WO2025154722A1 - Polyvinyl alcohol copolymer and particulate water-soluble diverting agent formed therefrom - Google Patents

Abstract

The present disclosure provides a particulate matter including (1) a hydrolyzed polyvinyl alcohol copolymer of vinyl acetate and one or more unsaturated acids, and (2) an alkalizing agent, and methods of manufacturing and use thereof.

Description

POLYVINYL ALCOHOL COPOLYMER AND PARTICULATE WATER-SOLUBLE DIVERTING AGENT FORMED THEREFROM

The present invention relates to particulate water-soluble diverting agents, which may be manufactured by compacting and/or agglomerating a polyvinyl alcohol copolymer, for example, an acid functional comonomer modified polyvinyl alcohol blended with an alkalizing agent. The acid functional comonomer modified polyvinyl alcohol may be selected from a hydrolyzed copolymer of vinyl acetate with a minor amount of an unsaturated acid comonomer component. The present invention also discloses a process for producing water-soluble diverting agents based on the acid functional comonomer modified polyvinyl alcohol for use in subterranean treatments.

During oil production from subterranean formations by natural forces, only a small fraction of the total oil present in the reservoir is recovered. A variety of techniques have been developed to recover oil beyond that produced by the natural forces. The normal procedure is to introduce a fluid into the oil-bearing formation in order to displace the oil to a production system comprising one or more production wells. The displacing fluid may be brine, fresh water, steam, or gas. The typical cost-effective recovery methods are known to utilize steam.

Some of the common injection drive fluids are much lighter than the reservoir fluids and thus rise toward the top of the flowing region bypassing the lower regions. It is therefore desirable to plug the regions of high permeability to divert the drive fluid into regions of lower permeability. Physical plugging of the high permeability regions by cements and solid slurries has been tried with varying degrees of success. These techniques have the drawback that still-productive sites may be permanently closed.

The displacement of the oil from the formation is improved by the addition of the polymeric thickening agents which increase the effective viscosity of the drive fluid to match to that of the oil to be displaced.

Several techniques of addressing the issue with the areas of differing permeability within a wellbore have been disclosed in the patent literature.

U.S. Patent No. 2,803,306 (PLT 1) relates generally to the treating of wells and, more particularly, to well treating operations in which a treating fluid is applied to an underground structure or formation which includes several zones having varying permeabilities and it is desired for the fluid to enter both the less permeable and the more permeable zones thereof.

U.S. Patent No. 3,797,575 (PLT 2) relates to additives for forming fluid loss or diverting agents in aqueous treating fluids used in the treatment of subterranean formations.

U.S. Patent No. 3,724,549 (PLT 3) relates to an oil soluble bridging agent for diverting oil well treating fluids to less permeable portions of an oil-producing subterranean formation having temperatures up to about 360°F.

U.S. Patent No. 3,872,923 (PLT 4) relates to temporary or permanent permeability reduction or plugging of porous medium to the flow of fluids effected by treating, preferably by injecting under pressure into the pores, the porous medium with an aqueous solution containing a water-soluble polymer obtained as a product of radiation-induced polymerization of acrylamide and/or methacrylamide and acrylic acid, methacrylic acid, and/or alkali metal salts thereof.

U.S. Patent Nos. 3,954,629 (PLT 5) and 4,005,753 (PLT 6) relate to a polymeric diverting agent, and methods of treating subterranean formations with the same polymeric diverting agent.

U.S. Patent No. 4,527,628 (PLT 7) describes a method of temporarily plugging a subterranean formation using a diverting material comprising an aqueous carrier liquid and a diverting agent comprising a solid azo compound having an azo component and a methylenic component.

U.S. Patent No. 6,367,548 (PLT 8) describes methods and compositions for stimulating multiple intervals in wells by diverting well treatment fluids into multiple intervals by alternately displacing diverting agent from the annulus into a subterranean formation and displacing treatment fluid from a tubing string into the subterranean formation.

WO 2015/072317 (PLT 9) relates to a temporary sealant for well drilling used in well drilling performed to produce hydrocarbon resources such as oil or natural gas, and a well drilling method.

JP-A-2016-56272 (PLT 10) describes a powder comprising hydrolyzable resin particles for use in drilling fluid.

U.S. Patent No. 11,597,870 B2 (PLT 11) relates to a diverting agent containing a polyvinyl alcohol-based resin and a method of filling a fracture using the diverting agent.

JP-A-2016-147972 (PLT 12) relates to polyoxalate particles which have hydrolyzability, circularity and a particle size that are suitable for hydraulic fracturing.

U.S. Patent No. 2,803,306 U.S. Patent No. 3,797,575 U.S. Patent No. 3,724,549 U.S. Patent No. 3,872,923 U.S. Patent No. 3,954,629 U.S. Patent No. 4,005,753 U.S. Patent No. 4,527,628 U.S. Patent No. 6,367,548 WO 2015/072317 JP-A-2016-56272 U.S. Patent No. 11,597,870 B2 JP-A-2016-147972

It would be desirable to provide a hydrolyzed polyvinyl alcohol copolymer that may be used to produce diverting agents commercially. The diverting agent of the present invention may have a combination of the desirable properties, such as particle size distribution, dissolution rate, temperature and pH stability. The diverting agent may be environmentally friendly as they may be non-toxic and biodegradable.

According to one aspect of the invention, a particulate matter may include (1) a hydrolyzed polyvinyl alcohol copolymer of vinyl acetate and one or more unsaturated acids, and (2) an alkalizing agent.

In some embodiments, the particulate matter may further include an anti-dusting agent.

In some embodiments, the anti-dusting agent may include polyglycol.

In some embodiments, the particulate matter may be compacted.

In some embodiments, the particulate matter may possess a particle size of from about 3 to 18 mesh.

In some embodiments, the particulate matter may possess a particle size of from about 6 to 12 mesh.

In some embodiments, the particulate matter may possess a particle size of from about 6 to 8 mesh.

In some embodiments, a concentration of the vinyl acetate in the particulate matter may be from 85 mol% to 99.9 mol% based on a total number of moles of monomers forming the hydrolyzed polyvinyl alcohol copolymer.

In some embodiments, the hydrolyzed polyvinyl alcohol copolymer may include the one or more unsaturated acids at an amount of from about 0.1 mol% to about 15 mol% based on a total number of moles of monomers forming the hydrolyzed polyvinyl alcohol copolymer.

In some embodiments, the hydrolyzed polyvinyl alcohol copolymer may possess a viscosity-average degree of polymerization of from about 300 to about 3000.

In some embodiments, the hydrolyzed polyvinyl alcohol copolymer may possess a degree of hydrolysis of from about 70 mol% to 100 mol%.

In some embodiments, the hydrolyzed polyvinyl alcohol copolymer may be substantially soluble in water at a temperature of 195°F or higher.

In some embodiments, the one or more unsaturated acids may include at least one selected from the group consisting of a monocarboxylic unsaturated acid, an alkyl ester of a monocarboxylic unsaturated acid, an alkali metal salt of a monocarboxylic unsaturated acid, an alkaline earth metal salt of a monocarboxylic unsaturated acid, an anhydride of a monocarboxylic unsaturated acid, a dicarboxylic unsaturated acid, an alkyl ester of a dicarboxylic unsaturated acid, an alkali metal salt of a dicarboxylic unsaturated acid, an alkali earth metal salt of a dicarboxylic unsaturated acid, and an anhydride of a dicarboxylic unsaturated acid.

In some embodiments, the one or more unsaturated acids may include an alkyl ester of the monocarboxylic unsaturated acid.

In some embodiments, the alkyl ester of the monocarboxylic unsaturated acid may be methyl acrylate.

In some embodiments, the alkalizing agent may include at least one selected from the group consisting of a metal oxide, a metal hydroxide, a metal carbonate, a metal bicarbonate, ammonia, a primary amine, a secondary amine, a tertiary amine, an aromatic amine, an amino acid, and a polymeric amine.

In some embodiments, the alkalizing agent may include a metal carbonate.

In some embodiments, the metal carbonate may include sodium carbonate.

In some embodiments, the metal bicarbonate may include sodium bicarbonate.

In some embodiments, the alkalizing agent may include a tertiary amine.

In some embodiments, the tertiary amine may include triethylamine.

In some embodiments, the alkalizing agent may include an amino acid.

In some embodiments, the amino acid may include arginine.

In some embodiments, a concentration of the alkalizing agent in the particulate matter may be from more than 0 to 50% by weight of a total weight of the hydrolyzed polyvinyl alcohol copolymer.

In some embodiments, a concentration of the alkalizing agent in the particulate matter may be from more than 0 to 25% by weight of a total weight of the hydrolyzed polyvinyl alcohol copolymer.

In some embodiments, a concentration of the alkalizing agent in the particulate matter may be from more than 0 to 10% by weight of a total weight of the hydrolyzed polyvinyl alcohol copolymer.

In some embodiments, the particulate matter may further include at least one additive selected from the group consisting of a plasticizer and a filler.

In some embodiments, the particulate matter may further include at least one other polyvinyl alcohol.

In some embodiments, the at least one other polyvinyl alcohol may possess a water solubility lower than that of the hydrolyzed copolymer.

In some embodiments, the at least one other polyvinyl alcohol may include a fully hydrolyzed polyvinyl alcohol homopolymer or a partially hydrolyzed polyvinyl alcohol homopolymer.

In some embodiments, a composition may include the particulate matter as disclosed herein. The composition may possess a bulk density of about 0.30 g/mL or greater.

In some embodiments, the composition may possess a bulk density of about 0.5 g/mL or greater.

In some embodiments, the composition may possess a bulk density of about 0.6 g/mL or greater.

In some embodiments, the composition may possess a bulk density of about 0.7 g/mL or greater.

In some embodiments, a use of the particulate matter or the composition as disclosed herein may include increasing the lactone Ring Open Ratio (ROR%), solubility of a polyvinyl alcohol copolymer.

In some embodiments, a use of the particulate matter or the composition as disclosed herein may include treating a surface formation to divert flow of a fluid from one zone of a subsurface formation to another zone of the subsurface formation.

In some embodiments, the particulate matter or the composition disclosed herein blended with sand, curing agent and other additives may be used as a joint filler for the gap between two or more tiles.

In some embodiments, a method of treating a surface formation to divert flow of a fluid from one zone of a subsurface formation to another zone of the subsurface formation, the method may include pumping into the subsurface formation a carrier liquid comprising water and the particulate matter as disclosed herein.

In some embodiments, the carrier liquid may further include sand.

In some embodiments, a method of filling a gap between two or more tiles, the method may include applying a fluid including the particulate matter as disclosed herein and sand to the gap.

In some embodiments, a method of producing the particulate matter as disclosed herein may include blending the hydrolyzed polyvinyl alcohol copolymer and the alkalizing agent to form a blend.

In some embodiments, the blending may be carried out by at least one process selected from the group consisting of dry mixing, blade mixing, fluidized bed mixing, mill mixing, spraying, and solvent system mixing.

In some embodiments, the method may further include, immediately before the blending, hydrolyzing a polyvinyl acetate copolymer to form the hydrolyzed polyvinyl alcohol copolymer.

In some embodiments, the method may further include, before the blending, neutralizing at least a portion of the hydrolyzed polyvinyl alcohol copolymer and/or heat treating the hydrolyzed polyvinyl alcohol copolymer.

In some embodiments, the method may include, before the blending, the neutralizing of at least a portion of the hydrolyzed polyvinyl alcohol copolymer.

In some embodiments, the heat treatment may not be carried out.

In some embodiments, the method may include, before the blending, the heat treating of the hydrolyzed polyvinyl alcohol copolymer.

In some embodiments, the neutralizing may not be carried out.

In some embodiments, the method may include, before the blending, the neutralizing of at least a portion of the hydrolyzed polyvinyl alcohol copolymer, and heat treating the hydrolyzed polyvinyl alcohol copolymer.

In some embodiments, the neutralizing may be carried out before the heat treating.

In some embodiments, a portion of the hydrolyzed polyvinyl alcohol copolymer may be neutralized.

In some embodiments, the neutralizing may include mixing the hydrolyzed polyvinyl alcohol copolymer with acetic acid to an acidic pH.

In some embodiments, the acidic pH may be from 5 to 6.

In some embodiments, the heat treating may include heating the hydrolyzed polyvinyl alcohol copolymer at more than 50°C and up to 115°C.

In some embodiments, the method may further include compacting the blend, then granulating the blend to granules, and then sorting the granules according to particle sizes, and selecting granules having a particle size of from about 3 to 18 mesh.

In some embodiments, the compacting of the blend may be carried out at a pressure of 5 to 100 tons.

According to another aspect of the invention, a method of increasing the lactone Ring Open Ratio (ROR%) of a polyvinyl alcohol copolymer, the method may include adding an alkalizing agent to the polyvinyl alcohol copolymer.

In some embodiments, the ROR% of the polyvinyl alcohol copolymer may increase from 2-4% to at least 15%.

In some embodiments, the alkalizing agent may include at least one selected from the group consisting of a metal oxide, a metal hydroxide, a metal carbonate, a metal bicarbonate, ammonia, a primary amine, a secondary amine, a tertiary amine, an aromatic amine, an amino acid, and a polymeric amine.

According to another aspect of the invention, a method of increasing solubility of a polyvinyl alcohol copolymer particulate matter, the method may include adding an alkalizing agent to the polyvinyl alcohol copolymer particle.

In some embodiments, the alkalizing agent may include at least one selected from the group consisting of a metal oxide, a metal hydroxide, a metal carbonate, a metal bicarbonate, ammonia, a primary amine, a secondary amine, a tertiary amine, an aromatic amine, an amino acid, and a polymeric amine.

In some embodiments, the method may increase the solubility of the polyvinyl alcohol copolymer particle in water such that the resultant solution may possess a pH of at least 7.

In some embodiments, the pH may be at least 8.

In some embodiments, the resultant solution may further possess a 30-minute percent warm water solubles (% WWS) at 35 °C of at least 50%.

In some embodiments, the 30-minute % WWS at 35 °C may be at least 60%.

According to another aspect of the invention, a particulate water-soluble diverting agent may comprise (1) a hydrolyzed polyvinyl alcohol copolymer of vinyl acetate and one or more unsaturated acids, and (2) an alkalizing agent.

FIG. 1A shows that the hydrolyzed polyvinyl alcohol copolymer treated with an alkalizing agent sticks much better to substrates such as glass, plastic and sand than a hydrolyzed polyvinyl alcohol copolymer that has not been treated with an alkalizing agent as shown in FIG. 1B.

In the context of the present description, all publications, patent applications, patents and other references mentioned herein, if not otherwise indicated, are explicitly incorporated by reference herein in their entirety for all purposes as if fully set forth.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. In case of conflict, the present specification, including definitions, will control.

Except where expressly noted, trademarks are shown in upper case.

Unless stated otherwise, all percentages, parts, ratios, etc., are by weight.

Unless stated otherwise, pressures expressed in psi units are gauge, and pressures expressed in kPa units are absolute. Pressure differences, however, are expressed as absolute (for example, pressure 1 is 25 psi higher than pressure 2).

When an amount, concentration, or other value or parameter is given as a range, or a list of upper and lower values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper and lower range limits, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the present invention be limited to the specific values recited when defining a range.

When the term “about” is used, it is used to mean a certain effect or result can be obtained within a certain tolerance, and the skilled person knows how to obtain the tolerance. When the term “about” is used in describing a value or an end-point of a range, the disclosure should be understood to include the specific value or end-point referred to.

As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

The transitional phrase “consisting of” excludes any element, step, or ingredient not specified in the claim, closing the claim to the inclusion of materials other than those recited except for impurities ordinarily associated therewith. When the phrase “consists of” appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.

The transitional phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps and those that do not materially affect the basic and novel characteristic(s) of the claimed invention. A “consisting essentially of” claim occupies a middle ground between closed claims that are written in a “consisting of” format and fully open claims that are drafted in a “comprising” format. Optional additives as defined herein, at a level that is appropriate for such additives, and minor impurities are not excluded from a composition by the term “consisting essentially of”.

Further, unless expressly stated to the contrary, “or” and “and/or” refers to an inclusive and not to an exclusive. For example, a condition A or B, or A and/or B, is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

The use of “a” or “an” to describe the various elements and components herein is merely for convenience and to give a general sense of the disclosure. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

The term “predominant portion” or “predominantly”, as used herein, unless otherwise defined herein, means greater than 50% of the referenced material. If not specified, the percent is on a molar basis when reference is made to a molecule (such as hydrogen and ethylene), and otherwise is on a mass or weight basis (such as for additive content).

The term “substantial portion” or “substantially”, as used herein, unless otherwise defined, means all or almost all or the vast majority, as would be understood by the person of ordinary skill in the context used. It is intended to take into account some reasonable variance from 100% that would ordinarily occur in industrial-scale or commercial-scale situations.

The term “depleted” or “reduced” is synonymous with reduced from originally present. For example, removing a substantial portion of a material from a stream would produce a material-depleted stream that is substantially depleted of that material. Conversely, the term “enriched” or “increased” is synonymous with greater than originally present.

As used herein, the term “copolymer” refers to polymers comprising copolymerized units resulting from copolymerization of two or more comonomers. In this connection, a copolymer may be described herein with reference to its constituent comonomers or to the amounts of its constituent comonomers, for example “a copolymer comprising ethylene and 15 mol% of a comonomer”, or a similar description. Such a description may be considered informal in that it does not refer to the comonomers as copolymerized units; in that it does not include a conventional nomenclature for the copolymer, for example International Union of Pure and Applied Chemistry (IUPAC) nomenclature; in that it does not use product-by-process terminology; or for another reason. As used herein, however, a description of a copolymer with reference to its constituent comonomers or to the amounts of its constituent comonomers means that the copolymer contains copolymerized units (in the specified amounts when specified) of the specified comonomers. It follows as a corollary that a copolymer is not the product of a reaction mixture containing given comonomers in given amounts, unless expressly stated in limited circumstances to be such.

For convenience, many elements of the present invention are discussed separately, lists of options may be provided and numerical values may be in ranges; however, for the purposes of the present disclosure, that should not be considered as a limitation on the scope of the invention or support of the present disclosure for any claim of any combination of any such separate components, list items or ranges. Unless stated otherwise, each and every combination possible with the present disclosure should be considered as explicitly disclosed for all purposes.

Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure, suitable methods and materials are described herein. The materials, methods, and examples herein are thus illustrative only and, except as specifically stated, are not intended to be limiting.

The present invention relates to particulate polyvinyl alcohol based water soluble diverting agents for use in subterranean treatments.

Particulate Matter
According to one aspect of the invention, a particulate matter may include (1) a hydrolyzed polyvinyl alcohol copolymer of vinyl acetate and one or more unsaturated acids, and (2) an alkalizing agent. As used herein, the term “particulate matter” is a composition comprising a plurality of particles of different sizes. The particulate matter may not be powder.

In some embodiments, wherein the powder may be compacted.

In some embodiments, the particulate matter may possess a particle size of from about 3 to 18 mesh. In some embodiments, the particulate matter may possess a particle size of from about 6 to 12 mesh. In some embodiments, the particulate matter may possess a particle size of from about 6 to 8 mesh. In some embodiments, the particulate matter may possess a particle size of from about 3, 4, 5, 6, 8, 10, 12, or 16 mesh to 18, 16, 12, 10, 8, 6, 5, or 4 mesh.

Hydrolyzed Polyvinyl Alcohol Copolymer
By way of background, polyvinyl alcohol homopolymers and copolymers are commercially available as an article of commerce for many years and has been found useful in films, fibers, sizes, and adhesives, as emulsifiers, binder, and thickeners, and in many other diverse applications. The solubility of polyvinyl alcohol in water may be attributable to its high polarity and to the large number of hydroxyl groups in the polymer chain. These hydroxyl groups may also confer upon polyvinyl alcohol its unique physical properties as compared with other water-soluble polymers. Their affinity for one another may results in large interchain molecular forces which contribute to high strength and toughness. In addition, polyvinyl alcohol is known to crystallize, and this also contributes to high strength and toughness.

The substitution of bulkier groups such as the methyl acrylate group for hydroxyls may inhibit the close packing of the molecules and minimize the tendency to form crystallites. The more closely packed, the more difficult it may be to dissolve polyvinyl alcohol in water. This may be manifested in the higher temperature required to dissolve polyvinyl alcohol.

U.S. Patent Application Publication No. 2017/0260309 A1 relates generally to a polyvinyl alcohol composition having higher amorphous polyvinyl alcohol polymer content, a process for making such a polyvinyl alcohol composition, and various end uses thereof.

WO2012/087821A1 relates to cold water-soluble PVOH/alkyl acrylate copolymers with a substantially random distribution of monomers which is reflected in the polymer’s cold water solubility, GPEC chromatograms and may be confirmed by C13 NMR.

The hydrolyzed polyvinyl alcohol copolymer of the invention after being subjected to treatment by alkalizing agents, on the other hand, readily dissolves in warm water. A goal of adding the alkalizing agent is to control the rate of dissolution of the diverting agent by varying the ratio of the hydrolyzed polyvinyl alcohol copolymer to the alkalizing agent.
As used herein, the term “hydrolyzed polyvinyl alcohol copolymer” refers to polyvinyl alcohol produced by polymerizing a vinyl ester and one or more unsaturated acids to generate a polyvinyl ester copolymer, after which the ester groups are hydrolyzed to hydroxyl groups in varying degrees. The term “hydrolyzed polyvinyl alcohol copolymer” may be interchangeable with the term “acid functional comonomer modified polyvinyl alcohol.”

Examples of vinyl esters suitable for use herein as a starting material include vinyl acetate, vinyl propionate, vinyl benzoate, vinyl stearate, vinyl versatate, vinyl pivalate, vinyl formate, vinyl valerate, vinyl caprinate, vinyl laurate, and vinyl carboxylate copolymers, such as ethylene-vinyl acetate copolymer. For reasons of economy, availability and performance, vinyl acetate may be selected.

In some embodiments, the concentration of the vinyl acetate in the particulate matter may be from 85 mol% to 99.9 mol% based on a total number of moles of monomers forming the hydrolyzed polyvinyl alcohol copolymer. In some embodiments, a concentration of the vinyl ester (e.g., vinyl acetate) in the particulate matter may be from 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, or 98 mol% and/or up to 99.9, 99.5, 99, 98, 97, 96, 95, 94, 93, 92, or 91 mol% based on a total number of moles of monomers forming the hydrolyzed polyvinyl alcohol copolymer.

In some embodiments, the hydrolyzed polyvinyl alcohol copolymer may include the one or more unsaturated acids at an amount of from about 0.1 mol% to about 15 mol% based on a total number of moles of monomers forming the hydrolyzed polyvinyl alcohol copolymer. In some embodiments, the hydrolyzed polyvinyl alcohol copolymer may include the one or more unsaturated acids at an amount of from about 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13 mol% and/or up to 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, or 5 mol% based on a total number of moles of monomers forming the hydrolyzed polyvinyl alcohol copolymer.

In some embodiments, the one or more unsaturated acids may include at least one selected from the group consisting of a monocarboxylic unsaturated acid, an alkyl ester of a monocarboxylic unsaturated acid, an alkali metal salt of a monocarboxylic unsaturated acid, an alkaline earth metal salt of a monocarboxylic unsaturated acid, an anhydride of a monocarboxylic unsaturated acid, a dicarboxylic unsaturated acid, an alkyl ester of a dicarboxylic unsaturated acid, an alkali metal salt of a dicarboxylic unsaturated acid, an alkali earth metal salt of a dicarboxylic unsaturated acid, and an anhydride of a dicarboxylic unsaturated acid. Examples of the one or more unsaturated acids may include methacrylic acid, methyl methacrylate, 2-hydroxyethyl acrylate, hydroxyl methacrylate, ethyl methacrylate, n-butyl methacrylate, maleic acid, monomethyl maleate, dimethyl maleate, maleic anhydride, itaconic acid, monomethyl itaconate, dimethyl itaconate, itaconic anhydride, neodecanoic acid, and vinyl neodecanoate. In some embodiments, the one or more unsaturated acids may include a lower alkyl (C2-C8 or C2-C4) acrylate and/or a lower alkyl methacrylate. Further non-limiting examples of the one or more unsaturated acids include methyl acrylate, ethyl acrylate, i-propyl acrylate, i-propyl methacrylate, n-propyl acrylate, n-propyl methacrylate, i-butyl acrylate, i-butyl methacrylate, n-butyl acrylate, t-butyl acrylate, t-butyl methacrylate, ethylhexyl acrylate, ethylhexyl methacrylate and others. In some embodiments, the one or more unsaturated acids may include an alkyl ester of the monocarboxylic unsaturated acid. In some embodiments, the alkyl ester of the monocarboxylic unsaturated acid may be methyl acrylate. In some embodiments, the one or more unsaturated acids may include dicarboxylic monomers such as maleic, fumaric, and itaconic acids, or corresponding acid anhydrides. In some embodiments, one of the carboxyl groups in the dibasic monomer unit may react with the adjacent hydroxyl group in the copolymer to form a five-membered lactone ring. Because of the low steric stability of six-membered or seven-membered lactone rings, the second carboxyl group in the dibasic monomer unit may remain unchanged.

The properties of polyvinyl alcohol may be varied, for example, by varying its molecular weight or its degree of hydrolysis. Properties that change with increasing molecular weight include, for example, an increase in solution viscosity and film strength and a decrease in rate of solution.

In some embodiments, the hydrolyzed polyvinyl alcohol copolymer may possess a viscosity-average degree of polymerization of from about 300 to about 3000. In some embodiments, the viscosity-average degree of polymerization may be from about 300, 400, 500, 700, 1000, 1200, 1500, 1700, 2000, or 2500 to about 3000, 2700, 2600, 2200, 1900, 1600, 1300, 1100, 800, or 600.

The degree of hydrolysis may have a profound effect on properties. Polyvinyl alcohol which is about 88 percent hydrolyzed may be soluble in both hot and cold water, and its concentrated aqueous solutions may not change appreciably in appearance or viscosity during prolonged storage at room temperature. In contrast, polyvinyl alcohol which is greater than 99 percent hydrolyzed may be soluble in hot water, but not cold water, and its concentrated aqueous solutions may have relatively poor storage stability at room temperature, first exhibiting an increase in viscosity and finally becoming gelatinous. Intermediate between these, polyvinyl alcohol which is about 98 percent or a little less hydrolyzed may be soluble in hot water and insoluble in cold water. Its concentrated aqueous solutions may exhibit relatively good storage stability at room temperature, and it is termed gel resistant.

In some embodiments, the hydrolyzed polyvinyl alcohol copolymer may possess a degree of hydrolysis of from about 70 mol% to 100 mol% (e.g., fully hydrolyzed). The degree of hydrolysis may be from 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 94, or 96 mol% to 100, 98, 95, 93, 91, 89, 87, 85, 83, 81, 79, or 77 mol%. As used herein, the term “partially hydrolyzed” may describe polyvinyl alcohol copolymer or homopolymer having a degree of hydrolysis that is from about 70 mol% to 99 mol%.

In some embodiments, the hydrolyzed polyvinyl alcohol copolymer may be substantially soluble in water at a temperature of 195°F or higher. As used herein, the term “substantially soluble in water at a temperature of 195°F or higher” may refer to a solubility of 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72 or 74% or higher, and may be obtained by dividing the mass of the solute in solution by the total mass of the solute added and multiplying by 100.

Alkalizing Agent
As used herein, the term “alkalizing agent” is a substance that may neutralize acid by reacting with a hydrogen ion.

In some embodiments, the alkalizing agent may include at least one selected from the group consisting of a metal oxide, a metal hydroxide, a metal carbonate, a metal bicarbonate, ammonia, a primary amine, a secondary amine, a tertiary amine, an aromatic amine, an amino acid, and a polymeric amine. Examples of the metal oxide may include sodium oxide, potassium oxide, and lithium oxide. Examples of the metal hydroxide may include sodium hydroxide, potassium hydroxide, and lithium hydroxide. In some embodiments, the alkalizing agent may include a metal carbonate. Examples of the metal carbonate may include sodium carbonate, potassium carbonate, and lithium carbonate. In some embodiments, the metal carbonate may include sodium carbonate. Examples of the metal bicarbonate may include sodium bicarbonate, potassium bicarbonate, and lithium bicarbonate. In some embodiments, the metal bicarbonate may include sodium bicarbonate.

Examples of a primary amine may include primary mono- or polyamines such as, for example, C1-C30 alkylamine. Examples of a secondary amine may have the general formula HNR₂ in which each R is independently a C1-C30 alkyl group. In some embodiments, the alkalizing agent may include a tertiary amine. Examples of a tertiary amine may have the general formula NR₃ in which each R is independently a C1-C30 alkyl group. In some embodiments, the tertiary amine may include triethylamine. Examples of an aromatic amine may include C6-C30-arylamine and C6-C30-heteroarylamine. In some embodiments, the alkalizing agent may include an amino acid. Examples of an amino acid may include arginine (Arg), lysine (Lys), and histidine (His). In some embodiments, the amino acid may include arginine. Examples of a polymeric amine may include 2-(2-(2-ethoxyethoxy)ethoxy)ethanamine, poly(ethylene glycol) bis(amine), and methoxypolyethylene glycol amine.

In some embodiments, a concentration of the alkalizing agent in the particulate matter may be from more than 0 to 50% by weight of a total weight of the hydrolyzed polyvinyl alcohol copolymer. In some embodiments, a concentration of the alkalizing agent in the particulate matter may be from more than 0 to 25% by weight of a total weight of the hydrolyzed polyvinyl alcohol copolymer. In some embodiments, a concentration of the alkalizing agent in the particulate matter may be from more than 0 to 10% by weight of a total weight of the hydrolyzed polyvinyl alcohol copolymer. The concentration of the alkalizing agent in the particulate matter may be from more than 0, 1, 2, 3, 5, 7, 11, 13, 15, 17, 20, 22, 26, 30, 35, 40, or 45% by weight to 50, 49, 47, 43, 42, 39, 37, 34, 31, 27, 23, 21, 18, 14, 12, or 9% by weight of a total weight of the hydrolyzed polyvinyl alcohol copolymer.

Additive
In some embodiments, the particulate matter may further include at least one additive selected from the group consisting of a plasticizer and a filler. In some embodiments, the particulate matter may further include at least one additive selected from the group consisting of a plasticizer, a filler, and starch.

Plasticizers may be included in manufacturing of the compositions of this invention to improve the flow characteristics of the hydrolyzed polyvinyl alcohol copolymer. In order to obtain a uniform plasticizer coating a spray mechanism may be used to coat the particulate matter. A secondary effect of such plasticizers may be to reduce any dusting issues with the particulate matter, or during the preparation of the particulate matter.

Materials commonly used as plasticizers for hydrolyzed polyvinyl alcohol copolymer are generally known to those of ordinary skill in the relevant art, and are generally commercially available. Suitable plasticizers include, for example, compounds such as water, glycerol, polyglycerol, ethylene glycol, polyethylene glycols, ethanol acetamide, ethanol formamide, and acetates of triethanolamine, glycerin, trimethylolpropane and neopentyl glycol, and mixtures of two or more of the above.

In some embodiments, the particulate matter may further include an anti-dusting agent. As used herein, an anti-dusting agent may be a material that prevents or minimizes dust when the particulate matter is being handled, mixed, or applied. In some embodiments, the anti-dusting agent may include polyglycol. Anti-dusting agent(s) known to one of ordinary skill in art may be used. The amount of anti-dusting agent used may vary up to about 0.5, 1, 3, 5, 7, 9, 10, 13, or 15 wt.%, based on a total weight of the hydrolyzed polyvinyl alcohol copolymer. In some embodiments, a polyglycol may be used as an anti-dusting agent. In some embodiments, the polyglycol may be polyethylene glycol having a molecular weight (Mn) of about 200 and 600 due to its desirable dust suppressant properties after extreme temperature recycling.

Plasticizers that are solid or crystalline at ambient temperatures, such as trimethylolpropane, may be dissolved in water, or another liquid medium that will not offset the plasticization effect, for use as a sprayable plasticizer. Alternatively, however, a plasticizer may be mixed with the hydrolyzed polyvinyl alcohol copolymer when both are dissolved or dispersed in a liquid, or when both are in dry form. When a plasticizer is mixed with hydrolyzed polyvinyl alcohol copolymer in liquid, the resulting mixture may be dried to form a particle containing plasticized hydrolyzed polyvinyl alcohol copolymer before other steps are taken, such as compaction of the dried mixture. When the particulate matter containing a plasticizer is compacted, the plasticizer may be added to the composition before or after compaction. In some embodiments, the plasticizer may be added before, during or after granulation.

The amount of plasticizer used may vary up to about 0.5, 1, 3, 5, 7, 9, 10, 13, 15, 18, 20, 23, 25, 28, 30, 32, 35, or 40 wt.%, based on a total weight of the hydrolyzed polyvinyl alcohol copolymer.

In some embodiments, the filler may be blended with the hydrolyzed polyvinyl alcohol copolymer to enhance mechanical properties and regulate the solubility curves of the compositions. The total amount of filler added may vary widely depending on the desired property modification, for example, up to about 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 wt.%, based on the total weight of the particulate matter.

An example of fillers includes an acid-soluble weighting agent. In some embodiments where the particulate matter may be used for downhole treatments, it may be desirable to have the specific gravity of the particulate matter be close to that of a carrier fluid in order to allow for pumping and satisfactory placement of a diverting agent or loss circulation control compositions using the selected carrier fluid. A weighting agent may be used for such purpose.

When used, an acid-soluble weighting agent filler may be blended with the hydrolyzed polyvinyl alcohol copolymer, before, during or after polymer blending. Weighting agent generally refers to any additive used to increase the density of the resin component. Acid-soluble weighting agents generally include substances such as natural minerals and inorganic and organic salts. For example, the weighting agent may include a metal ion selected from the group consisting of calcium, magnesium, silica, barium, copper, zinc, manganese and mixtures thereof, and a counterion is selected from the group consisting of fluoride, chloride, bromide, carbonate, hydroxide, formate, acetate, nitrate, sulfate, phosphate and mixtures thereof. Specific examples of such fillers include minerals such as CaCO₃, CaCl₂, and ZnO.

Other Polyvinyl Alcohol
In some embodiments, the particulate matter may further include at least one other polyvinyl alcohol. In some embodiments, the particulate matter may include a mixture including the hydrolyzed polyvinyl alcohol copolymer and the at least one other polyvinyl alcohol. In some embodiments, the hydrolyzed polyvinyl alcohol copolymer may be present in an amount of from about 10, 15, 20, 25, 30, 35, 40, 45, or 50 wt.%, to about 95, 90, 85, 80, 75, 70, 65, 60, or 55 wt.%, based on a total weight of the hydrolyzed polyvinyl alcohol copolymer and the at least one other polyvinyl alcohol.

In some embodiments, the at least one other polyvinyl alcohol may possess a water solubility lower than that of the hydrolyzed copolymer. The difference in water solubilities may allow users to modify the dissolution rate of the particulate matter as desired. For example, the at least one other polyvinyl alcohol may have a water solubility as low as 2, 3, 4, 2.6 or 5% or less at room temperature.

In some embodiments, the at least one other polyvinyl alcohol may include a fully hydrolyzed polyvinyl alcohol homopolymer or a partially hydrolyzed polyvinyl alcohol homopolymer. Examples of these polyvinyl alcohol homopolymers are generally commercially available, for example under the brands KURARAY POVAL^TM and ELVANOL^TM from Kuraray Co., Ltd. (Tokyo, Japan) and its affiliates.

Composition Including the Particulate Matter
In some embodiments, a composition may include the particulate matter as disclosed herein. In some embodiments, an amount of the particulate matter may be at least 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, or 99 wt.% of a total weight of the composition. The composition may possess a bulk density of about 0.3 g/mL or greater. In some embodiments, the composition may possess a bulk density of about 0.4 g/mL or greater. In some embodiments, the composition may possess a bulk density of about 0.5 g/mL or greater. In some embodiments, the composition may possess a bulk density of about 0.6 g/mL or greater. In some embodiments, the composition may possess a bulk density of about 0.7, 0.9, 1.1, 1.2, 1.3, 1.4, 1.6, 1.8, or 2 g/mL or greater.

Lactone Ring Open Ratio (ROR%)
The copolymerization of monocarboxylic vinyl monomers (or monocarboxylate vinyl monomers) with vinyl ester (e.g., vinyl acetate) may not result in hydrolyzed copolymers containing carboxyl groups since adjacent hydroxyl groups may react with carboxyl groups to form five-membered lactone rings. Chem.1 shows lactone formation of the acid-modified polyvinyl alcohol copolymer.

The lactone formation may negatively affect the solubility properties of the co-polymer. The solubility problem may become even more severe when the copolymer of polyvinyl alcohol come into contact with compounds that promote lactone formation.

Without being bound to theory, ester comonomers and the lactone rings they form may be less polar and hence less water sensitive than the vinyl alcohol units. Different comonomers may result in varying levels of water sensitivity in the resulting copolymer. The sensitivity may depend on the reduction in crystallinity due to increasing number of comonomer units (or derived lactone units) and on the net decrease in polarity with increasing comonomer level.

While long alkyl chain alkyl acrylates and methacrylates may be less polar than short alkyl chain ones, polyvinyl alcohol copolymers of long chain acrylates and methacrylates, on lactonization may contain the same in-chain lactone group as that from any other acrylate or methacrylate copolymer respectively. However, methacrylate derived lactone rings may not be the same as acrylate derived lactone rings. In addition, the amount of lactonization may vary.

The copolymer may have a water sensitivity which is a balance due to the amount of reduction in crystallinity the comonomer or derived lactone causes, and the overall decreased polarity of the copolymer with increasing comonomer or derived lactone content. The addition of comonomers, such as lower alkyl acrylate esters in and of itself, may improve water solubility of polyvinyl alcohols by lowering crystallinity of the resulting polymers; however, in hydrolysis of copolymers of vinyl acetate with minor amounts of an acrylate such as methyl acrylate by conventional processes, the resulting acrylate structures may cyclize with neighboring hydroxyl groups to form lactone rings. According to JP S49-36797 (1974), the presence of lactone rings may reduce water solubility of the polyvinyl alcohol copolymer, and may offset the water-solubility benefit of lower crystallinity. With methacrylate modified polyvinyl alcohol, as the comonomer level may be increased significantly, decreased polarity in the copolymer may result. At very high comonomer levels, decreasing polarity may eventually override the increasing water sensitivity which results from decreasing crystallinity.

Several different hydrolysis methods, as described herein, may be used for the purpose of completing the conversion to -OH groups of the pendant ester groups in the polymer formed from whatever vinyl ester is chosen as the beginning reactant.

The present invention relates to technology for controlling the rate of the dissolution of the particulate diverting agent by increasing lactone Ring Open Ratio (ROR%) of the hydrolyzed polyvinyl alcohol copolymer and/or lowering heat treatment temperature. In some embodiments, a use of the particulate matter or the composition as disclosed herein may include increasing the lactone Ring Open Ratio (ROR%), solubility of a polyvinyl alcohol copolymer. In some embodiments, the hydrolyzed polyvinyl alcohol copolymer may include at least one lactone ring formed from a hydroxyl group (from the hydrolysis of vinyl ester repeating unit) reacting with an adjacent carboxyl group (from the one or more unsaturated acid monomer).

As used herein, the term “Ring Open Ratio (ROR%)” refers to the amount of open lactone rings and may be determined by infrared (IR) spectroscopy by, for example, measuring the intensity of the IR peak at 1725 to 1750 cm^-1, attributed to lactone functional group, and the intensity of the IR peak at 1550 to 1575 cm^-1, attributed to the carboxylate unit that is not part of the lactone group. A higher ROR% may indicate that fewer, if any, lactone rings are present in the copolymer.

According to another aspect of the invention, a method of increasing the lactone Ring Open Ratio (ROR%) of a polyvinyl alcohol copolymer, the method may include adding an alkalizing agent to the polyvinyl alcohol copolymer. In some embodiments, the polyvinyl alcohol copolymer may include or may be the hydrolyzed polyvinyl alcohol copolymer as disclosed herein. In some embodiments, the ROR% of the polyvinyl alcohol copolymer may increase from 2-4% to at least 15%. In some embodiments, the ROR% of the polyvinyl alcohol copolymer may increase from 1, 2, 3, 4, or 5 % to at least 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, or above 90%. In some embodiments, the alkalizing agent may be any alkalizing agent disclosed herein. In some embodiments, the alkalizing agent may include at least one selected from the group consisting of a metal oxide, a metal hydroxide, a metal carbonate, a metal bicarbonate, ammonia, a primary amine, a secondary amine, a tertiary amine, an aromatic amine, an amino acid, and a polymeric amine.

Treating a Surface Formation
The diverting agents disclosed herein are suitable for use in subterranean formations where formation temperatures are 200°F or lower, e.g., from about 100, 120, 140, 160, or 180 °F. In some embodiments, the diverting agent may have a stability temperature of up to about 210, 220, 230, 240 or 250°F. The application temperature of the diverting agents of this invention may be extended to higher temperature wells by lowering the temperature within the wellbore and decreasing the solubility of the diverting agent by removing the native heat from surrounding formations during stimulation. The stimulation fluid may be circulated at a flow rate sufficient to cool the water-soluble diverting agent to a stable temperature where the diverting agent is stable for at least 3, 10, 20, 30, or 40 hours, and in some cases at least 2, 3, 4, 5, or 6 days. The diverting effect may be temporary as the hydrolyzed polyvinyl alcohol copolymer may be water-soluble.

In some embodiments, a use of the particulate matter or the composition as disclosed herein may include treating a surface formation to divert flow of a fluid from one zone of a subsurface formation to another zone of the subsurface formation. In some embodiments, a method of treating a surface formation to divert flow of a fluid from one zone of a subsurface formation to another zone of the subsurface formation, the method may include pumping into the subsurface formation a carrier liquid comprising water and the particulate matter as disclosed herein. In some embodiments, the carrier liquid may further include sand.

The particulate matter and composition thereof as disclosed herein may be used as plugging agents in fluid injection operations for subsurface wells by processes as generally known to those of ordinary skill in the art. The particulate matter and composition thereof may be used to temporarily plug cracks and decrease (or prevent) fluid and loss into such cracks. Example uses include as diverting agents and as loss control materials, as described above. The plugging agent may be designed to be temporary and may be removed by dissolving it using the fluids after completion of the treatment. The plugging agents may be used in the servicing of vertical wells, but they are equally applicable to wells of any orientation. In addition, although the description herein may be presented in terms of servicing hydrocarbon-production wells, it is to be understood that the disclosed methods may be used for wells for the production of other fluids, such as water or carbon dioxide, or, for example, for injection or storage wells.

When the particulate matter and composition thereof is being used for a downhole treatment, the particle size distribution thereof sought to be obtained from the processes and methods of this invention may vary widely depending on the permeability of the substrate, the nature of the carrier fluid, the subsurface temperature profile, and the particular polyvinyl alcohol composition being used, and may be adjusted as described above.

This invention therefore further provides a method of reducing the loss of one or more desired fluids from a subsurface formation, or from the confines of a wellbore installed within such formation, by introducing a particulate matter and composition thereof according to this invention into an opening in a wall of the formation. Performing such a method typically involves introducing the composition into an opening in a wall of the formation to temporarily or permanently seal the opening therein, which step of introducing may be or include a step of pumping, injecting, releasing, spotting, circulating, or otherwise emplacing a composition hereof into an opening in a wall of a formation. Access to the opening in the wall may be obtained from the wellbore, or from a device that has been inserted in the wellbore and is used for that purpose.

Any one or more of the particulate matter and composition thereof, whether described above in terms of size classification, or described elsewhere herein in other terms, may be used in the step of introducing such particulate matter and composition thereof into an opening in the wall of a subsurface formation.

A plugging agent may be pumped down the wellbore at high pressure and into the leaking zone(s) to be plugged, and the plugging agent may enter the weakest portions of the zone first followed then by other portions including those where fluids crossflow through the wellbore or blow out into the wellbore. The plugging agent may stop the loss of service fluids and allow high drilling fluid densities to be utilized when needed while drilling ahead. Once the plugging agent has been placed, it may increase the fracture gradient to a higher value that may eliminate the need for intermediate casing, drilling liners and the like. Because the plugging agent readily diverts drilling fluids to other weak zones in the well bore, the integrity of the entire well bore may be improved by the plugging agent.

In one embodiment, a plugging agent may be placed into a wellbore in the form of a “single pill” fluid; that is, all components of the plugging agent may be mixed and introduced into the wellbore as a single composition and as a single stream. In such case, the plugging agent may be typically activated by downhole conditions to form a seal in one or more leaking zones, and for such purpose the plugging agent may be placed downhole through multiple ports in the drill bit.

In an alternative embodiment, the plugging agent may be formed downhole by the mixing of a first stream containing one or more components and a second stream containing additional components. In such an embodiment, the compositional components may be selected such that the first and second streams react with each other, or one group of components may be encapsulated and introduced in that form instead of as a stream. When differing groups of components are introduced as independent fluid streams, one of them may be introduced through the tubular string of drill pipe, and the other may be introduced in the anulus between the drill string and the wall of the borehole.

Methods for introducing plugging agents into a wellbore to bridge, seal or plug leaks in leaking subterranean zones are further described, for example, in U.S. Patent. Nos. 5,913,364, 6,167,967 and 6,258,757.

Joint Filler
In some embodiments, the particulate matter or the composition disclosed herein blended with sand, curing agent and other additives may be used as a joint filler for the gap between two or more tiles. In some embodiments, a method of filling a gap between two or more tiles, the method may include applying a fluid including the particulate matter as disclosed herein and sand to the gap. In some embodiments, the fluid may further include sand, curing agent, and other additives. Examples of a suitable curing agent include boric acid, dialdehydes, calcium chloride and cement. Examples of an additive include a water reducing agent and a viscosity agent.

Examples of a water reducing agent include a polycarboxylic acid type water reducing agent, a lignin sulfonic acid type water reducing agent, a naphthalene sulfonic acid type water reducing agent, and a melamine sulfonic acid type water reducing agent. In some embodiments, a viscosity agent may be added to uniformly disperse the components. Examples of a viscosity agent include cellulosic compounds, for example, a cellulose compound having an alkoxy group, for example, methylcellulose, propylmethylcellulose, and hydroxyethylmethylcellulose.

Method of Producing the Particulate Matter
A method of manufacturing the particulate matter may include:
i. selecting the desired form of the hydrolyzed polyvinyl alcohol copolymer based on the desired dissolution rate;
ii. blending the hydrolyzed polyvinyl alcohol copolymer with the alkalizing agent;
iii. adding other optional additives such as starch, fillers, and plasticizers;
iv. compacting the blend from iii.; and
v. granulating the compacted material from iv. to generate the particulate matter.

The hydrolyzed polyvinyl alcohol copolymer disclosed herein may be used in any of the following forms:
i. neutralized and subjected to heat treatment;
ii. not neutralized and not subjected to heat treatment;
iii. fully neutralized and not subjected to heat treatment;
iv. not neutralized and subjected to heat treatment;
v. partially neutralized and heat treated;
vi. partially neutralized and not heat treated; and
vii. any combination of the forms i. to vi.

In some embodiments, a method of producing the particulate matter as disclosed herein may include blending the hydrolyzed polyvinyl alcohol copolymer and the alkalizing agent to form a blend. In some embodiments, the blending may be carried out by at least one process selected from the group consisting of dry mixing, blade mixing, fluidized bed mixing, mill mixing, spraying, and solvent system mixing. Methods known to those of ordinary skill in the art may be used as long as the mixing results in intimate contact between the hydrolyzed polyvinyl alcohol copolymer and alkalizing agent. In some embodiments, a solution containing the alkalizing agent may be sprayed onto the hydrolyzed polyvinyl alcohol copolymer.

In some embodiments, the method may further include, immediately before the blending, hydrolyzing a polyvinyl acetate copolymer to form the hydrolyzed polyvinyl alcohol copolymer. The hydrolyzed polyvinyl alcohol copolymer may be neither neutralized nor heat-treated. In some embodiments, the anti-dusting agent may be added before or after blending the alkalizing agent is added.

In some embodiments, the method may further include, before the blending, neutralizing at least a portion of the hydrolyzed polyvinyl alcohol copolymer and/or heat treating the hydrolyzed polyvinyl alcohol copolymer. In some embodiments, the method may include, before the blending, the neutralizing of at least a portion of the hydrolyzed polyvinyl alcohol copolymer. In some embodiments, the heat treatment may not be carried out. In some embodiments, the method may include, before the blending, the heat treating of the hydrolyzed polyvinyl alcohol copolymer. In some embodiments, the neutralizing may not be carried out.

In some embodiments, the method may include, before the blending, the neutralizing of at least a portion of the hydrolyzed polyvinyl alcohol copolymer, and heat treating the hydrolyzed polyvinyl alcohol copolymer. In some embodiments, the neutralizing may be carried out before the heat treating. In some embodiments, a portion of the hydrolyzed polyvinyl alcohol copolymer may be neutralized. In some embodiments, the neutralizing may include mixing the hydrolyzed polyvinyl alcohol copolymer with acetic acid to an acidic pH. In some embodiments, the pH od the neutralized polymer may be from 5 to 6. In some embodiments, the acidic pH may be from 5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, or 5.9 to 6, 5.9, 5.8, 5.7, 5.6, 5.5, 5.4, or 5.3.

In some embodiments, the heat treating may include heating the hydrolyzed polyvinyl alcohol copolymer at more than 50°C and/or up to 115°C. In some embodiments, the heat treating may include heating the methanol slurry of the hydrolyzed polyvinyl alcohol copolymer at more than 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, or 105°C and/or up to 120, 115, 113, 112, 111, or 110°C.

In some embodiments, the method may further include compacting the blend, then granulating the blend to granules, and then sorting the granules according to particle sizes, and selecting granules having a particle size of from about 3 to 18 mesh. In some embodiments, the selected granules may possess a particle size of from about 3, 4, 5, 6, 8, 10, 12, or 16 mesh to 18, 16, 12, 10, 8, 6, 5, or 4 mesh.

In some embodiments, the compacting of the blend may be carried out at a pressure of 5 to 100 tons. In some embodiments, the compacting of the blend may be carried out at a pressure of 5, 10, 20, 30, 40, 50, 60, 70, 80, 90 tons and/or up to 100, 95, 85, 75, 65, 55, 45, 35, 25, or 15 tons. In some embodiments, the compacting may include agglomerating the hydrolyzed polyvinyl alcohol copolymer and the alkalizing agent. The shape of the agglomerated particles may change in roundness, area, length, width, aspect ratio, and roughness.

Increasing Solubility of a Polyvinyl Alcohol Copolymer Particulate Matter
According to another aspect of the invention, a method of increasing solubility of a polyvinyl alcohol copolymer particulate matter, the method may include adding an alkalizing agent to the polyvinyl alcohol copolymer particle. In some embodiments, the polyvinyl alcohol copolymer particle may include or may be the hydrolyzed polyvinyl alcohol copolymer as disclosed herein. In some embodiments, the alkalizing agent may be any alkalizing agent disclosed herein. In some embodiments, the alkalizing agent may include at least one selected from the group consisting of a metal oxide, a metal hydroxide, a metal carbonate, a metal bicarbonate, ammonia, a primary amine, a secondary amine, a tertiary amine, an aromatic amine, an amino acid, and a polymeric amine.

In some embodiments, the method may increase the solubility of the polyvinyl alcohol copolymer particle in water such that the resultant solution may possess a pH of at least 7. In some embodiments, the pH may be at least 8. In some embodiments, the pH may be at least 7, 7.2, 7.4, 7.6, 7.8, 8, 8.2, 8.4, 8.6, 8.8, 9, 9.2, 9.4, 9.6, or 9.8.

In some embodiments, the resultant solution may further possess a 30-minute percent warm water solubles (% WWS) at 35°C of at least 65%. As used herein, the term “30-minute percent warm water solubles (% WWS)” refers to test method where a polyvinyl alcohol is added/dispersed into cold de-ionized water (35°C) to a concentration of 4 wt. % (g of polymer/g water). The mixture is then stirred with a triple bladed stirrer running at 200 rpm for 30 minutes at 35°C. The slurry is then transferred to a 40 ml centrifuge bottle and centrifuged at 1500 rpm for 10 minutes. An aliquot of the resulting supernatant liquid is evaporated to dryness and the WWS content is calculated as follows:
% WWS= (Wt. of aliquot * 200)/(Wt. of aliquot * 8) * 100

In some embodiments, the 30-minute % WWS at 35°C may be at least 70%. In some embodiments, the 30-minute % WWS at 35°C may be at least 50, 55, 65, 68, 70, 72, 75, 80, 82, 85, 90, 92, 95, 97, or 99%. In some embodiments, the mixture of polyvinyl alcohol copolymer particle in water before the adding of the alkalizing agent may be less than 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 % 30-minute % WWS.

Examples 1 to 9 will present a more complete understanding of the present invention by describing the effects of heat treatment, neutralization and treatment with alkalizing agents on the dissolution rate, crystallinity, porosity and swelling properties of the resin used in the manufacturing of the diverting agents of this invention.

The method used for producing the particulate diverting agents of the present disclosure comprises the steps of:
i. selecting the desired form of the fully hydrolyzed acid functional comonomer modified polyvinyl alcohol based on the desired dissolution rate;
ii. blending the “polyvinyl alcohol modified with acid-functional comonomer” with the alkalizing agent;
iii. adding optional additives such as fillers and plasticizers;
iv. compacting the blend from step iii.; and
v. granulating the compacted material blend from step iv. To generate the particulate diverting agent of specified particle size distribution.

The acid functional monomer modified polyvinyl alcohol copolymer of this disclosure may be used in several forms of its forms including:
i. subjected to neutralization and heat treatment;
ii. not subjected to neutralization and heat treatment;
iii. subjected to neutralization and not to heat treatment;
iv. not subjected to neutralization and subjected to heat treatment;
v. subjected to partial neutralization and heat treated;
vi. subjected to neutralization and not to heat treated; and
vii. any combination of the forms i to vii.

The examples below illustrate that treatment of the acid functional monomer modified polyvinyl alcohol copolymer with alkalizing agents increases the warm water solubility of the resin by increasing its polarity and decreasing its crystallinity. The following examples are provided for illustration and are not intended to limit the scope of this invention.

Example 1
The resins (R-0 to R-5) used for producing the particulate diverting agents in the examples below are fully hydrolyzed copolymers of vinyl acetate and the methyl acrylate comonomer. Table 1 shows the description of the resins used in the Examples 1 to Example 6 below.

The polyvinyl acetate copolymer samples R-0 to R-5 shown in Table 1 were produced by the free radical polymerization of the vinyl acetate monomer with methyl acrylate comonomer in the presence of a polymerization catalyst using methanol as a solvent.

The polymerization is typically conducted in the temperature range of 10°C to 80°C. The percent conversion of vinyl acetate to polyvinyl acetate may vary over a wide range. Though conversions ranging from 20% to 100% have been found satisfactory.

Desirably, the slurry alcoholysis process as described in U.S. Provisional Application No. 62/546781 (filed 17 August 2017, the disclosure of which is incorporated for all purposes as if fully set forth) is used for hydrolyzing the polyvinyl acetate copolymer to polyvinyl alcohol copolymer, as the described slurry alcohol process results in polyvinyl alcohol copolymers having suitable cold-water (20°C) solubility. Such a process produces polyvinyl alcohol copolymer agglomerate particles having a “popcorn-like” morphology as discussed in the above-incorporated disclosure.

The polyvinyl acetate is converted to polyvinyl alcohol via hydrolysis or alcoholysis processes generally known to those of ordinary skill in the relevant art. In such processes, the polyvinyl acetate is contacted with an alkali catalyst such as sodium hydroxide or sodium methylate. The major products of this reaction are polyvinyl alcohol and methyl acetate.

The resulting polyvinyl alcohols, of course, will have substantially the same monomer makeup and degree of polymerization as the starting polyvinyl acetates.

All the samples (R-0 to R-5) in the examples of the current disclosure have (i) methyl acrylate content of from about 0.1 mol% to about 15.0 mol% based on the total moles of monomers, (ii) a degree of polymerization of from about 300 to about 3000, and (iii) a degree of hydrolysis of from about 70% to 100%.

The samples (R-0 to R-5) of the current disclosures have a degree of hydrolysis of from about 70%, or from about 85%, or from about 93%, or from 95% or greater, or from about 98%, or from about 99%, to 100% (maximum).

In one embodiment, a first solution of typically about 30 wt.% to about 60 wt.% polyvinyl acetate copolymers in methanol, and a second solution of dilute sodium methylate alcoholysis catalyst in methanol, are continuously fed to an alcoholysis unit wherein the reaction proceeds to produce a first slurry of the alcoholyzed polyvinyl acetate (polyvinyl alcohol) and methyl acetate.

Catalyst amount typically ranges from about 0.2 wt.% to about 0.5 wt.% based on the weight of the reaction mixture.

The temperature of the alcoholysis reaction in the alcoholysis unit is typically from about 58°C, or from about 64°C, to about 70°C, or to about 68°C. The pressure within the alcoholysis unit ranges from slightly below atmospheric pressure to slightly above atmospheric pressure but is typically slightly above atmospheric pressure.

The alcoholysis unit contains an agitation means so that the alcoholysis is at least partially conducted under agitation conditions. Such agitation means are well known to those of ordinary skill in the relevant art.

When the alcoholysis reaches about 40-50%, the polymer partially precipitates. The insoluble material takes the form of a gel of polymer molecules solvated with methanol. As the solubility decreases by further alcoholysis, the gel becomes tougher and begins to reject the associated solvent molecules. When the alcoholysis is completed, the polymer and solvent are mutually insoluble. If this gel is allowed to stand undisturbed, alcoholysis proceeds and the product is obtained in a massive, unworkable form. However, if the gel is worked mechanically (agitated) during this range above about 40% alcoholysis, the polymer will break down to finely-divided solids insoluble in the alcohol. The collapsing gel traps and sticks together with the fine particles from the previous alcoholysis cycle producing polyvinyl alcohol of a desired “popcorn ball” morphology.

In one embodiment, the alcoholysis unit is made up of a primary alcoholysis vessel where the reaction proceeds to produce a slurry of partially alcoholyzed polyvinyl acetate. The slurry from the primary alcoholysis vessel overflows to an agitated hold vessel which provides additional residence time for completing the alcoholysis reaction. The slurry from the agitated hold vessel is then pumped through one or more finisher units to react short-circuited polyvinyl acetate, thus ensuring that the conversion is raised to 99.5% or higher of desired completion.

The resulting polyvinyl alcohol slurry is pumped to a neutralizing unit (samples R-0 to R-4) along with an acid to neutralize less than a predominant portion (less than 50 equivalent %), or less than 25 equivalent %, or less than 10 equivalent %, or less than 5 equivalent %, of any excess alkali catalyst, and generate a second slurry. Typically, the acid employed is acetic acid. The temperature entering neutralizing unit is slightly lower than in the alcoholysis unit, generally in the range of about 53°C to about 60°C, and typically in the range from about 55°C to about 58°C. Pressure conditions in the neutralizing unit are typically similar to those in the alcoholysis unit. The slurry is then subjected to heat treatment at the heat treatment unit for a period of 10 to 20 minutes (all the samples except R-1 and R-5 were subjected to heat treatment). Based on the percent crystallinity desired, temperature of the heat treatment unit may vary from 100 to 130°C.

The thermally treated slurry is fed to a solids-liquid separation unit where polyvinyl alcohol is separated from the slurry to generate a polyvinyl alcohol wet cake and separated liquids. The solids-liquid separation unit may be a centrifuge and/or filtration device or other conventional solids-liquid separation device.

The temperature of the first slurry may be reduced in the thermal treating unit to less than the temperature entering the thermal treating unit. Depending on the desired morphology of the final polyvinyl alcohol copolymer particulate, the temperature may be reduced to less than 50°C, or to less than 40°C, or to less than 35°C, or to less than 30°C, or to less than 25°C, or to less than ambient conditions, with the lower temperatures resulting in higher amorphous and less crystalline content. The thermal treatment unit may be a holding tank with mild heating, or no heating or even active cooling so that the temperature of the slurry is reduced between entry and exit. R-0 was the only sample that was not subjected to heat treat.

Lowering of the heat treatment temperature of the copolymers from 110°C to about 50°C (no heat added) alters the key properties of the polymer. For example %warm water solubles increased from under 2% to over 99% (compare samples R-0 to R-1, Table 2).

The process further comprises the step of washing the polyvinyl alcohol wet cake to produce a purified polyvinyl alcohol wet cake, which is then subject to the drying step. The resulting polyvinyl alcohol wet cake may optionally be purified by feeding the wet cake into a washing unit where it is contacted typically with a fresh or recycled methanol stream to remove ash components and other contaminates to generate a purified polyvinyl alcohol wet cake.

In order to generate the final particulate agglomerated copolymer particles, the purified polyvinyl alcohol wet cake after centrifugation, or the wet cake if the washing unit is not present or not utilized, is fed to a drying unit where it is dried via conventional means to remove sufficient remaining liquid content so that the resulting particulate agglomerated polyvinyl alcohol copolymer particles may be recovered. In some embodiments, the resulting particulate agglomerated polyvinyl alcohol copolymer particles may be in the form of a free-flowing powder.

D(90) particles sizes of the polyvinyl alcohol copolymer agglomerated particles produced by the above slurry alcohol process range from about 1 μm, or from about 10 μm, to about 1000 μm, or to about 400 μm.

Bulk density of the polyvinyl alcohol copolymer agglomerated particles produced by the above slurry alcohol process may be 0.55 g/cm³ or less, and for example, about 0.50 g/cm³ or less.

The mixing of the polyvinyl alcohol, alkalizing agent and optionally polyglycol may be carried out in any conventional manner, for example, dry mixing, blade mixing, fluidized bed mixing, mill mixing, solvent system mixing, or spraying as long as the mixing results in intimate contact between the polyvinyl alcohol and alkalizing agent.

The diverting agents of this disclosure are prepared by placing the resins described above under extreme pressure. As the copolymers adhere to themselves in the compaction process no binder may be needed to agglomerate the material fines. Additives such as fillers and plasticizers may be added to the resin as necessary prior to compaction. The compaction granulation is carried out using a double roll compactor. The resin is fed between two counter-rotating roll presses. The rolls apply extreme pressure, to press the resin into a sheet-like form. This sheet of material is then fed through a granulator, where it is broken up into uniformly sized granules. A screener sorts the agglomerated particle according to size. Particle that are outside the desired size range are recycled from the screener back to the compactor. This is a dry process that does not require an additional drying step.

Example 2
The sample identified as R-0 (CONTROL) is polyvinyl alcohol copolymer prepared by the copolymerization of vinyl acetate with methyl acrylate (MA), followed by the full hydrolysis of the vinyl acetate copolymer to the vinyl alcohol copolymer using sodium methylate as a catalyst. The resulting product was then neutralized with acetic acid to a slurry pH of 5.5. The methanol slurry of the neutralized product was subjected to heat treatment at 110°C. The samples were subjected to the compaction process described above. Table 2 below shows the amount of soda ash added to a 4% aqueous solution of R-0 (CONTROL) as well as the resulting change of pH.

Example 3
The samples identified as R-0 to R-5 are polyvinyl alcohol copolymers prepared by the copolymerization of vinyl acetate with methyl acrylate (MA), followed by the full hydrolysis of the vinyl acetate copolymer to the vinyl alcohol copolymer using sodium methylate as a catalyst. The resulting product is then neutralized with acetic acid to a slurry pH of 5.5. The methanol slurry of the neutralized product was subjected to heat treatment at 110°C (R-0 to R-4). Samples R-2 and R-3 were prepared by treating R-0 with 2% and 5% soda ash respectively.

R-1 was produced using 350 grams of the methanol slurry of the vinyl acetate with methyl acrylate (MA), copolymer collected from the neutralization tank prior to the heat treatment step (no heat added). The pH of the slurry was 5.5. The sample was placed in a 4-liter glass jar fitted with a three-blade glass agitator. 1000 mL of methanol was added to the sample and the mixture was continuously agitated. The product was maintained at room temperature. The product was discharged from the flask after a residence time of about 30 minutes. The polymer obtained was then filtered using cheesecloth. The procedure was repeated twice to remove impurities. The product was then dried in a vacuum oven at 50°C overnight. The resin obtained was a white, granular polymer with a degree hydrolysis of 99.7%. The yellowness index of the sample was 4.7. The percent ash was 0.44%. The viscosity was determined to be 29.6 cps (4% solids aqueous solution at 20°C determined by Hoeppler falling ball method).

R-5 was produced using 350 grams of the methanol slurry of the vinyl acetate with methyl acrylate (MA), copolymer collected from the hold-up tank prior to the neutralization step (no acetic acid added). The sample was placed in a 4-liter glass jar fitted with a three-blade glass agitator. 1000 mL of methanol was added to the sample and the mixture was continuously agitated. The product was maintained at room temperature. The product was discharged from the flask after a residence time of about 30 minutes. The polymer obtained was then filtered using cheesecloth. The procedure was repeated twice to remove impurities. The product was then dried in an oven at 110°C for 20 minutes.

Increasing the heat treatment temperature from 50°C (no heat added) to 110°C alters the key properties of the polymer. Percent warm water solubles at 35°C increased from around 2% to over 90% when the heat treatment temperature was lowered from 110°C to 50°C (compare R-0 and R-1, Table 3). Table 3 also shows that treatment of R-0 with soda ash (sample R-2 and R-3) increased the percent warm water solubles at 35°C to more or less the same level as R-1. Table 4 (in Example 4) shows that heat treatment increases the percent crystallinity and decreases the 15 minutes percent warm water solubles (% WWS) at 35°C.

Example 4
Increasing the heat treatment temperature from 50°C (no heat added) to 110°C alters the percent crystallinity (Table 4) and other key properties of the polymer including pore size, pore surface area and the porosity and crystallinity (Table 5 in Example 5).

Example 5
Table 5 shows effects of heat treatment on the key polymer properties that control the dissolution rate of the resin including pore size, pore surface area and the porosity and crystallinity. Table 5 shows that the pore size, pore surface area and the porosity of the polyvinyl alcohol significantly decreased when the heat treatment temperature was lowered from 110°C to 50°C (no heat added).

Wide Angle X-ray Diffraction (WAXD) analysis showed that the percent crystallinity decreased from 52.9% to 42.9% when the heat treatment temperature was lowered from 110°C to 50°C.

Example 6
Examples 2 to 5 show the use of soda ash to maintain the lactone ring open of acid functional comonomer modified polyvinyl alcohol. Example 6 on the other hand discloses treatment with an amine as an alternative lactone modification chemistry.

Without being bound to theory, most lactone chemistry is with nucleophiles (ring-open reactions), and in aqueous solvent systems most nucleophiles simply catalyze the hydrolysis reaction.

IR analysis shows that the major product is the amine salt from by base-catalyzed hydrolysis of lactone. No evidence for the amide product formation was observed by IR spectroscopy. Chem.2 shows lactone ring opening by treatment with amines.

In three 250 mL Erlenmeyer flasks 0% (CONTROL), 0.3% (AMINE-1), 0.4%, (AMINE-2) 0.5% and (AMINE-3) of triethyl amine (TEA) obtained from Sigma-Aldrich was added 100 ml of deionized water. The flask was placed in a water bath that was pre-set at 50°C for 30 minutes. Once the dissolution of the amine was completed, 4 grams of the neutralized and heat treated acid functional modified polyvinyl alcohol copolymer was added to each flask. At the end of 30 minutes the sample was filtered, and the filtrate was evaporated to dryness. The pH at the beginning of 30 minutes and the end of 30 minutes was also measured as shown in Table 6.

The samples treated with TEA completely dissolved due to the formation of the amine salt as a result of base-catalyzed hydrolysis of the lactone rings, and as a result, the percent warm water solubles significantly increased as shown in Table 6. The same experiment was repeated with using arginine obtained from Sigma-Aldrich (AMINE-4 to AMINE-6) and again the rate of dissolution was significantly enhanced as shown in Table 7.

Example 7
The samples shown in Table 8 were prepared by blending the neutralized and heat-treated copolymer of polyvinyl alcohol with varying amounts of soda ash to yield the pH value indicated in Table 8. The results show that the pH needs to be raised above 8.0 to obtain %WWS above 85%.

Example 8
Table 9 below shows that the %ROR increases linearly with an increase in pH (related to the concentration of the alkalizing agent).

Example 9
FIG. 1A shows that the hydrolyzed polyvinyl alcohol copolymer treated with an alkalizing agent sticks much better than a hydrolyzed polyvinyl alcohol copolymer that has not been treated with an alkalizing agent as shown in FIG. 1B.

Experimental Methods
Solubility percentage values are determined as follows: a polyvinyl alcohol is added/dispersed into de-ionized water (35°C) to a concentration of 4 wt% (g of polymer/g water). The mixture is then stirred with a triple bladed stirrer running at 200 rpm for at least 3 hours at 20°C. The slurry is then transferred to a 40 ml centrifuge bottle and centrifuged at 1500 rpm for 10 minutes. An aliquot of the resulting supernatant liquid is evaporated to dryness and the WWS content is calculated as follows:
% WWS= (Wt. of aliquot * 200)/(Wt. of aliquot * 8) * 100

All cold-water solubles percentage values reported herein were determined as follows: a polyvinyl alcohol was added/dispersed into cold de-ionized water (20° C.) to a concentration of 4 wt% (g of polymer/g water). The mixture was then stirred with a triple bladed stirrer running at 200 rpm for at least 3 hours at 20° C. The slurry was then transferred to a 40 ml centrifuge bottle and centrifuged at 1500 rpm for 10 minutes. An aliquot of the resulting supernatant liquid was evaporated to dryness and the CWS content is calculated as follows:
% CWS=(Wt. of aliquot * 200)/(Wt. of aliquot * 8) * 100

To determine swelling index, 1.0 gram of sample was placed into a test tube and was recorded as A1. The test tube was then filled halfway with deionized water and placed in a water bath which was set at 30°C. The height of the sample in the deionized water was recorded as A2 before reaching target time. The height of the sample in the deionized water was recorded after 15 minutes as A3. The sample was then removed from the test tube.

The viscosity values reported herein unless otherwise stated are of 4% aqueous solution at 20°C and were determined by Hoeppler falling ball method.

The pore size and pore surface area was measured by the mercury press-in method using a porosimeter (Autopore 950; manufactured by Shimadzu Corporation). The specific surface areas were calculated based on nitrogen absorption/desorption isotherms. An initial pressure: 2.5kPa, cell size of 5 cc and a sample size of 0.16g was employed. Table 1 clearly shows that pore size, pore surface area and percent porosity for the non-heat-treated polyvinyl alcohol was significantly lower than the heat treated polymer.

The yellowness index of the samples was determined Hunter colorimeter.

The pH of the sample was determined as a 4% aqueous solution.

The X-ray diffraction (XRD) measurements of the samples were recorded with a Rigaku Smart Lab. The following experimental conditions were used: Detector: Scintillation counter, SC-70, Scan axis: 2θ/θ, scan range: 2θ=5~80 deg, step size: 0.02 deg, current: 200mA, voltage: 45kV, soller/PSC: 5.0deg, IS longitudinal slit: 5.0deg, IS: 1 mm and RS2:2 0mm

Claims (66)

1. A particulate matter comprising (1) a hydrolyzed polyvinyl alcohol copolymer of vinyl acetate and one or more unsaturated acids, and (2) an alkalizing agent.
2. The particulate matter according to claim 1, further comprising an anti-dusting agent.
3. The particulate matter according to claim 2, wherein the anti-dusting agent includes polyglycol.
4. The particulate matter according to any one of claims 1 to 3, wherein the particulate matter is compacted.
5. The particulate matter according to any one of claims 1 to 4, wherein the particulate matter possesses a particle size of from about 3 to 18 mesh.
6. The particulate matter according to claim 5, wherein the particulate matter possesses a particle size of from about 6 to 12 mesh.
7. The particulate matter according to claim 6, wherein the particulate matter possesses a particle size of from about 6 to 8 mesh.
8. The particulate matter according to any one of claims 1 to 7, wherein a concentration of the vinyl acetate in the particulate matter is from 85 mol% to 99.9 mol% based on a total number of moles of monomers forming the hydrolyzed polyvinyl alcohol copolymer.
9. The particulate matter according to any one of claims 1 to 8, wherein the hydrolyzed polyvinyl alcohol copolymer includes the one or more unsaturated acids at an amount of from about 0.1 mol% to about 15 mol% based on a total number of moles of monomers forming the hydrolyzed polyvinyl alcohol copolymer.
10. The particulate matter according to any one of claims 1 to 9, wherein the hydrolyzed polyvinyl alcohol copolymer possesses a viscosity-average degree of polymerization of from about 300 to about 3000.
11. The particulate matter according to any one of claims 1 to 10, wherein the hydrolyzed polyvinyl alcohol copolymer possesses a degree of hydrolysis of from about 70 mol% to 100 mol%.
12. The particulate matter according to any one of claims 1 to 11, wherein the hydrolyzed polyvinyl alcohol copolymer is substantially soluble in water at a temperature of 195°F or higher.
13. The particulate matter according to any one of claims 1 to 12, wherein the one or more unsaturated acids comprises at least one selected from the group consisting of a monocarboxylic unsaturated acid, an alkyl ester of a monocarboxylic unsaturated acid, an alkali metal salt of a monocarboxylic unsaturated acid, an alkaline earth metal salt of a monocarboxylic unsaturated acid, an anhydride of a monocarboxylic unsaturated acid, a dicarboxylic unsaturated acid, an alkyl ester of a dicarboxylic unsaturated acid, an alkali metal salt of a dicarboxylic unsaturated acid, an alkali earth metal salt of a dicarboxylic unsaturated acid, and an anhydride of a dicarboxylic unsaturated acid.
14. The particulate matter according to claim 13, wherein the one or more unsaturated acids comprises an alkyl ester of the monocarboxylic unsaturated acid.
15. The particulate matter according to claim 14, wherein the alkyl ester of the monocarboxylic unsaturated acid is methyl acrylate.
16. The particulate matter according to any one of claims 1 to 15, wherein the alkalizing agent comprises at least one selected from the group consisting of a metal oxide, a metal hydroxide, a metal carbonate, a metal bicarbonate, ammonia, a primary amine, a secondary amine, a tertiary amine, an aromatic amine, an amino acid, and a polymeric amine.
17. The particulate matter according to claim 16, wherein the alkalizing agent comprises a metal carbonate.
18. The particulate matter according to claim 17, wherein the metal carbonate includes sodium carbonate.
19. The particulate matter according to claim 16, wherein the metal bicarbonate includes sodium bicarbonate.
20. The particulate matter according to claim 16, wherein the alkalizing agent comprises a tertiary amine.
21. The particulate matter according to claim 20, wherein the tertiary amine comprises triethylamine.
22. The particulate matter according to claim 16, wherein the alkalizing agent comprises an amino acid.
23. The particulate matter according to claim 22, wherein the amino acid comprises arginine.
24. The particulate matter according to any one of claims 1 to 23, wherein a concentration of the alkalizing agent in the particulate matter is from more than 0 to 50% by weight of a total weight of the hydrolyzed polyvinyl alcohol copolymer.
25. The particulate matter according to claim 24, wherein the concentration of the alkalizing agent in the particulate matter is from more than 0 to 25% by weight of a total weight of the hydrolyzed polyvinyl alcohol copolymer.
26. The particulate matter according to claim 25, wherein the concentration of the alkalizing agent in the particulate matter is from more than 0 to 10% by weight of a total weight of the hydrolyzed polyvinyl alcohol copolymer.
27. The particulate matter according to any one of claims 1 to 26, further comprising at least one additive selected from the group consisting of a plasticizer and a filler.
28. The particulate matter according to any one of claims 1 to 27, further comprising at least one other polyvinyl alcohol.
29. The particulate matter according to claim 28, wherein the at least one other polyvinyl alcohol possesses a water solubility lower than that of the hydrolyzed copolymer.
30. The particulate matter according to claim 28 or 29, wherein the at least one other polyvinyl alcohol includes a fully hydrolyzed polyvinyl alcohol homopolymer or a partially hydrolyzed polyvinyl alcohol homopolymer.
31. A composition comprising the particulate matter of any one of claims 1 to 30, wherein the composition possesses a bulk density of about 0.3 g/mL or greater.
32. The composition according to claim 31, wherein the composition possesses a bulk density of about 0.5 g/mL or greater.
33. The composition according to claim 32, wherein the composition possesses a bulk density of about 0.6 g/mL or greater.
34. The composition according to claim 33, wherein the composition possesses a bulk density of about 0.7 g/mL or greater.
35. Use of the particulate matter or the composition according to any one of claims 1 to 34 for increasing the lactone Ring Open Ratio (ROR%), solubility of a polyvinyl alcohol copolymer.
36. Use of the particulate matter or the composition according to any one of claims 1 to 34 for treating a surface formation to divert flow of a fluid from one zone of a subsurface formation to another zone of the subsurface formation.
37. Use of the particulate matter or the composition according to any one of claims 1 to 34 blended with sand, curing agent and other additives as a joint filler for the gap between two or more tiles.
38. A method of producing the particulate matter of any one of claims 1 to 30, the method comprising blending the hydrolyzed polyvinyl alcohol copolymer and the alkalizing agent to form a blend.
39. The method according to claim 38, wherein the blending is carried out by at least one process selected from the group consisting of dry mixing, blade mixing, fluidized bed mixing, mill mixing, spraying, and solvent system mixing.
40. The method according to claim 38 or 39, further comprising, immediately before the blending, hydrolyzing a polyvinyl acetate copolymer to form the hydrolyzed polyvinyl alcohol copolymer.
41. The method according to claim 38 or 39, further comprising, before the blending, neutralizing at least a portion of the hydrolyzed polyvinyl alcohol copolymer and/or heat treating the hydrolyzed polyvinyl alcohol copolymer.
42. The method according to claim 41, comprising, before the blending, the neutralizing of at least a portion of the hydrolyzed polyvinyl alcohol copolymer.
43. The method according to claim 42, wherein the heat treatment is not carried out.
44. The method according to claim 41, comprising, before the blending, the heat treating of the hydrolyzed polyvinyl alcohol copolymer.
45. The method according to claim 44, wherein the neutralizing is not carried out.
46. The method according to claim 41, comprising, before the blending, the neutralizing of at least a portion of the hydrolyzed polyvinyl alcohol copolymer, and heat treating the hydrolyzed polyvinyl alcohol copolymer.
47. The method according to claim 46, wherein the neutralizing is carried out before the heat treating.
48. The method according to claim 46, wherein a portion of the hydrolyzed polyvinyl alcohol copolymer is neutralized.
49. The method according to claim 42 or 46, wherein the neutralizing includes mixing the hydrolyzed polyvinyl alcohol copolymer with acetic acid to an acidic pH.
50. The method according to claim 49, wherein the acidic pH is from 5 to 6.
51. The method according to claims 44 or 46, wherein the heat treating includes heating the hydrolyzed polyvinyl alcohol copolymer at more than 50°C and up to 115°C.
52. The method according to any one of claims 38 to 51, further comprising compacting the blend, then granulating the blend to granules, and then sorting the granules according to particle sizes, and selecting granules having a particle size of from about 3 to 18 mesh.
53. The method according to claim 52, wherein the compacting of the blend is carried out at a pressure of 5 to 100 tons.
54. A method of increasing the lactone Ring Open Ratio (ROR%) of a polyvinyl alcohol copolymer, the method comprising adding an alkalizing agent to the polyvinyl alcohol copolymer.
55. The method according to claim 54, wherein the ROR% of the polyvinyl alcohol copolymer increases from 2-4% to at least 15%.
56. The method according to claim 54 or 55, wherein the alkalizing agent comprises at least one selected from the group consisting of a metal oxide, a metal hydroxide, a metal carbonate, a metal bicarbonate, ammonia, a primary amine, a secondary amine, a tertiary amine, an aromatic amine, an amino acid, and a polymeric amine.
57. A method of increasing solubility of a polyvinyl alcohol copolymer particulate matter, the method comprising adding an alkalizing agent to the polyvinyl alcohol copolymer particle.
58. The method according to claim 57, wherein the alkalizing agent comprises at least one selected from the group consisting of a metal oxide, a metal hydroxide, a metal carbonate, a metal bicarbonate, ammonia, a primary amine, a secondary amine, a tertiary amine, an aromatic amine, an amino acid, and a polymeric amine.
59. The method according to claims 57 or 58, wherein the method increases the solubility of the polyvinyl alcohol copolymer particle in water such that the resultant solution possesses a pH of at least 7.
60. The method according to claim 59, wherein the pH is at least 8.
61. The method according to claim 59 or 60, wherein the resultant solution further possesses a 30-minute percent warm water solubles (% WWS) at 35°C of at least 50%.
62. The method according to claim 61, wherein the 30-minute % WWS at 35°C is at least 60%.
63. A method of treating a surface formation to divert flow of a fluid from one zone of a subsurface formation to another zone of the subsurface formation, the method comprising pumping into the subsurface formation a carrier liquid comprising water and the particulate matter according to any one of claims 1 to 30.
64. The method according to claim 63, wherein the carrier liquid further comprises sand.
65. A method of filling a gap between two or more tiles, comprising applying a fluid including the particulate matter according to any one of claims 1 to 30 and sand to the gap.
66. A particulate water-soluble diverting agent comprising (1) a hydrolyzed polyvinyl alcohol copolymer of vinyl acetate and one or more unsaturated acids, and (2) an alkalizing agent.