Α-olefins – maleate copolymers, formulations thereof, and their use as pour point depressants or wax deposition inhibitors

Abstract

Copolymers comprising C16 to C50 olefins and at least three different mono- or di-maleates. The three types of mono- or di-maleates are firstly esters with linear C10 to C22 alkyl groups, secondly esters with linear C24 to C50 alkyl groups, and thirdly branched C20 to C50 alkyl groups. The invention further relates to a formulation comprising these copolymers and an organic solvent and to their use as pour point depressant for crude oil, fuel oil, mineral oil and / or mineral oil products, preferably as pour point depressant for crude oil.

Description

[0001] a-Olefins - maleate copolymers, formulations thereof, and their use as pour point depressants or wax deposition inhibitors

[0002] The present invention relates to copolymers comprising C16 to C50 olefins and at least three different mono- or dimaleates. The three types of mono- or di-maleates are firstly esters with linear C10 to C22 alkyl groups, secondly esters with linear C24 to C50 alkyl groups, and thirdly branched C20 to C50 alkyl groups. The invention further relates to a formulation comprising these copolymers and an organic solvent and to their use as pour point depressant for crude oil, fuel oil, mineral oil and / or mineral oil products, preferably as pour point depressant (PPD) for crude oil.

[0003] Background

[0004] The deposit temperature of oil deposits is generally above room temperature, for example 40° C to 100° C. Crude oil is produced from such deposits while still warm, and it naturally cools quickly to room temperature during or after production, or else to lower temperatures under corresponding climatic conditions.

[0005] According to their origin, crude oils have different proportions of long-chain n-paraffins. According to the type of crude oil, the proportion of such paraffins may typically be 1% to 40% by weight of the crude oil. They are frequently also referred to as waxes. When the temperature goes below a particular level while cooling, the paraffins can crystallize, typically in the form of platelets. The precipitated paraffins considerably impair the flowability of the oil. The plateletshaped n-paraffin crystals can form a kind of house-of-cards structure which encloses the crude oil, such that the crude oil ceases to flow, even though the predominant portion is still liquid. Precipitated paraffins can also block filters, pumps, pipelines, and other installations or be deposited in tanks, thus entailing a high level of cleaning.

[0006] The lowest temperature at which a sample of an oil still just flows while cooling is referred to as the pour point. For the measurement of the pour point, standardized test methods are used. Crude oils can have pour points above room temperature. Crude oils of this kind can solidify during or after conveying.

[0007] It is known that the pour point of crude oils can be lowered by suitable additives. This can prevent paraffins from precipitating in platelet-like form while cooling of produced crude oil. Suitable additives firstly prevent the formation of said house-of-cards-like structures and thus lower the temperature at which the crude oil solidifies. In addition, additives can promote the formation of fine, well-crystallized, non-agglomerating paraffin crystals, such that undisrupted oil transport is ensured. Such additives are referred to as pour point depressants or flow improvers.

[0008] Paraffin inhibitors or wax inhibitors refer to those substances intended to prevent the deposition of paraffins or paraffin waxes on surfaces in contact with crude oils or other wax-containing oils and / or mineral oil products.

[0009] The use of copolymers of olefins and esters of maleic acid as flow improvers is known. GB 1 468588 discloses a middle oil distillate which, for improvement of the low-temperature properties, comprises a maleic anhydride (MA)-olefin copolymer which has been esterified with C18 to C44 alcohols. One example discloses a copolymer of MA, C22 / 28-a-monoolefins and behenyl alcohol.

[0010] U.S. Pat. No. 2,542,542 discloses copolymers of dodecene, tetradecene, hexadecene or octadecene and maleic anhydride as additives to lubricant oils.

[0011] EP 214786 A1 discloses the use of copolymers of linear-chain olefins, for example 1-octene, 1-decene, 1-dodecene, 1 -tetradecene or 1 -octadecene, and maleic esters for improving the low-temperature properties of fuels. The alcohols used for esterification have at least 10 carbon atoms and they may be linear or branched. The document discloses that a mixture of linear alcohols and alcohols branched with a methyl radical can be used.

[0012] EP 1 746 147 A1 discloses the use of copolymers of olefins and esters of ethylenically unsaturated dicarboxylic acids for lowering the cloud point of fuel oils and lubricants. The copolymers comprise, as monomers, 03 to C50 olefins, preferably 08 to 030 olefins, and 01 to 040 mono- or diesters of ethylenically unsaturated dicarboxylic acids, especially of maleic acid. The 01 to 040 hydrocarbyl radicals of the ester groups are preferably linear or branched 01- to C40-alkyl radicals.

[0013] U.S. Pat. No. 10,781,385 B2 discloses copolymers of olefins and esters of ethylenically unsaturated dicarboxylic acids for use as pour point depressants for crude oil. The copolymers comprise 014 to 050 olefins and at least two different olefin-dicarboxylic esters and optionally maleic acid or maleic acid derivatives. The olefin-dicarboxylic esters are firstly esters with linear 018- to C50-alkyl groups and secondly esters with short-chain linear, branched, or cyclic alkyl groups, or esters with aromatic groups.

[0014] U.S. Pat. No. 11,193,053 B2 discloses the use of modified alpha-olefin maleic anhydride copolymers in reducing wax deposition from an oil, the copolymer made from 08-014 alpha-olefins and 012-060 alkyl esters of maleic anhydride.

[0015] U.S. Pat. No. 11,261,369 B2 discloses the use of modified alpha-olefin maleic anhydride copolymers in reducing wax deposition from an oil, the copolymer made from 012-032 alpha-olefins and 010-80 alkyl esters of maleic anhydride, with the proviso that the copolymer comprises some C>30-alky I esters of maleic anhydride.

[0016] The copolymers known from prior art documents are usually manufactured in chemical production sites and made available as organic concentrates with a high copolymer content, for example concentrates comprising a 30-60 wt.% of organic solvent and 40-70 wt.% of copolymer. Then the concentrates are transported from the chemical plant to the site of use, e.g. to an oilfield or an offshore platform. Most concentrates comprising 40-70 wt.% of copolymer are solid at an ambient temperature of 25 °C, and even more of concentrates are solid at 15 °C. Thus, to be able to pump the copolymers into the oil wellbore in regions having an ambient temperature lower than the pour point of the concentrates, for example an ambient temperature of < 15 °C during oilfield activities in winter, the concentrates must be heated and further diluted with organic solvent onsite to obtain ready-to-use formulations. The pour point is the minimum temperature at which a sample of a tested oil is still just free flowing. Ready-to-use formulations may comprise, for example, about 20% by weight of PPD copolymers in high-boiling organic solvents.

[0017] The dilution step onsite has several disadvantages:

[0018] • higher amounts of organic solvent are needed, which has a negative impact on the environment,

[0019] • the additional organic solvent needs to be transported to the site of use, e.g. to an oilfield or an offshore platform, and

[0020] • additional equipment is needed in the site of use, e.g. heated conduits to heat the concentrates and mixing vessels to mix the concentrates with the additional organic solvent.

[0021] Summary of the invention

[0022] It was an object of the present invention to provide improved a-olefin - maleate copolymers for use as pour point depressants for crude oils, which could be formulated into improved concentrates comprising high copolymer content in organic solvent. The improve concentrates having a low pour point, which allows the concentrate to stay liquid at low temperatures, e.g. 15 °C, and consequently, allows the concentrate to be pumped into the wellbore directly, eliminating the necessity of the additional dilution step onsite and reducing the amount of organic solvent needed.

[0023] Surprisingly, it has been found that this can be achieved through minor changes in the copolymer architecture.

[0024] In a first aspect of the invention the Applicant has found copolymers (X), comprising, as monomers, 40 to 60 mol%, based on the amount of all monomers, of o-olefins (A) of the formula H2C=CH-R1, and 60 to 40 mol %, based on the amount of all monomers, of a mixture of mono- or di-maleates comprising (B1 ) a mono- or di-maleate of the formula (R2OOC)HC=CH(COOR5), (B2) a mono- or di-maleate of the formula (R3OOC)HC=CH(COOR5), and (B3) a mono- or di-maleate of the formula (R4OOC)HC=CH(COOR5), wherein

[0025] R1is selected from a linear, cyclic or branched, aliphatic and / or aromatic hydrocarbyl radical having 16 to 50 carbon atoms,

[0026] R2is selected from linear C10 to C22 alkyl radicals,

[0027] R3is selected from linear C24 to C50 alkyl radicals,

[0028] R4is selected from branched C20 to C50 alkyl radicals,

[0029] R5are each independently selected from H, R2, R3and R4. In a second aspect of the invention, the Applicant has found a composition comprising the copolymer (X) described above and organic solvent (Y).

[0030] In a third aspect of the invention, the Applicant has found a process for preparing copolymers (X) described above comprising at least the following process steps:

[0031] I) providing a polymeric reactant by polymerizing at least the following monomers: the a-olefin monomers (A) of H2C=CH-R1(A) , where R1is a linear, cyclic or branched, aliphatic and / or aromatic hydrocarbyl radical having 16 to 50 carbon atoms, and maleic anhydride

[0032] II) polymer-analogous esterification of the polymeric reactant provided in step I at 100°C to 180°C with at least three alcohols R2OH, R3OH and R4OH where

[0033] R2is selected from linear C10 to C22 alkyl radicals,

[0034] R3is selected from linear C24 to C50 alkyl radicals,

[0035] R4is selected from branched C20 to C50 alkyl radicals.

[0036] In addition, copolymers (X) obtainable by means of the process described have been found.

[0037] In a further aspect of the invention, the use of copolymers (X) described above as a pour point depressant for crude oil, fuel oil, mineral oil and / or mineral oil products, especially as a pour point depressant for crude oils and for avoidance of wax deposits on surfaces, has been found.

[0038] Details of the invention

[0039] The inventive copolymers (X) comprise, as monomers, at least one a-olefin (A) and at least three different mono- or di-maleates (B1 ), (B2) and (B3). In addition, the copolymer (X) can optionally comprise, as monomers maleic acid and / or maleic anhydride.

[0040] Monomers (A)

[0041] The monomers (A) are o-olefins having the general formula H2C=CH-R1. In this case, R1is selected from a linear, cyclic, or branched, aliphatic and / or aromatic hydrocarbyl radical having 16 to 50 carbon atoms, preferably 18 to 30 carbon atoms. Preference is given to linear or branched alkyl radicals, particular preference to linear alkyl radicals. R1is more preferably a linear alkyl radical having 18 to 30 carbon atoms. According to the invention, it is possible to use a single a-olefin, or else it is possible to use mixtures of two or more different o-olefins of the general formula H2C=CH-R1.

[0042] Advantageously, it is possible to use mixtures comprising at least two and preferably at least three o-olefins having alkyl radicals R1, preferably linear alkyl radicals R1, having 18 to 30 carbon atoms.

[0043] The mixtures may especially be technical grade mixtures of linear aliphatic o-olefins. Technical grade mixtures of this kind comprise, as main constituents, aliphatic o-olefins having an even number of carbon atoms. It is advantageously possible to use a technical grade mixture comprising at least three o-olefins of the general formula H2C=CH-R1in which the R1radicals are n-octadecyl, n-eicosyl and n-docosyl radicals (i.e. a mixture of linear aliphatic C20, C22 and C24 o-olefins), especially mixtures comprising at least 80% by weight, preferably at least 90% by weight, of said o- olefins, based on the amount of all olefins.

[0044] Monomers (B)

[0045] The monomers (B) are mono- or di-maleates. According to the invention, the monomers (B) are at least three different monomers (B1), (B2) and (B3).

[0046] The monomers (B1), (B2) and (B3) are defined as follows

[0047] (B1) a mono- or di-maleate of the formula (R2OOC)HC=CH(COOR5),

[0048] (B2) a mono- or di-maleate of the formula (R3OOC)HC=CH(COOR5),

[0049] (B3) a mono- or di-maleate of the formula (R4OOC)HC=CH(COOR5), wherein

[0050] R1is selected from a linear, cyclic or branched, aliphatic and / or aromatic hydrocarbyl radical having 16 to 50 carbon atoms,

[0051] R2is selected from linear C10 to C22-alkyl radicals, preferably C16 to C22-alkyl radicals, R3is selected from linear C24 to C50-alkyl radicals, preferably C24 to C32-alkyl radicals, R4is selected from branched C20-C50 alkyl radicals, preferably C22 to C40-alky I radicals, R5are each independently selected from R2, R3, R4, H and an ammonium ion, preferably R2, R3, R4and H.

[0052] In one embodiment, at least 50 mol% of the R5radicals are H, preferably at least 75 mol% and more preferably at least 95 mol%. In one embodiment of the invention, all R5radicals are H. If R5in (B1 ), (B2) or (B3) is H, then that (B1), (B2) or (B3) is a monoester. If R5in (B1), (B2) or (B3) is H is R2, R3or R4, they are diesters.

[0053] The proportion of the monomers (B1)+(B2)+(B2) based on the sum of all mono- or di-maleates is at least 67 mol%, preferably at least 80 mol%, more preferably at least 90 mol%, most preferably at least 95 mol%.

[0054] In a preferred embodiment, no further mono- or di-maleates are present aside from (B1), (B2) and (B3).

[0055] The proportion of the R2, R3, R4can be as follows

[0056] • the sum of all R2radicals is 80 to 88 mol% or wt. %,

[0057] • the sum of all R3radicals is 2 to 7 mol% or wt. %, and

[0058] • the sum of all R4radicals is 5 to 13 mol% or wt. %, based on the total amount of R2+ R3+R4in all mono- or di-maleate.

[0059] The molar ratio of the R2: R3: R4is preferably 86:4:10.

[0060] There may be just one monomer (B1), or there may be two or more different monomers (B1) having different R2radical.

[0061] In one embodiment, there are at least two, preferably at least three, different monomers (B1) having different R2radicals, where R2in this embodiment comprises 16 to 22 carbon atoms.

[0062] In one embodiment of the invention, there are at least three different monomers (B1), specifically at least one monomer (B1) in which R2is an n-octadecyl radical, a monomer (B1) in which R2is an n-eicosyl radical, and a monomer (B1) in which R2is an n-docosyl radical.

[0063] There may be just one monomer (B2), or there may be two or more different monomers (B2) having different R3radicals.

[0064] In one embodiment, there are at least two different monomers (B2) having different R3radicals, where R3in this embodiment comprises 24 to 30 carbon atoms.

[0065] In one embodiment of the invention, there are at least two different monomers (B2), specifically at least one monomer (B2) in which R2is an n-tetracosyl radical, and a monomer (B2) in which R3is an n-hexacosyl radical.

[0066] There may be just one monomer (B3), or there may be two or more different monomers (B3) having different R4radicals. In one embodiment, there is one monomer (B2) having R4as a branched C32-alkyl radical. Further Monomers

[0067] In addition to the monomers (A), (B1 ), (B2) and (B3), the copolymer may optionally also comprise, as monomers, maleic acid and / or maleic anhydride.

[0068] In the copolymers (X) of the invention, the amount of all the a-olefin monomers (A) based on the amount of all monomers is 40 mol% to 60 mol%, preferably 45 mol% to 55 mol% and, more preferably 48 mol% to 52 mol%.

[0069] The amount of the mono- or di-maleate monomers (B) (i.e. (B1) +(B2) +(B3)) based on the amount of all monomers is 40 mol% to 60 mol%, preferably 45 mol% to 55 mol% and, more preferably 48 to 52 mol%.

[0070] If present, the amount of additional monomers (C) is not more than 20 mol%, preferably not more than 10 mol%, more preferably not more than 5 mol%, based on the amount of all monomers, and most preferably no further monomers (C) are present. and Hydrocarbons

[0071] In a further aspect, the invention relates to a composition for use as a pour point depressant, comprising copolymer (X), and organic solvent (Y).

[0072] The copolymers (X) of the invention and preferred embodiments of the copolymers (X) have already been described above.

[0073] The organic solvents (Y) may in principle be any organic solvents, provided that the copolymers (X) are soluble therein.

[0074] Organic solvents (Y) may be hydrocarbons. Examples of hydrocarbons include aliphatic, cycloaliphatic and / or aromatic solvents. In addition, it is also possible to use organic solvents comprising functional groups, for example alcohols or esters.

[0075] In one embodiment of the invention, the organic solvents are nonpolar solvents (Y1) comprising saturated aliphatic hydrocarbyl groups. Examples of such solvents include saturated aliphatic alcohols or esters of saturated aliphatic carboxylic acids and saturated aliphatic alcohols. Examples of esters comprise esters of saturated fatty acids having at least 8 carbon atoms with saturated aliphatic alcohols, for example methyl laurate or methyl stearate. Technical grade mixtures of various aliphatic esters are commercially available. In one embodiment of the invention, solvents used may be esters of aliphatic or cycloaliphatic dicarboxylic acids, for example dialkyl esters of cyclohexane-1,2- dicarboxylic acid, such as diisononyl cyclohexane-1,2-dicarboxylate.

[0076] In one embodiment of the invention, the organic solvents (Y) are saturated aliphatic hydrocarbons (Y2) or mixtures thereof. These may be either paraffinic or naphthenic, i.e. saturated cyclic, hydrocarbons. Suitable hydrocarbons include, for example, n-undecane or n-dodecane. For example, it is possible to use technical grade mixtures of hydrocarbons, for example mixtures of paraffinic hydrocarbons, mixtures of paraffinic and naphthenic hydrocarbons or mixtures of isoparaffins. It will be apparent to those skilled in the art that technical grade mixtures may still comprise small residues of aromatic or unsaturated hydrocarbons. Technical grade mixtures of saturated aliphatic solvents are commercially available, for example technical grade mixtures of the Shellsol® D series or the Exxsol® D series.

[0077] In a further embodiment of the invention, the organic hydrocarbons (Y) are aromatic hydrocarbons (Y3) or mixtures thereof. Preferred hydrocarbons (Y3) are xylene or high boiling aromatic hydrocarbons having a boiling point of at least 175° C and preferably a flashpoint >60° C. The flashpoint measured according to the standard ASTM D93.

[0078] Suitable aromatic hydrocarbons having a flashpoint > 60° C include, for example, naphthalene. It is possible with preference to use technical mixtures of aromatic hydrocarbons. Technical grade mixtures of aromatic solvents are commercially available, for example technical grade mixtures of the Shellsol® A series or the Solvesso® series. Preferably, the organic solvents (Y) are aromatic hydrocarbons (Y3).

[0079] The concentration of the copolymers (X) in the composition of the invention is chosen by the person skilled in the art in accordance with the desired properties of the composition. The concentration of the copolymers (X) may be at least 30 wt.%, preferably from 30 to 75 wt.%, more preferably 30% to 65 wt.%, more preferably 30 to 60 wt.%, more preferably 30 to 55 wt.%, more preferably 35 to 55 wt.%, based on the sum total of all components of the composition.

[0080] In a preferred embodiment of the invention, the composition comprises at least one copolymer (X) and xylene or a mixture or high-boiling aromatic hydrocarbons, such as Solvesso, wherein the concentration of the copolymers (X) is at least 30 wt.% based on the sum total of all components of the composition, and wherein the copolymer (X) is one of the type described above.

[0081] Process for the

[0082] The copolymers (X) of the invention can be prepared by free-radical polymerizing the monomers (A), (B) and optionally (C) mentioned with one another in the desired ratio. Techniques for free-radical polymerization are known to those skilled in the art. In this technique, previously prepared monomers (B1), (B2) and (B3) are thus used for polymerization.

[0083] The copolymers (X) can also be prepared by a two-steps process, wherein in step I, a polymeric reactant, formed from olefins and maleic anhydride is provided and, in step II, the maleic anhydride units of the reactant provided are esterified with alcohols in a polymer-analogous reaction. In this procedure, the repeat units of the copolymer (X) derived from the monomers (B1), (B2) and (B3) thus do not form until the polymer-analogous reaction.

[0084] Process Step l-Provision of a Polymeric Reactant from Olefins and Maleic Anhydride

[0085] In the course of process step I, a polymeric reactant is provided. This is a copolymer formed from the olefins (A), and maleic anhydride or maleic acid. Preference is given to using maleic anhydride as monomer.

[0086] Suitable o-olefins H2C=CH-R1(A) and preferred o-olefins (A), including preferred mixtures of o-olefins (A), have already been outlined.

[0087] In the polymeric reactant to be provided, the amount of the monomers (A) based on the amount of all monomers is 40 mol% to 60 mol%, preferably 45 mol% to 55 mol% and, more preferably 48 mol% to 52 mol%.

[0088] In addition, the amount of the monomers maleic acid or maleic anhydride, based on the amount of all monomers, is 40 mol % to 60 mol %, preferably 45 mol % to 55 mol % and, more preferably 48 to 52 mol%.

[0089] The preparation can be effected in a manner known in principle by free-radical polymerization of the o-olefins (A) and of the maleic acid or maleic anhydride. For example, it is possible to use the procedure described in EP 214 786 A1, especially page 6 lines 1 to 14. Polymerization is possible either in bulk or using solvent.

[0090] Suitable solvents are aprotic solvents such as xylene, aliphatics, alkanes, benzine or ketones. In a preferred embodiment of the invention, the solvents are at least one organic solvent (Y), especially a hydrocarbon, preferably xylene or hydrocarbons or hydrocarbon mixtures having a flashpoint > 60°C, such as Solvesso.

[0091] The hydrocarbons may, for example, be saturated aliphatic hydrocarbons (Y2) or mixtures thereof. These may be either paraffinic or naphthenic, i.e. saturated cyclic, hydrocarbons. Regarding examples and preferred hydrocarbons (Y2), reference is made to the above description of the hydrocarbons (Y2).

[0092] The hydrocarbons may also be aromatic hydrocarbons (Y3) or mixtures thereof. Regarding examples and preferred hydrocarbons (Y3), reference is made to the above description of the hydrocarbons (Y3). The free-radical polymerization can be undertaken using customary, thermally decomposing initiators at 80°C to 200°C, preferably at 100°C to 180°C and especially at 130°C to 170°C. The amount of initiator is typically 0.1 % to 10% by weight based on the amount of the monomers, preferably 0.2% to 5% by weight and more preferably 0.5% to 2% by weight. The polymerization time is typically 1-12 h.

[0093] The person skilled in the art is aware of how the desired range for the number-average molecular weight Mncan be established. The molecular weight can be controlled in a manner known in principle via the choice of the polymerization temperature (the lower the temperature, the higher Mn) or via the choice of reaction medium (aromatic solvents control molecular weight to a greater degree, i.e. lower Mn, aliphatic solvents control molecular weight to a lesser degree, i.e. higher Mn, without solvent even higher Mn).

[0094] According to the manner of polymerization, the polymeric reactants obtained occur in solvent-free form or as a solution. After polymerization in solution, the copolymer (X) can of course be isolated from the solvent by methods known to those skilled in the art and be used as such for process step II.

[0095] In one embodiment of the invention, the polymeric reactants are prepared in hydrocarbons or hydrocarbon mixtures, in this case the solution obtained is used directly for esterification in process step II without isolating the polymer. The person skilled in the art will select a suitable concentration of the monomers in the solvent for polymerization. For example, a concentration of the monomers in the solvent from 20% by weight to 80% by weight, for example 30% by weight to 60% by weight, may be chosen.

[0096] Process Step ll-Esterification

[0097] The polymeric reactants of Step I are subjected to polymer-analogous esterification in a second step with at least three alcohols R2OH, R3OH and R4OH.

[0098] In the esterification, the rings of the copolymerized anhydride groups are opened and, in a polymer-analogous reaction -according to the amount of the alcohols and the reaction conditions- the corresponding mono- or dimaleates are formed.

[0099] The alcohols R2OH are linear aliphatic alcohols and R2is a linear alkyl radical having 10 to 22 carbon atoms, preferably 16 to 22 carbon atoms.

[0100] There may be just one alcohol R2OH, or there may be two or more different alcohols R2OH having various R2radicals. In one embodiment, there are at least two, preferably at least three, different alcohols R2OH having different R2radicals, where R2in this embodiment comprises 16 to 22 carbon atoms. These may especially be mixtures of naturally occurring fatty alcohols or wax alcohols. Fatty alcohols or wax alcohols from natural sources typically have an even number of carbon atoms.

[0101] In one embodiment of the invention, there are at least three different alcohols R2OH, specifically at least one alcohol R2OH in which R2is an n-octadecyl radical, an alcohol R2OH in which R2is an n-eicosyl radical, and an alcohol R2OH in which R2is an n-docosyl radical. Preferably, the amount of the three alcohols mentioned is at least 70% by weight, preferably at least 80% by weight, based on the amount of all the alcohols R2OH used.

[0102] The alcohols R3OH are linear aliphatic alcohols and R3is a linear alkyl radical having 24 to 50 carbon atoms, preferably 24 to 40 carbon atoms.

[0103] There may be just one alcohol R3OH, or there may be two or more different alcohols R3OH having various R3radicals.

[0104] In one embodiment, there are at least two different alcohols R3OH having different R3radicals, where R3in this embodiment comprises 16 to 22 carbon atoms. These may especially be mixtures of naturally occurring fatty alcohols or wax alcohols. Fatty alcohols or wax alcohols from natural sources typically have an even number of carbon atoms.

[0105] In one embodiment of the invention, there are at least three different alcohols R3OH, specifically at least one alcohol R3OH in which R3is an n-tetracosyl radical, and an alcohol R3OH in which R3is an n-hexacosyl radical. Preferably, the amount of the two alcohols mentioned is at least 70% by weight, preferably at least 80% by weight, based on the amount of all the alcohols R3OH used.

[0106] The alcohols R4OH are branched aliphatic alcohols and R4is a branched alkyl radical having 20 to 50 carbon atoms, preferably 22 to 36 carbon atoms.

[0107] There may be just one alcohol R4OH, or there may be two or more different alcohols R4OH having various R4radicals.

[0108] In one embodiment, there is one alcohol R4OH having R4as a branched C32-alky I radical. Preferably, the amount of this alcohol mentioned is at least 70% by weight, preferably at least 80% by weight, based on the amount of all the alcohols R4OH used.

[0109] According to the invention, the proportion of the alcohols used is as follows • the sum of all R2OH alcohol is 80 to 88 mol% or wt. %,

[0110] • the sum of all R3OH alcohol is 2 to 7mol% or wt. %, and

[0111] • the sum of all R4OH alcohol is 5 to 13 mol% or wt. %, based on the total amount of alcohols R2OH + R3OH + R4OH. Preferably, the molar ratio of the R2: R3: R4is 86:4:10.

[0112] In addition, the amount of the alcohols R2OH, R3OH and R4OH used together is 0.5 to 1 .5 mol / mol of anhydride units in the copolymer (X), preferably 0.8 to 1.2 mol / mol, more preferably 0.9 to 1.1 mol / mol, most preferably 0.95 to 1.05 mol / mol.

[0113] The polymer-analogous esterification is generally conducted at a temperature of 100°C to 180°C.

[0114] The esterification can be conducted in bulk or else in the presence of inert solvents. The reaction mixture should remain liquid and homogeneous at the reaction temperature to assure a homogeneous reaction. The reaction can be run at ambient pressure or under pressure.

[0115] The alcohols may be initially charged in full or else added sequentially. The esterification can be undertaken, for example, in the presence of esterification catalysts, for example para-toluene sulfonic acid, methane sulfonic acid or sulfuric acid. In our case we use dodecenylsulfonic acid. A suitable procedure is disclosed, for example, in WO 2014 / 095408 Al. The amount may be 0.05 to 0.5 mol% based on the alcohols.

[0116] If process step I is conducted in solvents, it is advantageously possible to use a solution of the polymeric reactants obtained in the course of process step I for process step II. Otherwise, the polymeric reactants for process step II are dissolved in suitable inert solvents.

[0117] Preferably, the esterification is conducted in hydrocarbons. In this implementation, the esterification directly gives the composition of the invention, comprising at least one copolymer (X) and at least one hydrocarbon.

[0118] The hydrocarbons may, for example, be saturated aliphatic hydrocarbons (Y2) or aromatic hydrocarbons (Y3) mixtures thereof. These may be either paraffinic or naphthenic, i.e. saturated cyclic, hydrocarbons.

[0119] In a preferred embodiment of the invention, process step II is conducted in solution and the amount of the hydrocarbons used is such as to give a composition composed of at least one copolymer (X) and at least one hydrocarbon in a concentration of 30% to 75% by weight.

[0120] The invention further relates to copolymers (X) obtainable by the process just described.

[0121] Use of the Copolymers (X) as a Pour Point Depressant The inventive copolymers (X) can be used as pour point depressants for crude oil, fuel oils, and mineral oil and / or mineral oil products, by adding at least one of the copolymers (X) detailed to the crude oil, fuel oil, mineral oil and / or mineral oil products.

[0122] In a preferred embodiment of the invention, the inventive copolymers (X) are used as pour point depressants for crude oil, by adding a composition comprising copolymer (X) and organic solvent (Y) to the crude oil.

[0123] Pour point depressants reduce the pour point of crude oils, fuel oils, mineral oils and / or mineral oil products. The pour point refers to the lowest temperature at which a sample of an oil, while cooling, still just flows.

[0124] The formulation comprising copolymer (X) and organic solvent (Y) for use as PPD may optionally comprise additional components. For example, wax dispersants can be added to the formulation. Wax dispersants stabilize paraffin crystals which have formed and prevent them from sedimenting. Wax dispersants used may, for example, be alkylphenols, alkylphenol-formaldehyde resins or organic sulfonic acids, for example dodecyl benzenesulfonic acid.

[0125] The additional components may be mixed with the ready-to-use formulation comprising high-active content of of PPD already at the chemical plant or on the site for use, e.g. at the oilfield or offshore platform.

[0126] The amount of inventive copolymers (X) added to the crude oil, fuel oil, mineral oil and / or mineral oil products, preferably to the crude oil, is judged by the person skilled in the art such that the desired lowering of the pour point is achieved, it being obvious to the person skilled in the art that the amount necessary is dependent on the nature of the crude oil. On the other hand, it is desirable for economic reasons to use a minimum amount of pour point depressant.

[0127] It has been found to be useful to use the copolymers (X) in an amount of 50 to 3000 ppm based on the crude oil, fuel oil, mineral oil and / or mineral oil products. The amount is preferably 100 to 2000 ppm, more preferably 250 to 1500ppm and, for example, 300 to lOOOppm. The stated amounts are based on the copolymer (X) itself.

[0128] It is advisable here to add the copolymers (X) or formulations thereof to the crude oil before the precipitation of waxes has commenced, i.e. at a temperature above the pour point of the crude oil.

[0129] The site of addition of the copolymers (X) to the crude oil is suitably chosen by the person skilled in the art. The addition can be effected, for example, in the formation, in the well, at the wellhead or to a pipeline.

[0130] In one embodiment, copolymers (X) or solutions or formulations thereof are injected into a crude oil pipeline. The injection can preferably be effected at the oilfield, i.e. at the start of the crude oil pipeline, but the injection can of course also be effected at another site. For example, the pipeline may be one leading onshore from an offshore platform. The copolymers (X) can prevent blockage of pipelines if the crude oil cools down during transport in the pipeline. This risk is naturally particularly pronounced when the pipeline is one in a cold environment, e.g. regions with T < 25°C.

[0131] In a further embodiment of the invention, the copolymers (X) or solutions or formulations thereof are injected into a production well. In one embodiment, the production well may be an offshore production well. The injection can be effected, for instance, at the site where oil flows out of the formation into the production well. In this manner, the solidification of the crude oil in the production well and in downstream transport pipelines, an excessive increase in the viscosity thereof and the constriction of pipe cross sections by paraffin deposits can be prevented.

[0132] In one embodiment of the invention, the injection can be effected in an umbilical manner. This involves introducing a flexible string comprising at least one pipeline and optionally electrical wires or control wires in a protective shell axially into a well or a pipeline. The formulation of the copolymers (X) can be injected exactly at the desired site by pipeline in the flexible string.

[0133] Further Uses of the Copolymers (X)

[0134] The inventive copolymers (X) can also be used for other purposes.

[0135] In a further embodiment of the invention, the above-described copolymers (X) or formulations thereof are used to prevent wax deposits on surfaces in contact with crude oil, fuel oil, mineral oil and / or mineral oil products. These are preferably surfaces in contact with crude oil. The use is effected by adding at least one of the copolymers (X) or formulations thereof to the crude oil, fuel oil, mineral oil and / or mineral oil products. Preferred formulations have already been mentioned, and the manner of use is also analogous to the use as a pour point depressant.

[0136] Advantage of the Invention

[0137] The copolymers known from prior art documents are usually manufactured in chemical production sites and made available as organic concentrates with a high copolymer content, for example concentrates comprising a 30-60 wt.% of organic solvent and 40-70 wt.% of copolymer. Then the concentrates are transported from the chemical plant to the site of use, e.g. to an oilfield or an offshore platform. Most concentrates comprising 40-70 wt.% of copolymer are solid at an ambient temperature of 25 °C, and even more of concentrates are solid at 15 °C. Thus, to be able to pump the copolymers into the oil wellbore in regions having an ambient temperature lower than the pour point of the concentrates, for example an ambient temperature of < 15 °C during oilfield activities in winter, the concentrates must be heated and further diluted with organic solvent onsite to obtain ready-to-use formulations. The pour point is the minimum temperature at which a sample of a tested oil is still just free flowing. Ready-to-use formulations may comprise, for example, about 20% by weight of PPD copolymers in high-boiling organic solvents. The dilution step onsite has several disadvantages:

[0138] • higher amounts of organic solvent are needed, which has a negative impact on the environment,

[0139] • the additional organic solvent needs to be transported to the site of use, e.g. to an oilfield or an offshore platform, and

[0140] • additional eguipment is needed in the site of use, e.g. heated conduits to heat the concentrates and mixing vessels to mix the concentrates with the additional organic solvent.

[0141] Surprisingly, the Applicant has found that this problem can be solved through minor changes in the copolymer architecture.

[0142] In particular, the Applicant has found improved a-olefin - maleate copolymers for use as pour point depressants for crude oils, which can be formulated into improved concentrates comprising high copolymer content in organic solvent. The improve concentrates having a low pour point, which allows the concentrate to stay liguid at temperatures as low as 15 °C or even lower, and conseguently, allows the concentrate to be pumped into the wellbore directly, eliminating the necessity of the additional dilution step onsite and using smaller amounts of organic solvent.

[0143] Examples

[0144] Starting Materials Used:

[0145] Preparation of Unmodified C20 / 24 Olefin-MA Copolymer

[0146] C20 / 24 olefins + MA, 1 :1 molar, in aliphatic solvent

[0147] Equipment: Polymerization reactor of 1,5 L with MIG stirrer, internal thermometer and nitrogen inlet

[0148] Reactor is purged with N2. The C20 / 24 olefines are added into the reactor (178,3 g) under nitrogen, then 2,11g of Solvesso 150 ND is added. The mixture in the reactor is heated up under stirring (100 rpm) to 140°C to 142°C. Once the desired temperature has been reached, 58,31 g of maleic anhydride (preheated to 85 °C) and 2.40 g of initiator di-tert butyl peroxide (diluted in 2.40 g of Solvesso 150 ND) are feed continuously at constant dosage rate for 5 hours. After maleic anhydride and the initiator have been added in full, the mixture in the reactor is kept under stirring for 2 additional hours at 140°C.

[0149] The solid content during the main polymerization is approx. 98.5%

[0150] Properties of unmodified olefin-MA copolymer: Mn= 4000-5000 Da (GPC)

[0151] Mw= 15000-17000 g / mol (GPC)

[0152] Inventive Experiment 1

[0153] The same apparatus as for the synthesis of the unmodified C20 / 24 olefin-MA copolymer is used.

[0154] The system is cooled down to 80°C and the unmodified C20 / 24 olefin-MA copolymer is diluted in xylene (200g).

[0155] The alcohols are added to the reactor at moderate stirring at 80°C as a mixture containing Lanette 22 (137.27 g), Nafol 20+ (37.46 g) and Isofol 32 (28.4 g). Then 4-Cio-i3-sec-alkyl benzene sulfonic acid is also added at 80°C. The total amount of alcohols corresponds to 1 molar equivalent of the maleic anhydride monomers in the olefin-MA copolymer.

[0156] The molar ratio among the alcohols Lanette 22: Nafol 20+: Isofol 32 is 0.70 : 0.20 : 0.10.

[0157] The reaction mixture is heated up under nitrogen and stirred at higher speed until 140°C is achieved. Once the desired temperature has been reached, the mixture in the reactor is kept under stirring for 8 additional hours at 140°C.

[0158] Finally, the esterified copolymer is further diluted in xylene (345.7 g) to obtain ca. 1000 g of a ready-to-use formulation of about 45 wt.% of copolymer 1 in xylene.

[0159] Properties of the olefin-maleate copolymer 1 :

[0160] Mn= 4660 Da (GPC)

[0161] Mw= 22200 g / mol (GPC)

[0162] Inventive Experiment 2

[0163] Same process as for Inventive Experiment 1, but the alcohols added was a mixture containing Stenol 1822, Nafol 20+ and Isofol 28 in a molar ratio of 0.70 : 0.20 : 0.10. The total amount of alcohols corresponds to 1 molar equivalent of the maleic anhydride monomers in the olefin-MA copolymer.

[0164] Properties of the olefin-maleate copolymer 2:

[0165] Mn= 4640 Da (GPC)

[0166] Mw= 21700 g / mol (GPC)

[0167] Comparative Experiment 1 - No branched alcohol

[0168] Same process as for Inventive Experiment 1, but the alcohols added was a mixture containing Lanette 22 and Nafol 20+ in a molar ratio of 0.67 : 0.33. The total amount of alcohols corresponds to 1 molar equivalent of the maleic anhydride monomers in the olefin-MA copolymer.

[0169] Properties of the olefin-maleate copolymer C1:

[0170] Mn= 4300 Da (GPC)

[0171] Mw= 22100 g / mol (GPC)

[0172] Comparative Experiment 2 - No R3OH Alcohol Same process as for Inventive Experiment 1 , but the alcohols added was a mixture containing Lanette 22 and Isofol 32 in a molar ratio of 0.70 : 0.30. The total amount of alcohols corresponds to 1 molar equivalent of the maleic anhydride monomers in the olefin-MA copolymer.

[0173] Properties of the olefin-maleate copolymer C2:

[0174] Mn= 2640 Da (GPC)

[0175] Mw= 17600 g / mol (GPC) 3 - No R3OH Alcohol

[0176] Same process as for Inventive Experiment 1 , but the alcohols added are a mixture containing Lanette 22 and Isofol 32 in a molar ratio of 0.90 : 0.10. The total amount of alcohols corresponds to 1 molar equivalent of the maleic anhydride monomers in the olefin-MA copolymer.

[0177] Properties of the olefin-maleate copolymer C3:

[0178] Mn= 3000 Da (GPC)

[0179] Mw= 25300 g / mol (GPC) 4 - Amount of C20 / 24 olefins too low because shorter olefins are

[0180] Preparation of Unmodified C12 +C20 / 24 Olefin-MA Copolymer:

[0181] Same process as for the preparation of unmodified C20 / 24 Olefin-MA copolymer described above, but a mixture of

[0182] C12 olefin (1 -dodecene) and C20 / 24 olefin was used. The molar ratio of C12 olefin : C20 / 24 olefin used is 0.30 : 0.70 and the molar ratio between the total amount of a-olefi ns and maleic anhydride was 1 : 1.

[0183] The quantity of C20 / 24 olefins is 35 mol% of all monomers present (C12 olefins + C20 / 24 olefins + MA).

[0184] Esterification of C12 +C20 / 24 Olefin-MA Copolymer

[0185] Same process as for Inventive Experiment 1 , but the unmodified C12 +C20 / 24 Olefin-MA copolymer was used.

[0186] Properties of the olefin-maleate copolymer C4:

[0187] Mn= 4660 Da (GPC)

[0188] Mw= 20400 g / mol (GPC)

[0189] Methods of measurement:

[0190] Pour Point of 300 ppm of Copolymer (X) in Oil

[0191] The determination of the pour point was conducted to ASTM D 5853 "Test Method for Pour Point of Crude Oils". The pour point is the minimum temperature at which a sample of a tested oil is still just free flowing. According to ASTM D 5853, for this purpose, a sample of the oil is cooled in steps of 3°C each and the flowability is tested after each step. For the tests, a crude oil from an oilfield in Chad having a pour point of 27°C was used. To determine the lowering of the pour point, the polymers to be tested were used to the oil in an active concentration of 300 ppm of polymer based on the crude oil. Pour Point of 45 wt.% of Copolymer (X) in Organic Solvent (Y) - Ready-to-use composition

[0192] In a further measurement, the pour point of a 45 wt.% solution of the polymer of the invention itself was measured. The pour point is the minimum temperature at which the 45 wt.% solution is still just free flowing. The determination of the 45 wt.% pour point was conducted according to ASTM D5985-02. The experimental results are summarized in Table 1 along with comments.

[0193] le 1 : Pour Point results of tested o-olefin-maleate copolymers and comments

[0194] Embodiments of the present invention:

[0195] 1 . Firstly, the present invention is directed to a copolymer (X) comprising, as monomers,

[0196] 40 to 60 mol%, based on the amount of all monomers, of o-olefins (A) of the formula H2C=CH-R1, and

[0197] 60 to 40 mol %, based on the amount of all monomers, of a mixture of mono- or di-maleates comprising

[0198] (B1) a mono- or di-maleate of the formula (R2OOC)HC=CH(COOR5),

[0199] (B2) a mono- or di-maleate of the formula (R3OOC)HC=CH(COOR5), and

[0200] (B3) a mono- or di-maleate of the formula (R4OOC)HC=CH(COOR5), wherein

[0201] R1is selected from a linear, cyclic or branched, aliphatic and / or aromatic hydrocarbyl radical having 16 to 50 carbon atoms,

[0202] R2is selected from linear C10 to C22 alkyl radicals,

[0203] R3is selected from linear C24 to C50 alkyl radicals,

[0204] R4is selected from branched C20 to C50 alkyl radicals,

[0205] R5are each independently selected from H, R2, R3and R4.

[0206] 2. In one embodiment of the present invention, the copolymer (X) additionally comprises, as monomers, maleic anhydride and / or maleic acid.

[0207] 3. In one embodiment of the present invention, at least 50 mol% of the R5radicals are H.

[0208] 4. In one embodiment of the present invention,

[0209] • the sum of all R2radicals is 80 to 88 mol% or wt. %,

[0210] • the sum of all R3radicals is 2 to 7 mol% or wt. %, and

[0211] • the sum of all R4radicals is 5 to 13 mol% or wt. %, based on the total amount of R2+ R3+R4in all mono- or di-maleates.

[0212] 5. In one embodiment of the present invention, the molar ratio of the R2: R3: R4is 86:4:10.

[0213] 6. In one embodiment of the present invention, R1comprises a linear hydrocarbyl radical having 16 to 50 carbon atoms. 7. In one embodiment of the present invention, R1comprises a linear hydrocarbyl radical having 18 to 30 carbon atoms.

[0214] 8. In one embodiment of the present invention, the copolymer comprises at least two different o-olefins (A) H2C=CH-R1where R1is independently selected from linear alkyl radicals having 18 to 30 carbon atoms.

[0215] 9. In one embodiment of the present invention, the copolymer comprises at least three different o-olefins (A) H2C=CH-R1where R1is selected from n-octadecyl, n-eicosyl and n-docosyl radicals.

[0216] 10. In one embodiment of the present invention, R2is a linear alkyl radical having 16 to 22 carbon atoms.

[0217] 11. In one embodiment of the present invention, the copolymer comprises at least two different monomers (B1) where R2in each case is a linear alkyl radical having 16 to 22 carbon atoms.

[0218] 12. In one embodiment of the present invention, the copolymer comprises at least three different monomers (B1) where the R2radicals in each case are n-octadecyl, n-eicosyl and n-docosyl radicals.

[0219] 13. In one embodiment of the present invention, R3is a linear alkyl radical having 24 to 32 carbon atoms.

[0220] 14. In one embodiment of the present invention, the copolymer comprises at least two different monomers (B2) where R3in each case is a linear alkyl radical having 24 to 32 carbon atoms.

[0221] 15. In one embodiment of the present invention, the copolymer comprises at least two different monomers (B2) where R3in each case are n-tetracosyl and n-hexacosyl radicals.

[0222] 16. In one embodiment of the present invention, R4is a branched C22 to C40alkyl radical, preferably R4is a branched C32 alkyl radical.

[0223] 17. Secondly, the present invention is also directed to a composition comprising a copolymer (X) as defined in the above embodiments and at least one organic solvent (Y).

[0224] 18. In one embodiment of the present invention, the solvent is a hydrocarbon.

[0225] 19. In one embodiment of the present invention, the solvent is selected from aliphatic hydrocarbons, aromatic hydrocarbons, and mixtures thereof. 20. In one embodiment of the present invention, the solvent is selected from xylene, high-boiling hydrocarbons having a boiling point of at least 175° C and a flashpoint > 60° C. and mixtures thereof.

[0226] 21 . In one embodiment of the present invention, the concentration of the copolymer (X) in the composition is at least 30 wt.%, based on the sum of all components of the composition.

[0227] 22. In one embodiment of the present invention, the concentration of the copolymer (X) in the composition is 30-75 wt.%, based on the sum of all components of the composition. 23. Thirdly, the present invention is also directed to the use of the copolymer (X) as defined in the above embodiments as pour point depressants for crude oil, fuel oil, mineral oil and / or mineral oil products.

[0228] 24. Fourthly, the present invention is also directed to the use of the copolymer (X) as defined in the above embodiments in the prevention of wax deposits on surfaces in contact with crude oil, fuel oil, mineral oil and / or mineral oil products.

Claims

Claims1 . A copolymer (X) comprising, as monomers,40 to 60 mol%, based on the amount of all monomers, of o-olefins (A) of the formula H2C=CH-R1, and60 to 40 mol %, based on the amount of all monomers, of a mixture of mono- or di-maleates comprising(B1) a mono- or di-maleate of the formula (R2OOC)HC=CH(COOR5),(B2) a mono- or di-maleate of the formula (R3OOC)HC=CH(COOR5), and(B3) a mono- or di-maleate of the formula (R4OOC)HC=CH(COOR5), whereinR1is selected from a linear, cyclic or branched, aliphatic and / or aromatic hydrocarbyl radical having 16 to 50 carbon atoms,R2is selected from linear C10 to C22 alkyl radicals,R3is selected from linear C24 to C50 alkyl radicals,R4is selected from branched C20 to C50 alkyl radicals,R5are each independently selected from H, R2, R3and R4.

2. The copolymer (X) according to claim 1 , wherein the copolymer additionally comprises, as monomers, maleic anhydride or maleic acid.

3. The copolymer (X) according to any one of the previous claims, wherein at least 50 mol% of the R5radicals are H.

4. The copolymer (X) according to any one of the previous claims, wherein• the sum of all R2radicals is 80 to 88 mol% or wt. %,• the sum of all R3radicals is 2 to 7 mol% or wt. %, and• the sum of all R4radicals is 5 to 13 mol% or wt. %, based on the total amount of R2+ R3+R4in all mono- or di-maleate.

5. The copolymer (X) according to any one of the previous claims, wherein R1comprises a linear hydrocarbyl radical having 16 to 50 carbon atoms.

6. The copolymer (X) according to any one of the previous claims, wherein the copolymer comprises at least two different o-olefins (A) H2C=CH-R1where R1is independently selected from linear alkyl radicals having 18 to 30 carbon atoms.

7. The copolymer (X) according to any one of the previous claims, wherein R2is a linear alkyl radical having 16 to 22 carbon atoms.

8. The copolymer (X) according to any one of the previous claims, wherein R3is a linear alkyl radical having 24 to 32 carbon atoms.

9. The copolymer (X) according to any one of the previous claims, wherein the copolymer comprises at least two different monomers (B2) where R3in each case is a linear alkyl radical having 24 to 32 carbon atoms.

10. The copolymer (X) according to any one of the previous claims, wherein R4is a branched C22 to C40 alkyl radical, preferably R4is a branched C32 alkyl radical.11 . A composition comprising a copolymer (X) according to any one of the previous claims and at least one organic solvent (Y).

12. The composition according to claim 11, wherein the solvent is a hydrocarbon, preferably the solvent is selected from aliphatic hydrocarbons and aromatic hydrocarbons and mixtures thereof, more preferably the solvent is selected from xylene, high-boiling hydrocarbons having a boiling point of at least 175° C and a flashpoint > 60° C and mixtures thereof, the flashpoint measured according to the standard ASTM D93.

13. The composition according to any one of claims 11 to 12, wherein the concentration of the copolymer (X) is at least 30 wt.%, based on the sum of all components of the composition, preferably 30 to 75 wt.%14. Use of the copolymer (X) according to any one of claims 1 to 10 as pour point depressants for crude oil, fuel oil, mineral oil and / or mineral oil products.

15. Use of the copolymer (X) according to any one of claims 1 to 10 in the prevention of wax deposits on surfaces in contact with crude oil, fuel oil, mineral oil and / or mineral oil products.

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