Additive composition and use thereof for improving the pumpability of water and crude oil mixtures

Abstract

The present invention relates to an additive composition comprising: (1) at least one copolymer of ethylene and vinyl acetate grafted with at least one alkyl (meth)acrylate group, the alkyl chain of which is saturated and contains 12 to 30 carbon atoms; (2) at least one modified alkylphenol-aldehyde resin capable of being obtained by the Mannich reaction of an alkylphenol-aldehyde condensation resin with at least one aldehyde and / or a ketone having from 1 to 8 carbon atoms, and at least one hydrocarbon compound having from 1 to 30 carbon atoms and comprising at least one alkyl polyamine group; (3) at least one alkoxylated alkylphenol-aldehyde condensation resin; and (4) at least one organic solvent. The present invention also relates to the use of such an additive composition to lower the viscosity of a crude mineral oil and water mixture, and / or to improve the pumpability of such a mixture.

Description

[0001] DESCRIPTION TITLE: ADDITIVE COMPOSITION AND USE THEREOF FOR IMPROVING THE PUMPABILITY OF MIXTURES OF WATER AND CRUDE OIL Technical field The present invention relates to an additive composition comprising at least one first compound selected from ethylene and vinyl acetate (EVA) copolymers grafted with at least one alkyl (meth)acrylate, at least one second compound selected from alkylphenol-aldehyde resins modified with an alkylpolyamine, at least one third compound selected from alkoxylated alkylphenol-aldehyde resins and at least one organic solvent. The invention also relates to the use of this composition for controlling the viscosity of a mixture of water and crude oil and for improving its pumpability and transport. The invention further relates to a method for extracting a mixture comprising crude oil and water,comprising a step of introducing the additive composition into said mixture and a step of pumping the mixture comprising said composition. The invention finally relates to a crude oil composition comprising water and an additive composition as described below. State of the prior art Underground crude oil formations, also commonly referred to as "crude mineral oil" or "crude oil" or "crude oil" have relatively high temperatures. During its extraction from the underground formation to the surface,The crude oil cools. Its cooling varies depending on the production temperature and the storage or transport conditions. The extracted crude oil mainly comprises two classes of products: maltenes and asphaltenes. The main constituents of maltenes are resins and waxes. These so-called waxes consist of paraffins (saturated hydrocarbon compounds) and aromatics. Paraffins consist of linear or branched alkanes and can be liquid, oily or solid. Depending on their origin, crude oils have different proportions of waxes, which are essentially made up of long-chain n-paraffins. Depending on the type of crude oil, the proportion of these paraffins can typically be 1 to 30% by weight of the crude oil. As is known per se, when extracting crude oil from a well, the extracted crude oil cools. As a result, the paraffins crystallize,typically in the form of platelets or platelet aggregates and the viscosity (both dynamic and kinematic) of the oil increases. Platelet-shaped n-paraffin crystals can form a three-dimensional network that encloses the remaining liquid portion of the crude oil, so that the latter stops flowing, even if the predominant portion is still liquid. Crystallized paraffins, and thus highly viscous crude oil, can block filters, pumps, pipes / pipelines, plug the well, and other installations or be deposited in reservoirs, thus requiring a high level of cleaning. Crystallization of these paraffins and thus increased viscosity can occur in oil production wells and pumping installations. These crystallized paraffins significantly impair the fluidity of the oil,they increase its viscosity and make pumping and transport operations more difficult, and more expensive, particularly because they require more energy. An additional problem arises when the extracted crude oil is mixed with water. This is the case, for example, of a producing well, in which the quantity of water present increases gradually over time. The water comes from natural sources present in the ground or corresponds to water reinjected into the well to maintain a sufficient pressure level. This is also the case for subsea wells. In the case of the exploitation of a subsea well, the crude oil is extracted in the form of a mixture, typically an emulsion, of crude oil and more or less salty water with an additional difficulty induced by the low temperatures encountered in the seabed (of the order of 4°C): thus,the mixture of water and crude oil is strongly cooled which promotes the increase of its viscosity. The presence of water in the crude oil significantly increases the viscosity of the extracted mixture, and further complicates pumping and transport operations. The energy consumed during these operations is greatly increased by the presence of water in the extracted crude oil. This phenomenon also leads to a significant loss of productivity, a substantial increase in production costs and a reduction in the life of the well. In a manner known per se, it is conventional to add additives to crude oils aimed at reducing the phenomena of crystallization of paraffins at low temperature,in particular crystallization modifying additives for modifying the morphology and size of paraffin crystals and / or for limiting the phenomena of agglomeration of paraffin crystals. Known additives are, for example, modified alkylphenol-aldehyde resins, obtained by Mannich reaction of an alkylphenol-aldehyde condensation resin with at least one aldehyde and at least one hydrocarbon compound having at least one alkylamine group, in fuel compositions as anti-sedimentation additives WASA (from the English "wax anti-settling agents") (WO2012085865), for resistance to low temperatures (WO2013189868). However, the known additives are not sufficiently effective in the case of the extraction of a mixture of water and crude oil. As explained above, the presence of water significantly increases the phenomena of increase in the viscosity of the mixture during its cooling,such that the compounds conventionally used to control the formation and growth of paraffin crystals are not sufficiently effective. To remedy this, the known solutions consist either of heating the mixture of crude oil and water so as to lower its viscosity, or of increasing the additive contents. However, increasing the additive contents is not only expensive but also does not always allow the viscosity of the mixture to be sufficiently lowered. Furthermore, it is not always possible to heat the mixture during its extraction, particularly in the case of an underwater well. Such heating proves, in practice, complicated to implement and expensive in terms of energy. The Applicant has now discovered a particular composition of additives, which makes it possible to very effectively and synergistically lower the viscosity of mixtures of crude oil and water,and thus facilitate the pumping and transport operations of these mixtures. This composition has proven to be particularly effective during the exploitation of underwater oil reserves. Summary of the invention The subject of the present invention is an additive composition comprising: (1) at least one first compound chosen from copolymers of ethylene and vinyl acetate grafted with at least one alkyl (meth)acrylate group whose alkyl chain is saturated and contains from 12 to 30 carbon atoms; (2) at least one second compound chosen from modified alkylphenol-aldehyde resins; said modified alkylphenol-aldehyde resins being capable of being obtained by Mannich reaction of an alkylphenol-aldehyde condensation resin with - at least one aldehyde and / or a ketone having from 1 to 8 carbon atoms,and - at least one hydrocarbon compound having from 1 to 30 carbon atoms and comprising at least one alkylpolyamine group; said alkylphenol-aldehyde condensation resin itself being capable of being obtained by condensation: • of at least one alkylphenol substituted by at least one alkyl group, linear or branched, having from 1 to 30 carbon atoms, with • at least one aldehyde and / or one ketone having from 1 to 8 carbon atoms; (3) at least one third compound chosen from alkoxylated alkylphenol-aldehyde condensation resins; and; (4) at least one organic solvent. The present invention also relates to a composition comprising a crude mineral oil, water and an additive composition as defined above. The invention also relates to the use of the additive composition for lowering the dynamic and / or kinematic viscosity of a mixture of water and crude mineral oil,in particular (but not limited to) at low temperature. The use according to the invention also aims to improve the pumpability of mixtures of water and crude mineral oil and to facilitate their transport. The invention finally relates to a method for extracting a mixture of crude mineral oil and water, comprising injecting into said mixture during its pumping of the additive composition as defined above. According to a preferred embodiment, the crude mineral oil is extracted from an underwater well. Other objects, characteristics, aspects and advantages of the invention will appear even more clearly on reading the description and the examples which follow. In what follows, and unless otherwise indicated, the limits of a range of values ​​are included in this range, in particular in the expressions: "between... and...", "in the range from... to...", and "ranging from... to...". Furthermore,the expressions “at least one” and “at least” used in the present description are respectively equivalent to the expressions “one or more” and “greater than or equal”. Finally, in a manner known per se, the term “C compound” denotes, Na compound containing in its chemical structure N carbon atoms. Detailed description of the invention The grafted copolymer (1) The composition according to the invention comprises a first compound (1) chosen from copolymers of ethylene and vinyl acetate grafted with at least one alkyl (meth)acrylate whose alkyl chain is saturated and contains from 12 to 30 carbon atoms. In other words, the copolymer comprises a main chain or basic skeleton consisting of a copolymer of ethylene and vinyl acetate onto which are grafted at least one alkyl (meth)acrylate whose alkyl chain is saturated and contains from 12 to 30 carbon atoms. The ethylene and vinyl acetate skeleton The compound (1) comprises a main chain or basic skeleton consisting of a copolymer of ethylene and vinyl acetate. Such a copolymer therefore comprises a repeating unit of the following formula (I): This unit is derived from the ethylene monomer. Preferably, the unit of formula (I) represents from 71 to 94 mol% relative to the total number of moles of units of the graft copolymer (1), more preferably from 78 to 88 mol%, even more preferably from 80 to 88 mol%, and even better from 82 to 87 mol%. The copolymer also comprises one or more repeating vinyl acetate unit(s) corresponding to the following formula (II): in which R1, R2, and R 3 , represent a hydrogen atom, and R4 represents a methyl group (CH3). The unit(s) of formula (II) preferably represent(s) from 5 to 25 mol%, relative to the total number of moles of units of the graft copolymer (1), more preferably from 10% to 15 mol%. The units of formula (II) are derived from monomers of the C2 carboxylic acid ester and vinyl alcohols, i.e. the vinyl acetate ester of the following formula (IIA): in which R1, R2, R3 and R4 are as defined above. The distribution of the units (I) and (II) in the backbone is preferably of the statistical type. Preferably, the backbone of the copolymers (1) used in the present invention contains only units of formula (I) and units of formula (II). Such ethylene and vinyl acetate backbones can be prepared according to polymerization processes known per se. The different polymerization techniques and conditions are widely described in the literature and fall within the general knowledge of those skilled in the art. They can in particular be synthesized by conventional radical polymerization as described in document US3627838: the procedure is generally carried out by mixing the different monomers in a suitable solvent, such as benzene, and the copolymerization is initiated by means of a radical polymerization initiating agent, such as a peroxide such as tert-butyl hydroperoxide.The polymerization conditions are known to those skilled in the art. The reaction temperature can be from 150 to 280°C, and the reaction can be carried out at high pressure (1500 to 2000 bars). In the case where the skeleton is prepared by conventional radical polymerization, it may be necessary to carry out, after the actual polymerization, a purification by any appropriate separation technique (in particular by chromatography) so as to isolate a copolymer having the required characteristics in terms of molar mass and dispersity. According to a preferred embodiment, the ethylene and vinyl acetate skeleton is prepared using controlled radical polymerization (CRP) techniques.Controlled radical polymerization techniques, known per se, have the advantage of being able to lead directly to copolymers having the required molar mass and dispersity characteristics, such that a separation purification may, depending on the conditions used, not be necessary. Among these techniques, mention may be made in particular of polymerizations governed by reversible termination or by reversible transfer (or degenerative transfer). Among these PRC techniques, those controlled by degenerative transfer are preferred and among these, radical polymerization by reversible addition-fragmentation chain transfer (RAFT in English "Reversible Addition-Fragmentation Chain Transfer") is even more preferred.Alkyl (meth)acrylate grafts The basic skeleton consisting of a copolymer of ethylene and vinyl acetate as described above is grafted with at least one alkyl (meth)acrylate whose alkyl chain is saturated and contains from 12 to 30 carbon atoms. Such a graft typically corresponds to the following formula (III):. in which R5, R6, identical or different, represent a hydrogen atom or a C1 to C4 alkyl group; R7 represents a hydrogen atom or a methyl group and R8 represents a saturated C alkyl chain 12 to C 30 . In a preferred embodiment, the alkyl (meth)acrylate graft(s) have a saturated alkyl chain comprising from 14 to 26 carbon atoms, and preferably from 18 to 22 carbon atoms. According to a preferred embodiment, R5, R6, and R 7 ,identical or different, represent a hydrogen atom or a methyl group. Particularly preferably, R5, R6 and R7 all represent a hydrogen atom; or R5, R6 represent a hydrogen atom and R7 represents a methyl group. According to an equally preferred embodiment, R8 represents a linear saturated alkyl chain. More preferably, R8 is chosen from the nC groups 18 H 37 , nC 19 H 39 nC 20 H 41 , nC 21 H 43 , and nC 22 H 45 . According to a particularly preferred embodiment: - R5, R6, and R7 all represent a hydrogen atom, and - R8 is chosen from the nC groups 18 H 37 , nC 19 H 39 nC 20 H 41 , nC 21 H 43 , and nC 22 H 45 . Very preferably, R8 is chosen from a mixture of nC groups 18 H 37 , nC 20 H 41, and nC 22 H 45, that is to say that the alkyl (meth)acrylate is behenyl acrylate. Grafting by the alkyl (meth)acrylate function onto the ethylene and vinyl acetate backbone can be carried out by any grafting process known per se, such as grafting by the classical radical route or controlled radical route, or by ATRP (atom transfer polymerization). The different grafting techniques and conditions are widely described in the literature and fall within the general knowledge of those skilled in the art. Grafting by the radical route is particularly preferred. Grafting is carried out at the level of vinyl acetate: either on the methyl group of the acetate, or on the tertiary carbons of the copolymer backbone, depending on the nature of the polymerization initiating agent. If the initiating agent is benzoyl peroxide, the grafting is instead initiated on the methyl group of the acetate.If the initiating agent is dicumyl peroxide, the grafting is rather initiated on the tertiary carbons of the copolymer backbone, or the methyl group of the acetate. The graft(s) of formula (III) preferably represents from 1 to 4 mol%, relative to the total number of moles of units of the grafted copolymer (1), more preferably from 1.5 to 3 mol%. The number-average molar mass Mn of the grafted copolymers (1) according to the invention, measured by GPC, is preferably in the range from 5000 to 50,000 g.mol. -1 , preferably from 10,000 to 40,000 g.mol -1 , better from 12,000 to 32,000 g.mol -1 The molar mass by weight Mw of the graft copolymers (1) according to the invention, measured by GPC, is preferably in the range from 23,500 to 230,000 g.mol -1 , preferably from 46,500 to 190,000 g.mol -1 , better from 55,000 to 150,000 g.mol -1. Preferably, the total content of the grafted ethylene and vinyl acetate copolymer(s) is in the range from 1 to 15% by mass, preferably from 2 to 10% by mass, and more preferably from 2.5 to 5% by mass, relative to the total mass of the additive composition. The modified alkylphenol-aldehyde resin (2) The modified alkylphenol-aldehyde resin(s) used in the present invention is (are) capable of being obtained by Mannich reaction of an alkylphenol-aldehyde condensation resin with - at least one aldehyde and / or a ketone having from 1 to 8 carbon atoms, and - at least one hydrocarbon compound having from 1 to 30 carbon atoms and comprising at least one alkylpolyamine group.Said alkylphenol-aldehyde condensation resin is itself capable of being obtained by condensation: • of at least one alkylphenol substituted by at least one alkyl group, linear or branched, having from 1 to 30 carbon atoms, with • at least one aldehyde and / or a ketone having from 1 to 8 carbon atoms.According to a preferred embodiment, the modified alkylphenol-aldehyde resin(s) is (are) capable of being obtained by Mannich reaction of an alkylphenol-aldehyde condensation resin with - at least one aldehyde and / or a ketone having from 1 to 4 carbon atoms, and - at least one hydrocarbon compound having from 4 to 30 carbon atoms and comprising at least one alkylpolyamine group, said alkylphenol-aldehyde condensation resin itself being capable of being obtained by condensation: • of at least one mono-alkylphenol substituted by at least one alkyl group, linear or branched, having from 4 to 30 carbon atoms, with • at least one aldehyde and / or a ketone having from 1 to 4 carbon atoms. The alkylphenol-aldehyde condensation resin can be chosen from any resin of this type already known and in particular those described in documents EP857776 and EP1584673.The modified alkylphenol-aldehyde resin according to the invention is advantageously obtainable from at least one para-substituted alkylphenol. Para-nonylphenol is preferably used. According to a preferred embodiment, the average number of phenolic nuclei per molecule of nonylphenol-aldehyde resin is between 6 and 25, preferably between 8 and 17, and even more preferably between 9 and 16. The number of phenolic nuclei can be determined by nuclear magnetic resonance (NMR) or gel permeation chromatography (GPC). Advantageously, the modified alkylphenol-aldehyde resin is obtained from the same aldehyde or the same ketone as said alkylphenol-aldehyde condensation resin.According to a preferred embodiment, the modified alkylphenol-aldehyde resin is obtainable from at least one aldehyde and / or at least one ketone chosen from formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, 2-ethylhexanal, benzaldehyde and / or acetone. Preferably, the modified alkylphenol-aldehyde resin is obtainable from at least one aldehyde, preferably from at least formaldehyde (also called methanal). According to a particular embodiment, the modified alkylphenol-aldehyde resin is obtainable from at least one alkylpolyamine having at least two groups chosen from primary amine and secondary amine groups.In particular, the alkylpolyamine is advantageously chosen from primary and / or secondary polyamines substituted by, respectively, one or two alkyl groups preferably comprising from 12 to 24 carbon atoms, more preferably from 12 to 22 carbon atoms. According to a preferred embodiment, the modified alkylphenol-aldehyde resin is capable of being obtained from at least one alkylpolyamine having at least two amine groups, and preferably at least three amine groups. According to a preferred embodiment, the modified alkylphenol-aldehyde resin is capable of being obtained from at least one alkylpolyamine comprising a fatty chain having from 12 to 24 carbon atoms, preferably from 12 to 22 carbon atoms.According to a particularly preferred embodiment, the modified alkylphenol-aldehyde resin is capable of being obtained from at least one alkylpolyamine having at least two amine groups, preferably at least three amine groups, and comprising a fatty chain having from 12 to 24 carbon atoms, preferably from 12 to 22 carbon atoms. Commercial alkylpolyamines are generally not pure compounds but mixtures. Among the commercially available alkylpolyamines which are suitable, mention may in particular be made of fatty chain alkylpolyamines marketed under the names Trinoram®, Duomeen®, Dinoram®, Triameen®, Armeen®, Polyram®, Lilamin® and Cemulcat®. A preferred example is Trinoram®S which is a tallow dipropylenetriamine, also known under the name N-(Tallowalkyl)dipropylenetriamine (CAS 61791-57-9).Preferably, the total content of the modified alkylphenol-aldehyde resin(s) is in the range from 0.2 to 5% by mass, preferably from 0.5 to 3% by mass, and more preferably from 0.5 to 1.5% by mass, relative to the total mass of the additive composition. The alkoxylated alkylphenol-aldehyde condensation resin (3) Said resin consists of an alkylphenol-aldehyde condensation resin onto which (poly)alkoxy groups are grafted. The alkylphenol-aldehyde condensation resin is advantageously obtained by condensation: • of at least one alkylphenol whose linear or branched alkyl group contains from 1 to 30 carbon atoms, preferably from 4 to 18 carbon atoms, and even more preferably from 9 to 12 carbon atoms with • at least one aldehyde and / or a ketone having from 1 to 8 carbon atoms, preferably from 1 to 4 carbon atoms. The alkylphenol(s) are advantageously para-substituted.The resin is preferably obtained from at least one aldehyde and / or at least one ketone chosen from formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, 2-ethylhexanal, benzaldehyde and / or acetone. Preferably, the alkylphenol-aldehyde resin is obtained from at least one aldehyde, preferably from at least formaldehyde (also called methanal). According to a preferred embodiment, said resin is obtained by condensation of formaldehyde with at least one alkylphenol whose alkyl group contains from 4 to 18 carbon atoms, and more preferably from 9 to 12 carbon atoms. According to a preferred embodiment, the average number of phenolic nuclei per molecule of nonylphenol-aldehyde resin is between 5 and 15. The number of phenolic nuclei can be determined by nuclear magnetic resonance (NMR) or gel permeation chromatography (GPC).Said resin is alkoxylated, that is to say that it is grafted by (poly)alkoxy groups onto its phenol functions. Preferably, said resin is polyethoxylated and / or polypropoxylated, and more preferably polyethoxylated. The average molar percentage of alkoxy groups per mole of alkoxylated resin is preferably in the range from 75% to 95%. Preferably, the average molar percentage of ethoxy groups per mole of polyethoxylated resin is in the range from 75% to 95%. The molar mass by weight Mw of the alkoxylated alkylphenol-aldehyde condensation resin according to the invention, measured by GPC, is preferably in the range from 1,000 to 50,000 g.mol-. 1 , preferably from 2,000 to 10,000 g.mol - 1 and more preferably from 3,000 to 6,000 g.mol - 1. Preferably, the total content of the alkoxylated alkylphenol resin(s) is in the range from 1 to 20% by mass, preferably from 2 to 15% by mass, and more preferably from 3 to 10% by mass, relative to the total mass of the additive composition. The solvent (4) The additive composition according to the invention further comprises at least one organic solvent. By way of example, the organic solvent is chosen from aliphatic and / or aromatic hydrocarbons, and / or chosen from hydrocarbon mixtures, for example gasoline, diesel, kerosene fractions, decane, pentadecane, toluene, xylene, ethylbenzene, polyethers. Preferably, the solvent is chosen from aromatic hydrocarbons and more preferably from xylenes and mixtures of aromatic solvents comprising aromatic compounds having 9 and / or 10 carbon atoms.As non-limiting examples of aromatic solvents, the following commercial products may be used: Solvarex 10®, Solvarex 10 LN®, Solvent Naphtha®, Shellsol AB®, Shellsol D®, Solvesso 150®, Solvesso 150 ND®. The content of the organic solvent(s) is advantageously at least 30% by mass, preferably at least 40% by mass, relative to the total mass of the additive composition. Preferably, this content is in the range from 40 to 95% by mass, preferably from 50 to 90% by mass, more preferably from 60 to 85% by mass, relative to the total mass of the additive composition. The composition of additives The composition according to the invention is such that the mass ratio of the quantity of the first compound (1) to the quantity of the second compound (2) is advantageously within the range from 2 to 10, preferably from 2 to 5, more preferably from 2.5 to 4.Other additives of the composition The additive composition may also comprise one or more additional additive(s), different from the compounds (1), (2) and (3) described above. According to a preferred embodiment, the composition further comprises at least one ethylene oxide (EO) and propylene oxide (PO) block copolymer. The average molar ratio between the number of EO groups and the number of PO groups in the block copolymer may typically be in the range from 40:60 to 60:40. The molar mass by weight Mw of the EO / PO block copolymers useful in the invention, measured by GPC, is preferably in the range from 6,000 to 26,000 g.mol. -1. Preferably, the total content of the ethylene oxide and propylene oxide block copolymer(s) is in the range from 0.5 to 10% by mass, preferably from 1 to 5% by mass, relative to the total mass of the additive composition. According to a preferred embodiment, the composition further comprises at least one polyoxyalkylenated polyethyleneimine, and preferably at least one polyoxyethylenated polyethyleneimine. Preferably, the total content of the polyoxyethylenated polyethyleneimine(s) is in the range from 0.5 to 10% by mass, preferably from 1 to 5% by mass, relative to the total mass of the additive composition. Additional additives that may also be incorporated into the composition are, but are not limited to: dispersants, corrosion inhibitors, biocides, demulsifiers or anti-foaming agents, paraffin deposit inhibitors; pour point depressants,anti-sedimentation additives for paraffins; H2S scavengers, organic deposit inhibitors such as naphthenic acids, mineral deposit inhibitors, markers, thermal stabilizers, emulsifiers, friction reducing agents, surfactants, and mixtures thereof. Among the other additives, mention may be made more particularly of: a) anti-foam additives, in particular (but not limited to) chosen from polysiloxanes, oxyalkylated polysiloxanes, and fatty acid amides derived from vegetable or animal oils; (b) dispersant and / or anti-corrosion additives, in particular (but not limited to) chosen from the group consisting of amines, succinimides, alkenylsuccinimides, polyalkylamines, polyalkyl polyamines, polyetheramines; imidazolines; quaternary ammonium salts derived from the above-mentioned compounds; fatty acids and their ester or amide derivatives,in particular glycerol monooleate, and mono- and polycyclic carboxylic acid derivatives; c) crystallization modifying additives, paraffin deposition inhibiting additives, pour point depressant additives; low temperature rheology modifiers such as ethylene / vinyl propionate (EVP) copolymers, ethylene / vinyl acetate / vinyl versatate (EA / AA / EOVA) terpolymers; ethylene / vinyl acetate / alkyl acrylate terpolymers; polyacrylates; acrylate / vinyl acetate / maleic anhydride terpolymers; amidated maleic anhydride / alkyl(meth)acrylate copolymers obtainable by reaction of a maleic anhydride / alkyl(meth)acrylate copolymer and an alkylamine or polyalkylamine having a hydrocarbon chain of 4 and 30 carbon atoms, preferably,from 12 to 24 carbon atoms; amidated alpha-olefin / maleic anhydride copolymers obtainable by reaction of an alpha-olefin / maleic anhydride copolymer and an alkylamine or polyalkylamine, the alpha-olefin being able to be chosen from C10-C50 alpha-olefins, preferably C16-C20 and the alkylamine or polyalkylamine advantageously having a hydrocarbon chain of 4 and 30 carbon atoms, preferably 12 to 24 carbon atoms. Examples of terpolymers include those described in EP01692196, WO2009106743, WO2009106744, US4758365 and US4178951, d) acidity neutralizers. According to a preferred embodiment, the additive composition comprises a dispersing agent. For example, the dispersant is selected from surfactants, sulfonates, sulfonic acids (naphthalene,of dodecylbenzene…) … The composition of crude oil This composition comprises at least one crude mineral oil (or crude oil), water and a composition of additives as described above. The crude mineral oil comes from a natural reserve or rock formation, preferably underground, subsea, and more preferably underwater. It is extracted via a well or “wellbore”, which corresponds to a hole or well penetrating the rock formation containing the oil. The crude mineral oil(s) may be alone or in a mixture with other components, such as for example gas, or other additives used during drilling (anti-limescale, etc.). This composition comprises water, which may contain salts, in particular sodium chloride (brine). The water content of the composition is typically in the range from 1 to 80% by mass, preferably from 5 to 60% by mass,and more preferably from 8 to 50% by mass. Preferably, the content of the additive composition is in the range of from 20 to 1500 ppm by mass, preferably from 50 to 1000 ppm, more preferably from 75 to 500 ppm, and more preferably from 100 to 300 ppm by mass, relative to the total mass of the crude oil and water composition. Uses The invention also relates to the use of the additive composition described above for lowering the dynamic and / or kinematic viscosity of a mixture of water and crude mineral oil, preferably at a temperature less than or equal to 30°C, more preferably less than or equal to 25°C, more preferably less than or equal to 20°C, more preferably less than or equal to 15°C, more preferably less than or equal to 10°C, more preferably less than or equal to 5°C, more preferably still less than or equal to 0°C. In a manner known per se,dynamic viscosity characterizes the resistance to laminar flow of an incompressible fluid. The viscosity is measured with a rheometer, for example of the Anton Paar MCR 302 type, 27mm coaxial cylinder geometry, CSR (controlled shear rate) control: the flow curves are determined and the viscosity is obtained. This method of determination is well known to those skilled in the art. Another object of the invention is the use of the additive composition to improve the pumpability of mixtures of water and crude mineral oil. The additive composition according to the invention is also used to lower the pour point of a mixture of crude mineral oil and water. The pour point is the minimum temperature at which a substance (crude oil) still flows. It is measured according to ASTM D5853. The additive composition according to the invention is also used to reduce shear stress,the flow threshold and / or the viscosity (kinematic and / or dynamic) during the flow of the mixture, preferably at a temperature less than or equal to 85°C, more preferably less than or equal to 75°C, more preferably still less than or equal to 65°C, better still less than or equal to 55°C, more preferably less than or equal to 45°C, more preferably less than or equal to 35°C, more preferably less than or equal to 25°C, more preferably less than or equal to 10°C, more preferably less than or equal to 5°C, more preferably still less than or equal to 0°C. The shear stress is the ratio of a tangential force applied to a surface to the area of ​​the tangential section to the force. The shear stress is measured with an Anton Paar MCR 302 rheometer, 27mm coaxial cylinder geometry,CSR control. The flow curves allow the shear stress to be deduced. The mixture of crude mineral oil and water typically contains from 1 to 80% by mass of water, preferably from 5 to 60% by mass, and more preferably from 8 to 50% by mass of water, relative to the mass of said mixture. Preferably, the additive composition is used at a content in the range from 20 to 1500 ppm by mass, preferably from 50 to 1000 ppm, more preferably from 75 to 500 ppm, and more preferably from 100 to 300 ppm by mass, relative to the total mass of the composition of crude mineral oil and water. The method for reducing the viscosity of a liquid petroleum product The invention also relates to a method for extracting a mixture of crude mineral oil and water comprising a step of pumping said mixture,characterized in that an additive composition as described above is injected into said mixture. The injection of the additive composition is carried out during pumping of the mixture, preferably at the outlet of the well (or wellhead). The flow rate of the injected composition is preferably regulated proportionally to the pumping rate of the mixture of crude oil and water, so as to obtain the desired concentration. According to the method of the invention, the additive composition is injected into the mixture at a content in the range from 20 to 1500 ppm by mass, preferably from 50 to 1000 ppm, more preferably from 75 to 500 ppm, and better still from 100 to 300 ppm by mass, relative to the total mass of the composition of crude oil and water. According to a preferred embodiment, the mixture of crude mineral oil and water is extracted from an underwater well. The examples below are intended solely to illustrate the invention,and cannot be interpreted as limiting the scope thereof. EXAMPLES Example 1: preparation of an additive composition according to the invention The examples use the following additives: As first compound (1): a grafted ethylene and vinyl acetate (EVA) copolymer, comprising 5% by mass of vinyl acetate and 74% by mass of behenyl acrylate, and whose molar masses are Mn=24.471 g / mol, Mw=118.528 g / mol (polydispersity index Ip=4.8). The number-average molar masses (M, n ) and in mass (M w) were determined on an AGILENT PL-GPC50-Plus gel permeation size exclusion chromatographic system. The elution solvent is tetrahydrofuran and the standards are made of polystyrenes. As the second compound (2): a modified alkylphenol-aldehyde resin whose synthesis method is detailed below. As the third compound (3): an alkylphenol-aldehyde resin modified by polyethoxylation. Synthesis protocol for modified alkylphenol-aldehyde resin 2: In a first step, an alkylphenol-aldehyde condensation resin was prepared by condensation of para-nonylphenol and formaldehyde (for example according to the procedure described in EP857776). This resin has a viscosity at 50°C of between 1800 and 4800 mPa.s (viscosity measured at 50°C using a dynamic rheometer with a shear rate of 10 s -1on the resin diluted with 30% by mass of aromatic solvent (Solvesso 150 ®)). In a second step, the alkylphenol-aldehyde resin from the first step was modified by Mannich reaction by adding 2 molar equivalents of formaldehyde and 2 molar equivalents of tallow dipropylenetriamine, known under the name N-(Tallowalkyl)dipropylenetriamine and marketed for example under the name Trinoram S®, compared to the alkylphenol-aldehyde resin from the first step. The characteristics of the resin obtained at the end of the second step are listed in Table 1 below: [Table 1] (*) Viscosity at 50°C: measured on a resin diluted with 30% by mass of Solvesso 150® solvent, shear rate 10 s -1 , using a Haake RheoWin® rheometer. (**) Evaluation of the average number of phenolic nuclei per resin molecule or N Ph e: measured by proton nuclear magnetic resonance. An additive composition C according to the invention was prepared from the following components, the contents of which are indicated as percentages by mass of active material, relative to the total mass of composition C: - grafted ethylene and vinyl acetate copolymer (1): 2.8% by mass; - modified alkylphenol-aldehyde resin (2): 0.95% by mass; - ethoxylated alkylphenol aldehyde resin (3): 4.8% by mass; - aromatic solvents: Qs 100% by mass Example 2: dynamic viscosity measurements Viscosity measurements were carried out on crude oil alone, then on the same crude oil with the addition of water and finally on the mixture of crude oil, water and additive composition C of example 1. The crude oil used is an oil of Brazilian origin having a density at 15°C of 0.911 g.cm -3, a pour point (ASTM D5853) of +15°C, a wax content of 9.5% by mass and an asphaltene content of 2.11% by mass. The above crude oil was added with 10% by mass of water, and the viscosity of this mixture was measured. To the above crude oil and water mixture, 200 ppm by mass of composition C was added, and the viscosity of the mixture was measured. Dynamic viscosity measurements were carried out at 23°C and 18°C, using an Anton Paar MCR 302 rheometer, 27mm coaxial cylinder geometry, CSR control at a shear rate of 38 s -1 The viscosity values ​​obtained (expressed in mPa.s) are collected in Table 2 below. [Table 2] The above results show that the dynamic viscosity of crude oil increases very sharply when mixed with water. The addition of additive composition C according to the invention makes it possible to effectively reduce the viscosity of the mixture of water and crude oil, even at a low treatment rate of 200 ppm. Comparative Example 3: The crude oil used is an oil of Brazilian origin having a density at 15°C of 0.911 g.cm -3 , a pour point (ASTM D5853) of +12°C, and a wax content of 10.2% by mass. The above crude oil was supplemented with 15% by mass of water. The three additive compositions C, C1 and C2, the composition of which is detailed in Table 3 below, were compared. In the table below, the contents of each compound are indicated as a percentage by mass of active ingredient, relative to the total mass of the composition. [Table 3] To the above crude oil and water mixture, 200 ppm by mass of each of compositions C, C1 and C2 were added, and the viscosity of the mixture was measured. Dynamic viscosity measurements were carried out at 23°C and 18°C, using an Anton Paar MCR 302 rheometer, 27mm coaxial cylinder geometry, CSR control at a shear rate of 38 s -1 The viscosity values ​​obtained (expressed in mPa.s) are collected in Table 4 below. [Table 4]

[0002] The above results show that the dynamic viscosity of crude oil increases very sharply when mixed with water. The addition of the additive composition C according to the invention makes it possible to effectively reduce the viscosity of the mixture of water and crude oil, including at a low treatment rate of 200 ppm. The viscosity reduction obtained is 13.3% at 23°C and 6.7% at 18°C. Comparative compositions C1 and C2, which respectively contain either compounds (1) and (2) or compound (3), on the contrary, degrade the viscosity of the mixture of water and crude oil. With composition C1, the viscosity increase is 8.9% at 23°C and 8.3% at 18°C. With composition C2, the viscosity increase is 3.3% at 23°C and 5% at 18°C. These results are summarized in Table 5 below. [Table 5] These results illustrate the unexpected synergistic effect provided by the additive composition according to the invention.

Claims

CLAIMS 1. Additive composition comprising: (1) at least one first compound chosen from copolymers of ethylene and vinyl acetate grafted with at least one alkyl (meth)acrylate group whose alkyl chain is saturated and contains from 12 to 30 carbon atoms; (2) at least one second compound chosen from modified alkylphenol-aldehyde resins; said modified alkylphenol-aldehyde resins being capable of being obtained by Mannich reaction of an alkylphenol-aldehyde condensation resin with - at least one aldehyde and / or a ketone having from 1 to 8 carbon atoms, and - at least one hydrocarbon compound having from 1 to 30 carbon atoms and comprising at least one alkylpolyamine group;said alkylphenol-aldehyde condensation resin itself being capable of being obtained by condensation: • of at least one alkylphenol substituted by at least one alkyl group, linear or branched, having from 1 to 30 carbon atoms, with • at least one aldehyde and / or a ketone having from 1 to 8 carbon atoms; (3) at least one third compound chosen from alkoxylated alkylphenol-aldehyde condensation resins; and;(4) at least one organic solvent.

2. Composition according to the preceding claim, characterized in that the ethylene and vinyl acetate copolymers are grafted with at least one alkyl (meth)acrylate group whose alkyl chain is saturated and comprises from 14 to 26 carbon atoms, and preferably from 18 to 22 carbon atoms.

3. Composition according to any one of the preceding claims, characterized in that the total content of the grafted ethylene and vinyl acetate copolymer(s) is in the range from 1 to 15% by mass, preferably from 2 to 10% by mass, and more preferably from 2.5 to 5% by mass, relative to the total mass of the additive composition.; 4. Composition according to any one of the preceding claims, characterized in that the modified alkylphenol-aldehyde resin(s) is (are) capable of being obtained by Mannich reaction of an alkylphenol-aldehyde condensation resin with at least one aldehyde and / or a ketone having from 1 to 4 carbon atoms and at least one hydrocarbon compound having from 4 to 30 carbon atoms and comprising at least one alkylpolyamine group, said alkylphenol-aldehyde condensation resin itself being capable of being obtained by condensation: • of at least one mono-alkylphenol substituted by at least one alkyl group, linear or branched, having from 4 to 30 carbon atoms, with • at least one aldehyde and / or a ketone having from 1 to 4 carbon atoms, preferably chosen from formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, 2-ethyl-hexanal, benzaldehyde and / or acetone, preferably formaldehyde. 5.Composition according to any one of the preceding claims, characterized in that the modified alkylphenol-aldehyde resin is obtainable from at least one para-substituted alkylphenol, preferably para-nonylphenol.

6. Composition according to any one of the preceding claims, characterized in that the modified alkylphenol-aldehyde resin is obtainable from at least one alkylpolyamine having at least two amine groups, preferably at least three amine groups, and comprising a fatty chain having from 12 to 24 carbon atoms, preferably from 12 to 22 carbon atoms. 7.Composition according to any one of the preceding claims, characterized in that the total content of the modified alkylphenol-aldehyde resin(s) is in the range from 0.2 to 5% by mass, preferably from 0.5 to 3% by mass, and more preferably from 0.5 to 1.5% by mass, relative to the total mass of the additive composition.

8. Composition according to any one of the preceding claims, characterized in that the alkylphenol-aldehyde condensation resin (3) is obtained by condensation:. • at least one alkylphenol whose linear or branched alkyl group contains from 1 to 30 carbon atoms, preferably from 4 to 18 carbon atoms, and more preferably still from 9 to 12 carbon atoms with • at least one aldehyde and / or a ketone having from 1 to 8 carbon atoms, preferably from 1 to 4 carbon atoms, preferably chosen from formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, 2-ethyl-hexanal, benzaldehyde and / or acetone, and more preferably formaldehyde.

9. Composition according to any one of the preceding claims, characterized in that the alkylphenol-aldehyde condensation resin (3) is polyethoxylated and / or polypropoxylated, preferably polyethoxylated. 10.Composition according to any one of the preceding claims, characterized in that the total content of the alkoxylated alkylphenol resin(s) is in the range from 1 to 20% by mass, preferably from 2 to 15% by mass, and more preferably from 3 to 10% by mass, relative to the total mass of the additive composition.

11. Composition according to any one of the preceding claims, characterized in that the organic solvent is chosen from aliphatic and / or aromatic hydrocarbons, preferably from aromatic hydrocarbons and more preferably from xylenes and mixtures of aromatic solvents comprising aromatic compounds having 9 and / or 10 carbon atoms. 12.Composition according to any one of the preceding claims, characterized in that it further comprises at least one ethylene oxide and / or propylene oxide block copolymer, at a content preferably in the range from 0.5 to 10% by mass, more preferably from 1 to 5% by mass, relative to the total mass of the additive composition.

13. Composition according to any one of the preceding claims, characterized in that it further comprises at least one polyoxyalkylenated polyethyleneimine, and preferably at least one polyoxyethylenated polyethyleneimine, at a content preferably. included in the range from 0.5 to 10% by mass, more preferably from 1 to 5% by mass, relative to the total mass of the additive composition 14. Composition comprising at least one crude mineral oil, water and an additive composition as defined in any one of claims 1 to 13.

15. Use of the additive composition as defined in any one of claims 1 to 13 for lowering the dynamic and / or kinematic viscosity of a mixture of crude mineral oil and water and / or for improving the pumpability of a mixture of crude mineral oil and water.

16. Method for extracting a mixture of crude mineral oil and water comprising a step of pumping said mixture, characterized in that an additive composition as defined in any one of claims 1 to 13 is injected into said mixture.

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