WO2019005290A1

WO2019005290A1 - Low-temperature stabilized aqueous water clarifier composition and methods of use

Info

Publication number: WO2019005290A1
Application number: PCT/US2018/030766
Authority: WO
Inventors: Troy E. KNIGHT; Kaylie L. Young; Despina N. LOUFAKIS; Stephen M. Hoyles
Original assignee: Dow Global Technologies LLC
Current assignee: Dow Global Technologies LLC
Priority date: 2017-06-30
Filing date: 2018-05-03
Publication date: 2019-01-03
Anticipated expiration: 2019-12-30
Also published as: AR112244A1; TW201905085A

Abstract

Disclosed is an aqueous water clarifier composition stable at low temperatures, method to make, and method to use. Said aqueous water clarifier composition comprises: i) a hydrophobically modified alkylene oxide urethane copolymer; ii) a diol; iii) a glycol ether; and iv) optionally a viscosifier. The aqueous water clarifier compositions of the present invention are useful for demulsifying and clarifying oil-water dispersions and emulsions derived from petroleum industry operations.

Description

LOW-TEMPERATURE STABILIZED AQUEOUS WATER CLARIFIER

COMPOSITION AND METHODS OF USE

FIELD OF THE INVENTION

The present invention relates to a freeze protected aqueous water clarifier composition and method for demulsifying and clarifying oil-water emulsions and dispersions derived from petroleum production and refining operations using said aqueous water clarifier composition.

BACKGROUND OF THE INVENTION

A dispersion is a mixture in which one phase is dispersed in another, continuous phase, of a different composition or phase. An emulsion is a dispersion comprising two immiscible liquids, one of which is dispersed as droplets (internal phase) in the other

(continuous or external phase). Thus, all emulsions are dispersions, but not all dispersions are emulsions. Stable emulsions are those which are unable to resolve themselves into their constituent phases without some form of mechanical or chemical treatment.

In the petroleum industry, various operations including, but not limited to, exploration, production, refining and chemical processing of hydrocarbons including, but not limited to, crude oil, gas and their derivative products, routinely produce mixtures and dispersions of oil and water. Such mixtures typically also contain other compounds, including but not limited to, waxes, asphaltenes, various salts, suspended materials, biological surface active material from the ground, added surface active corrosion/scale inhibiting reagents, etc., which may vary from location to location. In addition, synthetic and natural surfactants, produced either in-situ or added in enhanced oil recovery techniques such as akali- surfactant (AS) and alkali- surfactant-polymer (ASP) floods, can cause phase separation issues. Along with the presence of these other compounds, high shear and mixing forces cause these oil and water mixtures to form dispersions and relatively stable emulsions. Some such emulsions are water in oil emulsions, commonly referred to in the petroleum industry as "regular" emulsions, in which oil is the continuous phase. Others are oil in water emulsions, commonly referred to in the petroleum industry as "reverse" emulsions, in which water is the continuous phase. "Breaking" oil-water emulsions means separation of the oil and water phases. The term "breaking" implies that the emulsifying films around the droplets of water or oil are "broken" so that coalescing may occur and result in separation of the oil and water phases over time, for example, by gravitational settling. For example, demulsifiers describe the class of agents which break or separate an emulsion, whether normal or reverse, into its constituent phases. Clarifiers describe compounds which are applied to break emulsions and separate the oil phase from the water, thereby, making the water "clearer." There is known to be some overlap in the types of compounds which effectively demulsify and those which clarify, i.e., some compounds are useful for both demulsifying and clarifying oil- water emulsions and dispersions.

During the production phase of an oil well, a large quantity of water may be pumped down into the ground via one or more injector wells to push oil in the underground formation toward the producing well and out of the ground. As the wells age, formation water is produced from the well in combination with the oil. Further, in many secondary and tertiary oil recovery techniques such as steam flooding, oil extraction from tar/oil sands and steam assisted gravity drainage (SAGD), large amounts of water are used to recover oil. In such circumstances, the oil typically comes out of the ground as an emulsion. To break this emulsion, i.e., separate the water from the oil phase, demulsifiers such as polyalkylene glycols (PAGs), block copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), and alkylphenol resin alkoxylates are generally used. In some cases water clarifiers are also added to the crude emulsion stream.

Once the emulsion is separated into an oil fraction and a water fraction, the produced water fraction (i.e., "produced water") may contain as little as 100 parts per million (ppm) oil entrained in the water phase. In other words, a "reverse" i.e., oil in water, emulsion is formed. This emulsion appears anywhere from brown to black, depending on the amount of impurities present. Such produced water may be generated in huge quantities (i.e., up to millions of gallons per day), and is either reinjected into the formation, or disposed of into the ocean. Governmental regulations, such as the US Clean Water Act and the US EPA Code of Federal Regulations in the United States, require reduction of the amount of oil content down to very low levels before the produced water may be discharged. Although the amount of oil permitted in discharged water under such regulations varies from jurisdiction to jurisdiction, the standard is generally very low, i.e., usually much less than 100 ppm oil in water. Further with the increasing cost and regulation on fresh water use, low levels of oil are demanded for water reuse. The practice of reducing the oil in water from the naturally occurring amount to below 50 ppm is commonly known as "clarification," and is simply the breaking of the reverse emulsion. Clarification of such demulsified oilfield water typically involves use of acrylate polymers, cationic polymers, cationic poly electrolytes, and water- soluble amphiphilic polymers to flocculate suspended oily and particulate materials and, thereby, obtain clear(er) water.

Successful selection and use of effective polymer compounds to demulsify and clarify oil-water emulsions formed during petroleum industry operations is very complex because whether or not a particular polymer will work depends on many factors including, but not limited to: the geology and location of underground oil-containing formations, the source of water, the nature of suspended solids, the type of oil, the nature of other reagents used, etc. Thus, there is no one solution for the practice of demulsification and clarification of oilfield emulsions. Depending on individual oilfields and the conditions involved, different polymers will provide optimum performance in different locations.

The prior art includes many patents and general literature relating to demulsification and clarification of oil- water dispersions and emulsions produced by petroleum industry operations.

For example, US Patent Application Publication US 2007/0244248 discloses the use of a polymer containing aromatic and oleophilic groups for demulsifying oil-water emulsions. USP 5,100,582 discloses a very specific composition of tetrapolymer containing random combinations of acrylic acid, methacrylic acid, methyl methacrylate and butyl acrylate for use as demulsifying agent for water-in-crude oil.

Further, USP 6,025,426 and USP 5,330,650 each teach the use of hydrophilic cationic copolymers of acrylamide having high molecular weight as water clarification aids. USP 4,582,628 discloses the use of vinyl-type polymers, derived from hydrophilic and hydrophobic vinyl monomers, for demulsifying petroleum industry emulsions of oil and water.

Low molecular weight, water soluble, cationic polymers of dimethylaminoethyl acrylate methyl chloride and benzyl chloride quaternary salt are disclosed in USP 5,643,460 for breaking oil in water emulsions resulting from oilfield operations. USP 5,472,617 provides a method for demulsifying a crude oil and water emulsion which involves adding demulsifiers made from (meth)acrylates of oxyalkylates copolymerized with hydrophilic monomers.

Chinese Patent Application Publication CN1883740 discloses the use of polymers derived from hydrophobic (meth)acrylate ester monomers and hydrophilic (meth)acrylic acid monomers, and having molecular weights of 5,000 to 100,000 g/mol, for demulsifying crude oil and water emulsions.

US Patent Publication US 2011 0031163 discloses hydrophobically modified, surfactant modified, and lightly crosslinked anionic acrylate copolymers for separating oil and water dispersions or emulsions generated in connection with oilfield operations.

However, none of the above mentioned patents and publications disclose stabilized polymers for breaking oil- water emulsions derived from oilfield and oil refining operations located and/or operating in extremely cold environments, such as arctic regions. Improved low-temperature stability, sometimes referred to as freeze protection, is important for not only use, but also for storage and transportation. This includes both shipping in barrels and pumping through pipes, polymer compounds to petroleum industry operations in cold environments. If aqueous solutions of polymers are stored in a location where the ambient temperature falls below 0°C, the solutions may freeze, separate, or form sediment thus inhibiting the ability to pump sufficient polymer solution to the desired fluid. There exists a need for a low-temperature aqueous water clarifier composition useful for demulsifying petroleum industry emulsions of oil and water that demonstrates improved low-temperature stability.

SUMMARY OF THE INVENTION

The present invention provides such a stabilized aqueous water clarifier composition and a method for use thereof for separating oil and water phases of an oil-water dispersion or emulsion derived from petroleum industry operations, wherein the aqueous water clarifier composition is stable between -40°C to 60°C. The aqueous water clarifier composition is provided to the oil-water emulsion in an amount to result in a demulsifying effective. The aqueous water clarifier composition comprises i) a hydrophobically modified alkylene oxide urethane copolymer, preferably a hydrophobically modified ethoxylated urethane (HEUR); ii) a diol, preferably ethylene glycol, propylene glycol, or mixtures thereof; iii) a glycol ether having the structure:

R¹ R

I I

R²-0-CH₂CH₂-OH wherein R and R¹ are independently H, or a Ci to C5 linear or branched alkyl group and R² is R³-(OCH2CH2)_n- wherein R³ is a H or a linear or branched Ci to C3 alkyl group and n is equal to 1 or 2, preferably ethyleneglycol monoethylether, ethyleneglycol monopropylether, ethyleneglycol monobutylether, ethyleneglycol monopentylether, or mixtures thereof; iv) optionally a viscosifier, preferably xanthan gum, wellan gum, schleroglucan, and/or guar gum; and v) water.

In another embodiment, the present invention provides a method for inhibiting and mitigating the formation of oil-water emulsions generated during petroleum industry operations from oil and aqueous precursors which become mixed during the operations. This method for inhibiting and mitigating the formation of oil- water emulsions comprises providing a demulsifying effective amount, preferably 1 to 10,000 ppm, of the aforesaid aqueous water clarifier composition to the oil precursor, the aqueous precursor, or both, prior to, during or after mixing of the precursors.

The oil-water dispersion or emulsion may be an oil in water dispersion or emulsion, or a water in oil dispersion or emulsion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plot of viscosity versus shear rate for Examples 8, 18, and 19. FIG. 2 is a photograph of the results of a water clarification test for examples with and without a water clarifier composition of the present invention.

DETAILED DESCRIPTION OF THE INVENTION A "polymer," as used herein and as defined by FW Billmeyer, JR. in Textbook of

Polymer Science, second edition, 1971, is a relatively large molecule made up of the reaction products of smaller chemical repeat units. Polymers may have structures that are linear, branched, star shaped, looped, hyperbranched, crosslinked, or a combination thereof; polymers may have a single type of repeat unit ("homopolymers") or they may have more than one type of repeat unit ("copolymers"). Copolymers may have the various types of repeat units arranged randomly, in sequence, in blocks, in other arrangements, or in any mixture or combination thereof. Chemicals that react with each other to form the repeat units of a polymer are known herein as "monomers," and a polymer is said herein to be made of, or comprise, "polymerized units" of the monomers that reacted to form the repeat units. The chemical reaction or reactions in which monomers react to become polymerized units of a polymer, whether a homopolymer or any type of copolymer, are known herein as "polymerizing" or "polymerization."

In all of the compositions herein the weight percentages will always total 100 percent. Thus, the percentages stated hereinbelow to describe the proportions of the various monomeric components in the polymer are all based on the total weight of the polymer, with the total being 100 percent

Polymer molecular weights can be measured by standard methods such as, for example, size exclusion chromatography (also called gel permeation chromatography) or intrinsic viscosity.

The term "petroleum industry operations," as used herein, includes, but not is limited to, activities and processes for exploration, production, refining and chemical processing of hydrocarbons including, but not limited to, crude oil, gas and their derivatives. For example, exploration often involves the initial drilling of wells wherein drilling fluid, or drilling mud, which is typically a mixture of liquid and gaseous fluids and solids, is used as lubricant and heat sink. Suitable dispersants are helpful to stabilize such mud to a homogenous composition. Production operations include, but are not limited to, pumping large quantities of water into the ground, as described above, which commensurately generates large quantities of "formation water," an oil in water dispersion or emulsion. Breaking of such emulsions with additives to remove and recover oil from the produced water is a common and beneficial practice. Oil refining processes, for example, include but are not limited to, the removal of inorganic solids and salts (referred to as "desalting") from produced oil. Desalting operations produce oil in water mixtures which require clarification and/or demulsifying prior to discharge or reuse. Lastly, chemical processing in the petroleum industry includes many various activities such as, for example, without limitation, production of ethylene by fractionation which involves water quench operations. The quench operations of ethylene manufacturing generate quench waters containing heavy, middle and light hydrocarbons and, therefore, require demulsifying and/or clarification. Persons of ordinary skill in the art will readily recognize the many various operations performed in the petroleum industry to which the present invention is reasonably applicable and the invention is intended to include all such applications.

The term "oil-water emulsion," as used herein, includes dispersions even where a stable emulsion does not exist and also includes water in oil emulsions and oil in water emulsions, as well as multiple emulsions, such as water in oil in water. Oil is the continuous, or external, phase in water in oil emulsions. For oil in water emulsions, the continuous, or external, phase is water.

Endpoints of ranges are considered to be definite and are recognized to incorporate within their tolerance other values within the knowledge of persons of ordinary skill in the art, including, but not limited to, those which are insignificantly different from the respective endpoint as related to this invention (in other words, endpoints are to be construed to incorporate values "about" or "close" or "near" to each respective endpoint). The range and ratio limits, recited herein, are combinable. For example, if ranges of 1-20 and 5-15 are recited for a particular parameter, it is understood that ranges of 1-5, 1-15, 5- 20, or 15-20 are also contemplated and encompassed thereby.

The term stable when referring to the aqueous water clarifier compositions of the present invention is defined herein to mean the composition does not form a gel or precipitate due to temperature, be it at a low-temperature, a high temperature, or cycling between a low-temperature and a high temperature. Typically, low temperatures are -40°C or higher and high temperatures are 60°C and lower.

The present invention provides an aqueous water clarifying composition, a method to make said clarifying composition, and for use thereof to separate oil and water phases of an oil-water dispersion or emulsion derived from petroleum industry operations.

The aqueous water clarifying composition comprises a hydrophobically modified alkylene oxide urethane copolymer, i.e., copolymers including both alkylene oxide and urethane groups. The copolymers preferably have a Mw of 1,000 to 500,000 Daltons but more preferably 10,000 to 100,000 Daltons. The copolymers are preferably non-ionic and may be branched or linear. The copolymers preferably include at least 40 wt%, 50 wt%, 85 wt%, 90 wt% and in some embodiments even 95 wt% of alkylene oxide groups along with urethane groups preferably serving as linking groups between blocks of alkylene oxide or as terminal groups. The term "alkylene oxide" is used interchangeable with the term

"oxyalkylene" and both collectively refer to units having the structure -(O-A)- wherein O-A represents the monomeric residue of the polymerization reaction product of a C2-4 alkylene oxide. Examples include but are not limited to: oxy ethylene with the structure -(OCH2CH2)- ; oxypropylene with the structure -(OCH(CH3)CH2)-; oxytrimethylene with the structure - (OCH2CH2CH2)-; and oxybutylene with the general structure -(OC4H8)-. Polymers containing these units are often referred to as "poly oxy alky lenes." The poly oxyalkylene units can be homopolymeric or copolymeric. Examples of homopolymers of

polyoxyalkylenes include, but are not limited to polyoxyethylene, which contains units of oxyethylene; polyoxy propylene, which contains units of oxypropylene;

polyoxytrimethylene, which contains units of oxytrimethylene; and polyoxybutylene, which contains units of oxybutylene. Examples of polyoxy butylene include a homopolymer containing units of 1,2-oxybutylene, - OCH(C2Hs)CH2)-; and polytetrahydrofuran, a homopolymer containing units of 1,4-oxybutylene, - (OCH2CH2CH2CH2)-. Alternatively the polyoxyalkylene segments can be copolymeric, containing two or more different oxyalkylene units. The different oxyalkylene units can be arranged randomly to form a random polyoxyalkylene; or can be arranged in blocks to form a block polyoxyalkylene. Block polyoxyalkylene polymers have two or more neighboring polymer blocks, wherein each of the neighboring polymer blocks contain different oxyalkylene units, and each polymer block contains at least two of the same oxyalkylene units. Oxyethylene is the preferred oxyalkylene segment. The subject copolymer preferably includes a plurality of oxyalkylene segments or blocks having a Mw of from 200 to 10,000 and more preferably 2,000 to 10,000. The oxyalkylene segments are preferably linked by reaction with a multi- functional isocyanate (forming a urethane). The multi-functional isocyanates can be aliphatic, cycloaliphatic, or aromatic; and can be used singly or in admixture of two or more, including mixtures of isomers. Examples of suitable organic polyisocyanates include 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-l,6- diisocyanato hexane, 1,10-decamethylene diisocyanate, 4,4'-methylenebis

(isocyanatocyclohexane), 1,4-cyclohexylene diisocyanate, l-isocyanato-3- isocyanatomethyl-3,5,5-trimethylcyclohexane, m- and p-phenylene diisocyanate, 2,6- and 2,4-toluene diisocyanate, xylene diisocyanate, 4-chloro-l,3-phenylene diisocyanate, 4,4'- biphenylene diisocyanate, 4,4'-methylene diphenylisocyanate, 1,5-naphthylene

diisocyanate, 1,5-tetrahydronaphthylene diisocyanate, hexamethylene diisocyanate trimer, hexamethylene diisocyanate biuret, and triphenylmethane-4,4',4"-triisocyanate.

Preferred species of copolymers include so-called "HEUR" materials (i.e.

hydrophobically modified ethoxylated urethane) conventionally used as rheology modifiers in water-based fluids including cosmetics, paints, detergents, personal care formulations. Examples of HEUR materials are described in: US2014/0011967, US2013/015819, US2012/0130000, US2009/0318595, US7741402, and US4155892 - the entire subject of which is incorporated herein by reference. HEUR materials are typically built up from water-soluble poly (oxyethylene) segments joined by urethane groups. Hydrophobic end groups may be incorporated by reacting hydrophobic alcohols, amines, or acids with the diisocyanate groups, the resulting hydrophobic group effectively including the hydrophobic residue of the diisocyanate. Alternatively, hydrophobic monoisocyanates may be reacted with terminal poly(oxy ethylene) chains. The diisocyanates used to link the water-soluble segments serve as internal hydrophobic groups, if the diisocyanate molecule is large enough and hydrophobic enough, or internal hydrophobes may be efficiently built up by reacting the diisocyanates with hydrophobic active hydrogen compounds, such as diols or diamines. Excess diisocyanate may also be reacted with water to build up hydrophobic blocks.

The hydrophobic ally modified alkylene oxide urethane copolymer is present in an amount equal to or greater than 2 weight percent, preferably equal to or greater than 4, and more preferably equal to or greater than 6 weight percent, based on the total weight of the aqueous water clarifier composition. The aqueous water clarifier composition comprises the hydrophobically modified alkylene oxide urethane copolymer in an amount equal to or less than 20 weight percent, preferably equal to or less than 15, and more preferably equal to or less than 10 weight percent, based on the total weight of the aqueous water clarifier composition.

The aqueous water clarifier composition further comprises one or more alcohol.

Suitable alcohols may be selected from the group consisting of glycols, glycol ethers, methanol, ethanol and combinations thereof. Preferably, the alcohol is represented by the following formula:

R¹ R

I I

R²-0-CH₂CH₂-OH wherein R and R¹ are independently H, or a Ci to Cs linear or branched alkyl group and R² is H, a Ci to Cs linear or branched alkyl group or R³-(OCH2CH2)_n- wherein R³ is a H or a linear or branched Ci to Cs alkyl group and n is equal to 1 or 2, with the proviso that if R¹ and/or R is a Ci to Cs alkyl group, R² is H or a Ci to C3 linear or branched alkyl group.

Preferably, the glycol ether has the structure: R¹ R

I I

R²-0-CH₂CH₂-OH wherein R and R¹ are independently H, or a Ci to Cs linear or branched alkyl group and R² is R³-(OCH2CH2)_n- wherein R³ is a H or a linear or branched Ci to C3 alkyl group and n is equal to 1 or 2. Preferably, the alcohol is selected from methanol, ethanol, propanol, isopropanol, diethyleneglycol monobutyl ether, ethyleneglycol monobutyl ether, diethylene glycol monoethyl ether, ethyleneglycol monobutylether, ethyleneglycol monopropylether, dipropyleneglycol monomethyl ether, dipropyleneglycol monobutyl ether, propylene glycol monomethyl ether, propyleneglycol monopropyl ether, propyleneglycol monobutyl ether, butyl acetate, propylene glycol, ethylene glycol, and combinations thereof.

In one embodiment of the present invention, the aqueous water clarifier composition comprises a diol, preferably ethylene glycol, propylene glycol, or a mixture thereof and a glycol ether, preferably ethyleneglycol monomethylether, ethyleneglycol monoethylether, ethyleneglycol monopropylether, ethyleneglycol monobutylether, ethyleneglycol monopentylether, or mixtures thereof.

The aqueous water clarifier composition comprises each one or more alcohol in an amount equal to or greater than 1 weight percent, preferably equal to or greater than 7.5, and more preferably equal to or greater than 15 weight percent, based on the total weight of the aqueous water clarifier composition. The aqueous water clarifier composition comprises each one or more alcohol in an amount equal to or less than 50 weight percent, preferably equal to or less than 40, and more preferably equal to or less than 30 weight percent, based on the total weight of the aqueous water clarifier composition.

The aqueous water clarifier composition may further comprises a viscosifier.

Suitable viscosifiers include galactomannans such as guar, derivatized guars such as hydroxypropyl guar, carboxymethyl guar, carboxymethylhydroxypropyl guar,

hydrophobically modified galactomannans, xanthan gum, hydroxyethylcellulose, and polymers, copolymers and terpolymers containing acrylamide monomer, and the like.

Some non-limiting examples of suitable viscosifiers include: polysaccharides, such as, for example, guar gums, high-molecular weight polysaccharides composed of mannose and galactose sugars, including guar derivatives such as hydroxypropyl guar (HPG), carboxymethyl guar (CMG), and carboxymethylhydroxypropyl guar (CMHPG), and other polysaccharides such as xanthan, diutan, and scleroglucan; cellulose derivatives such as hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC),

carboxymethylhydroxypropyl cellulose (CMHEC), and the like; synthetic polymers such as, but not limited to, acrylic and methacrylic acid, ester and amide polymers and copolymers, polyalkylene oxides such as polymers and copolymers of ethylene glycol, propylene glycol or oxide, and the like. The polymers are preferably water soluble. Also, associative polymers for which viscosity properties are enhanced by suitable surfactants and hydrophobically modified polymers can be used, such as cases where a charged polymer in the presence of a surfactant having a charge that is opposite to that of the charged polymer, the surfactant being capable of forming an ion-pair association with the polymer resulting in a hydrophobically modified polymer having a plurality of hydrophobic groups, as described published application US 2004209780.

Preferably, the viscosifier is xanthan gum, wellan gum, schleroglucan and/or guar gum.

If present, the viscosifier is present in an amount equal to or greater than lOOppm, preferably equal to or greater than 250ppm, and more preferably equal to or greater than 500ppm weight percent, based on the total weight of the aqueous water clarifier composition. If present, the aqueous water clarifier composition comprises the viscosifier in an amount equal to or less than 1 weight percent, preferably equal to or less than 0.1 weight percent, and more preferably equal to or less than 750ppm, based on the total weight of the aqueous water clarifier composition.

The aqueous water clarifier composition of the present invention comprises water. The amount of water will make up the balance of the weight of the aqueous water clarifier composition such that the weight percents for all the components, i.e., the hydrophobically modified alkylene oxide urethane copolymer, one or more alcohol, optionally a viscosifier, any additional components, and water will add up to a total of 100 weight percent.

The present invention also provides for a method to make the aqueous water clarifier composition of the present invention.

In one embodiment, the hydrophobically modified alkylene oxide urethane copolymer, one or more alcohol, optionally the viscosifier, and the water may be added together in any order or sequence and each component may be added in its entire amount at once or a partial amount at two or more times.

In one embodiment, the hydrophobically modified alkylene oxide urethane copolymer, is solubilized in part, or all, of the water with all, or part, of the glycol ether prior to adding the bulk of the diol (i.e., greater than 85 wt% of the diol). The viscosifier may be added at any time before or after the addition of the diol.

The present invention also provides a method for inhibiting and mitigating the formation of oil-water emulsions generated during petroleum industry operations from oil (organic) and water (aqueous) precursors which become mixed during said operations and otherwise form oil-water dispersions and emulsions. This method for inhibiting and mitigating the formation of oil-water emulsions comprises providing the above-described aqueous water clarifier composition to the oil precursor, the aqueous precursor, or both, prior to, during or after mixing of the precursors.

Whether provided to the precursors of oil- water dispersion or emulsions, or to already formed oil-water dispersions or emulsions, the use of the aqueous water clarifier composition in accordance with the present invention may reduce the viscosity of the resulting mixture of oil and water and, thus, better flow characteristics may be achieved which may facilitate further processing and handling.

The way in which the aqueous water clarifier composition is provided to the oil- water emulsion is not critical and many delivery methods are well known and understood by persons of ordinary skill in the relevant art.

The use of reverse emulsion breaker compounds, which are typically lower molecular weight, high charge materials that break reverse emulsions so that the flocculants can function better, is common in petroleum industry operations. Examples of such reverse emulsion breaker compounds are, without limitation, poly amines, poly amine quats, tannins, and metal salts (A1-, Fe-based chlorides, hydroxides, etc.). The method of the present invention may further comprise use of the above-described aqueous water clarifier compositions along with such reverse emulsion breaker compounds.

Blends and formulations of the aqueous water clarifier composition with other components such as, without limitation, additional antifreeze agents, solvents, biocides, neutralizing agents, flow aids, and the like, may be formed and used in accordance with the method of the present invention. Such blends and formulations may be prepared as an emulsion or aqueous solution or otherwise.

It will be understood that the embodiments of the present invention described hereinabove are merely exemplary and that a person skilled in the art may make variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the present invention.

EXAMPLES

In the Examples 1 to 24 and in the Tables: "HEUR" is a hydrophobically modified ethoxylated urethane available as

ACRYSOL™ RM-8 from The Dow Chemical Company;

"EG" is ethylene glycol;

"PG" is propylene glycol;

"EGPE" is ethyleneglycol monopropylether available as Propyl CELLOSOLVE™ from The Dow Chemical Company;

"EGBE" is ethyleneglycol monobutylether available as Butyl CELLOSOLVE from The Dow Chemical Company;

"EGHE" is ethyleneglycol monohexylether available as Hexyl CELLOSOLVE from The Dow Chemical Company;

"MTG" is methoxytriglycol available;

"PGBE" is propyleneglycol monobutylether available as DOWANOL™ PnB from The Dow Chemical Company;

"DEGHE" is diethylene glycol monohexyl ether available as Hexyl CARBITOL™ L from The Dow Chemical Company; and

"Xanthan gum" is xanthan gum.

In the Tables, characterization of appearance and flow are determined visually. Flow is determined by inverting the sample vial and seeing if the contents flow. Examples 1 to 6.

Table 1 shows formulations at different HEUR loading levels. Examples 2 to 6 demonstrate acceptable flow and phase stability.

Table 1

^;not an example of the present invention

Examples 7 to 10.

Examples 7 to 10 are allowed to remain at -40°C for 4 days. It can be seen that Examples 7 and 8 showed viscous flow while Examples 9 and 10 flowed easily when inverted. Pour point results showed very low values for Examples 9 and 10.

Table 2

^;not an example of the present invention Examples 11 to 16.

In Examples 11 to 17, xanthan gum is added at various levels to the composition of Example 8. As can be seen in Table 3, xanthan gum dosages equal to or greater than 500ppm yielded nearly homogeneous or homogeneous formulations for 1 week at -40 °C. Examples 14 to 17 all remained phase stable and flowable for 4 weeks at -40°C. Table 3

^;not an example of the present invention Examples 18 and 19.

Examples 18 and 19 are compositions corresponding to the compositions of

Examples 16 and 17, respectively, but are kept at -40°C for 4 weeks then subjected to temperature cycling. The one cycle of the "low/high" temperature cycling consists of cycling from -40°C for 20 hours, to room temperature for 4 hours, to 60°C for 20 hours, back to room temperature for 4 hours, back to -40°C for 20 hours, and back to room temperature. "Low/room temperature" temperature cycling consists of cycling from - 40°C for 20 hours, to room temperature for 4 hours and then repeated for a total of four cycles.

The viscosity profiles for the two sets of formulations is measured using the TA rheometer and is shown in FIG. 1.

Examples 20 to 22.

As can be seen from the data in Table 4, Examples 20 to 22 using diethylene glycol monohexyl ether, methoxytriglycol, and propyleneglycol monobutylether did not support low-temperature phase stability.

Table 4

^;not an example of the present invention Examples 23 and 24.

Water clarification is demonstrated via a bottle test. Example 23 is a blank (i.e., no clarifier added) and Example 24 is the results using the composition of Example 16. An artificial emulsion is prepared in the lab using aged crude oil. Then, 8 oz. (185 mL) prescription bottles are filled with emulsion to the 100 mL mark and are dosed with 50ppm actives of Example 16. One bottle was left blank to serve as the control. Both bottles are hand-shaken for 50 times and are allowed to stand in front of a light source to observe performance. The results are shown in FIG. 2. The test showed that the bottle that is dosed with a clarifier composition of the present invention resulted in good oil- water separation with the resulting water clearer than the blank.

Claims

What is claimed is:

An aqueous water clarifier composition comprising:

i) a hydrophobic ally modified alkylene oxide urethane copoly

ii) a diol;

iii) a glycol ether with the structure:

R¹ R

wherein R and R¹ are independently H, or a Ci to C5 linear or branched alkyl group and R² is R³-(OCH2CH2)_n- wherein R³ is a H or a linear or branched Ci to C3 alkyl group and n is equal to 1 or 2;

iv) water;

and

v) optionally, a viscosifier,

wherein the aqueous water clarifier composition is stable between -40°C to 60°C.

2. The composition of Claim 1 wherein the hydrophobic ally modified alkylene oxide urethane copolymer is a hydrophobically modified ethoxylated urethane (HEUR).

3. The composition of Claim 1 wherein the diol is ethylene glycol, propylene glycol, or mixtures thereof.

4. The composition of Claim 1 wherein the glycol ether is ethyleneglycol monoethylether, ethyleneglycol monopropylether, ethyleneglycol monobutylether, ethyleneglycol monopentylether, or mixtures thereof.

5. The composition of Claim 1 comprising a viscosifier selected from xanthan gum, wellan gum, schleroglucan, and/or guar gum.

6. A method for inhibiting and mitigating the formation of oil-water emulsions generated during petroleum industry operations from oil and aqueous precursors which become mixed during said operations, said method comprising providing to the oil precursor, the aqueous precursor, or both, prior to, during or after mixing of the precursors, a demulsifying effective amount of an aqueous water clarifier composition comprising: i) a hydrophobically modified alkylene oxide urethane copolymer;

ii) a diol;

a glycol ether with the structure: R¹ R

I I

R²-0-CH₂CH₂-OH wherein R and R¹ are independently H, or a Ci to Cs linear or branched alkyl group and R² is R³-(OCH2CH2)_n- wherein R³ is a H or a linear or branched Ci to C3 alkyl group and n is equal to 1 or 2;

iv) water;

and

v) optionally a viscosifier,

7. The method according to Claim 6, wherein the oil-water dispersion or emulsion is an oil in water dispersion or emulsion.

8. The method according to Claim 6, wherein the oil-water dispersion or emulsion is a water in oil dispersion or emulsion.

9. The method according to Claim 6, wherein the aqueous water clarifier composition is provided to the aqueous precursor.

10. The method according to Claim 6, wherein the demulsifying effective amount of the aqueous water clarifier composition is 1 to 10,000 ppm.