USE OF ESTERAMINE TO INHIBIT THE AGGLOMERATION OF GAS HYDRATES

Abstract

A process is described for inhibiting and/or delaying and/or preventing the agglomeration of gas hydrates, comprising adding one or more compounds of formula (1) or salts thereof:

##STR00001##

wherein RR, OQ, Ra, R.sub.1, R.sub.2, SS, X.sup.−, t, x and y are defined in the specification and for the use of said compounds for formula (1) for inhibiting and/or delaying and/or preventing the agglomeration of gas hydrates.

Claims

1. A process for limiting or preventing the formation and/or agglomeration of gas hydrates, comprising adding one or more compounds of formula (1) or salts thereof to a production fluid comprising an aqueous phase and one or more gases: ##STR00005## wherein: RR represents —C(═O)-G′, SS is chosen from G″ and —(OQ)-G″, QO represents an alkyleneoxy group containing from 2 to 4 carbon atoms, where all the QO groups present in the compound of formula (1) may be identical or different, Ra is chosen from the group consisting of a direct bond, a cycloalkylene, cycloalkenylene or arylene group and a saturated or unsaturated, linear or branched C.sub.1-C.sub.20 hydrocarbon chain optionally substituted by one or more —OH groups, R.sub.1 is chosen from a C.sub.1-C.sub.6 hydrocarbon radical, R.sub.2 is chosen from an R.sup.7 radical or an R.sup.10-(G).sub.u- radical, R.sup.7 is chosen from a hydrocarbon radical having 1 to 7 and a group of formula (2): ##STR00006## wherein R.sup.8 and R.sup.9, which are identical or different, are chosen from a hydrocarbon radical comprising from 1 to 6 carbon atoms, limits included, or else R.sup.8 and R.sup.9, together with the nitrogen atom to which they are bonded, form a cycle with 5, 6 or 7 vertices, optionally comprising one or more heteroatoms chosen from oxygen, nitrogen and sulfur, R.sup.10 is chosen from a hydrocarbon radical comprising from 1 to 24 carbon atoms, limits included, and a radical of formula R.sup.4—O-(QO).sub.w-T-, wherein QO is as defined above, R.sup.4 is chosen from hydrogen and a hydrocarbon radical comprising from 1 to 24 carbon atoms, limits included, where w represents an integer in the range of from 0 to 20, limits included, and T represents an alkylene group comprising from 1 to 6 carbon atoms, limits included, G represents a group of formula (3): ##STR00007## X.sup.− is chosen from halides, sulfates, carbonates, G′ is chosen from a saturated or unsaturated, linear or branched, hydrocarbon radical comprising from 6 to 30 carbon atoms, and an —Ra—C(═O)—SS radical, Ra and SS being as defined above, G″ is chosen from the —OH radical, an —OR radical, an —N.sup.(+)tR.sub.3R.sub.4(R.sub.1).sub.t radical, an —NH—C(═O)—R radical and an —NH—C(═O)—OR radical, R.sub.1 and R.sub.4 being as defined previously and where R.sub.3 is chosen from a linear or branched hydrocarbon radical comprising from 1 to 24 carbon atoms, limits included, an HO(CH.sub.2).sub.q— radical, and an H(OQ).sub.j- radical, a —(C═O)-G′ radical and a —(OQ).sub.x-(C═O)-G′ radical, R is a linear or branched hydrocarbon radical, limits included, j represents an integer between 1 and 20, limits included, q is an integer from 1 to 10, r represents an integer in the range from 1 to 15, s represents an integer between 1 and 5, limits included, t is chosen from 0 and 1, u is an integer from 0 to 5, x represents an integer between 1 and 20, limits included, y represents an integer between 1 and 20, limits included, wherein if more than one of the same variable is present in the compound of formula (1), the variable can be identical or different, independently of one another.

2. The process according to claim 1, wherein for the compounds of formula (1): G′ is chosen from an —Ra—C(═O)—OH radical, an —Ra—C(═O)—OR radical, and an —Ra—C(═O)—SS radical, Ra represents an alkylene radical of formula —(CH.sub.2).sub.z—, in which z is an integer from 1 to 20, t is equal to 0, u is equal to 0, j represents an integer between 1 and 6, limits included, x represents an integer between 1 and 6, limits included, y represents an integer between 1 and 6, limits included, wherein if more than one of the same variable is present in the compound of formula (1), the variable can be identical or different, independently of one another, the other variables being as defined in claim 1.

3. The process according to claim 1, wherein for the compounds of formula (1): RR represents —C—(═O)-G′, SS represents —(OQ)-G″, where G″ is an —N.sup.(+)tR.sub.3R.sub.4(R.sub.1).sub.t radical, G′ is chosen from a saturated or unsaturated, linear or branched, hydrocarbon radical comprising from 6 to 30 carbon atoms, R.sub.3 is an —(OQ).sub.x-C(═O)-G′ radical, OQ represents an alkyleneoxy group containing 2 or 3 carbon atoms, Ra is an alkylene radical of formula —(CH.sub.2).sub.z—, in which z is an integer from 1 to 10, R.sub.2 is an HO—(CH.sub.2).sub.q— radical, q is an integer from 2 to 6, limits included, R.sub.1 is chosen from a C.sub.1-C.sub.6 hydrocarbon radical, j represents an integer between 1 and 20, limits included, t is chosen from 0 or 1, x represents an integer between 1 and 20, limits included, y represents an integer between 1 and 20, limits included, wherein if more than one of the same variable is present in the compound of formula (1), the variable can be identical or different, independently of one another, the other variables being as defined in claim 1.

4. The process according to claim 1, wherein for the compounds of formula (1): RR represents —C—(═O)-G′ where G′ is an —Ra—C(═O)—SS radical, Ra is an alkylene radical of formula —(CH.sub.2).sub.z—, in which z is an integer from 1 to 10, SS represents —(OQ)-G″ with G″ being chosen from an —NH—C(═O)—R radical and an —NH—C(═O)—OR radical, R is a linear or branched hydrocarbon radical, limits included, j represents an integer between 1 and 20, limits included, t is chosen from 0 or 1, x represents an integer between 1 and 20, limits included, y represents an integer between 1 and 20, limits included, wherein if more than one of the same variable is present in the compound of formula (1), the variable can be identical or different, independently of one another, the other variables being as defined in claim 1.

5. The process according to claim 1, wherein the compound of formula (1) is present in an amount ranging from 0.1% to 10% by weight, relative to the total weight of the aqueous phase in a production fluid.

6. The process according to a claim 1, employing at least one compound of formula (1) in a carrier liquid.

7. The process according to a claim 1, employing at least one compound of formula (1) in a carrier liquid with low water miscibility.

8. The process according to claim 1, employing at least one compound of formula (1) in a carrier liquid, said carrier liquid comprising at least one alcohol comprising one (1) or more hydroxyl groups on a linear, branched or cyclic, saturated or unsaturated hydrocarbon chain, said hydrocarbon chain generally comprising from 1 to 30 carbon atoms.

9. The process according to a claim 1, employing at least one compound of formula (1) in a carrier liquid added to the production fluid in a proportion to make it possible to obtain a water fraction of 90% or less, expressed by volume of aqueous phase relative to the total volume of liquid.

10. (canceled)

11. The process according to claim 1, comprising a step of adding one or more compounds of formula (1), as defined in, in combination with one or more other additives, fillers, solvents.

12. The process according to claim 1, comprising a step of adding one or more compounds of formula (1) in combination with one or more other additives chosen from corrosion inhibitors, kinetic hydrate inhibitors, mineral deposit inhibitors, demulsifiers, deoilers, defoaming additives, paraffin inhibitors and dispersants, asphaltene inhibitors and dispersants, hydrogen sulfide scavengers, drag or friction reducers, aromas, dyes, preservatives, and optionally others.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0099] Within the meaning of the present invention, the miscibility is measured at ambient temperature and at ambient pressure by measuring the concentration of the species in question in water when the two phases are in contact at equilibriumt, by means of various assay methods such as for example gravimetric analysis, titrimetry, spectrophotometry, chromatography.

[0100] According to another preferred embodiment of the present invention, the carrier liquid comprises at least one alcohol comprising one (1) or more hydroxyl groups on a linear, branched or cyclic, saturated or unsaturated hydrocarbon chain. The hydrocarbon chain generally contains from 1 to 30 carbon atoms, preferably from 3 to 26 carbon atoms, more preferably from 5 to 22 carbon atoms, more preferably from 6 to 12 carbon atoms. The hydroxyl group(s) may be in the terminal position(s) and/or on all the other carbons of the hydrocarbon chain, that is to say that the hydroxyl functions may be, independently of one another, other primary, secondary or tertiary hydroxyl functions.

[0101] According to a preferred embodiment, the carrier liquid comprises at least one alcohol chosen from alcohols comprising from 1 to 3 hydroxyl functions and from 6 to 12 carbon atoms. According to another preferred embodiment, the carrier liquid comprises at least one alcohol of empirical formula C.sub.8H.sub.18O.

[0102] According to a very particularly preferred embodiment, the carrier liquid comprises at least one alcohol chosen from octan-1-ol, octan-2-ol, octan-3-ol, octan-4-ol, 2-methylheptan-1-ol, 2-methylheptan-4-ol, 5-methylheptan-1-ol, 5-methylheptan-2-ol, 4-methylheptan-2-ol, 4-methylheptan-4-ol, 2-methylheptan-4-ol, 2-ethylhexan-1-ol, 4-ethylhexan-1-ol, 3-ethylhexan-2-ol, 3-ethylhexan-3-ol, 4-ethylhexan-2-ol, 2-ethyl-2-methylpentan-1-ol, 2-ethyl-3-methylpentan-1-ol, 2-ethyl-4-methylpentan-1-ol, 2-ethyl-3-methylpentan-1-ol, 3-ethyl-2-methylpentan-1-ol, 3-ethyl-2-methylpentan-2-ol, 3-ethyl-4-methylpentan-2-ol, 3-ethyl-2-methylpentan-3-ol, 2-propylpentan-1-ol, 2,2-dimethylhexan-1-ol, 2,4-dimethylhexan-2-ol, 2,5-dimethylhexan-1-ol, 3,4-dimethylhexan-2-ol, 3,5-dimethylhexan-2-ol, 4,4-dimethylhexan-2-ol, 4,5-dimethylhexan-2-ol, 4,5-dimethylhexan-3-ol, 5,5-dimethylhexan-1-ol, 5,5-dimethylhexan-3-ol, 6-methylheptan-2-ol, 2-methylheptan-3-ol, 2,3-dimethylheptan-2-ol, 2,3-dimethylhexan-3-ol, 5,5-dimethylhexan-2-ol, 3-methylheptan-2-ol, 4-methylheptan-3-ol, 2,4-dimethylhexan-3-ol, 2,5-dimethylhexan-2-ol, 3,4-dimethylhexan-3-ol, 3,5-dimethylhexan-3-ol, 4-methylheptan-1-ol, 2-methylheptan-2-ol, 3-methylheptan-4-ol, 5-methylheptan-3-ol, 2,2-dimethylhexan-3-ol, 2,5-dimethylhexan-3-ol, 4-ethylhexan-3-ol, 2-ethyl-2,3-dimethylbutan-1-ol, 2,2,3-trimethylpentan-1-ol, 2,2,3-trimethylpentan-3-ol, 2,3,4-trimethylpentan-3-ol, 2,2,4-trimethylpentan-1-ol, 2,4,4-trimethylpentan-1-ol, 3,4,4-trimethylpentan-1-ol, and 3,4,4-trimethylpentan-2-ol.

[0103] More preferably, the carrier liquid comprises at least one alcohol chosen from octan-1-ol, octan-2-ol, octan-3-ol, octan-4-ol, 2-ethylhexan-1-ol, 4-ethylhexan-1-ol, 3-ethylhexan-2-ol, 3-ethylhexan-3-ol, 4-ethylhexan-2-ol, and 2-ethyl-2-methylpentan-1-ol, and very particularly preferably, the liquid carrier comprises at least one alcohol chosen from octan-1-ol, octan-2-ol and 2-ethylhexan-1-ol.

[0104] The carrier liquid may be added to the production fluid in a proportion to make it possible to obtain a water fraction of 90% or less, better still 85% or less, even better still 80% or less, even better still 75% or less, even better still 70% or less, even better still 65% or less, even better still 60% or less, even better still 55% or less, even better still 50% or less, even better still 45% or less, even better still 40% or less, even better still 35% or less, even better still 30% or less, even better still 25% or less, even better still 20% or less, expressed by volume of aqueous phase relative to the total volume of liquid. The carrier liquid is preferably added in a proportion that makes it possible to obtain a water fraction of 50% or less.

[0105] According to one embodiment, the carrier liquid should preferentially not interfere or react with the compound of formula (1) defined previously or with the other additives which may be used in the use according to the present invention, and in particular with the optional corrosion inhibitors, deposit inhibitors or other production chemical additives that can be used.

[0106] In addition to the presence of a carrier liquid during the use of the compound of formula (1) according to the present invention, it may also be advantageous to use jointly, separately or alternately, one or more other additives commonly used in oil and gas production, such as for example corrosion inhibitors, kinetic hydrate inhibitors, mineral deposit inhibitors, demulsifiers, deoilers, defoaming additives, paraffin inhibitors and dispersants, asphaltene inhibitors and dispersants, hydrogen sulfide scavengers, drag or friction reducers, aromas, dyes, preservatives, and others if necessary or if desired.

[0107] In a preferred embodiment, the use of the present invention may also include the use of one or more organic solvents. Preferably, the organic solvent(s) are chosen, without limitation, from C.sub.1 to C.sub.4 alcohols, glycols, glycol ethers, ketones and mixtures thereof, more preferentially from methanol, ethanol, isopropanol, n-butanol, isobutanol, ethylene glycol (or monoethylene glycol), 1,2-propylene glycol, 1,3-propylene glycol, hexylene glycol, butyl glycol, ethylene glycol dibutyl ether, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, N-methylpyrrolidone, cyclohexanone, xylenes, toluene, and mixtures of several glycols, for example ethylene glycol, butyl glycol and others.

[0108] It is also possible, if it is desired or proves necessary, to use jointly, separately or alternately, other agents capable of inhibiting and/or delaying and/or preventing the agglomeration of gas hydrates, such as for example thermodynamic hydrate inhibitors and kinetic hydrate inhibitors. If mixtures of gas hydrate inhibitors are used, these mixtures may be added concomitantly and/or before and/or after the injection of the composition according to the present invention.

[0109] According to another aspect, the present invention relates to a process that makes it possible to limit, or even prevent, the agglomeration and/or the formation of gas hydrates by using at least one compound of formula (1) as described previously, optionally in combination with one or more other additives, fillers, solvents and other components well known to a person skilled in the art, and in particular in combination with a carrier liquid and/or an anti-agglomerant, as defined previously.

[0110] The process of the present invention comprises a step of bringing at least one anti-agglomerant compound of formula (1) as defined previously into contact with production water. When a sufficient amount of anti-agglomerant compound is used, the formation of a gas hydrate plug is inhibited. In the absence of such an amount, the formation of a gas hydrate plug is not inhibited.

[0111] The anti-agglomerant compound of formula (1) may be injected into the production field by being premixed with other additives, as defined above, for example a carrier liquid, and/or independently with one or more other additives. Alternatively, the carrier liquid can be injected into the production field by being premixed with the anti-agglomerant compound of formula (1) or else independently of said anti-agglomerant compound of formula (1).

[0112] The appropriate amount of anti-agglomerant compound of formula (1) necessary for inhibiting the formation of a hydrate plug is determined for each particular system as a function of the temperature, pressure, salt composition of the water, the proportion of water and oil and the composition of the gas. Thus, the anti-agglomerant compound is used in an amount ranging preferably from 0.05% to 15% by weight, more preferentially from 0.1% to 8% by weight and better still from 0.1% to 5% by weight, relative to the total weight of the aqueous phase in the production fluid.

[0113] The process of the present invention makes it possible to inhibit the formation of hydrates irrespective of the nature of the hydrocarbon or of the mixture of hydrocarbons. The process is particularly effective for light gases or gases with a low boiling point, such as hydrocarbon gases having 1 to 5 carbons and mixtures of these gases, under ambient conditions. Non-limiting examples of these gases are methane, ethane, propane, n-butane, iso-butane, iso-pentane and mixtures thereof. The hydrocarbons may also include, for example, other compounds which may, for example, be carbon dioxide (CO.sub.2), hydrogen sulfide (H.sub.2S), dinitrogen (N.sub.2) and the other compounds commonly encountered during oil and gas production.

[0114] The compound of formula (1) may be introduced into the production fluid continuously, discontinuously, regularly or irregularly, or temporarily, in one or more portions. The anti-agglomerant compound of formula (1) is generally introduced upstream of the region at risk of the presence of hydrates, whether at the surface, at the well head or at the well bottom.

[0115] It may be useful or advantageous to also introduce, before, after and/or during the injection of the anti-agglomerant compound of formula (1), one or more injection additives, well known to a person skilled in the art, as indicated previously, and for example, and without limitation, those chosen from refined or unrefined hydrocarbons, such as petrol, diesel, gas oil, kerosene and others.

[0116] The invention will become more clearly apparent by means of the following examples, which are presented solely by way of illustration, without any intention of limiting the scope of the desired protection defined by the appended claims. Throughout the description, examples and claims, all the ranges of values should be understood as being “limits included” (that is to say that the limits are included in said ranges), unless otherwise specified.

[0117] In the examples that follow, all the amounts are indicated as weight percentages relative to the total weight of the composition, unless otherwise indicated.

EXAMPLES

Anti-Agglomeration Test of the Composition According to the Invention

[0118] The comparative composition (A) and the composition according to the invention (B) were prepared from the ingredients, the contents of which are indicated in Table 1 below:

TABLE-US-00001 TABLE 1 Composition A Composition B (comparative) (invention) Noramium ® M2C (1) 30 — Armohib CI-5150 (2) — 30 Butyl glycol (solvent) 70 70 [0119] (1) dicocodimethylammonium chloride, sold by Arkema [0120] (2) methyl-quaternized N-methyl dialkanolamine/oleic acid diacid copolymer sold by Nouryon.

[0121] The effectiveness of the preceding Compositions A and B, as anti-agglomerant, was determined on a model fluid representing a production fluid comprising tetrahydrofuran (THF). THF hydrates form at atmospheric pressure and are regularly used for detecting the effectiveness of compounds that are candidates as gas hydrate anti-agglomerants.

[0122] The model fluid comprises: [0123] 30% by weight of aqueous phase consisting of a mixture of demineralized water and tetrahydrofuran (THF) in a 1:1 volume ratio, and [0124] 70% by weight of iso-octanol.

[0125] The thermodynamic equilibrium temperature for hydrate formation of this model fluid is 2° C. at atmospheric pressure. In other words, the THF hydrates form at temperatures of less than or equal to 2° C.

[0126] 3 groups of 3 test cells each containing 18.7 mL of model fluid are provided. Group 1 represents the reference, added to group 2 is 1% by weight of Composition A, relative to the total weight of aqueous phase in each of the three cells, and added to group 3 is 1% by weight of Composition B, relative to the total weight of aqueous phase, in each of the three cells.

[0127] The anti-agglomerant effectiveness of the hydrate-inhibiting composition is measured at various subcoolings (−12° C. and −22° C.) for a dosage of 1% by weight of anti-agglomerant relative to the weight of the aqueous phase. The formation of hydrates depends mainly on the temperature and the pressure, and also on the composition of the guest gas(es). To be able to compare the performance of the additives, the notion of subcooling value is used. The subcooling (SC) value is thus defined as the difference between the temperature of the produced fluids (or exploitation temperature T) and the thermodynamic equilibrium temperature of formation of the hydrate crystals (Teq) for a given pressure and a given composition of the hydrate-forming gases and of the aqueous phase, according to the following equation: SC=T−Teq. When the subcooling value is less than or equal to 0° C., there is a risk of gas hydrate formation.

[0128] As indicated above, the subcooling value represents the temperature difference between the exploitation, or imposed, temperature and the thermodynamic equilibrium temperature for hydrate formation of the production fluid. In other words, for a subcooling value of −12° C., the imposed temperature must be −10° C. Similarly, for a subcooling value of −22° C., the temperature must be −20° C.

[0129] The experimental device, described especially by M. L. Zanota et al. (“Hydrate Plug Prevention by Quaternary Ammonium Salts”, Energy & Fuel, 19(2), (2005), 584-590), is composed of a motor which imposes an oscillating movement on a rack. The rack contains 12 borosilicate glass tubes having a diameter of 17 mm and a height of 60 mm.

[0130] Each tube is closed and contains the mixture described above and also a 316L stainless-steel ball 0.8 cm in diameter. The ball allows the mixture to be stirred, allows the agglomeration of the hydrate crystals to be observed visually and constitutes a crystallization initiator.

[0131] The rack is immersed in a thermostatic bath, comprising a water/ethylene glycol mixture (1/1), the temperature of which varies between −30° C. and +30° C. by means of a Huber variostat.

[0132] The various samples are subjected to cooling and heating cycles governed by the programmable variostat. The temperature descent rates are defined and programmed. The variostat is equipped with two temperature probes, an internal one and an external one, connected to a computer allowing the temperature to be monitored and recorded.

[0133] The tubes thus prepared are placed in a thermostatic bath at a temperature of +20° C. with stirring. The temperature is then lowered to −10° C. which corresponds to a subcooling of −12° C. At this temperature, the oscillation is maintained for 20 hours (the movement of the balls in the tubes is observed visually) before being stopped. After two hours of stoppage at −10° C., stirring is restarted, and the movement of the balls in the tubes is again observed.

[0134] The temperature is then lowered to −20° C. (again at a rate of −1° C. per minute), which corresponds to a subcooling of −22° C. At this temperature of −20° C., oscillation is maintained for 20 hours before being stopped. After two hours of stoppage at −20° C., stirring is restarted, and the movement of the balls in the tubes is observed visually.

[0135] The effectiveness of the composition is then evaluated visually by observing the movement of the balls in the tubes. If the balls circulate, the product tested is effective. Conversely, if the balls remain blocked, or if hydrate crystals are stuck to the wall of the tube, the product tested is not a good anti-agglomerant. The larger the number of blocked balls, the less effective the product. The results are presented in the Table 2 below:

TABLE-US-00002 TABLE 2 Number of balls blocked Number of balls blocked after 20 hours of stirring after 2 hours of stoppage Subcooling −12° C. −22° C. −12° C. −22° C. Reference without 3/3 3/3 3/3 3/3 anti-agglomerant Anti-agglomerant A 2/3 3/3 3/3 3/3 Anti-agglomerant B 1/3 1/3 1/3 1/3

[0136] The results above show that Composition B, comprising a compound of formula (1) according to the present invention, has good anti-agglomerant properties, of a higher level than composition A comprising a quaternary ammonium compound, quaternary ammoniums being known for their anti-agglomerant properties.