BR112019028283B1 - COMPOSITION OF LIQUID POLYMER OR INVERSE EMULSION - Google Patents

Abstract

Liquid polymer and inverse emulsion compositions comprising: one or more hydrophobic liquids having a boiling point of at least about 100°C; one or more acrylamide (co)polymers; one or more emulsifying surfactants; one or more inverting surfactants; and one or more poly(alkyl)acrylate compounds. When the composition is inverted into an aqueous solution, it provides an inverted solution having a filter ratio using a 1.2 micron filter (FR1.2) of about 1.5 or less.

Description

CROSS REFERENCE TO RELATED ORDER

[0001] This application claims priority to Provisional Application US 62/527,675, filed on June 30, 2017.

Field of Invention

[0002] The present disclosure relates to polymer compositions comprising (co)polymers and poly(alkyl)acrylate compounds, which provide greater stability without negatively affecting the filter ratio.

Fundamentals

[0003] Polymer flooding is a technique used in enhanced oil recovery (EOR). It involves injecting an aqueous solution of a water-soluble thickening polymer (e.g. high molecular weight polyacrylamide) into a deposit of mineral oil. As a result, it is possible to mobilize additional mineral oil into the formation. Details of polymer flooding and polymers suitable for this purpose are disclosed, for example, in “Petroleum, Enhanced Oil Recovery,” Kirk-Othmer, Encyclopedia of Chemical Technology, online edition, John Wiley and Sons, 2010.

[0004] The aqueous polymer solution used in polymer flooding typically has an active polymer concentration of about 0.05 weight percent to about 0.5 weight percent. Additional components can be added to the aqueous polymer solution, such as surfactants or biocides.

[0005] Large volumes of the aqueous polymer solution are required for polymer flooding and the process can last months or even years. Given the volumes required, conventional polymer flooding involves dissolving the polymer (in the form of a dry powder) on site using fresh water, brine, sea water, production water and/or formation waste. Unfortunately, the conventional dissolution process is time-consuming and there are few ways to shorten the time without damaging the polymer. The space required for in-situ dissolution of dry powder polymers is also significant. While space is typically not a limiting factor in onshore oil production, space is limited in offshore oil production. Whether onshore or offshore, the equipment required for conventional on-site, dry powder-based preparation of polymer flood solutions is expensive.

[0006] Inverse emulsions (water in oil) and liquid polymers offer an alternative to in-situ dissolution of dry powders, particularly for offshore oil production. The active polymer concentration in inverse emulsions is typically about 30 weight percent and is higher in the liquid polymer composition. For use, the inverse emulsion or liquid polymer composition is diluted with water to provide the desired final polymer concentration.

[0007] The description contained herein of certain advantages and disadvantages of known methods and devices is not intended to limit the scope of the present invention. In fact, the present embodiments may include some or all of the features described above without suffering the same disadvantages.

SUMMARY

[0008] In view of the foregoing, one or more embodiments include: a liquid polymer composition or inverse emulsion comprising: one or more hydrophobic liquids having a boiling point of at least about 100°C; one or more acrylamide (co)polymers; one or more emulsifying surfactants; one or more inverting surfactants; and one or more poly(alkyl)acrylate compounds; wherein, when the composition is inverted into an aqueous solution, it provides an inverted polymer solution having a filter ratio using a 1.2 micron filter (FR1.2) of about 1.5 or less.

[0009] Methods for recovering hydrocarbons are also provided here. Methods for recovering hydrocarbons may comprise providing a subsurface reservoir containing hydrocarbons therein; provide a wellbore in fluid communication with the subsurface reservoir; preparing an inverted polymer solution from the liquid or inverse emulsion polymer compositions described herein; and injecting the inverted polymer solution through the wellbore into the subsurface reservoir.

Detailed Description

[0010] Generally, the various embodiments described herein provide a liquid polymer composition or inverse emulsion with enhanced stability.

[0011] It has been observed that liquid or inverse emulsion polymer compositions typically used for EOR applications tend to form gels and experience separation of their oil and water phases over time. In particular, the shelf life stability of such compositions with high polymer actives may decrease as the solids content is increased. In some cases, these compositions may deteriorate to form an oil film and hard cake in packaging within the period of time necessary to manufacture and transport the compositions to the platform (e.g., about 30 days). The hard cake may not be easily redistributed into the composition, which results in lower overall polymer assets in the deteriorated composition. Thickening additives can be used to minimize sedimentation of inverse emulsion and liquid polymer compositions, however, they can have a detrimental effect on the filter ratio of the compositions.

[0012] In particular, the compositions described here provide greater stability without negatively affecting the filter ratio. The compositions comprise one or more stabilizing agents or poly(alkyl)acrylate compounds that can prevent or minimize sedimentation and/or caking of solids in the liquid polymer or inverse emulsion compositions. In embodiments, the compositions comprise an acrylamide (co)polymer and one or more poly(alkyl)acrylate compounds. In certain embodiments, the compositions are formed by adding one or more poly(alkyl)acrylate compounds to a liquid polymer composition or inverse emulsion comprising one or more acrylamide (co)polymers, one or more hydrophobic liquids, one or more emulsifying surfactants. and one or more inverting surfactants. The various embodiments described herein also provide inverted polymer solutions derived from the compositions and methods for preparing the compositions. Liquid polymer and inverse emulsion compositions can be used in EOR applications.

[0013] In EOR applications, inverting a conventional liquid polymer or inverse emulsion composition is generally difficult. End-user requirements are often very strict: total dissolution in less than 5 minutes, completely and continuously. In certain embodiments, a liquid polymer composition or inverse emulsion dissolves in an aqueous solution to a final concentration of about 50 to about 15,000 ppm, or about 500 to about 5,000 ppm in less than about 30 minutes or less. of about 20 minutes, or less than 10 minutes or less than 5 minutes.

[0014] An inverted polymer solution prepared from liquid polymer compositions or inverse emulsion provides excellent performance. An inverted polymer solution according to the embodiments flows through a formation without clogging the pores of the formation. Obstruction of the formation can slow or inhibit oil production. This is especially concerning when the permeability of the formation is low to begin with.

Definitions

[0015] As used herein, “enhanced oil recovery” (abbreviated “EOR”) refers to various techniques for increasing the amount of crude oil that can be extracted from an oil field that conventional techniques do not recover.

[0016] As used herein, “filter ratio” (abbreviated “FR”) or “filter quotient” are used interchangeably herein to refer to a test used to determine the performance of the liquid polymer composition (or the inverted polymer solution derived therefrom) under conditions of low formation permeability which consists of measuring the time taken by given volumes/concentrations of solution to flow through a filter. FR generally compares the filtration capacity of the polymer solution to two consecutive equivalent volumes, which indicates the tendency of the solution to clog the filter. Lower FRs indicate better performance.

[0017] Two filter ratio test methods are mentioned here. The first method, known as “FR5” or “filter ratio using a 5 micron filter”, involves passing a 500 mL sample of a polymer solution through a 47 mm diameter polycarbonate filter with 5 micron pores, under pressure of 1 bar (+/- 10%) of N2 or argon at room temperature (e.g. 25°C). The times required to obtain 100 g, 200 g, 400 g and 500 g of filtrate are recorded and the filter ratio FR5 is calculated as The second method, known as “FR1.2” or “filter ratio using a 1.2 micron filter”, involves passing a 200 mL sample of a polymer solution through a 47 mm diameter polycarbonate filter with pores. 1.2 microns, under pressure of 1 bar (+/- 10%) of N2 or argon at room temperature (e.g. 25°C). The times required to obtain 60 g, 80 g, 180 g and 200 g of filtrate are recorded and the filter rate FR1.2 is calculated as

[0018] Other filter ratio test methods are known and are used in this field. For example, the filter media used may be a different size (e.g. 90 mm), different pore size and/or a different substrate (e.g. nitrocellulose), the pressure may be different (e.g. 2 bar) , filtering intervals/amounts may be different and other changes are anticipated. For example, US Patent 8,383,560 (incorporated herein by reference) describes an FR test method that compares the time taken for certain volumes of a solution containing 1000 ppm of active polymer to flow through a 5 micron filter with a diameter 47 mm at a pressure of 2 bar. In comparison, the methods described here provide a better screening method for commercial conditions. In particular, the FR1.2 test method described here, which uses a smaller pore size under lower pressure, provides more predictable results in commercial field testing. Polymers providing acceptable results in test method FR1.2 exhibited easier processing with lower risk of formation damage.

[0019] As used herein, “inverted” means that the liquid polymer composition or inverse emulsion is dissolved in an aqueous solution, such that the dispersed polymer phase of the liquid polymer composition or inverse emulsion becomes a substantially continuous phase and the hydrophobic liquid phase becomes a discontinuous and dispersed phase. The inversion point can be characterized as the point at which the viscosity of the inverted polymer solution has substantially reached its maximum under a given set of conditions. In practice, this can be determined, for example, by measuring the viscosity of the composition periodically over time and when three consecutive measurements are within the error standard for the measurement, the solution will be considered inverted.

[0020] As used herein, the terms “polymer”, “polymers”, “polymeric” and similar terms are used in their ordinary sense, as understood by one skilled in the art, and, therefore, may be used herein to refer or describe a large molecule (or group of such molecules) that contains recurring units. Polymers can be formed in a variety of ways, including by the polymerization of monomers and/or by chemical modification of one or more recurring units of a precursor polymer. A polymer may be a “homopolymer” comprising substantially identical recurring units formed, for example, by polymerizing a particular monomer. A polymer may also be a “copolymer” comprising two or more different recurring units formed, for example, by copolymerizing two or more different monomers and/or chemically modifying one or more recurring units of a precursor polymer. The term “terpolymer” may be used herein to refer to polymers containing three or more different recurring units. The term “polymer” as used herein is intended to include both the acidic form of the polymer and its various salts.

[0021] As used herein, “polymer flooding” refers to an improved oil recovery technique using water viscosified with soluble polymers. Polymer flooding can generate a significant increase in oil recovery compared to conventional water flooding techniques. The viscosity is increased until the mobility of the injector is less than that of the oil phase in situ, so the mobility ratio is less than unity. This condition maximizes the efficiency of the oil recovery sweep, creating a smooth flood front without viscous fingerings. Polymer flooding is also applied to heterogeneous reservoirs; the viscous injector flows along the high permeability layers, decreasing flow rates within them and intensifying the sweep of zones with lower permeabilities. The two polymers that are most frequently used in polymer flooding are partially hydrolyzed polyacrylamide and xanthan. A typical polymer flooding design involves mixing and injecting polymer over an extended period of time until at least half of the reservoir pore volume has been injected.

Liquid Polymer Compositions

[0022] According to embodiments, the liquid polymer composition comprises one or more polymers dispersed in one or more hydrophobic liquids and one or more poly(alkyl) acrylate compounds. In embodiments, the liquid polymer composition further comprises one or more emulsifying surfactants and one or more inverting surfactants. In embodiments, the liquid polymer composition further comprises a small amount of water, e.g., less than about 12%, about 10%, about 5%, about 3%, about 2.5%, about 2% or about 1% by weight of water, based on the total amount of all components of the liquid polymer composition. In embodiments, the liquid polymer composition may be water-free or at least substantially water-free. The liquid polymer composition may include one or more additional components, which do not substantially diminish the desired performance or activity of the composition. It will be understood by a person skilled in the art how to properly formulate the liquid polymer composition to provide necessary or desired characteristics or properties.

[0023] In embodiments, a liquid polymer composition comprises: one or more hydrophobic liquids having a boiling point of at least about 100°C; at least about 39% by weight of one or more acrylamide (co)polymers; one or more emulsifying surfactants; one or more inverting surfactants; and one or more poly(alkyl)acrylate compounds; wherein, when the composition is inverted into an aqueous solution, it provides an inverted polymer solution having a filter ratio using a 1.2 micron filter (FR1.2) of about 1.5 or less. In embodiments, the liquid polymer composition may optionally comprise one or more additional stabilizing agents.

[0024] In embodiments, when the liquid polymer composition is inverted into an aqueous solution, providing an inverted polymer solution with about 50 to about 15,000 ppm, about 500 to about 5,000 ppm, or about 500 to about 3,000 ppm, active polymer concentration, the inverted polymer solution has a viscosity of at least about 10 cP, or at least about 20 cP, at about 40°C and an FR1.2 (1.2 filter microns) of about 1.5 or less.

[0025] In embodiments, when the liquid polymer composition is inverted into an aqueous solution, providing an inverted polymer solution with about 50 to about 15,000 ppm, about 500 to about 5,000 ppm, or about 500 to about 3,000 ppm, active polymer concentration, the inverted polymer solution has a viscosity of at least about 10 cP, or at least about 20 cP, at about 30°C and an FR1.2 (1.2 micron filter ) of about 1.5 or less.

[0026] In embodiments, when the liquid polymer composition is inverted into an aqueous solution, providing an inverted polymer solution with about 50 to about 15,000 ppm, about 500 to about 5,000 ppm, or about 500 to about 3,000 ppm, active polymer concentration, the inverted polymer solution has a viscosity of at least about 10 cP, or at least about 20 cP, at about 25°C and an FR1.2 (1.2 micron filter ) of about 1.5 or less.

[0027] In embodiments, when the liquid polymer composition is inverted into an aqueous solution, providing an inverted polymer solution with about 50 to about 15,000 ppm, about 500 to about 5,000 ppm, or about 500 to about 3,000 ppm, active polymer concentration, the inverted polymer solution has a viscosity of at least about 10 cP, or at least about 20 cP, at about 40°C and an FR1.2 (1.2 filter microns) from about 1.1 to about 1.3.

[0028] In embodiments, when the liquid polymer composition is inverted into an aqueous solution, providing an inverted polymer solution with about 50 to about 15,000 ppm, about 500 to about 5,000 ppm, or about 500 to about 3,000 ppm, active polymer concentration, the inverted polymer solution has a viscosity of at least about 10 cP, or at least about 20 cP, at about 30°C and an FR1.2 (1.2 micron filter ) from about 1.1 to about 1.3.

[0029] In embodiments, when the liquid polymer composition is inverted into an aqueous solution, providing an inverted polymer solution with about 50 to about 15,000 ppm, about 500 to about 5,000 ppm, or about 500 to about 3,000 ppm, active polymer concentration, the inverted polymer solution has a viscosity of at least about 10 cP, or at least about 20 cP, at about 25°C and an FR1.2 (filter 1.2 microns) from about 1.1 to about 1.3.

[0030] In embodiments, when the liquid polymer composition is inverted into an aqueous solution, providing an inverted polymer solution with about 50 to about 15,000 ppm, about 500 to about 5,000 ppm, or about 500 to about 3,000 ppm, active polymer concentration, the inverted polymer solution has a viscosity of at least about 10 cP, or at least about 20 cP, at about 40°C and an FR1.2 (1.2 micron filter ) of about 1.2 or less.

[0031] In embodiments, when the liquid polymer composition is inverted into an aqueous solution, providing an inverted polymer solution with about 50 to about 15,000 ppm, about 500 to about 5,000 ppm, or about 500 to about 3,000 ppm, active polymer concentration, the inverted polymer solution has a viscosity of at least about 10 cP, or at least about 20 cP, at about 30°C and an FR1.2 (1.2 micron filter ) of about 1.2 or less.

[0032] In embodiments, when the liquid polymer composition is inverted into an aqueous solution, providing an inverted polymer solution with about 50 to about 15,000 ppm, about 500 to about 5,000 ppm, or about 500 to about 3,000 ppm, active polymer concentration, the inverted polymer solution has a viscosity of at least about 10 cP, or at least about 20 cP, at about 25°C and an FR1.2 (1.2 micron filter ) of about 1.2 or less.

[0033] In embodiments, the liquid polymer composition, prior to inversion, comprises less than about 12% water by weight, less than about 10% by weight, less than about 7% water by weight, less than about about 5% water by weight or less than about 3% water by weight. In embodiments, the liquid polymer composition prior to inversion comprises from about 1 to about 12% water by weight, or about 1% to about 5% water by weight based on the total amount of all components. of the composition.

[0034] In embodiments, the liquid polymer composition, prior to inversion, comprises at least about 39%, about 40%, about 45%, about 50%, about 55%, about 60%, about of 65%, about 70% or about 75% polymer by weight based on the total amount of all components of the composition.

[0035] In embodiments, the water in the liquid polymer composition may be fresh water, salt water, or a combination thereof. Generally, the water used can be from any source, as long as it does not contain an excess of compounds that could adversely affect other components in the composition.

[0036] In embodiments, the inverted polymer solution has a viscosity greater than about 10 cP at about 25°C. In embodiments, the inverted polymer solution has a viscosity in the range of about 10 cP to about 35 cP, about 15 to about 30, about 20 to about 35, or about 20 to about 30, to about of 25°C. In embodiments, the inverted polymer solution has a viscosity greater than about 10 cP at about 30°C. In embodiments, the inverted polymer solution has a viscosity in the range of about 10 cP to about 30 cP, about 15 cP to about 30 cP, about 15 cP to about 25 cP, about 25 cP to about from 30 cP, about 15 cP to about 22 cP, about 20 cP to about 30 cP, at about 30°C. In embodiments, the inverted polymer solution has a viscosity greater than about 10 cP at about 40°C. In embodiments, the inverted polymer solution has a viscosity in the range of about 10 cP to about 35 cP, about 15 cP to about 35 cP, about 15 cP to about 25 cP, about 15 cP to about from 22 cP, about 20 cP to about 30 cP, at about 40°C.

[0037] In embodiments, liquid polymer compositions, when inverted in an aqueous solution, provide an inverted polymer solution having an FR1.2 of about 1.5 or less. In other words, an inverted polymer solution that is derived from the liquid polymer composition disclosed herein provides an FR1.2 of about 1.5 or less. In field tests, the compositions (after inversion) exhibit improved injectivity over commercially available polymer compositions, including other polymer compositions with an FR5 (using a 5 micron filter) of about 1.5 or less. In embodiments, the liquid polymer compositions, when inverted in an aqueous solution, provide an inverted polymer solution with an FR1.2 of about 1.1 to about 1.4, about 1.1 to about 1, 35, about 1.0 to about 1.3, or about 1.1 to about 1.3.

[0038] In embodiments, a liquid polymer composition when inverted has an FR1.2 (1.2 micron filter) of about 1.5 or less, about 1.4 or less, about 1.3 or less , about 1.2 or less or about 1.1 or less. In embodiments, the liquid polymer composition that is inverted has an FR5 (5 micron filter) of about 1.5 or less, about 1.4 or less, about 1.3 or less, about 1.2 or less or about 1.1 or less. In embodiments, the liquid polymer composition that is inverted has an FR1.2 of about 1.2 or less and an FR5 of about 1.2 or less.

[0039] In embodiments, the inverted polymer solution has an FR1.2 of about 1.5 or less, about 1.4 or less, about 1.3 or less, about 1.2 or less, or about 1.1 or less. In embodiments, the inverted polymer solution has an FR5 of about 1.5 or less, about 1.4 or less, about 1.3 or less, about 1.2 or less, or about 1.1 or less. In other embodiments, the inverted polymer solution has an FR5 of about 1.5 or less and an FR1.2 of about 1.5 or less.

Inverse Emulsion Compositions

[0040] According to embodiments, an inverse emulsion composition comprises one or more polymers emulsified in one or more hydrophobic liquids and one or more poly(alkyl) acrylate compounds. In embodiments, the inverse emulsion composition further comprises one or more emulsifying surfactants and one or more inverting surfactants. The inverse emulsion composition may include one or more additional components, which do not substantially diminish the desired performance or activity of the composition. It will be understood by one skilled in the art how to properly formulate the inverse emulsion composition to provide necessary or desired characteristics or properties.

[0041] In embodiments, the inverse emulsion composition further comprises water. In embodiments, the water is in the emulsified polymer phase. In embodiments, the inverse emulsion comprises more than about 12% by weight water, based on the total amount of all components of the composition. In embodiments, the water in the inverse emulsion composition may be fresh water, salt water, or a combination thereof. Generally, the water used can be from any source, as long as it does not contain an excess of compounds that could adversely affect other components in the composition.

[0042] In embodiments, an inverse emulsion composition comprises: one or more hydrophobic liquids having a boiling point of at least about 100°C; up to about 35% by weight of one or more acrylamide (co)polymers; one or more emulsifying surfactants; one or more inverting surfactants; and one or more poly(alkyl)acrylate compounds; When the composition is inverted into an aqueous solution, it provides an inverted polymer solution having a filter ratio using a 1.2 micron filter (FR1.2) of about 1.5 or less. In embodiments, the inverse emulsion composition may optionally comprise one or more other stabilizing agents.

[0043] In embodiments, when the inverse emulsion composition is inverted into an aqueous solution, providing an inverted polymer solution with about 500 to about 5,000 ppm or about 500 to about 3,000 ppm, active polymer concentration, the Inverted polymer solution has a viscosity of at least 20 cP at about 40°C and an FR1.2 (1.2 micron filter) of about 1.5 or less.

[0044] In embodiments, when the inverse emulsion composition is inverted into an aqueous solution, providing an inverted polymer solution with about 500 to about 5,000 ppm or about 500 to about 3,000 ppm, active polymer concentration, the Inverted polymer solution has a viscosity of at least 20 cP at 30°C and an FR1.2 (1.2 micron filter) of about 1.5 or less.

[0045] In embodiments, the inverse emulsion composition, prior to inversion, comprises up to about 35% polymer by weight, or up to about 30% polymer by weight, based on the total amount of all components of the composition.

[0046] In embodiments, the inverted polymer solution has a viscosity in the range of about 25 cP to about 35 cP at about 30°C. In embodiments, the inverted polymer solution has a viscosity greater than about 10 cP at about 40°C. In embodiments, the inverted polymer solution has a viscosity in the range of about 20 cP to about 30 cP at about 40°C.

[0047] In embodiments, the inverse emulsion compositions, when inverted in an aqueous solution, provide an inverted polymer solution having an FR1.2 of about 1.5 or less. In other words, an inverse emulsion solution that is derived from the liquid polymer composition disclosed herein provides an FR1.2 of about 1.5 or less. In field tests, inverse emulsion compositions, after inversion, provide improved injectivity over commercially available polymer compositions, including other polymer compositions with an FR5 (using a 5 micron filter) of about 1.5 or less.

[0048] In embodiments, the inverse emulsion composition, when inverted, provides an inverted polymer solution that has an FR1.2 (1.2 micron filter) of about 1.5 or less, about 1.4 or less, about 1.3 or less, about 1.2 or less, or about 1.1 or less. In embodiments, the inverse emulsion composition, when inverted, provides an inverted polymer solution that has an FR5 (5 micron filter) of about 1.5 or less, about 1.4 or less, about 1.3 or less, about 1.2 or less, or about 1.1 or less. In embodiments, an inverse emulsion composition, when inverted, provides an inverted polymer solution that has an FR1.2 of about 1.2 or less and an FR5 of about 1.2 or less.

[0049] In embodiments, the inverted polymer solution of the inverted emulsion composition has an FR1.2 of about 1.5 or less, about 1.4 or less, about 1.3 or less, about 1, 2 or less, or about 1.1 or less. In embodiments, the inverted polymer solution of the inverted emulsion composition has an FR5 of about 1.5 or less, about 1.4 or less, about 1.3 or less, about 1.2 or less, or about 1.1 or less. In other embodiments, the inverted polymer solution of the inverted emulsion composition has an FR5 of about 1.5 or less and an FR1.2 of about 1.5 or less.

[0050] Below, the components of liquid polymer and inverse emulsion compositions are discussed in more detail.

Polymer Component

[0051] In embodiments, the liquid polymer composition or inverse emulsion comprises at least one polymer or copolymer. The at least one polymer or copolymer may be any suitable polymer or copolymer, such as a water-soluble thickening polymer or copolymer. Non-limiting examples include high molecular weight polyacrylamide, acrylamide copolymers and other comonomers, for example, vinylsulfonic acid or acrylic acid. Polyacrylamide may be partially hydrolyzed polyacrylamide, in which some of the acrylamide units have been hydrolyzed into acrylic acid. Furthermore, it is also possible to use naturally occurring polymers, for example xanthan or polyglucosylglucan, as described, for example, by US Patent 6,392,596 B1 or CA 832 277.

[0052] In embodiments, the liquid polymer composition or inverse emulsion comprises one or more acrylamide copolymers. In embodiments, the one or more acrylamide (co)polymers is a useful polymer for enhanced oil recovery (EOR) applications. In a particular embodiment, the at least one polymer is a high molecular weight polyacrylamide or partially hydrolyzed products thereof.

[0053] In embodiments, the one or more acrylamide (co)polymers are in the form of particles, which are dispersed in the liquid polymer composition or inverse emulsion. In embodiments, the particles of the one or more acrylamide (co)polymers have an average particle size of about 0.4 μm to about 5 μm, or about 0.5 μm to about 4 μm, or about 0. .5μm to about 2μm. Average particle size refers to the d50 value of the particle size distribution (average number), which can be measured by one skilled in the art using known techniques for determining particle size distribution.

[0054] According to embodiments, the one or more acrylamide (co)polymers are selected from water-soluble acrylamide (co)polymers. In various embodiments, the acrylamide (co)polymers comprise at least 30% by weight, or at least 50% by weight, of acrylamide units relative to the total amount of all monomeric units in the (co)polymer.

[0055] Optionally, the acrylamide (co)polymers may comprise, in addition to acrylamide, at least one additional co-monomer. In embodiments, the additional comonomer is a water-soluble, ethylenically unsaturated, in particular monoethylenically unsaturated, comonomer. Additional water-soluble comonomers must be miscible with water at any rate, but it is sufficient for the monomers to sufficiently dissolve in an aqueous phase to copolymerize with acrylamide. In general, the solubility of these additional monomers in water at room temperature should be at least 50 g/L, preferably at least 150 g/L, and most preferably at least 250 g/L.

[0056] Other water-soluble comonomers comprise one or more hydrophilic groups. Hydrophilic groups are in particular functional groups comprising atoms selected from the group of O-, N-, S- or P atoms. Examples of such functional groups comprise carbonyl groups > C=O, ether groups -O-, in particular polyethylene oxide -(CH2-CH2-O-)n-, where n is preferably a number from 1 to 200, hydroxy groups -OH, ester groups -C(O)O-, primary, secondary or tertiary amino groups, ammonium, amide groups -C(O)-NH- or acidic groups such as carboxyl groups -COOH, sulfonic acid groups -SO3H, phosphonic acid groups -PO3H2 or phosphoric acid groups -PO4H2.

[0057] Monoethylenically unsaturated comonomers comprising acidic groups include monomers that include -COOH groups, such as acrylic acid or methacrylic acid, crotonic acid, itaconic acid, maleic acid or fumaric acid, monomers that comprise sulfonic acid groups, such as vinylsulfonic acid, allylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid, 2-acrylamidobutanesulfonic acid, 3-acrylamido-3-methylbutanesulfonic acid or 2-acrylamido-2,4,4-trimethylpentanesulfonic acid or monomers comprising groups of phosphonic acid, such as vinylphosphonic acid, allylphosphonic acid, N-(meth)acrylamidoalkylphosphonic acids or (meth)acrylyloxyalkylphosphonic acids. Obviously, monomers can be used as salts.

[0058] The -COOH groups in polyacrylamide copolymers can not only be obtained by copolymerizing acrylamide and monomers comprising -COOH groups, but also by hydrolyzing derivatives of -COOH groups after polymerization. For example, the amide -CO-NH2 groups of acrylamide can hydrolyze, thus producing -COOH groups.

[0059] Acrylamide derivatives should also be mentioned, such as, for example, N-methyl(meth)acrylamide, N,N'-dimethyl(meth)acrylamide and N-methylolacrylamide, N-vinyl derivatives, such as N-vinylformamide , N-vinylacetamide, N-vinylpyrrolidone or N-vinylcaprolactam and vinyl esters such as vinyl formate or vinyl acetate. N-vinyl derivatives can be hydrolyzed after polymerization to vinylamine units, vinyl esters to vinyl alcohol units.

[0060] Other comonomers include monomers comprising hydroxy and/or ether groups, such as, for example, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, allyl alcohol, hydroxyvinyl ethyl ether, hydroxylvinyl propyl ether, hydroxyvinyl propyl ether, ether butyl hydroxyvinyl or polyethylene oxide (meth)acrylates.

[0061] Other comonomers are monomers with ammonium groups, that is, monomers with cationic groups. Examples include salts of 3-trimethylammonium propylacrylamides or 2-trimethylammonium ethyl(meth)acrylates, for example, the corresponding chlorides such as 3-trimethylammonium propylacrylamide chloride (DIMAPAQUAT) and 2-trimethylammonium ethyl methacrylate chloride (MADAME- QUAT).

[0062] Still other comonomers include monomers that can cause hydrophobic association of (co)polymers. Such monomers comprise, in addition to the ethylene group and a hydrophilic part, also a hydrophobic part. Such monomers are disclosed, for example, in WO 2012/069477 A1.

[0063] In certain embodiments, each of the one or more acrylamide polymers (optionally) may optionally comprise cross-linking monomers, that is, monomers comprising more than one polymerizable group. In certain embodiments, the one or more acrylamide (co)polymers may optionally comprise cross-linking monomers in an amount of less than about 0.5% or about 0.1% by weight, based on the amount of all monomers.

[0064] In one embodiment, each of the one or more acrylamide (co)polymers comprises at least one monoethylenically unsaturated comonomer comprising acidic groups, for example monomers comprising at least one group selected from -COOH, -SO3H, -PO3H2 or -PO4H2 Examples of such monomers include, but are not limited to, acrylic acid, methacrylic acid, vinylsulfonic acid, allylsulfonic acid or 2-acrylamido-2-methylpropanesulfonic acid, particularly preferably acrylic acid and/or 2-acrylamido-2-methylpropanesulfonic acid single and most preferred acrylic acid or salts thereof. The amount of such comonomers comprising acid groups can be from about 0.1% to about 70%, about 1% to about 50%, or about 10% to about 50% by weight based on the amount of all the monomers.

[0065] In one embodiment, each of the one or more acrylamide (co)polymers comprises from about 50% to about 90% by weight of acrylamide units and from about 10% to about 50% by weight of acrylic acid units and/or their respective salts. In one embodiment, each of the one or more acrylamide (co)polymers comprises from about 60% to 80% by weight of acrylamide units and from 20% to 40% by weight of acrylic acid units.

[0066] In embodiments, the one or more acrylamide (co)polymers have an average molecular weight (Mw) greater than about 5,000,000 Daltons, or greater than about 10,000,000 Daltons, or greater than about 15,000. 000 Dalton, or greater than about 20,000,000 Dalton; or greater than about 25,000,000 Dalton.

[0067] In embodiments, the solution viscosity (SV) of a solution of liquid polymer composition or inverse emulsion with 0.1% active polymer in a 1.0 M NaCl aqueous solution at 25°C is greater than about 3.0 cP or greater than about 5 cP or greater than about 7 cP. The SV of the liquid polymer composition or inverted emulsion can be selected based, at least in part, on the intended active concentration of the inverted polymer solution, to provide the desired performance characteristics in the inverted polymer solution. For example, in embodiments where the inverted polymer solution is to have an active concentration of about 2,000 ppm, it is desirable that the SV of a 0.1% solution of the liquid polymer composition or inverted emulsion be in the range of about from 7.0 to about 8.6, because at this level, the inverted polymer solution has desired FR1.2 and viscosity properties. A liquid polymer composition or inverse emulsion with a lower or higher SV range may still provide desirable results, but may require changing the active concentration of the invert polymer solution to obtain the desired FR1.2 and viscosity properties. For example, if the liquid polymer composition or inverted emulsion has a lower SV range, it would be desirable to increase the active concentration of the inverted polymer solution.

[0068] In embodiments, the amount of one or more acrylamide (co)polymers in the liquid polymer composition is at least about 39% by weight based on the total amount of all components of the composition (prior to dissolution). In embodiments, the amount of one or more acrylamide (co)polymers in the liquid polymer composition is from about 39% to about 80%, or about 40% to about 60%, or about 45% to about of 55% by weight based on the total amount of all components of the composition (before dissolution). In embodiments, the amount of one or more acrylamide (co)polymers in the liquid polymer composition is about 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47% , 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59% or about 60% or more, by weight, based on total amount of all components of the composition (before dilution).

[0069] In embodiments, the amount of one or more acrylamide (co)polymers in the inverse emulsion composition is less than about 35% or less than about 30% by weight, based on the total amount of all components of the composition (before dissolution). In the embodiment, the amount of one or more acrylamide (co)polymers in the inverse emulsion composition is from about 10% to about 35%, or about 15% to about 30%, or about 20% to about of 30% by weight based on the total amount of all components of the composition (before dissolution). In embodiments, the amount of one or more acrylamide (co)polymers in the inverse emulsion composition is about 35%, 34%, 33%, 32%, 31%, 30%, 29%, 28%, 27% , 26%, 25%, 24%, 23%, 22%, 21%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 13%, 11% or approximately 10% or less by weight based on the total amount of all components in the composition (before dilution).

Hydrophobic Liquid

[0070] In embodiments, the liquid polymer composition or inverse emulsion comprises a hydrophobic liquid component. Any suitable hydrophobic liquid component can be used. The hydrophobic liquid component includes at least one hydrophobic liquid.

[0071] In embodiments, the one or more hydrophobic liquids are organic hydrophobic liquids. In embodiments, each one or more hydrophobic liquids has a boiling point of at least about 100°C, about 135°C, or about 180°C. If the organic liquid has a boiling range, the term “boiling point” refers to the lower limit of the boiling range.

[0072] In embodiments, the one or more hydrophobic liquids are aliphatic hydrocarbons, aromatic hydrocarbons or mixtures thereof. Hydrophobic liquids include, but are not limited to: water-immiscible solvents, such as paraffin hydrocarbons, naphene hydrocarbons, aromatic hydrocarbons, olefins, oils, stabilizing surfactants and mixtures thereof. Paraffin hydrocarbons can be saturated, linear or branched paraffin hydrocarbons. Aromatic hydrocarbons include, but are not limited to, toluene and xylene. In embodiments, the hydrophobic liquids comprise oils, for example, vegetable oils, such as soybean oil, rapeseed oil, and canola oil, and any other oil produced from the seed of any of several varieties of the rapeseed plant.

[0073] In embodiments, the amount of one or more hydrophobic liquids in the liquid polymer composition or inverse emulsion is from about 20% to about 60%, about 25% to about 55%, or about 35% to about of 50% by weight based on the total amount of all components of the liquid dispersion polymer composition.

Emulsifying Surfactants

[0074] In embodiments, the liquid polymer composition or inverse emulsion optionally comprises one or more emulsifying surfactants.

[0075] In embodiments, the one or more emulsifying surfactants are surfactants capable of stabilizing water-in-oil emulsions. Emulsifying surfactants, among other things, decrease the interfacial tension between water and the water-immiscible liquid in the liquid polymer composition or inverse emulsion, so as to facilitate the formation of a water-in-oil polymer emulsion. It is known in the art to describe the ability of surfactants to stabilize water-in-oil emulsions or oil-in-water emulsions using the so-called “HLB value” (hydrophilic-lipophilic balance). The HLB value is usually a number from 0 to 20. In surfactants with a low HLB value, the lipophilic parts of the molecule predominate and consequently are generally good water-in-oil emulsifiers. In surfactants with a high HLB value, the hydrophilic parts of the molecule predominate and consequently they are generally good oil-in-water emulsifiers. In embodiments, the one or more emulsifying surfactants are surfactants with an HLB value of about 2 to about 10, or the mixture of the one or more emulsifying surfactants has an HLB value of about 2 to about 10.

[0076] Emulsifying surfactants include, but are not limited to, sorbitan esters, in particular sorbitan monoesters with C12-C18 groups, such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan mono- sorbitan oleate, sorbitan esters, sorbitan esters with more than one ester group, such as sorbitan ursorate, sorbitan trioleate, ethoxylated fatty alcohols with 1 to 4 ethylene-oxy groups, for example, polyoxyethylene dodecylether ether (4) , polyoxyethylene hexadecyl ether (2) or polyoxyethylene oleyl ether (2).

[0077] Emulsifying surfactants include, but are not limited to, emulsifiers with HLB values in the range of about 2 to about 10, preferably less than about 7. Such suitable emulsifiers include sorbitan esters, phthalic esters, glycerides of fatty acids, glycerin esters, as well as ethoxylated versions of the above and any other well-known relatively low HLB emulsifier. Examples of such compounds include sorbitan monooleate, the product of the reaction of oleic acid with isopropanolamide, sodium hexadecyl phthalate, sodium decyl phthalate, sorbitan stearate, ricinoleic acid, hydrogenated ricinoleic acid, lauric acid glyceride monoester, monoester of stearic acid glyceride, oleic acid, 12-hydroxystearic acid glycerol triester, ricinoleic acid glycerol triester and ethoxylated versions thereof containing 1 to 10 moles of ethylene oxide per mole of the basic emulsifier. Thus, any emulsifier can be used that allows the formation of the initial emulsion and stabilizes the emulsion during the polymerization reaction. Examples of emulsifying surfactants also include modified polyester surfactants, anhydride-substituted ethylene copolymers, N,N-dialkanol-substituted fatty amides, and tallow amine ethoxylates.

[0078] In one embodiment, the liquid polymer composition or inverse emulsion comprises about 0% to about 8%, about 0.05% to about 5%, about 0.1% to about 5% or about 0.5% to about 3% by weight of one or more emulsifying surfactants.

[0079] These emulsifying surfactants, used alone or in mixtures, are used in amounts greater than about 0.5% or greater than about 1% of the liquid polymer composition or total inverse emulsion.

Inverting surfactants

[0080] In embodiments, the liquid polymer composition or inverse emulsion optionally comprises one or more inverting surfactants. In embodiments, the one or more inverting surfactants are surfactants that can be used to accelerate the formation of an inverted polymer solution (e.g., a (co)polymer solution) upon mixing the liquid polymer composition or inverse emulsion with a aqueous solution.

[0081] The one or more inverting surfactants are not those that are used as emulsifying surfactants in the embodiments. Inverting surfactants include, but are not limited to, ethoxylated alcohols, alcohol ethoxylates, ethoxylated sorbitan esters, ethoxylated fatty acid esters, ethoxylated fatty acid esters, and ethoxylated sorbitol fatty acid esters, or any combination of the foregoing. Inverted surfactants include nonionic surfactants comprising a hydrocarbon group and a polyalkylenoxy group of sufficient hydrophilic nature. Preferably, nonionic surfactants of the general formula R1—O—(CH(R2)—CH2—O)nH (I) may be used, wherein R1 is a C8-C22-hydrocarbon group, preferably a C10-C18-hydrocarbon group aliphatic, n is a number of ^4, preferably ^6, and R2 is H, methyl or ethyl, provided that at least 50% of the R2 groups are H. Examples of such surfactants include polyethoxylates based on C10-C18-alcohols, such as C12/14-, C14/18- or C16/18-fatty alcohols, C13- or C13/15-oxoalcohols. The HLB value can be adjusted by selecting the number of ethoxy groups. Specific examples include tridecyl alcohol ethoxylates comprising 4 to 14 ethyleneoxy groups, e.g. tridecyl alcohol EO or C12/14 fatty alcohol ethoxylates, e.g. Ci2/i4-8 EO. Examples of inverting surfactants also include modified polyester surfactants, anhydride-substituted ethylene copolymers, N,N-dialkanol-substituted fatty amides, and tallow amine ethoxylates.

[0082] Additional inverting surfactants comprise anionic surfactants, for example surfactants comprising phosphate or phosphonic acid groups.

[0083] In embodiments, the amount of one or more inverting surfactants in the liquid polymer composition or inverse emulsion is from about 0.5% to about 10%, or from about 1% to about 6% by weight, based on the total amount of all components of the liquid polymer composition or inverse emulsion.

[0084] In certain embodiments, the one or more inverting surfactants are added to the liquid polymer composition or inverse emulsion directly after preparation of the composition comprising one or more acrylamide (co)polymers dispersed in one or more hydrophobic liquids and, optionally, o one or more emulsifying surfactants (for example, they can be added after polymerization and/or after dehydration); that is, the liquid polymer composition or inverse emulsion that is transported from the place of manufacture to the place of use already comprises one or more inverting surfactants. In another embodiment, one or more inverting surfactants may be added to the liquid polymer composition or inverse emulsion at the site of use, for example, at an offshore production site.

Stabilizing Agents

[0085] In embodiments, the liquid polymer composition or inverse emulsion comprises one or more stabilizing agents, wherein at least one stabilizing agent is selected from the group consisting of poly(alkyl) acrylate compounds. The stabilizing agents aim to stabilize the dispersion of the polyacrylamide (co)polymer particles in the hydrophobic organic phase and, optionally, also to stabilize the droplets of the aqueous monomer phase in the organic hydrophobic liquid before and during the course of polymerization. The term "stabilization" means, as in the usual way, that the stabilizing agents prevent the dispersion of aggregation and flocculation, or prevent the sedimentation and/or hardening of the solids or particles in the composition and/or creation of the separated oily phase. As used herein, “hardening” refers to the formation of lumps or masses from solids or particles in the composition. Generally, rigid hardening is characterized by strong adhesive forces between particles and/or the formation of a cake that is difficult to redisperse. Soft hardening may be characterized by weak adhesive forces between particles and/or the formation of a cake that is more easily redispersed. Ideally, the solids and particles of the composition remain substantially uniformly dispersed in the liquids of the composition. In certain embodiments, the stabilizing agent increases the stability of the liquid polymer composition or inverse emulsion so that the composition shows no hardening, or only mild hardening, after about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90 or about 100 days at a temperature in the range of about 30 to 50°C. In certain embodiments, compositions that undergo gentle hardening are redispersible with gentle stirring or movement. In certain embodiments, the compositions show no hardening, or only mild hardening, after about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, or about 100 days at a temperature in the range of about 30 to 50°C. In embodiments, less than about 10%, about 5%, or about 2% of the solids or particles in the composition have settled into a soft cake after about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90 or about 100 days at a temperature in the range of about 30 to 50°C.

[0086] In one embodiment, the liquid polymer composition or inverse emulsion comprises about 0.5% to about 8%, about 1% to about 5%, about 1.5% to about 5% or about 1.5% to about 3.5% by weight of one or more poly(alkyl)acrylate compounds.

[0087] Poly(alkyl)acrylate compounds used alone or in mixtures are used in amounts of about 0.5% to about 1.5%, or about 0.5% to about 1.5% , by weight of the total liquid polymer composition or inverse emulsion.

[0088] In embodiments, the composition comprises a poly(alkyl) acrylate compound of Formula III:

[0089] Where R' is a linear or branched C6-14 alkyl group; It is

[0090] p is an integer from 2,000 to 5,000.

[0091] In one embodiment, the poly(alkyl)acrylate compound is, for example, poly(2-ethylhexyl)acrylate.

[0092] In embodiments, poly(2-ethylhexyl) acrylate has a MW in the range of about 90,000 to 95,000 Daltons.

[0093] In embodiments, the compositions may further comprise additional stabilizing agents, for example, agents that aim to stabilize the dispersion or emulsion, such as oligomeric or polymeric surfactants. Due to the fact that oligomeric and polymeric surfactants have many anchor groups, they very strongly absorb the surface of the particles, and in addition, the oligomers/polymers are able to form a dense steric barrier on the surface of the particles, which prevents aggregation . The number average molecular weight of Mn of these oligomeric or polymeric surfactants may, for example, range from 500 to 60,000 Daltons, from 500 to 10,000 Daltons, or from 1,000 to 5,000 Daltons. Oligomeric and/or polymeric surfactants for stabilizing polymer dispersions are known to those skilled in the art. Examples of such stabilizing polymers include amphiphilic copolymers comprising hydrophilic and hydrophobic moiety, amphiphilic copolymers comprising hydrophobic and hydrophilic monomers, and amphiphilic comb polymers comprising a hydrophobic backbone and hydrophilic side chains or, alternatively, a hydrophilic backbone and hydrophobic side chains.

[0094] Examples of amphiphilic copolymers comprise copolymers comprising a hydrophobic moiety comprising alkylacrylates with longer alkyl chains, for example, C6 to C22-alkyl chains, such as, for example, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate , octyl(meth) acrylate, dodecyl(meth) acrylate, hexadecyl(meth) acrylate or octadecyl(meth) acrylate. The hydrophilic portion may comprise hydrophilic monomers such as acrylic acid, methacrylic acid or vinyl pyrrolidone.

[0095] In one embodiment, the liquid polymer composition or inverse emulsion comprises about 0% to about 8%, about 0.1% to about 5%, or about 1% to about 5% by weight of the one or more additional stabilizing agents described herein.

Other Components

[0096] In embodiments, the liquid polymer composition or inverse emulsion may optionally comprise one or more additional components, for example, to provide necessary or desirable properties to the composition or application. Examples of such components include radical scavengers, oxygen scavengers, chelating agents, biocides, stabilizers, or sacrificial agents.

Preparation of liquid polymer and inverse emulsion compositions

[0097] In embodiments, the liquid polymer composition or inverse emulsion can be synthesized according to the following procedures.

[0098] In a first step, an inverse emulsion (water-in-oil emulsion) of acrylamide (co)polymers is synthesized using procedures known to those skilled in the art. Such inverse emulsions are obtained by polymerizing an aqueous solution of acrylamide and other comonomers, such as water-soluble ethylenically unsaturated comonomers, emulsified in a hydrophobic oil phase. In certain embodiments, in a subsequent step, the water within such inverse emulsions is reduced to an amount of less than about 12%, or less than about 10%, or less than about 5%, by weight. Such techniques are described, for example, in US Patent 4,052,353, US Patent 4,528,321, or DE 24 19 764 A1.

[0099] For polymerization, an aqueous monomer solution comprising acrylamide and optionally other comonomers is prepared. Acrylamide is a solid at room temperature and aqueous solutions comprising about 50% by weight of acrylamide are commercially available. If comonomers with acidic groups, such as acrylic acid, are used, the acidic groups can be neutralized by the addition of aqueous bases, such as aqueous sodium hydroxide. The concentration of all monomers together in the aqueous solution should normally be from about 10% to about 60% by weight, based on the total of all components of the monomer solution, or from about 30% to about 50%. , or about 35% to about 45% by weight.

[00100] The aqueous solution of acrylamide and comonomers is emulsified in one or more hydrophobic liquids using one or more emulsifying surfactants. The one or more emulsifying surfactants may be added to the mixture or before the monomer solution or hydrophobic liquid. Other surfactants may be used in addition to the one or more emulsifying surfactants, such as a stabilizing surfactant. Emulsification can be done in the usual way, for example by stirring the mixture.

[00101] After the formation of an emulsion, polymerization can be initiated by the addition of an initiator that results in the generation of a suitable free radical. Any known free radical initiator can be employed. Initiators can be dissolved in a solvent, including but not limited to water or water-miscible organic solvents, such as alcohols, and mixtures thereof. Initiators can also be added in the form of an emulsion. Initiators include, but are not limited to: azo compounds, including 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2, 2'-azobis(isobutyronitrile) (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile) (AIVN), 2,2'-azobis(2-methylpropionamidine) dihydrochloride and the like. Other initiators include peroxide initiators, for example benzoyl peroxide, t-butyl peroxide, t-butyl hydroperoxide and t-butyl perbenzoate. Other initiators include, for example, sodium bromate/sulfur dioxide, potassium persulfate/sodium sulfite, and ammonium persulfate/sodium sulfite, as well as initiators disclosed in US Patent 4,473,689.

[00102] In certain embodiments, one or more chain transfer agents can be added to the mixture during polymerization. Generally, chain transfer agents have at least one weak chemical bond, which facilitates the chain transfer reaction. Any conventional chain transfer agent can be employed, such as propylene glycol, isopropanol, 2-mercaptoethanol, sodium hypophosphite, dodecyl mercaptan, thioglycolic acid, other thiols and halocarbons such as carbon tetrachloride. The chain transfer agent is generally present in an amount of about 0.001 percent to about 10 percent by weight of the total emulsion, although more may be used.

[00103] The polymerization temperature is generally about 30°C to about 100°C, or about 30°C to about 70°C, or about 35°C to about 60°C. Heating can be done by external heat sources and/or the heat can be generated by the polymerization reaction itself, in particular when starting polymerization. Polymerization times can, for example, be from about 0.5 h to about 10 h.

[00104] The polymerization produces an inverse emulsion comprising an aqueous phase of one or more acrylamide (co)polymers dissolved or swollen in water in which the aqueous phase is emulsified in an organic phase comprising the one or more hydrophobic liquids.

[00105] To convert the obtained inverse emulsion into liquid polymer compositions for use in the methods described here, after polymerization, part or all of the water is distilled from the emulsion, producing particles of the one or more acrylamide (co)polymers dispersed in one or more hydrophobic liquids. Liquid polymer compositions with lower water content can provide many of the same advantages as inverse emulsions, but with significantly reduced water content. They can provide a more convenient and economically viable form of distribution that offers improved properties to dry emulsions or polymers. Due to the low/no water content, they are substantially a dispersion of the polymer in a hydrophobic oil phase. Some liquid polymers and their manufacture are disclosed, for example, in German Patent Publication 2419764 A1, US Patent 4,052,353, US Patent 4,528,321, US Patent 6,365,656 B1 or US Patent 6,833,406 B1 (each which is incorporated herein by reference in its entirety).

[00106] For liquid polymer compositions, water is removed to a level of less than about 12%, or less than about 10%, or less than about 7%, or less than about 5%, or less to about 3% by weight. In embodiments, water removal is accomplished by any suitable means, e.g., at reduced pressure, e.g., at a pressure of about 0.00 to about 0.5 bar, or about 0.05 to about 0.25 bar. The temperature for the water removal steps may typically be from about 50°C to about 150°C, although techniques that remove water at higher temperatures may be used. In certain embodiments, one or more of the hydrophobic liquids used in the inverse emulsion may be a low-boiling liquid, which may distill together with water as a mixture.

[00107] Before or after removing the desired amount of water, one or more inverting surfactants and other optional components may be added.

[00108] In embodiments, the one or more poly(alkyl)acrylate compounds are added to a liquid polymer composition or an inverse emulsion comprising one or more acrylamide (co)polymers, one or more hydrophobic liquids, one or more surfactants emulsifiers and one or more inverting surfactants. In certain embodiments, the composition is stirred or stirred after adding the one or more stabilizing agents, as necessary, to mix the one or more stabilizing agents into the composition, for example, for a period of at least about 20 minutes.

[00109] In embodiments, the one or more stabilizing agents may be added at any time during the preparation of a liquid polymer composition or inverse emulsion, as long as it does not adversely affect the formation or resulting properties of the liquid polymer composition or inverse emulsion. In certain embodiments, the one or more stabilizing agents may be added, for example, after dehydration of the composition or after the step of removing water from the composition during its preparation. In embodiments, the one or more stabilizing agents may be added alone or with one or more inverting surfactants. When one or more stabilizing agents are added with one or more inverting surfactants, they can be added to the composition separately or substantially simultaneously, or mixed to combine and then added to the composition as a mixture.

[00110] In embodiments, the manufacture of liquid polymer compositions or inverse emulsion is carried out in chemical production plants.

Aqueous Solutions

[00111] In embodiments, the aqueous solution may comprise produced reservoir brine, reservoir brine, sea water, fresh water, produced water, water, salt water (e.g., water containing one or more salts dissolved therein), brine, synthetic brine, synthetic seawater brine or any combination thereof.

[00112] The term “brine” or “aqueous brine”, as used herein, refers to seawater; naturally occurring brine; a chloride-based, bromide-based, formate-based or acetate-based brine containing monovalent and/or polyvalent cations or combinations thereof. Examples of suitable chloride-based brines include, without limitation, sodium chloride and calcium chloride. Furthermore, without limitation, examples of suitable bromide-based brines include sodium bromide, calcium bromide and zinc bromide. Additionally, examples of formate-based brines include, without limitation, sodium formate, potassium formate, and cesium formate.

[00113] In certain embodiments, the aqueous solution comprises about 15,000 to about 160,000; about 15,000 to about 100,000; about 15,000 to about 50,000; about 30,000 to about 40,000; about 15,000 to about 16,000 ppm total dissolved solids (tds). In one embodiment, the aqueous solution comprises a brine with about 15,000 ppm TDS.

[00114] In embodiments, the aqueous solution has a temperature of about 1°C to about 120°C, about 4°C to about 45°C, or about 45°C to about 95°C.

[00115] Generally, the aqueous solution may comprise water from any readily available source, as long as it does not contain an excess of compounds that may adversely affect other components in the inverted polymer solution or render the inverted polymer solution unsuitable for the intended use (e.g., unsuitable for use in an oil and gas operation, such as an EOR operation). If desired, the aqueous solution obtained from naturally occurring sources may be treated before use. For example, the aqueous solution may be softened (e.g., to reduce the concentration of divalent and trivalent ions in the aqueous fluid) or otherwise treated to adjust its salinity. In certain embodiments, the aqueous solution may comprise soft brine or hard brine. In certain embodiments, the aqueous solution may comprise produced reservoir brine, reservoir brine, seawater, or a combination thereof.

[00116] In one embodiment, seawater is used as the aqueous solution, since offshore production facilities tend to have an abundance of seawater available, limited storage space, and the costs of transportation to and from a location. offshore are typically high. If seawater is used as an aqueous solution, it can be softened before adding the suspended polymer, thereby removing multivalent ions in the water (e.g., specifically Mg2+ and Ca2+).

Preparation of inverted polymer solutions

[00117] According to various embodiments, a method for preparing an inverted polymer solution may include inverting and diluting a liquid polymer composition or inverse emulsion according to the embodiments described herein in an aqueous solution to provide an inverted polymer solution. In embodiments, the liquid polymer composition or inverse emulsion and an aqueous solution are mixed until the liquid polymer composition or inverse emulsion is inverted into an aqueous solution to provide an inverted polymer solution. Various processes can be employed to prepare inverted polymer solutions. Inverted polymer solutions are useful, for example, in enhanced oil recovery methods or in friction reduction applications. In embodiments, an inverted polymer solution comprises a liquid polymer composition or inverted emulsion according to the embodiments and an aqueous solution. In embodiments, an inverted polymer solution comprises a liquid polymer composition or inverted emulsion according to the embodiments, which has been inverted into an aqueous solution.

[00118] According to various embodiments, a method for enhanced oil recovery may include inverting and/or diluting a liquid polymer composition or inverse emulsion according to the embodiments described herein in an aqueous solution to provide an inverted polymer solution. In embodiments, the liquid polymer composition or inverse emulsion and an aqueous solution are mixed until the liquid polymer composition is inverted into the aqueous solution to provide an inverted polymer solution.

[00119] In embodiments, the liquid polymer composition or inverse emulsion is inverted and diluted in the aqueous solution to provide an inverted polymer solution with an active acrylamide (co)polymer polymer concentration between about 50 to about 15,000 ppm , or about 500 and about 5,000 ppm. In embodiments, the inverted polymer solution has an FR1.2 of about 1.5 or less. In embodiments, the inverted polymer solution has an FR1.2 of about 1.1 to about 1.3. In embodiments, the inverted polymer solution has an FR1.2 of about 1.2 or less.

[00120] In some embodiments, the inverted polymer solution may have a concentration of one or more synthetic (co)polymers (e.g., one or more acrylamide (co)polymers) of at least 50 ppm (e.g., at least 100 ppm, at least 250 ppm, at least 500 ppm, at least 750 ppm, at least 1,000 ppm, at least 1,500 ppm, at least 2,000 ppm, at least 2,500 ppm, at least 3,000 ppm, at least 3,500 ppm, at least 4,000 ppm, at least 4,500 ppm, at least 5,000 ppm, at least 5,500 ppm, at least 6,000 ppm, at least 6,500 ppm, at least 7,000 ppm, at least 7,500 ppm, at least 8,000 ppm, at least 8,500 ppm, at least 9,000 ppm, at least 9,500 ppm, at least 10,000 ppm, at least 10,500 ppm, at least 11,000 ppm, at least 11,500 ppm, at least 12,000 ppm, at least 12,500 ppm, at least 13,000 ppm, at least 13,500 ppm, at least 14,000 ppm or at least 14,500 ppm).

[00121] In some embodiments, the inverted polymer solution may have a concentration of one or more synthetic (co)polymers (e.g., one or more acrylamide (co)polymers) of 15,000 ppm or less (e.g., 14,500 ppm or less, 14,000 ppm or less), 13,500 ppm or less, 13,000 ppm or less, 12,500 ppm or less, 12,000 ppm or less, 11,500 ppm or less, 11,000 ppm or less, 10,500 ppm or less, 10,000 ppm or less, 9,500 ppm or less, 9,000 ppm or less, 8,500 ppm or less, 8,000 ppm or less, 7,500 ppm or less, 7,000 ppm or less, 6,500 ppm or less, 6,000 ppm or less, 5,500 ppm or less, 5,000 ppm or less, 4,500 ppm or less, 4,000 ppm or less, 3,500 ppm or less, 3,000 ppm or less, 2,500 ppm or less, 2,000 ppm or less, 1,500 ppm or less, 1,000 ppm or less, 750 ppm or less, 500 ppm or less, 250 ppm or less, or 100 ppm or less).

[00122] The inverted polymer solution may have a concentration of one or more synthetic (co)polymers (e.g., one or more acrylamide (co)polymers) ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, the inverted polymer solution may have a concentration of one or more synthetic (co)polymers (e.g., one or more acrylamide (co)polymers) of 500 to 5,000 ppm (e.g., 500 to 3,000 ppm) or from 500 to 1,500 ppm).

[00123] In some embodiments, the inverted polymer solution may be an unstable aqueous colloidal suspension. In other embodiments, the inverted polymer solution may be a stable aqueous solution.

[00124] In some embodiments, the inverted polymer solution may have a filter ratio of 1.5 or less (e.g., 1.45 or less, 1.4 or less, 1.35 or less, 1.3 or less, less, 1.25 or less, 1.2 or less, 1.15 or less, 1.1 or less less or less than 1.05) at 15 psi using a 1.2 μm filter. In some embodiments, the inverted polymer solution may have a filter ratio greater than 1 (e.g., at least 1.05, at least 1.1, at least 1.15, at least 1.2, at least 1, 25, at least 1.3, at least 1.35, at least 1.4, or at least 1.45) at 15 psi using a 1.2 μm filter.

[00125] The inverted polymer solution can have a filter ratio of 15 psi using a 1.2 μm filter ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, the inverted polymer solution may have a filter ratio of 1 to 1.5 (e.g., 1.1 to 1.4 or 1.1 to 1.3) at 15 psi using a 1.2 μm filter.

[00126] In certain embodiments, the inverted polymer solution may have a viscosity based on shear rate, temperature, salinity, polymer concentration, and molecular weight of the polymer. In some embodiments, the inverted polymer solution may have a viscosity of 2 cP to 100 cP, where the 2 cP to 100 cP is an output using the ranges in the following table:

[00127] In embodiments, the time required for the liquid polymer composition or inverse emulsion to invert into the aqueous solution once dissolution has begun is less than 30 minutes.

Usage Methods

[00128] The inverted polymer solutions described herein can be used in various oil and gas operations, including an EOR operation, an enhanced oil recovery (IOR) operation, a polymer flooding operation, an AP flooding operation , an SP flooding operation, an ASP flooding operation, a compliance control operation, a hydraulic fracturing operation, a friction reduction operation, or any combination thereof. Inverted polymer solutions can even be used in water treatment operations associated with oil and gas operations. In one embodiment, the inverted polymer solution can be used as an injection fluid. In another embodiment, the inverted polymer solution may be included in an injection fluid. In another embodiment, the inverted polymer solution can be used as a hydraulic fracturing fluid. In another embodiment, the inverted polymer solution may be included in a hydraulic fracturing fluid. In another embodiment, the inverted polymer solution can be used as a drag reducer that reduces friction during transport of a fluid in a pipeline. In another embodiment, the inverted polymer solution may be included in a drag reducer that reduces friction during transport of a fluid in a pipeline. In summary, in certain embodiments, the inverted polymer solutions described herein can be used in the recovery of hydrocarbons.

[00129] Hydrocarbon recovery methods may comprise providing a subsurface reservoir containing hydrocarbons therein; provide a wellbore in fluid communication with the subsurface reservoir; preparing an inverted polymer solution using the methods described above; and injecting the inverted polymer solution through the wellbore into the subsurface reservoir. For example, the underground reservoir may be a submarine reservoir and/or the underground reservoir may have a permeability of 10 millidarcy to 40,000 millidarcy.

[00130] The wellbore in the second step may be an injection wellbore associated with an injection well, and the method may further comprise providing a production well spaced from the injection well at a predetermined distance and having a production in fluid communication with the subsurface reservoir. In these embodiments, injection of the inverted polymer solution can increase the flow of hydrocarbons into the production wellbore.

[00131] In some embodiments, hydrocarbon recovery methods may also include a recycling step. For example, in some embodiments, the hydrocarbon recovery methods may further comprise producing production fluid from the production well, the production fluid including at least a portion of the injected inverted polymer solution; and using the production fluid to invert an additional liquid polymer or inverse emulsion composition, for example, to form a second inverted polymer solution. The second inverted polymer solution can be injected into at least one wellbore (e.g., an injection well, the same wellbore discussed in the second step or a different wellbore, etc.). Thus, in some embodiments, the inverted polymer solution is included in an injection fluid.

[00132] The wellbore in the second stage may be a wellbore for hydraulic fracturing that is in fluid communication with the subsurface reservoir. Thus, in one embodiment, the inverted polymer solution injected in the fourth stage functions as a drag reducer that reduces friction during injection in the fourth stage. In doing so, the inverted polymer solution is used as a drag reducer that reduces friction when transporting a fluid (e.g., hydraulic fracturing fluid) in a pipeline (e.g., the wellbore or components of same). In another embodiment, the inverted polymer solution is included in a hydraulic fracturing fluid.

[00133] The liquid polymer composition or inverse emulsion and the inverted polymer solutions according to the embodiments can be used in an underground treatment. Such underground treatments include, among others, drilling operations, stimulation treatments, production and completion operations. Those skilled in the art, with the benefit of this disclosure, will be able to recognize suitable underground treatment.

[00134] The liquid polymer composition or inverse emulsion or an inverted polymer solution of the present embodiments may have various uses, for example, in the development and production of crude oil from oil-bearing formations which may include primary, secondary or enhanced recovery . Chemical techniques, including, for example, the injection of surfactants (surfactant flooding) to reduce the interfacial tension that prevents or inhibits the movement of oil droplets through a reservoir or the injection of polymers that allow the oil present to mobilize more easily through training, can be used before, during or after implementing primary and/or secondary recovery techniques. These techniques can also be used for enhanced oil recovery or to complement other enhanced oil recovery techniques.

[00135] Liquid polymer compositions or inverse emulsion and invert polymer solutions can be used in various processes as flocculation aids, centrifugation aids, mineral sludge dewatering, fine lift dewatering, emulsion breaking, sludge dewatering, clarification of raw and waste water, drainage and retention aids in pulp and paper manufacturing, flotation aids in mining processing, color removal and agricultural applications. Generally, the liquid polymer compositions and inverted polymer solutions described herein can be used as process aids in a variety of solid-liquid separation processes, including, but not limited to, flocculation, dehydration, clarification processes or applications. and/or thickening. As stated herein, the term “dewatering” refers to the separation of water from solid material or soil by a solid-liquid separation process, such as wet classification, centrifugation, filtration, or similar processes. In some cases, dehydration processes and apparatus are used to rigidify or improve the rigidification of particulate materials dispersed in the suspension.

[00136] The liquid polymer compositions or inverse emulsion and inverted polymer solutions described herein can be used in a variety of dehydration, clarification and/or thickening applications. For example, liquid polymer compositions or inverse emulsion and invert polymer solutions can be used in the treatment of municipal and industrial wastewater; clarification and decantation of primary and secondary industrial and municipal waste; clarification of drinking water; in applications in which some or all of the dehydrated solids or clarified water are returned to the environment, such as sludge composting, soil application of sludge, pelletizing for fertilizer application, release or recycling of clarified water, papermaking; food processing applications such as waste dehydration, including dehydration of poultry, pork and potato waste, as well as sugar decolorization, sugar processing clarification and sugar beet clarification; mining and mineral applications, including treatment of various mineral slurries, dewatering and thickening of coal residues, thickening of tailings, and Bayer process applications such as red mud settling, red mud washing, Bayer process filtration, hydrate flocculation and precipitation; biotechnological applications, including dehydration and clarification of waste, such as dehydration and clarification of fermentation broths; and the like.

[00137] In embodiments, the liquid polymer composition or inverse emulsion or inverted polymer solution can be used to dehydrate suspended solids. In embodiments, a method for dehydrating a suspension of dispersed solids comprises: (a) mixing an effective amount of the liquid polymer composition or inverse emulsion or inverted polymer solution, with a suspension of dispersed solids, and (b) dehydrating the suspension of dispersed solids.

[00138] In embodiments, a method of dehydrating an aqueous suspension of dispersed solids comprises: (a) adding an effective amount of a liquid polymer composition or inverse emulsion or inverted polymer solution to the suspension; (b) mixing the liquid polymer composition or inverted emulsion or inverted polymer solution into the suspension to form a treated suspension; and (c) subjecting the treated suspension to dehydration.

[00139] Liquid polymer compositions or inverse emulsion or inverted polymer solutions may be employed only in the above applications, in conjunction with, or in series with, other known treatments.

[00140] In embodiments, liquid polymer compositions or inverse emulsion or inverted polymer solutions can be used in the paper mill process water deinking method.

[00141] In other embodiments, a method of clarifying industrial wastewater comprises: adding to the wastewater an effective amount of a liquid polymer composition or inverse emulsion; and clarifying industrial wastewater.

[00142] In methods, liquid polymer compositions or inverse emulsion or inverted polymer solutions can be used as the sole treatment agent or process aid. In other embodiments, liquid polymer compositions or inverse emulsion or invert polymer solutions may be used in combination with other treating agents and process aids. In embodiments, the method further comprises adding an organic or inorganic coagulant to the wastewater.

[00143] In embodiments, liquid polymer compositions or inverse emulsion or inverted polymer solutions can be used in the sludge dewatering method.

[00144] In embodiments, liquid polymer compositions or inverse emulsion or inverted polymer solutions can be used in the oily wastewater clarification method.

[00145] Liquid or inverse emulsion polymer compositions or inverted polymer solutions can be used to treat, clarify or demulsify such wastewater.

[00146] Liquid polymer compositions or inverse emulsion or inverted polymer solutions can also be used in a method of clarifying food processing waste.

[00147] In another embodiment, the liquid polymer composition or inverse emulsion or inverted polymer solution can be used in a process for making paper or cardboard from a cellulosic stock.

[00148] Other applications that may benefit from liquid polymer compositions or inverse emulsion or inverted polymer solutions include soil amendment, reforestation, erosion control, seed protection/growth, etc., in which the liquid polymer composition or inverse emulsion or inverted polymer solution is applied to the soil.

[00149] The following examples are presented for illustrative purposes only and are not intended to be limiting.

[00150] Example 1. Preparation of an inverse emulsion composition

[00151] To a 1,000 mL beaker (containing a magnetic stir bar), acrylamide (as a 53% by weight solution in water, 276.89 g of solution) was added. The solution was stirred and to this was added glacial acrylic acid (63.76 g), diethylenetriaminepentaacetic acid (Versenex 80, 40%, 0.53 g) and water (183.31 g). Sodium hydroxide (50% by weight, 70.79 g) was added slowly maintaining the temperature of the solution below 30°C until a pH of 6.0 - 6.5 was reached. The pH was checked again and adjusted to 6.0 - 6.5 if necessary.

[00152] To a 1,000 mL beaker (containing a magnetic stir bar) a packet of high-boiling paraffin solvent (211.1 g) was added. Emulsifying surfactant (12.18 g) was added and the mixture was allowed to stir until the surfactants were dissolved. The monomer solution was added to the oil phase (over a period of 30 seconds) with vigorous mixing to form the crude monomer emulsion. Once added, the mixture was allowed to stir for 20 minutes.

[00153] The raw monomer emulsion was then homogenized for 20 seconds (using a Ross ME100L homogenizer operating at 4500 rpm). The homogenized emulsion was then transferred to a 1,000 mL jacketed reactor equipped with an overhead stirrer, nitrogen gas and sulfur dioxide inlets, thermocouple, ventilation, and temperature-controlled recirculation bath. The contents of the reactor were then sprayed for 1.0 hour.

[00154] The polymerization reaction was started and the reaction temperature was maintained between about 40 and about 45°C. After the end of the exotherm, the reaction mixture was heated to 50°C and maintained for 1.5 hours. At the end of 1.5 hours, a solution of sodium metabisulfite (37.5% by weight, 17.88 g) was added and allowed to mix for 10 minutes.

[00155] Example 2. Preparation of a liquid polymer composition

Emulsion preparation:

[00156] To a 1,000 mL beaker (containing a magnetic stir bar), acrylamide (as a 53% by weight solution in water, 276.89 g of solution) was added. The solution was stirred and to this was added glacial acrylic acid (63.76 g), diethylenetriaminepentaacetic acid (Versenex 80, 40%, 0.53 g) and water (183.31 g). Sodium hydroxide (50% by weight, 70.79 g) was added slowly maintaining the temperature of the solution below 30°C until a pH of 6.0 - 6.5 was reached. The pH was checked again and adjusted to 6.0 - 6.5 if necessary.

[00157] To a 1,000 mL beaker (containing a magnetic stir bar), a packet of high-boiling paraffin solvent (211.1 g) was added. Emulsifying surfactant (12.18 g) was added and the mixture was allowed to stir until the surfactants were dissolved. The monomer solution was added to the oil phase (over a period of 30 seconds) with vigorous mixing to form the crude monomer emulsion. Once added, the mixture was allowed to stir for 20 minutes.

[00158] The raw monomer emulsion was then homogenized for 20 seconds (using a Ross ME100L homogenizer operating at 4500 rpm). The homogenized emulsion was then transferred to a 1,000 mL jacketed reactor equipped with an overhead stirrer, nitrogen gas and sulfur dioxide inlets, thermocouple, ventilation, and temperature-controlled recirculation bath. The contents of the reactor were then sprayed for 1.0 hour.

[00159] The polymerization reaction was started and the reaction temperature was maintained between about 40°C and about 45°C. After the end of the exotherm, the reaction mixture was heated to 50°C and maintained for 1.5 hours. At the end of 1.5 hours, a solution of sodium metabisulfite (37.5% by weight, 17.88 g) was added and allowed to mix for 10 minutes.

Water removal:

[00160] The initial emulsions were heated under vacuum in a rotary evaporator at 50°C until no additional distillate condensed. The inverse surfactants were stirred into the resulting dehydrated emulsions, followed by dissolving them in stirred brine solutions.

[00161] Example 3. Bench preparation and storage tests of exemplary liquid polymer compositions comprising a poly(alkyl) acrylate stabilizing agent

[00162] Approximately 160 g of a liquid polymer composition prepared according to Example 2 is combined with 6% by weight of a breaker in a 200 mL beaker and stirred with a Teflon overhead stirrer at 500 rpm. 1% by weight of a stabilizing agent was slowly added to the composition. Stirring was maintained for at least 20 minutes before beginning bench storage tests. The stabilizing agent included in the compositions tested was a microemulsion of ~41% poly(2-ethylhexyl)acrylate.

[00163] Bench storage tests were performed by placing a standard amount (e.g., 40-45 g) of the exemplary liquid polymer compositions comprising a poly(alkyl)acrylate stabilizing agent or a control liquid polymer composition into vials. sample. The samples were kept at about 35°C and checked for bleeding and surface hardening. Samples containing 1 wt% poly(alkyl)acrylate stabilizing agent did not exhibit rigid hardening for 30 days.

[00164] Example 4. Preparation of inverted polymer solutions from exemplary compositions

[00165] A synthetic saline solution was prepared that included the following: Na+, Ca2+, Mg2+, Cl-, and tds of about 15,000 ppm. The brine formulation was prepared and filtered through a 0.45 μm filter before use.

[00166] Using a 1,000 mL beaker, Teflon-coated mixing blade and an overhead stirrer, 360 g of brine was added to the beaker. The brine was stirred at 500 rpm and the liquid polymer composition prepared in Example 2 was added to the brine solution via a syringe at a dosage to result in 10,000 ppm, based on the active polymer concentration. It was left to mix for 2 hours at a constant 500 rpm. This stock solution was diluted to 2,000 ppm using 80 g of stock solution and 320 g of additional brine. Brine was added to the beaker first, which has a mixing blade stirring with an overhead mixer at 500 rpm, and the mother solution was added to the vortex shoulder into the mixing brine. This was mixed for another 2 hours.

[00167] Example 5: Testing inverted polymer solutions from exemplary composition for impact on filter ratio

[00168] Samples of liquid polymer compositions were prepared as described here. Each liquid polymer composition included a standard inverting surfactant (6% by weight). The stabilizing agent included in the compositions tested was a microemulsion of ~41% poly(2-ethylhexyl)acrylate.

[00169] Standard viscosity (SV) was measured by preparing the liquid polymer composition (or base emulsion) a 0.20 wt% active polymer solution in deionized water. The polymer composition was added to the water while stirring at 500 rpm. Mixing was continued for 45 min. The 0.20 wt% active polymer solution was diluted to a 0.10 wt% active polymer solution with an 11.7 wt% NaCl solution and mixed for 15 min. The pH was adjusted to 8.0-8.5 and then filtered through a 200 μm nylon mesh screen. Viscosity was measured at 25°C on a Brookfield DV-III viscometer.

[00170] The liquid polymer compositions were inverted in brine as described in Example 4.

[00171] The viscosities of the brine solutions were measured using an Anton Paar MC302, performing a shear rate of 0.1 s-1 to 100 s-1 at a controlled temperature of 40°C using a concentric circle screw attachment . Data was recorded at 10 s-1 with a target viscosity of 20 cP +/- 1 cP.

Filter reason:

[00172] The filter ratio was measured in two ways. The FR5 (filter ratio using a 5 micron filter) was determined by passing 500 mL samples of inverted polymer solution prepared as described above through a 5 μm, 47 mm diameter polycarbonate filter under pressure of 1 bar of N2. or argon. FR5 was calculated as . For this example, a passing result was considered FR5 < 1.2. In samples with an FR5 > 1.2, the product was considered unapproved and further testing was not completed.

[00173] FR1.2 (filter ratio using a 1.2 micron filter) was determined by passing 200 mL samples of inverted polymer solution prepared as described above through a 1.2 μm 47 mm polycarbonate filter in diameter under pressure of 1 bar of N2 or Argon. The FR1.2 was time in 200g - time in 180g calculated as and reported. For this example, a passing result was considered FR1.2 < 1.5, but the objective for the examples was FR1.2 < 1.2. The results of FR1.2 are presented in Table 2. Table 2.

[00174] Exemplary stabilizing agents have been observed to have minimal or substantially no adverse effect on filter ratio. In particular, the compositions that included the exemplary stabilizing agents retained the property that, when the composition is inverted in an aqueous solution, it provides an inverted polymer solution with a filter ratio using a 1.2 micron filter (FR1.2) of about 1.3, or about 1.2 or less. The poly(alkyl)acrylate stabilizing agent shows good performance with respect to viscosity and filter ratio when less than 2% by weight dosage is added to the exemplary compositions.

[00175] In the previous descriptive report, several modalities were described. It will, however, be apparent that various modifications and changes may be made, and additional embodiments may be implemented, without departing from the broader scope of the embodiments as set forth in the following claims. The descriptive report should therefore be considered in an illustrative rather than a restrictive sense.

Claims (12)

1. LIQUID POLYMER COMPOSITION OR INVERSE EMULSION, characterized by the fact that it comprises: a. one or more hydrophobic liquids having a boiling point of at least 100°C; B. one or more acrylamide (co)polymers; w. one or more emulsifying surfactants; d. one or more inverting surfactants; and is. one or more poly(alkyl) acrylate compounds of Formula: wherein R' is a linear or branched C6-14 alkyl group; ep is an integer from 2000 to 5000; wherein one or more poly(alkyl)acrylate compounds are present, in total, in an amount of 0.5% to 1.5% by weight of the composition; wherein, when the composition is inverted into an aqueous solution, it provides an inverted polymer solution with an active polymer concentration of 50 ppm to 15,000 ppm, and wherein, when the composition is inverted into an aqueous solution, it provides a inverted polymer solution having a filter ratio using a 1.2 micron filter of 1.5 or less, wherein the filter ratio is determined by passing 200 mL of the inverted polymer solution through a 1.2 polycarbonate filter μm, 47 mm diameter under pressure of 1 bar of N2 or argon. 2. COMPOSITION, according to claim 1, characterized by the fact that the composition is a liquid polymer composition comprising 39% by weight of one or more acrylamide (co)polymers. 3. COMPOSITION, according to claim 1, characterized by the fact that the composition is an inverse emulsion composition comprising 35% by weight of one or more acrylamide (co)polymers. 4. COMPOSITION, according to claim 1, characterized by the fact that the aqueous solution comprises produced water, fresh water, salt water, brine, sea water or a combination thereof. 5. COMPOSITION, according to claim 1, characterized by the fact that the liquid polymer composition further comprises water in an amount of less than 10% by weight, based on the total amount of all components of the composition. 6. COMPOSITION, according to claim 1, characterized by the fact that when the composition is inverted in an aqueous solution to provide an inverted polymer solution comprising 2,000 ppm of active polymer, the inverted polymer solution has a viscosity of at least 10 cP at 40°C. 7. COMPOSITION, according to claim 1, characterized by the fact that when the composition is inverted in an aqueous solution, the inverted polymer solution has a filter rate using a 1.2 micron filter of 1.1 to 1.3. 8. COMPOSITION according to claim 1, characterized by the fact that when the composition is inverted into an aqueous solution, the inverted polymer solution has a filter ratio using a 1.2 micron filter of 1.2 or less . 9. COMPOSITION according to claim 1, characterized in that the one or more hydrophobic liquids having a boiling point of at least 100 ° C are selected from the group consisting of paraffin hydrocarbons, naphthene hydrocarbons, aromatic hydrocarbons , olefins, oils, stabilizing surfactants and mixtures or combinations of the above. 10. COMPOSITION, according to claim 1, characterized by the fact that each of the one or more acrylamide (co)polymers comprises at least 30% by weight of acrylamide monomer units in relation to the total amount of all units monomeric in the (co)polymer and that each of the one or more acrylamide (co)polymers comprises at least one additional ethylenically unsaturated monomer. 11. COMPOSITION, according to claim 1, characterized by the fact that at least one of the one or more acrylamide (co)polymers comprises 2-acrylamido-2-methylpropanesulfonic acid or salts thereof. 12. COMPOSITION, according to claim 1, characterized by the fact that the composition provides the inverted polymer solution in less than 30 minutes.