EP3622018A1

EP3622018A1 - Composition making it possible to delay the formation of gas hydrates

Info

Publication number: EP3622018A1
Application number: EP18728923.6A
Authority: EP
Inventors: Tong Eak Pou; Frédéric Moser
Original assignee: Arkema France SA
Current assignee: Arkema France SA
Priority date: 2017-05-09
Filing date: 2018-05-03
Publication date: 2020-03-18
Also published as: AR111915A1; FR3066198A1; MX2019012935A; US11421142B2; FR3066198B1; US20200115616A1; WO2018206881A1

Abstract

The present invention relates to a composition comprising at least one polymer in which the repeating unit comprises at least one amide function, at least one polyetheramine having a molecular weight (M_W) of more than 100 g.mol^-1, and having at least two secondary and/or tertiary amine functions, and optionally, but preferably, at least one organic solvent. The invention also relates to the use of said composition for delaying, or even preventing, the formation of gas hydrates, in particular in a method for extracting crude oil and/or gas and/or condensates, as well as to the method for delaying or even preventing the formation and/or agglomeration of gas hydrates, using a composition as defined above.

Description

COMPOSITION FOR DELAYING THE FORMATION OF HYDRATE GAS

The present invention relates to the field of hydrocarbon extraction and more particularly the field of additives used to facilitate the extraction and transport of said hydrocarbons to the surface. The present invention particularly relates to a method for inhibiting the formation of gas hydrates which are commonly known to disrupt the flow of hydrocarbons in the extraction and transport lines of said hydrocarbons.

The extraction of hydrocarbons, mainly oil, gas, condensate and others, is now carried out in very diverse environments, and especially in offshore sites, submarines, or in sites with meteorological periods. cold. These various environments can often lead to a significant cooling of the extracted fluids in contact with the cold walls of the transport pipes.

[0003] Fluids extracted (or fluids produced, or production fluids), fluids including oil, gas, condensate, water and mixtures thereof. By petroleum is meant in the sense of the present invention crude oil, that is to say unrefined, from a deposit.

For the purposes of the present invention, the term "gas" means raw natural gas, that is to say untreated gas, directly extracted from a deposit, such as, for example, hydrocarbons, such as methane, ethane, propane, butane, hydrogen sulphide, carbon dioxide and other gaseous compounds under operating conditions, and mixtures thereof. The composition of the extracted natural gas varies considerably according to the wells. Thus, the gas may include gaseous hydrocarbons, water and other gases.

For the purposes of the present invention, condensates are understood to mean hydrocarbons having an intermediate density. The condensates generally comprise hydrocarbon mixtures which are liquid under the operating conditions.

It is known that these production fluids usually comprise an aqueous phase in greater or lesser amount. The origin of this aqueous phase can be endogenous and / or exogenous to the underground reservoir containing the hydrocarbons, the exogenous aqueous phase generally coming from a water injection, also called injection water. The depletion of previously discovered sites often leads the oil and gas industry to extract, especially on new sites, from deeper and deeper depths, on offshore sites and with ever-increasing weather conditions. extremes.

In offshore sites in particular, the fluid transport pipes produced are often placed on the seabed, at increasingly greater depths, where the seawater temperature is often less than 15 ° C. , more often less than 10 ° C, even close to or equal to 4 ° C.

[0009] Similarly, it is not uncommon to find extraction sites located in geographical areas where air and / or surface water can be at relatively cold temperatures, typically below 15 ° C. ° C, or even below 10 ° C. However, at such temperatures, the fluids produced undergo a significant cooling during their transport. This cooling can be further amplified in the case of a stop or a slowing down of production, cases in which the contact time between the fluids produced and the cold walls of the pipe can increase, often considerably.

One of the disadvantages directly related to a more or less brutal lowering of the temperatures of the fluids produced is the formation of clathrates, also called hydrate crystals, gas hydrates or more simply hydrates. The risk of formation of such hydrates in the production fluids, and in particular during the oil, gas and condensate extraction, is all the greater as the temperature of the production fluids is low and the pressure of these fluids is high.

These clathrates are solid crystals (similar to those of water in the form of ice) formed by water molecules, also called "recipient", around one or more molecules of gas, also called "guests" Such as methane, ethane, propane, butane, carbon dioxide or hydrogen sulphide.

The formation and growth of these crystals are most often induced by a lowering of the temperature of production fluids that come out hot geological reservoirs that contain them and that enter a cold zone. These crystals can grow more or less rapidly and agglomerate and can cause clogging or clogging of production lines, hydrocarbon transport lines (oil, condensate, gas), valves, valves and other elements that may be clogged totally. or at least partially.

These clogging / blockages can lead to losses in production of oil, condensate and / or gas, resulting in significant economic losses or very significant. Indeed, these blockages and / or closures will have the consequence a decrease in the production rate, or even a shutdown of the production unit. In case, plugging the search for the plug area and its removal will result in a loss of time and profit for this unit. These clogging and / or clogging can also cause malfunctions on safety elements (safety valves for example).

These problems of formation and / or agglomeration of hydrates can also be encountered within the drilling muds or within the completion fluids, during a drilling operation or a completion operation.

To reduce, delay or inhibit the formation and / or agglomeration of hydrates, various solutions have already been proposed or envisaged. Among these, there may be mentioned a first solution which consists of dehydrating the production fluid, crude oil or gas, upstream of the zone of the pipe where the temperature promotes the formation of said hydrates. However, this solution is difficult, if not impossible, to implement under satisfactory economic conditions.

A second approach, also very expensive, is to maintain the temperature of the pipe at a temperature above the formation temperature and / or agglomeration of hydrates at a given pressure.

A third approach, frequently used, is to add an additive called "thermodynamic hydrate inhibitor" or "THI" in the English language, usually an alcohol or alcohol derivative, for example methanol, or glycol, in product fluids containing the guest water / gas mixture (s). It is nowadays widely recognized that the addition of such an additive makes it possible to shift the equilibrium hydrate formation temperature. In order to obtain an acceptable efficiency, about 30% by weight of alcohol, relative to the amount of water, are generally introduced. However, the toxicity of alcohols or derivatives of alcohols and the large amount of additive used lead more and more industrialists to adopt a fourth approach.

This fourth solution is to add a low dosage additive, called LDHI ("Low Dosage Hydrate Inhibitor" in English) in fluids products including the water / guest gas mixture (s). This additive is also called anti-hydrate and is introduced at a low dosage, generally between 1% and 4% by weight, relative to the weight of water, it being understood that higher or lower amounts are of course possible. Two types of anti-hydrate additives are currently known, anti-caking agents and kinetic anti-hydrates.

As indicated above, the formation of hydrates depends mainly on the temperature and the pressure, as well as the composition of the guest gas (s). For To be able to compare the performance of additives, we use the notion of "subcooling" or "sub-cooling" (SC) in English. Subcooling is defined as the difference between the thermodynamic equilibrium hydrate crystal formation temperature (Teq), for a given pressure and composition of the hydrate-forming gas and the aqueous phase, and the temperature produced fluids (or operating temperature T), according to the following equation: SC = T _q - T.

When the sub-cooling is greater than or equal to 0 ° C, there is a risk of formation of gas hydrate and this risk is all the more important that the sub-cooling is large.

The anti-caking agents are not inhibitors of the formation of hydrate crystals, but have the property of dispersing them, which consequently prevents said hydrate crystals from agglomerating with each other. The hydrate crystals thus dispersed can no longer clog the transport lines of oil and gas production fluids, thus increasing production, particularly oil and gas extraction.

The anti-caking agents retain their effectiveness even at low temperatures. They make it possible in particular to avoid the problems of clogging the ducts at temperatures generally 15 ° C. below the minimum temperature at which the hydrate crystals are formed, for a given pressure.

The kinetic anti-hydrates, in turn, act on the germination and growth of hydrate crystals, by delaying the formation of crystals by several hours or even several days. However, unlike anti-caking agents, kinetic antihydrates work hard with strong sub-coolings. Indeed, at temperatures of more than 10 ° C below the minimum temperature at which the hydrate crystals are formed for a given pressure (SC≥10 ° C), the effectiveness of the anti-caking agents is reduced.

In other words, at these sub-cooling levels, the time of appearance of the crystals is sufficiently short for them to appear, thus increasing the pressure drop in the transport lines of the oil production fluids and gas.

US5741758 and US6180699 patents show that kinetic anti-hydrates, such as polyoxyalkylenated diamines, associated or not with polymers comprising at least one vinylcaprolactam-type monomer, lose in effectiveness to sub-coolings of more than 10 ° vs.

There is therefore a real need to develop additives to delay the formation of hydrates (kinetic anti-hydrates) even more effective and in particular that can work sub-coolings greater than 10 ° C, better still greater than 12 ° C, more preferably greater than 13 ° C, more preferably greater than 15 ° C. In other words, there remains a real need for kinetic antihydrates which have the longest possible induction times (hydrate formation time).

Another object of the present invention is to provide a kinetic hydrate inhibitor which is effective under the usual conditions of use, that is to say for a dosage of between 0.1% and 10% by weight. weight, based on the total weight of the aqueous phase in a production fluid. Another objective is to propose a kinetic hydrate inhibitor which is not very toxic for the environment, but also inexpensive and easy to produce.

It has now surprisingly been found that compositions comprising mixtures of specific polymers make it possible to satisfy the abovementioned objectives and in particular to behave as kinetic anti-hydrates with relatively long induction times, and in particular longer than those observed with the known kinetic anti-hydrates of the prior art, and this for relatively important sub-coolings. These polymer compositions are also environmentally friendly and easy to prepare with reasonable production costs.

Other objectives, features, aspects and advantages of the invention will emerge even more clearly on reading the description and examples which follow. In what follows, and unless otherwise indicated, the boundaries of a domain of values are included in this field, especially in the expressions "between ... and ..." and "ranging from ... to .. . "

Thus, and according to a first aspect, the present invention relates to a composition comprising:

a) at least one polymer whose repeating unit comprises at least one amide function, b) at least one polyetheramine of molecular weight in weight (Mw) greater than

100 g. mol ^"1 , preferably greater than 200 g. mol ^{" 1} and having at least two secondary and / or tertiary amine functions, and

c) optionally, but preferably, at least one organic solvent.

The polymer whose repeating unit comprises at least one amide function is a polymer whose amide functions are connected to the polymer chain. The nitrogen atoms of the amide functions may be substituted, and are preferably substituted, more preferably mono-substituted, more preferably disubstituted. When the Nitrogen atoms of the pendant amide functions are disubstituted, the two substituents can form a ring so as to form a lactam with the amide chain.

The substituents of the nitrogen atoms of the pendant amide functions may also comprise one or more nitrogen atom (s), preferably a nitrogen atom. This or these nitrogen atom (s) which substitute the nitrogen atoms of the pendant amide functions may also have reacted with one or more alkylating agent (s), so as to form an ammonium cation, the anion which can be chosen from all the anions known to those skilled in the art, and in particular from halides (for example chloride, bromide), sulphonates (for example methanesulfonate, para-toluenesulfonate), sulphates (for example methyl sulfate, ethyl sulfate), carbonates (eg methyl carbonate), and others.

In the composition according to the present invention, the polymer whose repeating unit comprises at least one amide function is preferably a polymer obtained by polymerization of one or more monomers chosen from (meth) acrylamides substituted or not, the monomers vinyl with lactam groups, in particular vinylpyrrolidones, vinylcaprolactams.

More particularly from the abovementioned monomers, non-limiting examples are vinylpyrrolidone (VP), vinylcaprolactam (VCap), acrylamide, methacrylamide, N-alkylacrylamide, N-alkylmethacrylamide and Ν, Ν-dialkylacrylamide. N, N-dialkylmethacrylamide, Ν, Ν-dialkylaminoalkylacrylamide, N, N-dialkylaminoalkylmethacrylamide and their quaternary alkylammonium salts (halides, sulfonates, sulfates, carbonates and the like).

The polymer whose repeating unit comprises at least one amide function may of course be a homopolymer, a co-polymer or a terpolymer. The term "co-polymer" in this invention means a polymer resulting from the polymerization of two different monomers. Similarly, the term "terpolymer" in the present invention is understood to mean a polymer resulting from the polymerization of three different monomers.

The co-polymers and ter-polymers that may be used in the context of the present invention may be co-polymers, and terpolymers, blocks or grafts, random, periodic or random, preferably of low molecular weight. . By low molecular weight is meant a mass of between 1000 and 5000 atomic mass units (uma) and preferably between 1500 and 4000 uma.

The monomers that can be used to form the co-polymers and other ter-polymers explained above can be of any type and are advantageously chosen from functionalized and vinyl-unsaturated monomers, such as, for example, and, but not limited to, those selected from acrylic acid, substituted alkyl acrylates, Ν, Ν-dialkylaminoalkyl acrylates and their corresponding quaternary alkyl chlorides, hydroxyalkyl acrylates, methacrylic acid, substituted alkyl methacrylates, Ν, Ν-dialkylaminoalkyl methacrylates and their corresponding quaternary alkyl chlorides, hydroxyalkyl methacrylates, and the like, as well as mixtures of two or more of them in all proportions.

In the present description, the term "alkyl" or "alkyl" represents, unless otherwise indicated, a saturated hydrocarbon radical, linear or branched having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, more preferably from 1 to 4 carbon atoms.

Still other monomers may enter into the formation of the abovementioned co-polymers and ter-polymers, and among these may be mentioned, without being limiting, the monomers containing at least one hydroxyl function and / or at least one a functional group convertible to hydroxyl function. Such monomers are in particular described in detail in WO20101 17660. Among these monomers, mention may be made especially of vinyl acetate.

According to a preferred embodiment of the present invention, the monomers used for the preparation of the polymer whose repeating unit comprises at least one amide function (polymer a) of the composition of the present invention) are chosen from the monomers of vinylcaprolactam type (VCap) and vinylpyrrolidone type (VP).

By copolymers and ter-polymers resulting from the copolymerization of at least one vinyl monomer containing amide groups and / or cyclic amides (lactams) with a monomer containing a hydroxyl function and / or a functional group convertible to the hydroxyl function, refers to the copolymers resulting, for example, from the polymerization of the monomers of the vinylpyrrolidone (VP), vinylcaprolactam (VCap) and acrylamide type with monomers containing a hydroxyl function and / or a functional group convertible to the hydroxyl function and in particular the monomers thus described in detail in WO20101 17660.

Preferably, the copolymers of this type according to the invention are obtained by polymerization of vinylcaprolactams (VCap) and / or vinylpyrrolidones (VP) with vinyl acetate and more preferably by polymerization of vinylcaprolactams (VCap) with vinyl acetate. These polymers are known and commercially available or easily prepared from procedures known and described in the scientific literature, on the internet, in patent applications, and for example in the aforementioned document WO20101 17660. According to a preferred embodiment, when the vinyl-caprolactam type monomer (VCap) is polymerized in the presence of a vinylpyrrolidone (VP) type monomer, the VCapA / P mass ratio is between 95/5 and 50. / 50, preferably between 75/25 and 50/50 and even more preferably between 60/40 and 50/50.

According to a very particularly preferred aspect, the polymer a) of the composition of the present invention is a polyvinylcaprolactam / polyvinylpyrrolidone copolymer (1/1) (in mol), such as for example the product sold by BASF under the Luvicap 55W ^{® name} .

In another preferred aspect of this invention, the copolymer a) of the composition according to the present invention is a VCap / VOH polymer obtained by polymerization of N-vinyl-2-caprolactam and vinyl acetate in a suitable solvent. known to those skilled in the art (butylglycol for example) followed by hydrolysis of the polymer in an alkaline medium. The mass ratio VCap / VOH in the final polymer is between 50/50 and 95/5, preferably between 60/40 and 85/15 and even more preferably between 65/35 and 75/25. Among the copolymers of interest for this invention, mention may be made of the product sold by Ashland Inc. under the trade name Inhibex BIO 800.

The total amount of the copolymer or copolymers a) present in the composition of the invention is preferably between 1% and 50% by weight, more preferably between 5% and 40% by weight, and better still between 10% and 50% by weight. % and 30% by weight, relative to the total weight of the composition.

As for the polyetheramine b) of the composition of the present invention, it advantageously has at least two secondary and / or tertiary amine functions. Preferably, this polyetheramine has two terminal amine functional groups, the two functions being secondary or tertiary amine functions, it is most preferably the two terminal amine functions are both secondary amine functions.

According to a preferred aspect the polyetheramine b) of the composition according to the invention has a molecular weight (Mw) greater than 100 g. mol ^"1 , more preferably greater than 200 g mol ^-1 .

This polyetheramine b) may for example be represented by formula (I) below:

in which,

R 1 and R 2, which are identical or different, represent a saturated or unsaturated, linear or branched hydrocarbon-based chain containing from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 1 to 6 carbon atoms; , and quite preferably R 1 and R 2, which are identical or different, represent a saturated linear or branched hydrocarbon chain containing from 3 to 6 carbon atoms, inclusive limits,

R3 represents the hydrogen atom, the methyl radical or the ethyl radical, and

• n represents an integer between 1 and 50 inclusive.

When n is strictly greater than 1, it should be understood that the radicals R3 may be identical or different, so that the polyetheramine of formula (I) may comprise alternating sequences, in blocks or random, of ethylene chains. oxy, propyleneoxy and / or butyleneoxy, preferably ethyleneoxy and / or propyleneoxy chains.

According to a preferred embodiment, the polyetheramine b) present in the composition according to the present invention corresponds to the formula (I) in which R 1, R 2 and R 3 are as defined above and n represents an integer between 1 and 40, preferably between 1 and 30, more preferably between 1 and 20, most preferably between 1 and 10 inclusive, and typically between 4 and 8 inclusive.

[0052] Representative examples of such polyether amines are for example those marketed by Huntsman under the generic name Jeffamine ^®, and described for example in the document available on the website of Huntsman to http: // www .huntsman.com / portal / page / portal / performance products / Media% 20Library / globai / files / jeffamine polyetheramines.pdf.

Among the secondary diamines that can be used quite appropriately in the composition according to the present invention, there may be mentioned the polyetheramine sold by Huntsman under the name Jeffamine ^® SD401 or Jeffamine ^® SD2001.

The total amount of the polyetheramine (s) present (s) in the composition of the invention is generally between 0.5% and 40% by weight, preferably between 1% and 30% by weight. and more preferably between 5% and 20% by weight, relative to the total weight of the composition.

The composition according to the present invention may optionally comprise one or more organic solvents. The organic solvents that can be used are advantageously chosen from alkyl alcohols containing from 1 to 4 carbon atoms. carbon, glycol ethers and their mixtures. In a preferred aspect, the organic solvent used is a glycol or a glycol mixture, and most preferably the organic solvent is butyl glycol.

The total amount of organic solvent (s) present in the composition of the invention is generally between 30% and 90%, preferably between 50% and 90%, and more preferably between 60% and 90%. % and 85% by weight, relative to the total weight of the composition.

The composition according to the present invention can be easily prepared for example by mixing the various components, according to any means well known to those skilled in the art, in any order, according to the compatibilities and miscibility of the components between them. The compositions can thus be prepared by mixing by means of a stirrer, at ambient temperature and at atmospheric pressure.

It has been quite surprisingly observed that the composition according to the invention allows the formation and / or agglomeration of hydrate crystals to be delayed for several hours or even several days, in particular for subunits. -coolings above 10 ° C. It has further been observed that the composition useful in the context of the present invention often results in a longer induction time than the compositions or products currently available commercially.

A direct consequence is that the composition according to the present invention thus allows to work at lower temperatures than current temperatures while increasing the extraction efficiency and in particular the production yield of oil and / or gas .

It has also been found that this composition is effective at low concentrations, for example at dosages of between 0.1% and 10% by weight, preferably between 0.2% and 7% by weight, preferably still between 0.2% and 5% by weight and better still between 1% and 4% by weight, relative to the total weight of the aqueous phase in a production fluid, and very particularly between 0.2% and 4%, typically between 0.2% and 3%, in particular between 1% and 3% by weight. The composition according to the present invention is also inexpensive, easy to produce and low in toxicity.

Thus, and in another aspect, the present invention relates to a method for retarding or even preventing the formation and / or agglomeration of gas hydrates, comprising a step of adding a composition as defined herein. above in a mixture of composition capable of forming hydrates, as described previously in this text, and in particular in a production fluid comprising an aqueous phase and one or more gases. More specifically, the total content of the aqueous phase, present in the production fluid, is generally between 10% and 90% by weight, relative to the total weight of the production fluid, that is to say relative to the total weight of the fluids (aqueous phase and hydrocarbons). However, the treatment of fluid with a very high content in aqueous phase or containing less than 10% of aqueous phase, or even less than 1% of aqueous phase would not be outside the scope of the invention.

The total content of the aqueous phase defined above corresponds to the total proportion of aqueous phase initially present in the production fluid, that is to say in the initial mixture (aqueous phase and other extraction liquids). crude oils such as hydrocarbons, condensates, ...).

The aqueous phase of the production fluid further comprises one or more dissolved gases capable of forming gas hydrates with water at a given temperature and pressure. Some of the gases present in the aqueous phase of the production fluid are so-called "guest" gases, as defined above, and generally comprise methane, ethane, propane, butane, carbon dioxide, hydrogen sulphide, and their mixtures.

The composition according to the invention is added in an amount of between 0.1% and 10% by weight, preferably between 0.2% and 7% by weight, more preferably between 0.2% and 5% by weight. and more preferably between 1% and 4% by weight, relative to the total weight of the aqueous phase in a production fluid, and more particularly between 0.2% and 4%, typically between 0.2% and 3%, in especially between 1% and 3% by weight.

The composition may be introduced into the production fluid continuously, discontinuously, regularly or not, or temporarily, in one or more times. The introduction of the composition is generally carried out upstream of the zone at risk of presence of hydrates, whether on the surface, at the wellhead or downhole.

According to another embodiment of the method of the invention, the fluid treated with the composition according to the invention is a drilling mud or a completion fluid. In this embodiment, the composition is introduced into the drilling mud or into the completion fluid, before or during the injection of the drilling mud or the completion fluid.

Finally, the present invention also relates to the use of a composition as defined above for retarding or even preventing the formation and / or agglomeration of hydrates, and preferably in a process of extraction of oil and / or gas and / or condensates. The invention will be better understood in light of the following examples, given for purposes of illustration only and not intended to restrict the scope of the invention, defined by the appended claims.

EXAMPLES

Example 1

The kinetic efficiency of various anti-hydrate compositions was tested on a mixture comprising:

a gaseous phase consisting of 98% (molar) of methane and 2% (molar) of propane; and

an aqueous phase comprising a solution of NaCl at 1 μL ^-1 .

The tests were carried out at a pressure of 135 bar (13.5 MPa) pressure value which is characteristic of the operating conditions where there is a risk of hydrate formation. The equilibrium temperature of this mixture at 135 bar (13.5 MPa) is about 19.5 ° C. In other words, at 135 bars (13.5 MPa), the gas hydrates form when the temperature becomes lower than or equal to 19.5 ° C.

The tests are carried out in a mechanically stirred cell and temperature controlled by a double jacket. The cell is cylindrical in shape with an internal volume of approximately 292.6 cm ³ (149 mm high and 50 mm in diameter). It is made of steel resistant to 200 bar (20 MPa) and protected by valve. The operating pressure is provided by a Haskel AG-30 gas booster. The cell is instrumented to be able to follow continuously the internal pressure, the stirring torque and the temperature.

In order to carry out the evaluations of the different products, it is first introduced into the cell, under suction vacuum 250 cm ³ of aqueous phase containing the additive to be evaluated, or without additive (reference). After equilibration of the temperature at 19.5 ° C., the gaseous mixture is charged with stirring into the cell until a stable pressure of 135 bar (13.5 MPa) is obtained.

The assembly is then heated and maintained at 30 ° C for 24 hours to erase the thermal history of the mixture and then lowered at a rate of 0.2 ° C / min to the temperature corresponding to the sub-cooling target (here 9.5 ° C and 4.5 ° C for respective sub-cooling of 10 ° C and 15 ° C).

The kinetic efficiency of the anti-hydrate compositions is measured at different sub-cooling (10 ° C and 15 ° C) but also at different dosages. The dosage corresponds here to the amount (weight) of anti-hydrate composition introduced into the aqueous phase relative to the weight of the water. The kinetic performance of the anti-hydrate compositions is determined by measuring the delay time in the formation of hydrate crystals. This time, also called induction time, is expressed in hours or days. In other words, the longer the induction time, the better the anti-hydrate.

Here, this time is measured from the moment when the temperature in the cell reaches the target temperature of the test corresponding to the sub-cooling studied (9.5 ° C. and 4.5 ° C. for sub-cooling). 10 and 15 ° C) and the pressure in the cell is stabilized. The end point for measuring the induction time corresponds to the beginning of hydrate formation. It is marked on the pressure curve as a function of time by the point where the pressure begins to fall in the cell (pressure drop corresponding to the gas consumption to form solid hydrates) and confirmed by an increase in the torque of the agitator (viscosification of the solid loading medium) and possibly a very slight exothermic peak on the temperature curve.

The composition A according to the invention and the comparative compositions B, C, D and E (according to the teaching of patent US6180699) were prepared by mixing the various components whose amounts are expressed in Table 1 below.

Unless otherwise indicated, all amounts are given as a percentage by weight relative to the total weight of the composition.

- Table 1 -

^(a) Vinylpyrrolidone (VP) / Vinylcaprolactam copolymer (Vcap) 1: 1 sold by the company BASF

^(b) polyvinylcaprolactam homopolymer (VCap) sold by the company BASF

^(c) polyalkoxydiamine (primary diamine) marketed by Hunstman

^(d) polyalkoxydiamine (secondary diamine) marketed by Hunstman

The kinetic efficiency of the anti-hydrate compositions, for a sub-cooling of 10 ° C., is evaluated for respective dosages of 1% and 3% by weight for each of the compositions A (invention), B, C, D and E (comparative). Each of the compositions to be tested is introduced into the aqueous phase and the experiment is conducted as described above. The kinetic performance of these compositions, characterized by the induction time, was measured twice, and the average of these measurements is expressed in Table 2 below.

- Table 2 -

Results for a sub-cooling of 10 ° C

The above results show that, for a sub-cooling of 10 ° C, the compositions of the present invention are more efficient than the comparative compositions. Indeed, in the composition according to the present invention or when the vinylcaprolactam / vinylpyrrolidone copolymer is mixed with a secondary diamine (composition A), it takes 105 hours to see the appearance of gas hydrates (for a dosage of 1% by weight) and 120 hours (for a dosage of 3% by weight).

By way of comparison, the composition C comprising only the solvent and the same secondary diamine only delays by 10 hours the appearance of the hydrates, for a dosage of 1% by weight, and 15 hours for a dosage of 3% by weight. Composition B comprising only the solvent and the same copolymer only allows their formation to be delayed by 86 hours (for a dosage of 1% by weight) and 90 hours (for a dosage of 3% by weight).

These results also show that the composition according to the present invention (composition A) is much more efficient than the known compositions of the prior art, for example the composition E according to US6180699, which does not delay the formation of hydrate. than 50 hours (for a dosage of 1% by weight) and 60 hours (for a dosage of 3% by weight).

The same tests are then performed for a larger sub-cooling, now 15 ° C. Each of compositions A (invention) and B, C, D and E (comparative) is evaluated, according to the protocol described above, at the doses of 1% and 3% by weight of each of compositions A (invention), and B, C, D and E (comparative).

The kinetic performance of these compositions was measured twice, and the average of these measurements is expressed in the table below. - Table 3 -

Results for a sub-cooling of 15 ° C

These results lead to quite similar conclusions. At a dosage of 1% by weight, comparative composition D delays the formation of gas hydrates by only 8 hours, while the composition according to the invention (composition A) delays this formation by 26 hours.

Furthermore, the vinylcaprolactam / vinylpyrrolidone copolymer alone (composition B), as well as the secondary diamine alone (composition C), are poor kinetic anti-hydrates with strong sub-cooling, since they found that they do not delay. little or no hydrate formation in these temperature conditions.

Finally, with a dosage of 3% by weight of composition A, the formation of gas hydrates is delayed by 90 hours, for a sub-cooling of 15 ° C.

It is thus clearly established an advantage over the prior art, in that the composition according to the present invention results in a longer induction time for larger sub-coolings (15 ° C) than observed with the compositions of the prior art. It is thus possible to work at lower temperatures than current temperatures while increasing the production yield of oil and / or gas.

EXAMPLE 2

Is carried out, according to the same protocol as that defined in Example 1, a study of the kinetic efficiency of different anti-hydrate compositions.

The kinetic efficiency of the anti-hydrate compositions is measured at different sub-cooling (10 ° C. and 11 ° C.). The dosage corresponds here to the amount (weight) of the antihydrate composition introduced into the aqueous phase relative to the weight of the water.

As indicated in Example 1, the induction time is measured from the moment when the temperature in the cell reaches the temperature of 9.5 ° C. for a sub-cooling of 10 ° C. and the pressure in the cell is stabilized. In the absence of training after a certain time, the test is continued by lowering the temperature in the cell to reach 8.5 ° C for a sub-cooling of 1 1 ° C. Once the pressure in the cell stabilized at 8.5 ° C, the induction time at 8.5 ° C is measured. The end point for measuring the induction time corresponds to the beginning of hydrate formation. It is marked on the pressure curve as a function of time by the point where the pressure begins to fall in the cell (pressure drop corresponding to the gas consumption to form solid hydrates) and confirmed by an increase in the torque of the agitator (viscosification of the solid loading medium) and possibly a very slight exothermic peak on the temperature curve.

The composition F according to the invention was prepared by mixing the various components whose amounts are expressed in Table 4 below.

Unless otherwise indicated, all amounts are given in percent by weight relative to the total weight of the composition.

- Table 4 -

^(b) polyalkoxydiamine (secondary diamine) marketed by Hunstman

The kinetic efficiency of the composition F for a sub-cooling of 10 ° C and 1 1 ° C, is evaluated for a dosage of 1% by weight. The test composition is introduced into the aqueous phase and the experiment is conducted as described above.

The kinetic performance of these compositions, characterized by the induction time, was measured twice, and the average of these measurements is expressed in Table 5 below.

- Table 5 -

Results for a sub-cooling of 10 ° C

The above results show that, for a sub-cooling of 10 ° C, the composition of the present invention is more efficient than the comparative composition B which is eliminated for the sub-cooling of 10 ° C. Indeed, in the composition according to the present When the vinylcaprolactam / vinylpyrrolidone copolymer is in a mixture with a secondary diamine (composition F), it was not possible in 106 hours to see the appearance of gas hydrates (for a dosage of 1% by weight).

The test with the composition F was continued for a greater sub-cooling, now 1 1 ° C, according to the protocol described above, at a dose of 1% by weight.

The kinetic performance of this composition was measured twice, and the average of these measurements is expressed in Table 6 below.

- Table 6 -

Result for a sub-cooling of 1 1 ° C

It is thus clearly established an advantage over the prior art, in that the composition according to the present invention makes it possible to work at temperatures lower than the current temperatures and corresponding to sub-cooling values encountered during from production.

EXAMPLE 3

The objective of the thermal stability injection test is to determine whether the anti-hydrate composition can be injected into the line transporting the water / gas / condensate fluids, when they are still hot, without causing deposition or clogging. The test consists of two parts. The anti-hydrate composition F is stored in a closed bottle in a climatic chamber for 24 hours at 90 ° C. without noting the slightest change in appearance. An aqueous solution of 30 g of sodium chloride (NaCl) per liter is prepared and heated to 90 ° C on a hot plate. In a few seconds, the composition F is injected with a syringe into the aqueous solution so as to have a concentration of 1% by weight. We do not note the appearance of any deposit or gel or suspension for 1 hour.

EXAMPLE 4

The objective of the emulsion test is to determine whether the anti-hydrate composition can be injected into the line transporting the water / gas / condensate fluids, without causing problems in the downstream installations related to the presence of emulsion. stable. In a flask, at room temperature, an aqueous solution of 30 g of NaCl per liter and of white spirit in equal proportion is poured. This operation is repeated in two other bottles. The mixtures are completed by the addition of 2% by weight of formulation A or F respectively for the second and third vials. The three flasks are shaken vigorously until a visually homogeneous emulsion is obtained.

The vials are observed after 19 seconds, 43 seconds and 1 minute and 2 seconds. In the bottle containing no anti-hydrate, the emulsion has almost completely disappeared as early as 19 seconds. In the vial containing composition A and the vial containing composition F, the emulsion is still stable at 43 seconds. At 1 minute and 2 seconds, no emulsion is stable, there is a separation of the two phases. These durations during which the emulsions are stable are perfectly acceptable for this use.

EXAMPLE 5

The purpose of the dehydration test is to determine whether the antihydrate composition can be separated from the water which contains it, by evaporation of the water. Indeed, it may be useful to separate the anti-hydrate additive, once the fluids are out of the thermally favorable zone hydrates, before rejecting the water produced during the exploitation of the field, so as to limit the environmental impact or on the rock receiving the produced water.

[0106] was prepared 200 ml of a 0.5% aqueous solution by weight of formulation F and 1 gL ^"1 NaCl. The solution is placed in a container in narrow and wide glass, so as to have a large area contact between the solution and the glass The open container is placed in an oven at 130 ° C until there is only 2 mL of liquid left, no deposit on the walls excepted a few spots containing crystals of NaCl and resulting from the evaporation of a few drops of water sprayed on the walls during filling.Also the aqueous solution remains clear.Thus the antihydrate composition F can be separated from the water without risking deposit in the facilities.

Claims

1. Composition comprising:

a) at least one polymer whose repeating unit comprises at least one amide function, b) at least one polyetheramine of molecular weight (Mw) greater than 100 g. mol ^"1 , preferably greater than 200 g. mol ^{" 1} and having at least two secondary and / or tertiary amine functions, and

c) optionally, but preferably, at least one organic solvent.

2. Composition according to claim 1, wherein the polymer whose repeating unit comprises at least one amide function is a polymer obtained by polymerization of one or more monomers chosen from (meth) acrylamides substituted or unsubstituted, vinyl monomers groupings lactams.

3. Composition according to claim 1 or claim 2, wherein the polymer whose repeating unit comprises at least one amide function is a polymer obtained by polymerization of one or more monomers chosen from vinyipyrrolidone (VP), vinylcaprolactam (VCap ), acrylamide, methacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, Ν, Ν-dialkylacrylamide, Ν, Ν-dialkylmethacrylamide, Ν, Ν-dialkylaminoalkylacrylamide, Ν, Ν-dialkylaminoalkylmethacrylamide, as well as their quaternary alkylammonium salts (halides, sulfonates, sulfates, carbonates and the like).

4. Composition according to claim 1 or claim 2, wherein the polymer whose repeating unit comprises at least one amide function is a polymer obtained by polymerization of vinylcaprolactam type monomers (VCap) and vinyipyrrolidone type (VP).

5. Composition according to any one of the preceding claims, in which the total amount of the copolymer or copolymers a) is between 1% and 50% by weight, preferably between 5% and 40% by weight, and more preferably between 10%. and 30% by weight, relative to the total weight of the composition.

6. Composition according to any one of the preceding claims, in which the polyetheramine b) has at least two secondary and / or tertiary amine functional groups, preferably two terminal, secondary or tertiary amine functional groups, most preferably two functions. secondary terminal amines.

A composition according to any one of the preceding claims wherein polyetheramine b) is represented by formula (I) below:

in which,

R3 represents the hydrogen atom, the methyl radical or the ethyl radical, and

• n represents an integer between 1 and 50 inclusive.

8. Composition according to any one of the preceding claims, in which the total amount of the polyetheramine (s) is between 0.5% and 40% by weight, preferably between 1% and 30% by weight, and more preferably between 5% and 20% by weight, relative to the total weight of the composition.

9. Composition according to any one of the preceding claims, in which the at least one organic solvent is chosen from alkyl alcohols having 1 to 4 carbon atoms, glycol ethers and mixtures thereof, preferably the organic solvent used is a glycol or a mixture of glycol, and very particularly preferably, the organic solvent is butylglycol.

Process for retarding, or preventing, the formation and / or agglomeration of gas hydrates, comprising a step of adding a composition as defined in one of any of claims 1 to 9 in a composition mixture capable of forming hydrates.

11. Process according to claim 10, in which the composition according to the invention is added in an amount of between 0.1% and 10% by weight, preferably between 0.2% and 7% by weight, more preferably between 0% and 10% by weight. 2% and 5% by weight and more preferably between 1% and 4% by weight, relative to the total weight of the aqueous phase in a production fluid, and especially between 0.2% and 4%, typically between 0, 2% and 3%, in particular between 1% and 3% by weight.

12. The method of claim 10 or claim 1 1, wherein the composition is introduced into the production fluid continuously, discontinuously, regularly or not, or temporarily, in one or more times.

13. The method of claim 10 or claim 1 1, wherein the fluid treated with the composition according to the invention is a drilling mud or a completion fluid.

14. Use of a composition according to any one of claims 1 to 9 for retarding or preventing the formation and / or agglomeration of hydrates, and preferably in a process for extracting oil and / or gas and / or condensates.