Multiphase suspension of water-soluble polymers

Abstract

This invention relates to multiphase suspensions of at least one synthetic water-soluble polymer with a weight-average molecular weight greater than or equal to 1 million Daltons. The invention also relates to the use of such multiphase suspensions in industrial water treatment, municipal water treatment, enhanced oil recovery in mineral deposits, hydraulic fracturing, mining wastewater treatment, drilling operations in civil engineering, drilling operations in the petroleum industry, drilling operations in the natural gas industry, paper or paperboard manufacturing, agriculture, textiles, detergents, or cosmetics.

Description

Technical Field

[0001] This invention relates to concentrated multiphase suspensions of high molecular weight water-soluble synthetic polymer particles used as rheology modifiers, flocculants, suspending agents or friction reducers in a variety of applications, such as industrial and municipal water treatment, enhanced oil recovery in mineral deposits, hydraulic fracturing, mining wastewater treatment, drilling operations in civil engineering and oil and gas operations, paper and paperboard manufacturing, agriculture, textiles, detergents, and cosmetics. Background Technology

[0002] High molecular weight synthetic water-soluble polymers are commonly used in many applications, particularly due to their flocculating, thickening, or drag-reducing properties. In fact, these polymers are used in the oil and gas industry, hydraulic fracturing, papermaking processes, sludge dewatering, water treatment, construction, mining, cosmetics, agriculture, textiles, and detergent industries.

[0003] For example, the flocculation properties of these high molecular weight water-soluble synthetic polymers are used in water treatment / sludge dewatering. In fact, flocculation represents the process of particles aggregating into high molecular weight aggregates to produce rapid sedimentation, following an optional coagulation step where existing colloidal particles (similar to spheres smaller than 1 micrometer) are destabilized. Therefore, water-soluble polymers used for water treatment are primarily in the form of powders or water-in-oil reverse emulsions. The physical properties of the flocculant are tailored to the water to be treated. Thus, the ionic properties (nonionic, anionic, cationic, amphoteric, zwitterionic), molecular weight, or even structure (linear or structured, even crosslinked) of the water-soluble polymer can be adjusted.

[0004] The rheologically modifying properties of these polymers can be used in enhanced oil recovery (EOR). The efficiency of water sweeping is typically improved by adding high molecular weight, water-soluble synthetic (co)polymers. The anticipated and proven benefits of using these (co)polymers are improved sweeping and reduced viscosity differences between fluids to control their flowability in the subsurface formation for rapid and efficient oil recovery. These (co)polymers increase the viscosity of the water.

[0005] It is also known that high molecular weight water-soluble polymers can act as friction reducers in aqueous solutions. The stretching of the polymer chains in solution delays the turbulence state established during high-speed fluid transport, thus reducing the energy required to transport the aqueous solution. In the field of hydraulic fracturing, these polymers can also be used as rheology modifiers and / or suspending agents for proppants (e.g., sand).

[0006] Finally, these polymers can also produce viscosity and induced suspension properties in aqueous formulations used in cosmetics, detergents and industrial hygiene, textiles and agriculture.

[0007] High molecular weight synthetic water-soluble polymers can be obtained using all polymerization techniques known to those skilled in the art. In particular, this can include solution polymerization; gel polymerization; precipitation polymerization; emulsion polymerization (direct or reverse); suspension polymerization; reactive extrusion polymerization; water-in-water polymerization; or micellar polymerization.

[0008] Polymerization is typically free radical polymerization, preferably via reverse emulsion polymerization or gel polymerization. Free radical polymerization includes free radical polymerization initiated by UV, azo, redox, or thermal initiators, as well as controlled radical polymerization (CRP) or matrix polymerization techniques.

[0009] Depending on the chosen polymerization technology, the (co)polymer can be in liquid or solid form (powder or microspheres), and can be in the form of an aqueous dispersion, a reverse emulsion, or a suspension (a suspension of particles in oil).

[0010] For the logistics, transport, and supply of flocculants, thickeners, or friction reducers, the preferred physical form of these water-soluble polymers, regardless of the intended application, is powder or microspheres, as they provide a high weight percentage of active material. The physical powder form of these polymers can be obtained through drying, thermal drying, spray drying, and drum drying. However, their redissolution requires suitable equipment, such as powder milling units in a humid environment, like PSUs (“Polymer Chip Units”).

[0011] Reverse emulsions are of interest, but their formulations require rigorous optimization to ensure the fastest conversion in aqueous media and to guarantee their stability (during storage and transport, especially during freeze / thaw cycles).

[0012] These high-molecular-weight water-soluble polymers can be obtained in the form of aqueous dispersions using a method known as polymerization in aqueous dispersions. The polymer is directly polymerized in an aqueous solution containing at least one compound selected from mineral salts, organic salts, dispersed organic polymers, and mixtures thereof.

[0013] Another technique, as described in application WO 2018 / 154219, includes formulating an aqueous dispersion of a high molecular weight water-soluble polymer by dispersing solid polymer particles in an aqueous solution containing at least one compound selected from mineral salts, organic salts, dispersed organic polymers, thickening rheology modifiers, and mixtures thereof.

[0014] Another technique involves formulating a particle suspension of a high molecular weight water-soluble polymer by dispersing polymer particles in an oil phase or a solvent phase.

[0015] However, regardless of the technology used to obtain it, aqueous or oil-based dispersions / suspensions of high molecular weight water-soluble polymers are particularly unstable, viscous, and have poor resistance to freeze / thaw cycles. Even if these aqueous or oil-based or solvent-based dispersions / suspensions of the polymer are prepared not by dispersion polymerization, but by dispersing polymer particles in a brine solution (containing, among other substances, a balancing agent such as a dispersant polymer), these aqueous or oil-based or solvent-based dispersions / suspensions of the polymer still have storage and stability issues, especially at low temperatures (freezing).

[0016] Oil is not recommended or even prohibited for certain applications for ecological reasons, and oil suspensions are also rarely used because they have pumpability issues. Summary of the Invention

[0017] With the booming global market for flocculants, rheology modifiers, and synthetic friction reducers, there is a need for high molecular weight water-soluble synthetic polymers whose properties (high percentage of active ingredients, pumpability) and stability enable them to meet the requirements and characteristics of a wide range of envisioned applications.

[0018] In response to these needs, the applicant made a surprising discovery: a novel multiphase suspension of a high molecular weight synthetic water-soluble polymer. This multiphase suspension was prepared by using an innovative method to disperse and concentrate solid particles of the high molecular weight water-soluble polymer in a mixture containing brine and a lipophilic, nonpolar solvent with added additives.

[0019] This multiphase suspension of polymer particles is particularly stable, both over long periods and at low temperatures (low sedimentation, minimal emulsification, and no increase in viscosity). The multiphase suspension also resists freeze / thaw cycles. A key advantage of this multiphase suspension is its high limiting threshold for incorporating and dispersing polymer particles (defined by the limit of observed formulation instability leading to gelation). Finally, the viscosity of this multiphase suspension remains low even at polymer concentrations greater than 10%.

[0020] Furthermore, since the preparation of this multiphase solution does not require heating, no heat transfer fluid is used. Also, due to its low oil content and its concentrated polymer form, it means lower transportation costs. Not to mention, its use does not require dissolution equipment, reducing the carbon footprint of this multiphase solution.

[0021] Therefore, a first aspect of the present invention relates to at least one multiphase suspension MS of a synthetic water-soluble polymer P with a weight-average molecular weight greater than or equal to 1 million Daltons, said multiphase suspension MS being prepared according to a method comprising the following steps:

[0022] a) An oily suspension O is prepared by adding 40 to 80% by weight of particles of at least one synthetic water-soluble polymer P with an average size less than or equal to 300 μm and 0.5 to 5.0% by weight of at least one emulsifier to a lipophilic nonpolar solvent (advantageously under stirring), the percentages being expressed by weight relative to the weight of the lipophilic nonpolar solvent.

[0023] b) Salt water B is prepared by adding 30 to 60 wt% of at least one calcium halide and 0.05 to 1.50 wt% of at least one rheology modifier to water, the percentages being expressed by weight relative to the weight of water.

[0024] c) Mix brine B and oily suspension O to obtain a multiphase suspension Msa containing 10 to 65 wt% of synthetic water-soluble polymer P, the percentage being expressed as weight relative to the multiphase suspension Msa; d) Prepare a multiphase suspension MS by adding 0.1 to 4.0 wt% of a reversing agent to the multiphase suspension MSa, the percentage being expressed as weight relative to the multiphase suspension MSa.

[0025] Another aspect of the invention relates to the use of such a multiphase suspension MS of particles of a synthetic water-soluble polymer P for industrial water treatment, municipal water treatment, enhanced oil recovery in mineral deposits, hydraulic fracturing, mining wastewater treatment, drilling operations in civil engineering, drilling operations in the petroleum industry, drilling operations in the natural gas industry, paper or paperboard manufacturing, agriculture, textiles, detergents or cosmetics.

[0026] As used herein, the term "water-soluble polymer" refers to a product that, when stirred at 25°C for 4 hours, yields a product at a concentration of 20 g / L. -1 When dissolved in water at a concentration of [specific concentration], the polymer produces an aqueous solution without insoluble particles.

[0027] According to the present invention, the "weight-average molecular weight" of the synthesized water-soluble polymer P is determined by measuring its intrinsic viscosity. Intrinsic viscosity can be measured by methods known to those skilled in the art, and can be calculated, in particular, graphically from specific viscosity values ​​at different concentrations. This graphical method involves plotting the specific viscosity value (on the y-axis) as a function of concentration (on the x-axis) and extrapolating the curve to zero concentration. The intrinsic viscosity value is read on the y-axis, or using the least squares method. The weight-average molecular weight can then be determined using the well-known Mark-Houwink equation:

[0028] [η]=KM α

[0029] [η] represents the intrinsic viscosity of the polymer as determined by solution viscosity measurement.

[0030] K represents an empirical constant.

[0031] M represents the polymer molecular weight.

[0032] α represents the Mark-Houwink coefficient.

[0033] α and K depend on the specific polymer-solvent system. Tables known to those skilled in the art provide values ​​for α and K based on the polymer-solvent system.

[0034] The average molecular weight of the synthetic water-soluble polymer P contained in the multiphase suspension MS of the present invention is advantageously greater than or equal to 1 million Daltons. Preferably, the average molecular weight is from 1 million to 40 million Daltons, more preferably from 5 million to 30 million Daltons.

[0035] The term "polymer" refers to homopolymers and copolymers.

[0036] Preferably, the water-soluble polymer P is synthesized by using the following nonionic and / or anionic and / or cationic and / or zwitterionic water-soluble monoene-bonded unsaturated monomers:

[0037] - A nonionic monomer, advantageously selected from the group comprising: acrylamide, methacrylamide, N-alkylacrylamide, N-alkylmethylacrylamide, N,N-dialkylacrylamide, N,N-dialkylmethylacrylamide, alkoxylated acrylate, alkoxylated methacrylate, N-vinylpyridine, N-vinylpyrrolidone, hydroxyalkyl acrylate, hydroxyalkyl methacrylate, preferably acrylamide.

[0038] - Anionic monomers, advantageously selected from the group comprising: monomers having a carboxyl functional group and their salts, including acrylic acid, methacrylic acid, itaconic acid, and maleic acid; monomers having a sulfonic acid functional group and their salts, including acrylamido tert-butyl sulfonic acid (ATBS), allyl sulfonic acid, and methyl allyl sulfonic acid and their salts; monomers having a phosphonic acid functional group and their salts; preferably selected from acrylic acid, acrylamido tert-butyl sulfonic acid (ATBS), and their alkali metal or alkaline earth metal or ammonium salts.

[0039] - A cationic monomer, advantageously selected from the group comprising: quaternized or salted dimethylaminoethyl acrylate (ADAME), quaternized or salted dimethylaminoethyl methacrylate (MADAME), diallyl dimethylammonium chloride (DADMAC), acrylamidopropyltrimethylammonium chloride (APTAC), and methacrylamidopropyltrimethylammonium chloride (MAPTAC).

[0040] - A zwitterionic monomer, which is advantageously selected from the group comprising: sulfobetaine monomers, such as sulfopropyl dimethylammonium ethyl methacrylate, sulfopropyl dimethylammonium propyl methacrylamide, sulfopropyl 2-vinylpyridine; phosphate betaine monomers, such as ethyl trimethylammonium phosphate ethyl methacrylate; carboxybetaine monomers.

[0041] Generally, unless otherwise stated, alkyl or alkoxy means linear or branched group and advantageously has 1 to 5 carbon atoms, more advantageously has 1 to 3 carbon atoms.

[0042] Typically, the quaternization or salt formation of monomers is advantageously achieved via alkyl halides (e.g., chloromethane) or via acids (e.g., hydrochloric acid).

[0043] The synthetic water-soluble polymer P can be a (co)polymer prepared by combining the above-described monomers with, optionally, monomers selected from: hydrophobic monomers, such as styrene, alkyl acrylates, alkyl methacrylates, aryl acrylates, aryl methacrylates, and hydrophobic derivatives of acrylamide; amphiphilic monomers, such as dodecyl poly(oxyethylene) methacrylate and docosyl poly(oxyethylene) methacrylate; or natural polymers, such as cellulose derivatives, polysaccharides, and clays. In the case of hydrophobic monomers, alkyl groups represent linear or branched groups and advantageously have 6 to 14 carbon atoms, more advantageously 6 to 10 carbon atoms. Additionally, aryl groups advantageously contain 6 to 14 carbon atoms, more advantageously 6 to 10 carbon atoms.

[0044] The synthesized water-soluble polymer P particles can be obtained using any polymerization technique well known to those skilled in the art. In particular, the polymerization technique can be solution polymerization; gel polymerization; precipitation polymerization; emulsion polymerization (direct or reverse); suspension polymerization; reactive extrusion polymerization; water-in-water polymerization; or micellar polymerization.

[0045] The particulate physical form of these polymers can be achieved by drying, heat drying, spray drying, and drum drying of liquid polymers.

[0046] The synthesized water-soluble polymer P can be linear or structured. The term "structured" means that the polymer can be in the form of a branched polymer, a comb-like form, or a star-like form.

[0047] The synthesized water-soluble polymer P can be structured by at least one structural agent, which can be selected from the group comprising polyene-bonded unsaturated monomers (i.e., having at least two unsaturated functional groups), such as vinyl, allyl, acrylic, and epoxy functional groups. Examples include methylenebisacrylamide (MBA), triallylamine, tetraallyl ammonium chloride, and 1,2-dihydroxyethylene bis-(N-acrylamide).

[0048] For the steps in the method for preparing multiphase suspensions (MS), various components can be added under stirring. Advantageously, synthetic water-soluble polymer P particles and emulsifiers are added to a lipophilic, nonpolar solvent.

[0049] For step a) of the method for preparing multiphase suspension MS, 40 to 80% by weight of particles of at least one polymer P, preferably 50 to 70% by weight, are added to a lipophilic nonpolar solvent. As indicated, this weight percentage is determined relative to the weight of the nonpolar solvent.

[0050] The average size of the synthesized water-soluble polymer P particles is less than or equal to 300 μm, preferably from 0.1 μm to 300 μm, and more preferably from 1 μm to 300 μm. The average size of the particles can be determined by any method known to those skilled in the art, such as by binocular microscopy.

[0051] According to a particular embodiment, step a) involves adding 50% to 70% by weight of at least one synthetic water-soluble polymer P particles with an average size of 0.1 μm to 300 μm and 1.0% to 2.0% by weight of at least one emulsifier.

[0052] The lipophilic nonpolar solvent in step a) is advantageously selected from mineral oils (containing saturated hydrocarbons, such as alkanes, isoalkanes or cycloalkanes) and / or synthetic oils.

[0053] The emulsifier used in step a) of preparing the multiphase suspension MS is preferably selected from sorbitol esters, polyethoxylated sorbitol esters, diethoxylated oleocetyl alcohol, polyesters with an average molecular weight of 1,000 to 3,000 Daltons formed by the condensation of poly(isobutylene)succinic acid or its anhydride with polyethylene glycol, block copolymers with an average molecular weight of 2,500 to 3,500 Daltons formed by the condensation of hydroxystearic acid with polyethylene glycol, ethoxylated fatty amines, dialkylolamide derivatives, stearyl methacrylate copolymers, and mixtures of these emulsifiers.

[0054] For step a), add 0.5 to 5.0% by weight, preferably 1.0 to 2.0% by weight, of emulsifier. This weight percentage is determined relative to the weight of the lipophilic nonpolar solvent.

[0055] Generally, the order in which the components of the oily suspension O (step a)), brine B (step b)), multiphase suspension Msa (step c) or multiphase suspension Msa (step d) are added is not important. However, it is preferable to follow the above order, particularly by adding a synthetic water-soluble polymer P and then adding an emulsifier in a lipophilic nonpolar solvent to form the oily suspension O.

[0056] For the preparation of brine B (step b) in the method for preparing multiphase suspension MS, the calcium halide is advantageously calcium chloride or calcium bromide or a mixture thereof. According to one particular embodiment, brine B does not contain alkali metal salts and / or alkaline earth metal salts other than calcium. According to another particular embodiment, the brine consists of water and calcium halide, advantageously water and calcium chloride.

[0057] Salt solution B is advantageously prepared by adding 30 to 60% by weight, preferably 40 to 50% by weight, of calcium halide to water. The weight percentage is determined by the weight of water.

[0058] The brine rheology modifier B is preferably selected from hydroxyethyl cellulose, attapulgite, synthetic laponite, lithium montmorillonite, fumed silica, and mixtures thereof. These reagents may be in micronized form, i.e., in particle form with a size of 0.1 to 100 μm, prior to the preparation of the oily suspension O.

[0059] For step b), add 0.05% to 5.0% by weight, preferably 0.1% to 1.0% by weight, of a rheology modifier. The weight percentage is determined by the weight of water.

[0060] For step c) of the method for preparing the multiphase suspension MS, the multiphase suspension MSa contains 10% to 65% by weight of particles of at least one synthetic water-soluble polymer P, preferably 15% to 55% by weight of particles of synthetic water-soluble polymer P. This percentage is expressed as weight relative to the weight of the multiphase suspension MSa.

[0061] For step d) of the method for preparing multiphase suspension MS, the reversing agent is preferably selected from the following: ethoxynonylphenol, preferably having 4 to 10 ethoxylations (i.e., preferably having a degree of ethoxylation of 4 to 10); ethoxylated / propoxylated alcohol, preferably having ethoxylations / propoxylations comprising 10 to 25 carbon atoms; ethoxylated tridecyl alcohol; ethoxylated / propoxylated fatty alcohol; ethoxylated sorbitol ester (advantageously having 20 molar equivalents of ethylene oxide); polyethoxylated sorbitol lauryl ester (advantageously having 20 molar equivalents of ethylene oxide); polyethoxylated castor oil (advantageously having 40 molar equivalents of ethylene oxide); decaethoxylated oleodecyl alcohol; eptaoxyethylated lauryl alcohol. alcohol); polyethoxylated sorbitan monostearate (advantageously having 20 molar equivalents of ethylene oxide); polyethoxylated alkylphenol (advantageously having 10 molar equivalents of ethylene oxide) hexadecyl ether; polyethylene oxide alkyl aryl ether; N-cetyl-N-ethylmorpholinium ethyl sulfate (N-cetyl-N-ethylmorpholinium) The reversing agent may contain: sodium lauryl sulfate; condensation products of fatty alcohols and ethylene oxide (advantageously having 10 molar equivalents of ethylene oxide); condensation products of alkylphenols and ethylene oxide (advantageously having 12 molar equivalents of ethylene oxide); condensation products of fatty amines and 5 or more molar equivalents (preferably 5 to 50 molar equivalents) of ethylene oxide; ethoxylated tristyrylphenol; condensation products of ethylene oxide and partially esterified polyols having aliphatic chains, and their anhydrous forms; amine oxides, advantageously having alkyl polyglycosides; glucosamides; phosphate esters; alkylbenzene sulfonic acids and their salts; and water-soluble polymers of surfactants. The reversing agent may be one or more of these reversing agents or mixtures thereof. The alkyl groups of these reversing agents represent linear or branched groups and advantageously have 1 to 20 carbon atoms, more advantageously 3 to 15 carbon atoms. Additionally, the aryl groups of these reversing agents advantageously contain 6 to 20 carbon atoms, more advantageously 6 to 12 carbon atoms.

[0062] During step d), 0.1 to 4.0% by weight, preferably 0.2 to 2.0% by weight, of the reversing agent is mixed with the multiphase suspension Msa. This weight percentage is determined relative to the weight of the multiphase suspension Msa (oil suspension O + brine B).

[0063] Optionally, at least one co-solvent is added to the multiphase suspension MS obtained during step d) of this method. The co-solvent is advantageously one of the following: a lipophilic nonpolar solvent, more advantageously selected from mineral oils (containing saturated hydrocarbons, such as alkanes, isoalkanes, or cycloalkanes) and / or synthetic oils; or a polar solvent selected from linear or branched alcohols, advantageously having 1 to 5 carbon atoms, or ethoxylated alcohols.

[0064] Another aspect of the invention relates to the use of the multiphase suspension MS of at least one synthetic water-soluble polymer P particles for industrial water treatment, municipal water treatment, enhanced oil recovery in mineral deposits, hydraulic fracturing, mining wastewater treatment, drilling operations in civil engineering, drilling operations in the petroleum industry, drilling operations in the natural gas industry, paper or paperboard manufacturing, agriculture, textiles, detergents or cosmetics. Detailed Implementation

[0065] The following examples illustrate the present invention, but do not limit its scope.

[0066] Example 1: Preparation and stability comparison of multiphase suspensions of water-soluble polymer particles and oily suspensions of water-soluble polymers.

[0067] a) Preparation of multiphase suspensions and oily suspensions of water-soluble polymer particles.

[0068] The synthesized water-soluble polymer P1 is a copolymer of acrylamide and sodium acrylate, containing 30 mol% sodium acrylate. Prior to preparing the suspension, the copolymer was in powder form with particle sizes ranging from 5 μm to 500 μm, and its active material (polymer) content was 90 wt%. The weight-average molecular weight of polymer P1 was 15 million Daltons.

[0069] According to the method of the present invention, a multiphase suspension MS1 ​​containing 50 wt% polymer P1 is prepared by adding 60 wt% polymer particles P1 and 1.5 wt% emulsifier to mineral oil under stirring to prepare an oily suspension, and then adding a calcium chloride solution containing attapulgite to the oily suspension to obtain a multiphase suspension. The final step in this preparation is the addition of a reversing agent (ethoxylated alcohol (8 ethoxylated)).

[0070] An oily suspension OS1 containing 50% by weight of polymer P1 was prepared by suspending P1 particles in mineral oil with added ingredients.

[0071] [Table 1]

[0072]

[0073]

[0074] Table 1: (qsp: sufficient quantity)

[0075] b) Dynamic stability assessment of multiphase and oily suspensions of water-soluble polymers

[0076] The dynamic stability of the MS1 and OS1 suspensions was characterized by measuring the settling velocity. The equipment used was a product sold by LUMGMMBmbH. It is an analytical centrifuge that allows for the accelerated determination of the stability of polymer suspensions. Thanks to its high-performance optical system, The settling and / or emulsification rates of solid polymer particles can be analyzed. This rate is expressed in mm / month. The higher the value, the less stable the dispersion (see Table 2).

[0077] [Table 2]

[0078] suspension Sedimentation rate (mm / month) MS1 12 OS1 31

[0079] Table 2

[0080] c) Stability assessment of freezing / thawing cycles

[0081] The MS1 and OS1 suspensions were subjected to three cycles of heating to 30°C and cooling to -30°C.

[0082] Table 3 describes the visual observation results of different suspensions.

[0083] [Table 3]

[0084]

[0085] Table 3

[0086] This example demonstrates that the multiphase dispersion of polymer MS1 is more stable than the oily suspension OS1. This example also shows that the multiphase suspension MS1 ​​maintains its homogeneity, flowability, and pumpability even after multiple freeze / thaw cycles, unlike the oily suspension OS1, which only becomes viscous after two freeze / thaw cycles and then gels after six freeze / thaw cycles.

[0087] Example 2: Preparation and stability comparison of multiphase suspensions of water-soluble polymer particles and aqueous dispersions of water-soluble polymers.

[0088] a) Preparation of multiphase suspensions and aqueous dispersions of water-soluble polymer particles.

[0089] The synthesized water-soluble polymer P2 is a terpolymer of acrylamide, sodium acrylate (20 mol%), and sodium acrylamide tert-butyl sulfonate (5 mol%). Prior to preparing the suspension / dispersion, the copolymer was in powder form with particle sizes ranging from 5 μm to 500 μm, and its active material (polymer) content was 90% by weight. The weight-average molecular weight of polymer P1 was 24 million Daltons.

[0090] According to the method of the present invention (the same as that of MS1), a multiphase suspension containing 15% by weight of polymer P2 is prepared, MS2.

[0091] An aqueous suspension AS1 containing 15% by weight of polymer P1 was prepared by dispersing P2 particles in a brine solution containing other components.

[0092] [Table 4]

[0093]

[0094]

[0095] Table 4

[0096] b) Dynamic stability assessment of water-soluble polymer suspensions / dispersions

[0097] The dynamic stability of MS2 suspension and AS2 dispersion was characterized by measuring sedimentation rate (same as in Example 1).

[0098] [Table 5]

[0099] Dispersion / Suspension Sedimentation rate (mm / month) MS2 12 AS2 33

[0100] Table 5

[0101] This new embodiment demonstrates that the multiphase suspension (MS2) of the present invention, containing 15% by weight of polymer P2, is more stable than the aqueous dispersion AS2 (which also contains 15% by weight of P2).

[0102] Example 3: Preparation and viscosity comparison of multiphase suspensions and inverse emulsions of water-soluble polymers.

[0103] a) Preparation of multiphase suspensions and reverse emulsions of water-soluble polymers.

[0104] The multiphase suspension MS1 ​​from Example 1 (prepared according to the same scheme) is used here.

[0105] According to methods known to those skilled in the art, a reverse emulsion IE1 containing 50% by weight of polymer P1 (see Example 1) was prepared by controlled free radical polymerization in a reverse emulsion.

[0106] b) Stability assessment

[0107] Table 6 summarizes the observation results and viscosity measurements (12 rpm, ambient temperature T°, LV3 module).

[0108] [Table 6]

[0109]

[0110] Table 6

[0111] This example demonstrates that the multiphase dispersion MS1 ​​containing 50% by weight of polymer P1 is more stable and fluid than the reverse emulsion IE1 (containing 50% by weight of polymer P1). This example also demonstrates that the multiphase suspension MS1 ​​maintains its homogeneity, fluidity, and pumpability even after several months, unlike the reverse emulsion IE1, which becomes viscous and non-pumpable after 6 months.

Claims

1. A multiphase suspension MS of at least one synthetic water-soluble polymer P having a viscosity average molecular weight greater than or equal to 1 million Daltons, prepared according to a process comprising the following steps: a) preparing an oily suspension O by adding from 40% to 80% by weight of particles of at least one synthetic water-soluble polymer P having an average size less than or equal to 300 pm and from 0.5% to 5.0% by weight of at least one emulsifier in a lipophilic non-polar solvent, the percentages being expressed by weight with respect to the weight of the lipophilic non-polar solvent, b) preparing a brine B by adding from 30% to 60% by weight of at least one calcium halide and from 0.05% to 1.50% by weight of at least one rheology modifier to water, the percentages being expressed by weight with respect to the weight of water, c) mixing the brine B and the oily suspension O, thereby obtaining a multiphase suspension MSa containing from 10% to 65% by weight of synthetic water-soluble polymer P, the percentages being expressed by weight with respect to the weight of the multiphase suspension MSa, d) preparing the multiphase suspension MS by adding from 0.1% to 4.0% by weight of an inversion agent to the multiphase suspension MSa, the percentages being expressed by weight with respect to the weight of the multiphase suspension MSa, the viscosity average molecular weight being determined by the Mark-Houwink equation.

2. The multiphase suspension MS according to claim 1, characterized in that said synthetic water-soluble polymer P being obtained from water-soluble monoethylenically unsaturated monomers selected from the group comprising non-ionic monomers, anionic monomers, cationic monomers, zwitterionic monomers and mixtures thereof, - said non-ionic monomers being selected from the group comprising acrylamide, methacrylamide, N-alkyl acrylamides, N-alkyl methacrylamides, N,N-dialkyl acrylamides, N,N-dialkyl methacrylamides, alkoxylated acrylates, alkoxylated methacrylates, N-vinylpyridine, N-vinylpyrrolidone, hydroxyalkyl acrylates, hydroxyalkyl methacrylates, - said anionic monomers being selected from the group comprising monomers having carboxylic functions and salts thereof, including acrylic acid, methacrylic acid, itaconic acid, maleic acid; monomers having sulfonic functions and salts thereof, including acrylamidotert-butylsulfonic acid (ATBS), allyl sulfonic acid and methallyl sulfonic acid and salts thereof; monomers having phosphonic functions and salts thereof, - said cationic monomers being selected from the group comprising quaternized or salted dimethylaminoethyl acrylate (ADAME), quaternized or salted dimethylaminoethyl methacrylate (MADAME), diallyldimethylammonium chloride (DADMAC), acrylamidopropyltrimethylammonium chloride (APTAC), methacrylamidopropyltrimethylammonium chloride (MAPTAC), - said zwitterionic monomers being selected from the group comprising sulfobetaine monomers, including sulfopropyl dimethylammonium ethyl methacrylate, sulfopropyl dimethylammonium propyl methacrylamide, sulfopropyl 2-vinylpyridine; phosphobetaine monomers, including phosphoethyl trimethylammonium ethyl methacrylate; carboxybetaine monomers.

3. Multiphase suspension MS according to claim 1 or 2, characterized in that The emulsifier of step a) is selected from the group consisting of sorbitan esters, polyethoxylated sorbitan esters, diethoxylated oleyl cetylic alcohol, polyesters with an average molecular weight of 1000 to 3000 Dalton, resulting from the condensation of poly(isobutenyl) succinic acid or its anhydride with polyethylene glycol, block copolymers with an average molecular weight of 2500 to 3500 Dalton, resulting from the condensation of hydroxystearic acid with polyethylene glycol, ethoxylated fatty amines, dialkanolamide derivatives, stearyl methacrylate copolymers and mixtures of these emulsifiers.

4. Multiphase suspension MS according to claim 1 or 2, characterized in that The rheology modifier is selected from the group consisting of hydroxyethylcellulose, attapulgite, synthetic hectorite, hectorite, fumed silica and mixtures thereof.

5. Multiphase suspension MS according to claim 1 or 2, characterized in that The invert agent is selected from the group consisting of ethoxylated nonylphenol with 4 to 10 ethoxylations, ethoxylated tridecanol, ethoxylated sorbitan esters, polyethoxylated sorbitan laurate, polyethoxylated castor oil, decethoxylated oleyl cetylic alcohol, heptaoxethoxylated lauryl alcohol, polyethoxylated sorbitan monostearate, polyethoxylated alkylphenol cetyl ether, polyoxyethylene alkyl aryl ether, N-cetyl-N-ethyl morpholinium ethyl sulfate, sodium lauryl sulfate, condensation products of fatty alcohols with ethylene oxide, condensation products of alkylphenols and ethylene oxide, condensation products of fatty amines with 5 or more molar equivalents of ethylene oxide, ethoxylated triphenyl ethenyl phenol, condensates of ethylene oxide with partially esterified polyols having fatty chains and their anhydrous forms, amine oxides, alkyl polyglycosides, glucamides, phosphate esters, alkylbenzene sulfonic acids and their salts, surfactant water-soluble polymers and mixtures of several of these invert agents.

6. Multiphase suspension MS according to claim 1 or 2, characterized in that Step a) implements the addition of 50 to 70 weight percent of particles of at least one synthetic water-soluble polymer P with an average size of 0.1 to 300 pm and 1.0 to 2.0 weight percent of at least one emulsifier.

7. Multiphase suspension MS according to claim 1 or 2, characterized in that Step b) implements the addition of 0.1 to 1.0 weight percent of a rheology modifier.

8. Multiphase suspension MS according to claim 1 or 2, characterized in that The multiphase suspension MSa of step c) comprises 15 to 55 weight percent of particles of water-soluble polymer P.

9. Multiphase suspension MS according to claim 1 or 2, characterized in that Step b) implements the addition of 0.2 to 2.0 weight percent of an invert agent.

10. Use of the multiphase suspension MS according to any one of claims 1 to 9 for municipal water treatment, enhanced oil recovery in a deposit, hydraulic fracturing, mining wastewater treatment, drilling operations in civil engineering, drilling operations in the petroleum industry, drilling operations in the natural gas industry, paper or paperboard manufacturing, agriculture, textile, detergent or cosmetic.

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