2 5000 1.25 99.7% 10 000  1.7 A3 2500 2.50 99.6% 5000 1.7 A4 1000 6.24 >99.9% 2100 1.8
1.2: Synthesis of Diblock Copolymers from the Blocks A1 to A4 Polymers P1 to P17

(7) The blocks A1 to A4 prepared as shown in section 1.1 were employed in their reaction medium obtained, without purification, with a weight of polymer w.sub.A given in table 2 below. The chosen block, in its reaction mixture without purification, was introduced into a 250 ml round-bottomed flask at ambient temperature and then N,N-dimethylacrylamide DMA, a 50% by weight aqueous AMPS solution (25% by molar ratio to the amount of N,N-dimethylacrylamide) and distilled water, with a final solids content of approximately 20% by weight, and ammonium persulfate as a 5.0% by weight aqueous solution were added (in amounts given in table 2 below).

(8) The mixture was degassed by bubbling with nitrogen for 20 minutes. Sodium formaldehyde sulfoxylate, in the form of a 1.0% by weight aqueous solution, was added to the medium, the same weight of this solution being introduced as that of the ammonium persulfate solution (see table 2).

(9) The polymerization reaction was allowed to take place without stirring at ambient temperature (20° C.) for 24 hours.

(10) On conclusion of the 24 hours of reaction, the conversion was measured by .sup.1H NMR (results in table 3).

(11) An analysis by size exclusion chromatography in a mixture of water and acetonitrile (80/20 v/v) additivated with NaNO.sub.3 (0.1N) with a refractive index detector provides the number-average molar mass (M.sub.n) and polydispersity index (M.sub.w/M.sub.n) values which are listed in table 3.

(12) TABLE-US-00002 TABLE 2 polymers P1 to P17: amounts of reactants employed during the synthesis Polymer Short block w.sub.DMA w.sub.AMPS w.sub.water w.sub.persulf w.sub.sfs synthesized w.sub.A (g) (g) (g) (g) (g) (g) P1 A1 0.835 15.3 17.7 75.6 6.0 6.0 P2 A1 1.65 15.2 17.6 75.7 6.0 6.0 P3 A1 1.65 6.16 7.12 29.1 3.0 3.0 P4 A1 2.68 5.06 5.85 25.4 3.0 3.0 P5 A1 3.99 5.60 6.47 27.9 3.0 3.0 P6 A1 5.51 5.19 6.00 27.3 3.0 3.0 P7 A2 0.426 15.2 17.6 75.6 6.0 6.0 P8 A2 0.847 15.2 17.6 75.6 6.1 6.3 P9 A2 0.840 6.28 7.27 29.6 3.0 3.0 P10 A2 1.59 5.93 6.86 29.6 3.0 3.0 P11 A2 2.13 5.98 6.91 29.0 3.0 3.0 P12 A2 3.05 5.67 6.55 28.8 3.0 3.0 P13 A3 0.703 25.6 29.6 138.1 3.0 3.0 P14 A3 1.74 25.3 29.3 137.6 3.0 3.0 P15 A4 0.177 31.7 36.6 157.5 12.0 12.0 P16 A4 0.287 25.6 29.6 139 3.0 3.0 P17 A4 0.709 25.3 29.3 138.7 3.0 3.0 P18 A4 5.33 25.3 29.3 138.7 0.5 0.5 w.sub.water: weight of distilled water added, with the exclusion of the water added in the other solutions w.sub.persulf: weight of the 5% by weight aqueous ammonium persulfate solution added w.sub.sfs: weight of the 1% by weight aqueous sodium formaldehyde sulfoxylate solution

(13) TABLE-US-00003 TABLE 3 polymers P1 to P17 Polymer Short Conversion M.sub.w synthesized block DMA AMPS (kg/mol) M.sub.w/M.sub.n P1 A1  99.4%  98.0% 620 5.2 P2 A1  99.7%  99.2% 420 3.2 P3 A1 >99.9% >99.9% P4 A1 >99.9% >99.9% P5 A1 >99.9% >99.9% P6 A1 >99.9% >99.9% P7 A2  99.6%  99.8% 600 3.0 P8 A2  99.8%  99.2% 390 3.3 P9 A2 >99.9% >99.9% P10 A2 >99.9% >99.9% P11 A2 >99.9% >99.9% P12 A2 >99.9% >99.9% P13 A3  99.7%  98.7% 450 2.3 P14 A3 >99.9% >99.9% 210 1.9 P15 A4  99.4%  99.6% 760 2.5 P16 A4  99.8%  99.5% 410 2 P17 A4  99.7%  99.4% 180 1.9 P18 A4 .sup. >99% .sup. >99% 47.5 1.5

EXAMPLE 2 (COMPARATIVE)

Synthesis of a poly(N,N-dimethylacrylamide-co-AMPS) Monoblock Polymer

(14) 15.3 g of N,N-dimethylacrylamide, 18 g of AMPS, 75.6 g of distilled water, 1.03 g of a 1% by weight ethanolic solution of O-ethyl S-(1-(methoxycarbonyl)ethyl) xanthate of formula (CH.sub.3CH(CO.sub.2CH.sub.3))S(C═S)OEt and 6.0 g of a 5% by weight aqueous solution of ammonium persulfate were introduced into a 250 ml round-bottomed flask at ambient temperature. The mixture was degassed by bubbling with nitrogen for 20 minutes.

(15) 6.0 g of a 1% by weight aqueous solution of sodium formaldehyde sulfoxylate were subsequently added. The two aqueous solutions of ammonium persulfate and sodium formaldehyde sulfoxylate had been degassed beforehand by bubbling with nitrogen.

(16) The polymerization reaction was then allowed to take place without stirring at ambient temperature (20° C.) for 24 hours.

(17) On conclusion of the 24 hours of reaction, a conversion of 99.8% of N,N-dimethylacrylamide and of 99.6% of AMPS was obtained, as determined by .sup.1H NMR.

(18) An analysis by size exclusion chromatography in water additivated with NaNO.sub.3 (0.1N) with a refractive index detector provides the following number-average molar mass (M.sub.n) and polydispersity index (M.sub.w/M.sub.n) values (relative to the PEO standards):

(19) M.sub.w=1 070 000 g/mol

(20) M.sub.w/M.sub.n=2.8.

EXAMPLE 3

Evaluation of Diblock Polymer in Combination with a Latex in Cement Grouts

(21) The diblock polymer P13 prepared in example 1 and dried by evaporation on a plate is used in the powder form in combination with a styrene/butadiene latex to prepare oil cement grouts having the following formulations, in grams:

(22) TABLE-US-00004 3-1 3-2 3-3 3-4 3-5 3-6 Latex (g) 103.9 86.6 69.24 0 0 69.2 Diblock P13 (g) 0 0 0 3.9 2.34 2.34 Dispersant (polymelamine sulfonate) (g) 1.95 1.17 1.56 0 1.56 1.17 Retarder (calcium lignosulfonate) (g) 0.39 0.39 0.39 0.78 0.78 0.39 Organic antifoaming agent (g) 1.38 1.38 1.38 1.38 1.38 1.38 Municipal water (g) 245 262 278.9 344.8 345.5 277.8 Cement (g) 780 780 780 780 780 780

(23) The latex is added to the municipal water and to the liquid additives. The diblock and the solid additives are mixed with cement before incorporation in the liquid.

(24) The formulation and the conditioning and the filtration test were carried out according to the standard of the American Petroleum Institute (API recommended practice for testing well cements, 10B, 2nd edition, April 2013).

(25) After mixing and dispersing all the constituents of the formulation, the grout obtained was conditioned at 88° C. for 20 minutes in an atmospheric consistometer (model 1250 supplied by Chandler Engineering Inc.), prestabilized at this temperature, which makes it possible to simulate the conditions experienced by the cement grout during descent in a well.

(26) The fluid loss control performance was determined by a static filtration at 88° C. in a double-ended cell with a capacity of 175 ml equipped with 325 mesh (45 μm) metal screens (supplied by Ofite Inc., reference 170-45). The gas migration control tests are carried out on a Model 120-57 gas migration tester supplied by Ofite. The principle of this appliance consists in allowing the cement grout to set under pressure during a prolonged filtration. If no gas diffuses through the cell, the grout is regarded as impermeable to gas migration.

(27) The performance qualities of the polymers in the cement formulations are given in the table below:

(28) TABLE-US-00005 Formulation No. 3-1 3-2 3-3 3-4 3-5 3-6 Fluid loss V API (ml) 85 400 381 80 121 39 Gas migration control yes no no no no yes

(29) These results show that a combination of latex and of diblock polymer can advantageously be used to control both the fluid loss and the gas migration with a concentration of latex and a diblock which are greatly reduced with respect to the use of each of these additives used alone.

EXAMPLE 4

Evaluation of Diblock Polymer in Combination with Silica Particles in Cement Grouts

(30) The diblock polymer P13 prepared in example 1 and dried by evaporation on a plate is used in the powder form in combination with a silica fume (supplied by Condensil, grade 95ND) to prepare oil cement grouts having the following formulations, in grams:

(31) TABLE-US-00006 4-1 4-2 4-3 Silica fume (g) 39 0 35.9 Diblock P13 (g) 0 3.12 3.12 Dispersant (polymelamine sulfonate) (g) 2.34 0.59 0.78 Retarder (calcium lignosulfonate) (g) 0.78 0.78 0.78 Organic antifoaming agent (g) 1.38 1.38 1.38 Municipal water (g) 345.1 350.2 Cement (g) 780 780 780 4-4 4-5 Silica fume (g) 22.1 27.63 Diblock P13 (g) 3.9 4.88 Hydroxyethylcellulose suspending agent (g) 0.325 0.325 Retarder (calcium lignosulfonate) (g) 3.25 5.85 Organic antifoaming agent (g) 1.4 1.4 Municipal water (g) 365.8 366.1 Cement (g) 650 650 Silica flour (g) 227.5 227.5

(32) The silica fume is added to the municipal water and to the liquid additives and to the municipal water. The diblock and the solid additives are mixed with the cement before incorporation in the liquid.

(33) The formulation and the conditioning and the filtration test were carried out according to the standard of the American Petroleum Institute (API recommended practice for testing well cements, 10B, 2nd edition, April 2013).

(34) After mixing and dispersing all the constituents of the formulation, the grout obtained was conditioned at 88° C. for 20 minutes in an atmospheric consistometer (model 1250 supplied by Chandler Engineering Inc.), prestabilized at this temperature, which makes it possible to simulate the conditions experienced by the cement grout during descent in a well.

(35) The fluid loss control performance was determined by a static filtration at 88° C. (for the formulations 4-1, 4-2 and 4-3), at 120° C. (for the formulation 4-4) and at 150° C. (for the formulation 4-5) in a double-ended cell with a capacity of 175 ml equipped with 325 mesh (45 μm) metal screens (supplied by Ofite Inc., reference 170-45). The gas migration control tests are carried out on a Model 120-57 gas migration tester supplied by Ofite. The principle of this appliance consists in allowing the cement grout to set under pressure during a prolonged filtration. If no gas diffuses through the cell, the grout is regarded as impermeable to gas migration.

(36) The performance qualities of the polymers in the cement formulations are given in the table below:

(37) TABLE-US-00007 Formulation No. 4-1 4-2 4-3 4-4 4-5 Temperature (° C.) 88 88 88 120 150 Fluid loss V API 400 80 46 15 14 Gas migration control no no yes yes yes

(38) These results show that a combination of latex and of diblock polymer can advantageously be used to control both the fluid loss and the migration in combination with a dispersion of silica fume.